Gel TreatmentUsing Gel is a newer and better method of controlling cockroaches. It has revolutionizedpest control in modern times. You dont have the unpleasant smell of insecticides. You donthave to remove anything from the kitchen. You dont have to close your house and go awayand there is no mess caused by spraying of insecticides, to be cleared.Method of Treatment:Minute amounts of Gel are applied in strategic locations with the help of a syringe.Cockroaches are mostly in the kitchen and pantries and we concentrate on these areas,although the Gel is applied in the toilet and the entire premises. The method of applicationof Gel is such that it is inaccessible to infants and pets.How Gel Works:Gel has an edible product specially attractive to cockroaches. Gel has a cascading effect.Once some cockroaches have eaten Gel they contaminate other cockroaches also and theresult is better control over the population of cockroaches.Gel can be applied to sensitive areas such as electrical control boxes, kitchen appliances,computers etc. on which water based insecticide cannot be sprayed. Back to Products & Services Life Cycle / Egg / Larva / Pupa / AdultThere are over 2500 different species of mosquitoes throughout the world of which 150species occur in the United States. 52 species occur in California, and 19 species occurin Alameda County. In the course of the Districts operation about 10 species are
commonly found in the County. Eight of the species account for over 99% of complaintsfrom the public.Each of the species has a scientific name that is latin, such as Culex tarsalis. Thesenames are used in a descriptive manner so that the name tells something about thisparticular mosquito. Some species have what is called "common names" as well asscientific names, such as Anopheles freeborni, the "Western malaria mosquito".All mosquitoes must have water in which to complete their life cycle. This water canrange in quality from melted snow water to sewage effluent and it can be in anycontainer imaginable. The type of water in which the mosquito larvae is found can be anaid to the identification of which species it may be. Also, the adult mosquitoes show avery distinct preference for the types of sources in which to lay their eggs. They lay theireggs in such places such as tree holes that periodically hold water, tide water pools insalt marshes, sewage effluent ponds, irrigated pastures, rain water ponds, etc. Eachspecies therefore has unique environmental requirements for the maintenance of its lifecycle.The feeding habits of mosquitoes are quite unique in that it is only the adult females thatbite man and other animals. The male mosquitoes feed only on plant juices. Somefemale mosquitoes prefer to feed on only one type of animal or they can feed on avariety of animals. Female mosquitoes feed on man, domesticated animals, such ascattle, horses, goats, etc; all types of birds including chickens; all types of wild animalsincluding deer, rabbits; and they also feed on snakes, lizards, frogs, and toads.Most female mosquitoes have to feed on an animal and get a sufficient blood mealbefore she can develop eggs. If they do not get this blood meal, then they will diewithout laying viable eggs. However, some species of mosquitoes have developed themeans to lay viable eggs without getting a blood meal.The flight habits of mosquitoes depend again on the species with which we are dealing.Most domestic species remain fairly close to their point of origin while some speciesknown for their migration habits are often an annoyance far from their breeding place.The flight range for females is usually longer than that of males. Many times wind is afactor in the dispersal or migration of mosquitoes. Most mosquitoes stay within a mile ortwo of their source. However, some have been recorded as far as 75 miles from theirbreeding source.The length of life of the adult mosquito usually depends on several factors: temperature,humidity, sex of the mosquito and time of year. Most males live a very short time, abouta week; and females live about a month depending on the above factors.Return to Information Directory
Mosquito Life CycleThe mosquito goes through four separate and distinct stages of its life cycle and theyare as follows: Egg, Larva, pupa, and adult. Each of these stages can be easilyrecognized by their special appearance. There are four common groups of mosquitoesliving in the Bay Area. They are Aedes, Anopheles, Culex, and Culiseta.Egg : Eggs are laid one at a time and they float on the surface of the water. In the caseof Culex and Culiseta species, the eggs are stuck together in rafts of a hundred or moreeggs. Anopheles and Aedes species do not make egg rafts but lay their eggsseparately. Culex, Culiseta, and Anopheles lay their eggs on water while Aedes lay theireggs on damp soil that will be flooded by water. Most eggs hatch into larvae within 48hours.Larva : The larva (larvae - plural) live in the water and come to the surface to breathe.They shed their skin four times growing larger after each molting. Most larvae havesiphon tubes for breathing and hang from the water surface. Anopheles larvae do nothave a siphon and they lay parallel to the water surface. The larva feed on micro-organisms and organic matter in the water. On the fourth molt the larva changes into apupa.Pupa: The pupal stage is a resting, non-feeding stage. This is the time the mosquitoturns into an adult. It takes about two days before the adult is fully developed. Whendevelopment is complete, the pupal skin splits and the mosquito emerges as an adult.Adult: The newly emerged adult rests on the surface of the water for a short time toallow itself to dry and all its parts to harden. Also, the wings have to spread out and dryproperly before it can fly.
The egg, larvae and pupae stages depend on temperature and species characteristicsas to how long it takes for development. For instance, Culex tarsalis might go throughits life cycle in 14 days at 70 F and take only 10 days at 80 F. Also, some species havenaturally adapted to go through their entire life cycle in as little as four days or as longas one month.The following pages show a typical mosquito egg raft, larva, pupa, and adult, andexplains more about each stage.Return to Information Directory Mosquito Egg RaftCulex mosquitoes lay their eggs on the surface of fresh or stagnant water. The watermay be in tin cans, barrels, horse troughs, ornamental ponds, swimming pools, puddles,creeks, ditches, or marshy areas. Mosquitoes prefer water sheltered from the wind bygrass and weeds.Culex mosquitoes usually lay their eggs at night. A mosquito may lay a raft of eggsevery third night during its life span.Culex mosquitoes lay their eggs one at a time, sticking them together to form a raft offrom 200- 300 eggs. A raft of eggs looks like a speck of soot floating on the water and isabout 1/4 inch long and 1/8 inch wide.Tiny mosquito larvae emerge from the eggs within 24 hours.Notes: Anopheles mosquitoes lay their eggs singly on the water, not in rafts. Aedesmosquitoes lay their eggs singly on damp soil. Aedes eggs hatch only when floodedwith water (salt water high tides, irrigated pastures, treeholes, flooded stream bottoms,etc.).Return to Information Directory
Mosquito LarvaMosquito larvae, commonly called "wigglers" or "wrigglers", must live in water from 7 to14 days depending on water temperature.Larvae must come to the surface at frequent intervals to obtain oxygen through abreathing tube called a siphon. The larva eats algae and small organisms which live inthe water.During growth, the larva molts (sheds its skin) four times. The stages between molts arecalled instars. At the 4th instar, the larva reaches a length of almost 1/2 inch.When the 4th instar larva molts it becomes a pupa.Note : Anopheles are unlike Culex and Aedes larvae since they do not have a breathingtube, they must lie parallel to the water surface in order to get a supply of oxygenthrough a breathing opening.Return to Information Directory Mosquito PupaMosquito pupae, commonly called "tumblers", must live in water from 1 to 4 days,depending upon species and temperature.The pupa is lighter than water and therefore floats at the surface. It takes oxygen
through two breathing tubes called "trumpets". When it is disturbed it dives in a jerking,tumbling motion and then floats back to the surface. The pupa does not eat.The metamorphosis of the mosquito into an adult is completed within the pupal case.The adult mosquito splits the pupal case and emerges to the surface of the water whereit rests until its body can dry and harden.Return to Information Directory Mosquito AdultOnly female mosquitoes bite animals and drink blood. Male mosquitoes do not bite, butfeed on the nectar of flowers.Aedes mosquitoes are painful and persistent biters, attacking during daylight hours (notat night). They do not enter dwellings, and they prefer to bite mammals like humans.Aedes mosquitoes are strong fliers and are known to fly many miles from their breedingsources.Culex mosquitoes are painful and persistent biters also, but prefer to attack at dusk andafter dark, and readily enter dwellings for blood meals. Domestic and wild birds arepreferred over man, cows, and horses. Culex tarsalis is known to transmit encephalitis(sleeping sickness) to man and horses. Culex are generally weak fliers and do not movefar from home, although they have been known to fly up to two miles. Culex usually liveonly a few weeks during the warm summer months.Those females which emerge in late summer search for sheltered areas where they"hibernate" until spring. Warm weather brings her out in search of water on which to layher eggs.Culiseta mosquitoes are moderately aggressive biters, attacking in the evening hoursor in shade during the day.Anopheles mosquitoes are the only mosquito which transmits malaria to man.Mosquito adult, larva and pupa drawings modified from Aquatic Entomology , by W. PatrickMcCafferty; Illustrations by Arwin V. Provonsha; Jones and
demiologyFrequencyUnited StatesIn the United States, approximately 4 million people are believed to be infected. High-riskgroups include international travelers, recent immigrants (especially from Latin America andAsia), refugees, and international adoptees. Ascariasis is indigenous to the rural southeast, wherecross-infection by pigs with the nematode Ascaris suum is thought to occur. (Children aged 2-10years are thought to be more heavily infected in this and all other regions.)InternationalWorldwide, 1.4 billion people are infected with A lumbricoides, with prevalence amongdeveloping countries as low as 4% in Mafia Island, Zanzibar, to as high as 90% in some areasof Indonesia. Local practices (eg, termite mound–eating in Kenya ) may predispose toascariasis in some populations. Other risk factors like dog/cat ownership, presence of pets withinthe house, and a previous history of geophagia have been noted. In some regions, Ascarisinfection is thought to contribute significantly to the burden of abdominal surgical emergencies.Mortality/MorbidityThe rate of complications secondary to ascariasis ranges from 11-67%, with intestinal and biliarytract obstruction representing the most common serious sequelae. Although infection with Alumbricoides is rarely fatal, it is responsible for an estimated 8,000-100,000 deaths annually,mainly in children, usually from bowel obstruction or perforation in cases of high parasiteburden. Due to similarities in the means of infection, many individuals infected with Ascaris arealso co-infected with other intestinal parasites.RaceNo racial predilection is known. A genetic predisposition has been described in a study offamilies from Nepal.SexMale children are thought to be infected more frequently, owing to a greater propensity to eatsoil.AgeChildren, because of their habits (eg, directly or indirectly consuming soil), are more commonlyand more heavily infected than adults. Neonates may be infected by transplacental infection.
Frequently, families may be infected and reinfected in group fashion due to shared food andwater sources as well as hygiene practices.PreviousProceed to Clinical PresentationRead more about Ascaris Lumbricoides on Meds convergedinfrastructure.com - Compare Private vs. Public Clouds.life cycle, Info & ToolsSearch Results
The Mosquito Life Cycle91rate or flag this pageBy sharkaramaA Look into the Life Cycle of the Mosquito Species andWhat Makes Them Treat You the Way That They DoHave you ever actually thought about the mosquito anatomy or how mosquitoes turn into theblood sucking creatures that everyone loves to hate? For most, the answer to that question isprobably an extra large NO. With the worlds largest mosquito reaching 1.5 inches in length andthe smallest being almost invisible to the eye, mosquitoes and mosquito facts can be just as
riveting as any other subjects story. Understanding the life cycle of a mosquito and what makesthese mosquitoes tick can also help you be prepared for when they decide to invade your territorywhich includes your own skin.Ads by GoogleMasters Degree Program www.aiu.edu/_Masters_Arts, Science, Business, Humanities programs available via distance.Mosquito Net manufacturer www.chinadongren.com/various kinds of mosquito nets warp knitted fabrics,superior qualityLifecycle www.IndustryWeek.comGet Lifecycle news & manufacturing info at IndustryWeekThe Life Cycle of a MosquitoLike most creatures of the Earth, the mosquito goes through various stages before it becomes afull, grown adult. While the mosquito life span may not be very long - a female mosquito mayonly live for 3 to 100 days while a male mosquito may last for about 10 to 20 days - they gothrough a lot to get to the point where your blood is their favorite course. This life cycle can bebroken up into a few basic parts which are: The Egg Stage The Larva Stage The Pupa Stage The Adult StageThese four main stages follow the mosquito lifespan from beginning to end. Thankfully, as youalready know, this life wont last long enough to do mass amounts of damage, but is just longenough to possibly aggravate your life.
A Mosquito Laying EggsMosquito EggsAs one may expect, the egg stage for the mosquito is the first stage. Also as one may expect,these eggs do not just appear out of thin air. Yep you guessed it; they come from a mothermosquito that can produce up to 250 eggs at a time. These 250 eggs can only come about afterthe female mosquito feasts on at least one blood meal in order to have enough nutrients for themass amount of mosquito eggs to be born. Once enough nutrients are consumed, possibly fromyour very own blood, it is time to watch out.Watch out because within 48 to 72 hours, those eggs will be hatching into the next stage of themosquito lifecycle. Before you start really getting scared, there are a few common places thatfemale mosquitoes love to lay their eggs. You just may be able to find the root of a mosquitoinfestation without having to look too hard. Here are the most common places you will find amosquito eggs waiting to hatch and take over the world: The top surface of any stagnant water A depression or ridge of a container where rain water collects Close to small bodies of water such as ponds or moats Inside marshlands The inside of an outdoor flower potBasically, wherever there is an ideal aquatic location, a mosquito habitat will be formed. If youdo find a nest, then it is most certainly time to get to work. You can spray down the area with anaerosol mosquito killer, but that is not the best thing to do for the environment. Instead, you maywant to use a product like a Mosquito Trap, a safe and technologically proven device that willget rid of those pesky insects in your life.
Mosquito LarvaeMosquito LarvaeMosquito larvae and mosquito larva pictures are an interesting sight to see. Commonly referredto as "Wrigglers", these newly hatched insects can be seen wriggling up and down from thesurface of the water. Get too close, though, and they will seemingly disappear. This is becausethe larvae are on a mission to protect themselves from mosquito predators. So to keep themselvessafe, they quickly dive to the bottom of whatever water they were born into.Within five to six days, the mosquito larvae stage is complete. In this time period, the insectsstart to take form. A nicely shaped head and legs can been detected along with a wider thoraxstemming from the abdomen. At the tip of the abdomen is where the siphon is found, whichallows the larvae to breathe air from the surface. Some mosquito larvae do not have this siphonand get their air from the dorsal surface of the abdomen.There are many mosquito types, but no matter how they get their air, these larvae are on theverge of stepping into their next stage which is known as the Pupa stage. This means that theyare also almost ready to introduce themselves into the living world and maybe to your flesh.The Pupa StageWhen it comes to mosquito pictures, the pupa stage is not the most photographed of themosquito stages. While an adult mosquito picture may be common, yet hard to get, the pupastage is pretty much impossible to capture. This is mostly due to the fact that the pupa stage ofmosquitoes causes these forming insects to somersault through the water. Staying close to the
surface for air until they are disturbed, mosquito pupae finish this stage in about two to threedays.Adult Female MosquitoThe Adult StageAfter their brief stint with metamorphosis, the hatched eggs are finally ready to step intoadulthood. And seeming we are not considered mosquito eaters, that is bad news for us. Whilevegans may value mosquito life, most would rather dispose of these adult bugs before theybecome too big of a problem.When it comes down to it though, it is the female mosquito that is really the arch nemesis ofhumankind. Here is what the female mosquitoes of the world love to eat: Plant Nectar Honey Dew Sugar Sources Your BloodDepending on their species, some females do indulge themselves on other animals such as birdsand horses. So for all of you who are just expecting to go and stick mosquito eating birds in yourbackyard, think again. The same goes for male mosquitoes, minus the feasting on blood.So how exactly does the female get to your blood? Does it have teeth and if so how many teethdoes a mosquito have? The answers to these questions are simple, yet at the same time tricky.Mosquitoes technically do not have teeth but do have serrated teeth that surround a pair of thintubes. The tubes are used for: Dripping a Pain Suppressor Sucking BloodAnd those are two things that could most certainly start your day off all wrong. The mosquitoesmost commonly found around homes will follow this protocol in order to get the nutrients theyneed from your blood:
1. Stab the skin 2. Saw into the skin 3. Shoot saliva mixed with an anesthetic so you will never notice 4. Shoot an anticoagulant into you in order for the blood to keep flowing freelyOnce the female feeds off of you, the life cycle of the mosquito is almost through. All that is leftis for her to go lay her eggs and begin the cycle for a new batch of blood thirsty villains all overagain.DEET SprayWhat You Can DoThe best thing that you can do to protect yourself from mosquito bites and potential mosquitoborne diseases is be prepared for the worst. You dont have to know mosquito identification,mosquito classification, or the scientific name in order to stop the pesky buggers from flyingyour way. All you really need is a mosquito control product like DEET spray for your skin, amosquito net for your yard, or a Mega-Catch mosquito trap for your yard or hallway. As long asyou have these products by your side, you wont have to worry about having nightmares aboutmosquito eyes lurking in the night. A sensible and safe plan is all you really need.
Mosquito TrapDid you like this Hubpage?Help spread the love, Please rate it and click on the share it button below to bookmark on yourfavourite site. Thank you!Ads by GoogleTuition fee from $20.000 WaldenU.edu/Adult-Adult-EducationStudy For Your Doctoral Online! Adult Adult Education at Walden.High Quality Mosquito Net www.muscanets.co.zaMUSCANETS lets you experience style quality hand made mosquito nets.mining industry service www.polysius.com/en/service/mining/custom-tailored solutio
WUMCD MenuDistrict Information- About the District- Integrated Mosquito Management- Management / Key Personnel- Board of Trustees- Budget Committee- District History- Professional Affiliations- Directions to Office- Contact UsMosquito Information- Introduction- The Name "Mosquito"- Mosquito Life Cycle- Mosquito Egg Raft- Mosquito Larvae- Mosquito Pupae- Mosquito AdultDisease Information- West Nile Virus- St. Louis Encephalitis- Western Equine Encephalitis- Lyme Disease- Canine Heartworm
Mosquito FishService Requests- Mosquito Control- No SprayMosquito Surveillance Adult Surveillance- Mosquito Light Traps- Mosquito Landing Rates Disease Surveillance- Sentinel Chickens- Mosquito Pools- Wild Bird Testing- If You Find a Dead Bird...Mosquito Control- Larval Mosquito Control- Adult Mosquito ControlVideosPress ReleasesWUMCD Home Page MOSQUITO LIFE CYCLEThe mosquito goes through four separate and distinct stages of its lifecycle: Egg, Larva, Pupa, and Adult. Each of these stages can be easilyrecognized by its special appearance.Egg: Eggs are laid one at a time or attached together to form "rafts."They float on the surface of the water. In the case of Culex andCuliseta species, the eggs are stuck together in rafts of up to 200.Anopheles, Ochlerotatus and Aedes , as well as many other genera, donot make egg rafts, but lay their eggs singly. Culex, Culiseta, andAnopheles lay their eggs on the water surface while many Aedes andOchlerotatus lay their eggs on damp soil that will be flooded by water.Most eggs hatch into larvae within 48 hours; others might withstandsubzero winters before hatching. Water is a necessary part of theirhabitat.
Larva: The larva (plural - larvae) lives in the water and comes to thesurface to breathe. Larvae shed (molt) their skins four times, growinglarger after each molt. Most larvae have siphon tubes for breathingand hang upside down from the water surface. Anopheles larvae donot have a siphon and lie parallel to the water surface to get a supplyof oxygen through a breathing opening. Coquillettidia and Mansonialarvae attach to plants to obtain their air supply. The larvae feed onmicroorganisms and organic matter in the water. During the fourthmolt the larva changes into a pupa.Pupa: The pupal stage is a resting, non-feeding stage of development,but pupae are mobile, responding to light changes and moving(tumble) with a flip of their tails towards the bottom or protectiveareas. This is the time the mosquito changes into an adult. Thisprocess is similar to the metamorphosis seen in butterflies when thebutterfly develops - while in the cocoon stage - from a caterpillar intoan adult butterfly. In Culex species in the southern United States thistakes about two days in the summer. When development is complete,the pupal skin splits and the adult mosquito (imago) emerges.Adult: The newly emerged adult rests on the surface of the water for ashort time to allow itself to dry and all its body parts to harden. Thewings have to spread out and dry properly before it can fly. Bloodfeeding and mating does not occur for a couple of days after the adultsemerge.How long each stage lasts depends on both temperature and speciescharacteristics. For instance, Culex tarsalis, a common California(USA) mosquito, might go through its life cycle in 14 days at 70� Fand take only 10 days at 80� F. On the other hand, some specieshave naturally adapted to go through their entire life cycle in as littleas four days or as long as one month.The following pictures show a typical mosquito egg raft, larva, pupa,and adult, and explain more about each stage.
West Umatilla Mosquito Control District3005 South 1st Street, Hermiston, OR 97838info@w
at Life CycleOnly the life cycle of the Roof Rat (rattus rattus) is discussed on this page, since this is theonly rat that is common here in central Florida. Roof Rats are born in a nest, in a litter of 6-8 young. The nest is often in a secure place with nesting debris such as in an attic in the insulation. They are born tiny and hairless (pinkies), with eyes sealed shut. After two weeks of nursing, their eyes open, and within 4 weeks, they are weaned. After three months of life, they are independent and on their own, although they typically use the same habitat as their birthplace (i.e. they live in the same home or attic).Here we can see a photo of a juvenile rat and amature adult rat. Older ones sometimes tend tobrown a bit, although most of the rats we catchare gray. A lot of the rats that we catch are smallrats. This is because they breed in such highnumbers, and there are so many young ones.When were trapping rats in an attic, well oftenget a big one or two, and a number of smallones. This is not the rule, but it does happenfrom time to time, indicating a possible familyof rats. Rats dont live particularly long in the wild. Like all rodents, they rely upon breeding in high numbers and eating a lot and growing quickly. In this respect, they are somewhat like insects, and thus can sometimes swell to large numbers given the right conditions. In normal circumstances, disease and predators keep their numbers in check. Rarely do rats live for more than a year in the wild. During that year, however, they can create a lot of new rats and a lot of damage. Just one adult female can create more than 40 new rats in a year. In their
Family: MuridaeSubfamily: MurinaeGenus: RattusSpecies: R. norvegicus Binomial name Rattus norvegicus (Berkenhout, 1769) Brown rat rangeThe brown rat, common rat, sewer rat, Hanover rat, Norway rat, Brown Norway rat,Norwegian rat, or wharf rat (Rattus norvegicus) is one of the best known and most commonrats.One of the largest muroids, it is a brown or grey rodent with a body up to 25 cm (10 in) long, anda similar tail length; the male weighs on average 350 g (12 oz) and the female 250 g (9 oz).Thought to have originated in northern China, this rodent has now spread to all continents,except Antarctica, and is the dominant rat in Europe and much of North America—making it themost successful mammal on the planet after humans. Indeed, with rare exceptions the brownrat lives wherever humans live, particularly in urban areas.Selective breeding of Rattus norvegicus has produced the laboratory rat, an important modelorganism in biological research, as well as pet rats.Contents[hide] 1 Naming and etymology 2 Description 3 Biology and behavior o 3.1 Communication 3.1.1 Chirping 3.1.2 Audible communication o 3.2 Diet o 3.3 Reproduction and life cycle o 3.4 Social behavior o 3.5 Burrowing 4 Distribution and habitat
o 4.1 Alaska o 4.2 Alberta, Canada o 4.3 New Zealand 5 Diseases 6 In captivity o 6.1 Uses in science o 6.2 As pets 7 References 8 External links Naming and etymologyOriginally called the "Hanover rat" by people wishing to link problems in 18th century Englandwith the House of Hanover, it is not known for certain why the brown rat is named Rattusnorvegicus (Norwegian rat) as it did not originate from Norway. However, the English naturalistJohn Berkenhout, author of the 1769 book Outlines of the Natural History of Great Britain, ismost likely responsible for popularizing the misnomer. Berkenhout gave the brown rat thebinomial name Rattus norvegicus believing that it had migrated to England from Norwegianships in 1728, although no brown rat had entered Norway at that time.By the early to middle part of the 19th century, British academics were aware that the brown ratwas not native to Norway, hypothesizing (incorrectly) that it may have come from Ireland,Gibraltar or across the English Channel with William the Conqueror. As early as 1850,however, a more correct understanding of the rats origins was beginning to develop. TheBritish novelist Charles Dickens acknowledged the misnomer in the 2 June 1888 edition of hisweekly journal, All the Year Round, writing:"Now there is a mystery about the native country of the best known species of rat, the commonbrown rat. It is frequently called, in books and otherwise, the Norway rat, and it is said to havebeen imported into this country in a ship-load of timber from Norway. Against this hypothesisstands the fact that when the brown rat had become common in this country, it was unknown inNorway, although there was a small animal like a rat, but really a lemming, which made its homethere."Academics began to understand the origins and corrected etymology of the brown rat towards theend of the 19th century, as seen in the 1895 text Natural History by American scholar AlfredHenry Miles:"The brown rat is the species common in England, and best known throughout the world. It issaid to have travelled from Persia to England less than two hundred years ago and to have spreadfrom thence to other countries visited by English ships."Though the assumptions surrounding this species origins were not yet entirely accurate, by the20th century it was established among naturalists that the brown rat did not originate in Norway,
rather that the species came from central Asia and (likely) China. Despite this, this speciescommon name of "Norway rat" is still in use today. DescriptionComparison of the physique of a black rat (Rattus rattus) with a brown rat (Rattus norvegicus)The fur is coarse and usually brown or dark grey, while the underparts are lighter grey or brown.The length can be up to 25 cm (10 in), with the tail a further 25 cm (10 in), the same length asthe body. Adult body weight averages 550 g (19 oz) in males and about 350 g (12 oz) in females,but a very large individual can reach 900 g (32 oz). Rats weighing over 1 kg (2.2 lb) areexceptional, and stories of rats as big as cats are exaggerations, or misidentifications of otherrodents such as the coypu and muskrat.Brown rats have acute hearing, are sensitive to ultrasound, and possess a very highly developedolfactory sense. Their average heart rate is 300 to 400 beats per minute, with a respiratory rate ofaround 100 per minute. The vision of a pigmented rat is poor, around 20/600, while a non-pigmented (albino) with no melanin in its eyes has both around 20/1200 vision and a terriblescattering of light within its vision. Brown rats are dichromates who perceive colours rather likea human with red-green colorblindness, and their colour saturation may be quite faint. Their blueperception, however, also has UV receptors, allowing them to see ultraviolet lights that somespecies cannot. Biology and behavior
Brown rat skullThe brown rat is usually active at night and is a good swimmer, both on the surface andunderwater, but unlike the related Black Rat (Rattus rattus) they are poor climbers. Brown ratsdig well, and often excavate extensive burrow systems. A 2007 study found brown rats topossess metacognition, a mental ability previously only found in humans and some primates,but further analysis suggested that they may have been following simple operant conditioningprinciples. CommunicationBrown rats are capable of producing ultrasonic vocalizations. As pups, young rats use differenttypes of ultrasonic cries to elicit and direct maternal search behavior, as well as to regulatetheir mothers movements in the nest. Although pups will produce ultrasounds around anyother rats at 7 days old, by 14 days old they significantly reduce ultrasound production aroundmale rats as a defensive response. Adult rats will emit ultrasonic vocalizations in response topredators or perceived danger; the frequency and duration of such cries depending on the sexand reproductive status of the rat. The female rat will also emit ultrasonic vocalizationsduring mating. ChirpingRats may also emit short, high frequency, ultrasonic, socially induced vocalization during roughand tumble play, before receiving morphine, or mating, and when tickled. The vocalization isdescribed as a distinct "chirping", has been likened to laughter, and is interpreted as anexpectation of something rewarding. Like most rat vocalizations, the "chirping" is too high in
pitch for humans to hear without special equipment. Bat detectors are often used by pet ownersfor this purpose.In clinical studies, the chirping is associated with positive emotional feelings, and social bondingoccurs with the tickler, resulting in the rats becoming conditioned to seek the tickling. However,as the rats age, there appears to be a decline in the tendency to chirp.Rat chirp also can be utilized for mosquito control.Other ultrasonic vocalisations, including a lower-frequency boom or whoom noise can beproduced by bucks in a calm state, when grooming or settling down to sleep. Audible communicationBrown rats also produce communicative noises capable of being heard by humans. The mostcommonly heard in domestic rats is bruxing, or tooth-grinding, which is most usually triggeredby happiness, but can also be self-comforting in stressful situations, such as a visit to the vet.The noise is best described as either a quick clicking or burring sound, varying from animal toanimal.In addition, they commonly squeak along a range of tones from high, abrupt pain squeaks to soft,persistent singing sounds during confrontations. DietThe brown rat is a true omnivore and will consume almost anything, but cereals form asubstantial part of its diet.Brown rat eating sunflower seedsMartin Schein, founder of the Animal Behavior Society in 1964, studied the diet of brown ratsand came to the conclusion that the most-liked foods of brown rats were (in order) scrambledeggs, macaroni and cheese, and cooked corn kernels. According to Schein, the least-liked foodswere raw beets, peaches, and raw celery.Foraging behavior is often population-specific, and varies by environment and food source.Brown rats living near a hatchery in West Virginia catch fingerling fish. Some colonies alongthe banks of the Po river in Italy will dive for mollusks, a practice demonstrating social
learning among members of this species. Rats on the island of Norderoog in the North Seastalk and kill sparrows and ducks. Reproduction and life cycleThe brown rat can breed throughout the year if conditions are suitable, a female producing up tofive litters a year. The gestation period is only 21 days and litters can number up to fourteen,although seven is common. They reach sexual maturity in about 5 weeks. The maximum lifespan is up to three years, although most barely manage one. A yearly mortality rate of 95% isestimated, with predators and interspecies conflict as major causes.When lactating, female rats display a 24 hour rhythm of maternal behavior, and will usuallyspend more time attending to smaller litters than large ones.Brown rats live in large hierarchical groups, either in burrows or subsurface places such assewers and cellars. When food is in short supply, the rats lower in social order are the first to die.If a large fraction of a rat population is exterminated, the remaining rats will increase theirreproductive rate, and quickly restore the old population level. Social behaviorIt is common for rats to groom each other and sleep together. As with dogs, rats create a socialhierarchy, and each rat has its own place in the pack. Rats are said to establish an order ofhierarchy and so one rat will be dominant over another one. Groups of rats tend to "playfight", which can involve any combination of jumping, chasing, tumbling, and boxing. Playfighting involves rats going for each others necks, while serious fighting involves strikes at theothers back ends. BurrowingRats are known to burrow extensively, both in the wild and in captivity, if given access to asuitable substrate. Rats generally begin a new burrow adjacent to an object or structure, as thisprovides a sturdy "roof" for the section of the burrow nearest to the grounds surface. Burrowsusually develop to eventually include multiple levels of tunnels, as well as a secondaryentrance. Older male rats will generally not burrow, while young males and females willburrow vigorously.Burrows provide rats with shelter and food storage as well as safe, thermoregulated nest sites.Rats use their burrows to escape from perceived threats in the surrounding environment—forexample, rats will retreat to their burrows following a sudden, loud noise or while fleeing anintruder. Burrowing can therefore be described as a "pre-encounter defensive behavior", asopposed to a "post-encounter defensive behavior", such as flight, freezing, or avoidance of athreatening stimulus. Distribution and habitat
Likely originating from the plains of Asia, Northern China and Mongolia, the brown rat spreadto other parts of the world sometime in the Middle Ages. The question of when brownrats became commensal with humans remains unsettled, but as a species they have spread andestablished themselves along routes of human migration and now live almost everywherehumans do.The brown rat may have been present in Europe as early as 1553, a conclusion drawn from anillustration and description by Swiss naturalist Conrad Gesner in his book Historiae animalium,published 1551-1558. Though Gesners description could apply to the black rat, his mention ofa large percentage of albino specimens—not uncommon among wild populations of brownrats—adds credibility to this conclusion. Reliable reports dating to the 18th century documentthe presence of the brown rat in England in 1730, France in 1735, Germany in 1750, and Spainin 1800, becoming widespread during the Industrial Revolution. It did not reach NorthAmerica until around 1750-1755.As it spread from Asia, the brown rat generally displaced the black rat in areas where humanslived. In addition to being larger and more aggressive, the change from wooden structures andthatched roofs to bricked and tiled buildings favored the burrowing brown rats over the arborealblack rats. In addition, brown rats eat a wider variety of foods, and are more resistant to weatherextremes.In the absence of humans, brown rats prefer damp environments such as river banks.However, the great majority are now linked to man-made environments, such as sewage systems.Brown rat in a flower box in the East Village of New York City.It is often said that there are as many rats in cities as people, but this varies from area to areadepending on climate, living conditions, etc. Brown rats in cities tend not to wander extensively,often staying within 20 m (66 ft) of their nest if a suitable concentrated food supply is available,but they will range more widely where food availability is lower. In New York City there is greatdebate over the size of the rat population with estimates from almost 100 million rats to as few as250,000. Experts suggest New York is a particularly attractive place for rats because of itsaging infrastructure, high moisture and poverty rates. In addition to sewers, rats are verycomfortable living in alleyways and residential buildings, as there is usually a large andcontinuous food source in those areas.
In the United Kingdom some figures show that the rat population has been rising, withestimations that 81 million rats reside in the UK. Those figures would mean that there are 1.3rats per person in the country. High rat populations in the UK are often attributed to the mildclimate, which allow them higher survival rates during the winter months.The only brown rat-free zones in the world are the Arctic, the Antarctic, some especially isolatedislands, the province of Alberta in Canada, and certain conservation areas in NewZealandAntarctica is almost completely covered by ice and has no permanent human inhabitants, makingit uninhabitable by rats. The Arctic has extremely cold winters that rats cannot survive outdoors,and the human population density is extremely low making it difficult for rats to travel from onehabitation to another. When the occasional rat infestation is noticed and eliminated, the rats areunable to re-infest it from an adjacent one. Isolated islands are also able to eliminate ratpopulations because of low human population density and geographic distance from other ratpopulations. AlaskaRat Island in Alaska was infested with brown rats after a Japanese shipwreck in 1780. They hada devastating effect on the native bird life. An eradication program was started in 2007 and theisland was declared rat free in June 2009. Alberta, CanadaAlberta, Canada, is unusual in that rat infestation was eliminated by aggressive governmentaction. Although it is a major agricultural area, it is far from any seaport and only a portion of itseastern boundary with Saskatchewan provides a favorable entry route for rats. They cannotsurvive in the boreal forest to the north, the Rocky Mountains to the west, nor the semi-arid HighPlains of Montana to the south. The first brown rat did not reach Alberta until 1950, and in 1951the province launched a rat-control program that included shooting and poisoning rats, andbulldozing, burning down, and blowing up rat-infested buildings. The effort was backed bylegislation that required every person and every municipality to destroy and prevent theestablishment of designated pests. If they failed, the provincial government could carry out thenecessary measures and charge the costs to the landowner or municipality.In the first year of the program, 64 tonnes (71 short tons) of arsenic trioxide were spreadthroughout 8,000 buildings on farms along the Saskatchewan border. In 1953 the much less toxicand more effective poison, Warfarin, was introduced. By 1960 the number of rat infestations inAlberta dropped to below 200 per year.Currently, only zoos, universities, and research institutes are allowed to own caged rats inAlberta, and possession of an unlicensed rat (including pet rats) is punishable by a $5,000 fine or60 days in jail. The adjacent and similarly landlocked province of Saskatchewan initiated a ratcontrol program in 1972, and has managed to reduce the number of rats in the provincesubstantially, although they have not been eliminated.
 New ZealandFirst arriving before 1800 (perhaps on James Cooks vessels), brown rats have posed a seriousthreat to many of New Zealands native animals. Rat eradication programmes within NewZealand have led to rat-free zones on offshore islands and even on fenced "ecological islands" onthe mainland. Before an eradication effort was launched in 2001, the sub-Antarctic CampbellIsland had the highest population density of brown rats in the world. DiseasesSimilar to other rodents, brown rats may carry a number of pathogens which can result indisease, including Weils disease, rat bite fever, cryptosporidiosis, Viral hemorrhagic fever(VHF), Q fever and hantavirus pulmonary syndrome. In the United Kingdom, brown rats are animportant reservoir for Coxiella burnetii, the bacteria that cause Q fever, with seroprevalence forthe bacteria found to be as high as 53% in some wild populations.This species can also serve as a reservoir for Toxoplasma gondii, the parasite that causestoxoplasmosis, though the disease usually spreads from rats to humans when domestic cats feedon infected brown rats. The parasite has a long history with the brown rat, and there areindications that the parasite has evolved to alter an infected rats perception to cat predation,making it more susceptible to predation and increasing the likelihood of transmission.Surveys and specimens of brown rat populations throughout the world have shown that thisspecies is often associated with outbreaks of trichinosis, but the extent to which the brownrat is responsible in transmitting Trichinella larvae to humans and other synanthropic animals isat least somewhat debatable. Trichinella pseudospiralis, a parasite previously not consideredto be a potential pathogen in humans or domestic animals, has been found to be pathogenic inhumans and carried by brown rats.Brown rats are sometimes mistakenly thought to be a major reservoir of bubonic plague, apossible cause of The Black Death. However, the bacterium responsible, Yersinia pestis, iscommonly endemic in only a few rodent species and is usually transmitted zoonotically by ratfleas—common carrier rodents today include ground squirrels and wood rats. However, brownrats may suffer from plague, as can many non-rodent species including dogs, cats, andhumans. The original carrier for the plague-infected fleas thought to be responsible for theBlack Death was the black rat, and it has been hypothesized that the displacement of black ratsby brown rats led to the decline of bubonic plague. This theory has, however, beendeprecated, as the dates of these displacements do not match the increases and decreases inplague outbreaks. In captivity Uses in scienceMain article: Laboratory rat
Selective breeding of albino brown rats rescued from being killed in a now-outlawed sport calledrat-baiting has produced the albino laboratory rat. Like mice, these rats are frequentlysubjects of medical, psychological and other biological experiments and constitute an importantmodel organism. This is because they grow quickly to sexual maturity and are easy to keep andto breed in captivity. When modern biologists refer to "rats", they almost always mean Rattusnorvegicus. As petsMain article: Fancy ratThe brown rat is kept as a pet in many parts of the world. Australia, the United Kingdom, and theUnited States are just a few of the countries that have formed fancy rat associations similar innature to the American Kennel Club, establishing standards, orchestrating events, and promotingresponsible pet ownership.There are many different types of domesticated brown rats. These include variations in coatpatterns as well as the style of the coat, such as Hairless or Rex, and more recently developedvariations in body size and structure including dwarf and tailless fancy rats. References uestion: What is the life and life cycle of the flea, & why is flea control sodifficult?Fleas. They make pets lives miserable, and humans begin to itch just at the thought of them.Vets are often asked what pill, drop, dip, collar, or shampoo works the best to get rid of thesepersistent parasites. The answer is that there is no single method or insecticide that willcompletely eradicate (or at least control) a flea problem. The flea life cycle is fairly complex, andunderstanding the various stages will make it easier to get rid of them.Answer: Collectively, all of the species of fleas are categorized under the order name ofSiphonaptera. The cat flea, Ctenocephalides felix, is the most commonly found flea in the USand infests cats, dogs, humans, and other mammalian and avian hosts.Fleas thrive in warm, moist environments and climates. The main flea food is blood from thehost animal. Host animals are many species - cats, dogs, humans, etc. Fleas primarily utilizemammalian hosts (about 95%). Fleas can also infest avian species (about 5%). Flea saliva, likeother biting skin parasites, contains an ingredient that softens, or "digests" the hosts skin foreasier penetration and feeding. The saliva of fleas is irritating and allergenic -- the cause of allthe itching, scratching, and other signs seen with Flea Allergy Dermatitis, or FAD.Fleas have four main stages in their life cycle: egg, larva, pupa, and adult. The total flea lifecycle can range from a couple weeks to several months, depending on environmental conditions.
ADULT: The adult flea is very flat side to side. There are hair-like bristles on the flea body andlegs to aid in their navigation through pet hair. Fleas have 3 pairs of legs, the hindmost pairdesigned for jumping. Fleas are well known for their jumping abilities.Adult fleas prefer to live on the animal and their diet consists of blood meals courtesy of the hostanimal. The female flea lays white, roundish eggs. The adult female flea can lay up to 50 eggsper day1, 500-600 eggs2 over several months.EGG: The eggs are not sticky (like some parasites), and they usually fall off of the animal intothe carpet, bedding, floorboards, and soil. When the flea egg hatches varies -- anywhere fromtwo days to a few weeks, depending on environmental conditions. The larva emerges from theegg using a chitin tooth, a hard spine on the top of the head that disappears as the flea matures.LARVA (plural = larvae): The larval stage actually has three developmental stages within thisstage. Larvae are about 1/4" (6.35 mm) long, and semi-transparent white. They have small hairsalong their body and actively move. They eat the feces of adult fleas (which is mostly driedblood) and other organic debris found in the carpet, bedding, and soil. Depending on the amountof food present and the environmental conditions, the larval stage lasts about 5 to 18 days (longerin some cases) then the larva spins a silken cocoon and pupates.PUPA (plural = pupae): The pupa is the last stage before adult. The adult flea can emerge fromthe cocoon as early as 3 to 5 days, or it can stay in the cocoon for a year or more, waiting for theright time to emerge. When is the right time? (Never, say pet lovers everywhere!) Stimuli such aswarm ambient temperatures, high humidity, even the vibrations and carbon dioxide emitted froma passing animal will cause the flea to emerge from the cocoon faster. This brings us back to theadult flea.The entire life cycle is quite variable, as evidenced by the variability in each life stageprogression. As mentioned above, the cycle can be as short as two weeks or as long as two years.That is why it is so important to remain vigilant, even when a flea problem is thought to be undercontrol!Related Reading:he Life Cycle of FleasBy Cat Carson, eHow Contributor Print this article
The Life Cycle of FleasA flea is a parasite that goes through four primary stages in its life cycle: egg, larva, pupa andadult. The entire flea life cycle ranges from two weeks to eight months depending onenvironmental factors such as temperature, food sources and humidity.Related Searches: Fleas Bites Treat Fleas 1. Egg o An adult female flea begins laying eggs about two days after mating. These eggs are loosely laid on a host, and usually fall off into the environment where they hatch in about two to three days. Larva o A flea goes through three larval phases that last one week to several months. Flea larvae feed on adult flea feces, hair, feathers, dead skin and other organic debris. Pupa o Flea pupae mature to adulthood inside of a cocoon they weave in their larval phase. Pupa live in the cocoon for five days to two weeks. Adult o Adult fleas emerge from their cocoons when they sense warmth, carbon dioxide, motion and vibrations, all of which tell it that an animal host is nearby. Adult fleas must find a blood meal within their first 30 days of life in order to survi
Read more: The Life Cycle of Fleas | eHow.com http://www.ehow.com/facts_5188387_life-cycle-fleas.html#ixzz4SHhCspz0Life Cycle of LiceBy an eHow Contributor Print this articleHead lice are insects that feed off the of the blood of their host. One louse can produce hundredsof eggs during its lifespan. Head lice live for nearly two months and have three stages of life.Related Searches: Lice Pictures Lice Comb 1. Nits o A head lice egg is called a nit. Nits are laid by female lice at the base of the hair shaft. Once laid, nits take five to 10 days to hatch. Eggs, which are about the size of sesame seeds, are yellowish-brown to white in color. Nymphs o When the nits hatch, they release nymphs. Nymphs look like adult lice, but are smaller in size. Nymphs molt (outgrow their exoskeleton) three times before becoming an adult. The nymph stage lasts up to seven days. Adults o The adult is the third stage of head lice. Adults can live up to 30 days and feed off the host up to five times a day. Adult females will lay up to a dozen eggs a day. Hosts Needed o Adults and nymphs can live only two or three days without a host. Nits can survive up to two weeks without a host. Transmission
o Head lice are often transmitted from host to host via objects that come in contact with hair. Head lice can go two or three days without feeding and can live on detached hair strands, clothing, hats, combs, towels and bedding. mining industry servicewww.polysius.com/en/service/mining/ custom-tailored solutions for grinding and crushing equipment Lifecyclewww.IndustryWeek.com Get Lifecycle news & manufacturing info at IndustryWeek NoNo 8800 Hair Removalwww.iseenon.tv Painless Hair Removal Get Free 60 Day Trial Limited Time Only Longray fogger machinewww.longrayfog.com The Advanced Spraying Equipments for the disinfecting and pestAds by GoogleRead more: Life Cycle of Lice | eHow.com http://www.ehow.com/facts_5137724_life-cycle-lice.html#ixzz4SHfXzh4Vallery Index: Lice - Lice PicturesLice Life Cycle - Lice PicturesLice PicturesUpdated October 20, 2010About.com Healths Disease and Condition content is reviewed by the Medical Review BoardHaving a hard time figuring out what you are looking for when you think your kids have lice? This pictureof the 3 stages of the head lice life cycle can help.11 of 11Previous Next
Sponsored LinkEmbroidery LibraryThe best designs, the best prices! 70,000+ designs, alldownloadable.www.emblibrary.comHead Lice Life Cycle StagesPhoto courtesy of the Centers for Disease Control and PreventionThis picture shows the three stages of the head lice life cycle, including the head lice egg or nit,nymph, and adult louse, as compared to the size of a penny for scale.Lice Life CycleA mature or adult head louse can lay up to 10 eggs or nits each day.These nits, or lice eggs, hatch in about 7 to 12 days. Baby lice or nymphs are about the size of apinhead when they hatch, and quickly mature into adult lice in about a 9 to 12 days.In just a few days, adult lice are ready mate, starting this lice life cycle all over again during their3 to 4 week lifespan.Of course, a proper lice treatment regimen can interrupt the lice life cycle and help you get rid ofthe lice on your childs hair.Sources:American Academy of Pediatrics Clinical Report. Head Lice. PEDIATRICS Vol. 126 No. 2 August 2010, pp. 392-403.Previous Next
Ascaris Lumbricoides Ascaris lumbricoides , common saying “round worm of man”, is the largest of theintestinal nematodes parasitizing humans. It is the most common worm found inhuman. It is worldwide in distribution and most prevalent through out the tropics,sub-tropics and more prevalent in the countryside than in the city.I. Morphology
1. Adult: The adults are cylindrical in shape, creamy-white and pinkish in color. Thefemale averages 20~35cm in length, the largest 49cm. The male is smaller, averaging15~31cm in length and distinctly more slender than the female. The typical curledtail with a pair sickle like copulatory spine readily distinguishes males. On the tip ofthe head there are three lips, arranged as a Chinese word “ 品 ”. They have acomplete digestive tract. Reproductive organs are tubular. male has a singlereproductive tubule. The female has two reproductive tubules and the vulva isventrally located at the posterior part of the anterior 1/3 of the body.2. Egg: There are three kind of the eggs. They are fertilized eggs, unfertilized eggsand decorticated eggs. We usually describe a egg in 5 aspects: size, color, shape,shell and content. Fertilized eggs: broad oval in shape, brown in color, an average size 60 x45µm . Theshell is thicker and consists of ascaroside, chitinous layer, fertilizing membrane andmammillated albuminous coat. The content is a fertilized ovum. There is a new-moon shaped space at the each end inside the shell.Unfertilized egg: Longer and slender than a fertilized egg. The chitinous layer andalbuminous coat are thinner than those of the fertilized eggs without ascaroside andfertilizing membrane. The content is made of many refractable granules various insize.Decorticated eggs: Both fertilized and unfertilized eggs sometimes may lack theirouter albuminous coats and are colorless.II. Life Cycle
1. Site of inhabitation: small intestine 2. Infetive stage: embryonated eggs 3. Route of infection: by mouth 4. No intermediate and reservoir hosts 5. Life span of the adult: about 1 yearIII. Diagnosis The symptoms and signs are for reference only. The confirmative diagnosisdepends on the recovery and identification of the worm or its egg.1. Ascaris pneumonitis: Examination of sputum for Ascaris larvae is sometimessuccessful.2. Intestinal ascariasis: Feces are examined for the ascaris eggs.(1) Direct fecal film: It is simple and effective. The eggs are easily found using thisway due to a large number of the female oviposition, approximately 240,000 eggsper worm per day. So this method is the first choice.(2) Brine-floatation method:(3) Recovery of adult worms: When adults or adolescents are found in feces or vomitand tissues and organs from the human infected with ascarids , the diagnosis may bedefined.IV. Requirements1. Study the morphological characters of ova and adult worms of Ascaris.
2. Realize the life cycle of the worm.3. Master the methods of the diagnosis.V. Individual observationFertilized eggs and unfertilized eggsVI. workDraw a fertilized and unfertilized Ascaris egg. Trichuris trichiura ( Whipworm )I. Morphology: Adult: The worm looks like a buggy whip, the anterior 3/5 is slender and theposterior 2/5 is thick. It is pinkish gray in color. The female worm is 3-5 cm in length and has a long slender esophageal region. Themale is smaller than the female and has a curved tail. Egg: It is barrel or spindle in shape and 50 x 20µm µm in size. It is brownish and hasa translucent polar plug at either ends. The content of the egg is an undevelopedcell.II. Life Cycle: 1. Site of inhabitation: cecum 2. Infective stage: embryonic egg
3. Infectve mode and route: passively swallowed by the mouthIII.. Diagnosis: Discover the eggs in feces by floatation method or direct fecal smear.IV.Requirements1.Study the morphological characters of ova and adult worms of T. trichiura.2.Realize the life cycle of the worm.3.Master the methods of the diagnosis.V. Individual observationThe eggs and the adultsVI.work [Last Modified: 07/20/2009 07:14:39][Ancylostoma braziliense] [Ancylostoma caninum] [Ancylostoma duodenale] [Necatoramericanus]Causal Agents:The human hookworms include the nematode species, Ancylostoma duodenale and Necator americanus. A largergroup of hookworms infecting animals can invade and parasitize humans (A. ceylanicum) or can penetrate thehuman skin (causing cutaneous larva migrans), but do not develop any further (A. braziliense, A. caninum,Uncinaria stenocephala). Occasionally A. caninum larvae may migrate to the human intestine, causing eosinophilicenteritis. Ancylostoma caninum larvae have also been implicated as a cause of diffuse unilateral subacuteneuroretinitis.Life Cycle (intestinal hookworm infection):
Eggs are passed in the stool , and under favorable conditions (moisture, warmth, shade),larvae hatch in 1 to 2 days. The released rhabditiform larvae grow in the feces and/or thesoil , and after 5 to 10 days (and two molts) they become filariform (third-stage) larvaethat are infective . These infective larvae can survive 3 to 4 weeks in favorableenvironmental conditions. On contact with the human host, the larvae penetrate the skinand are carried through the blood vessels to the heart and then to the lungs. Theypenetrate into the pulmonary alveoli, ascend the bronchial tree to the pharynx, and areswallowed . The larvae reach the small intestine, where they reside and mature intoadults. Adult worms live in the lumen of the small intestine, where they attach to theintestinal wall with resultant blood loss by the host . Most adult worms are eliminated in1 to 2 years, but the longevity may reach several years.Some A. duodenale larvae, following penetration of the host skin, can become dormant (inthe intestine or muscle). In addition, infection by A. duodenale may probably also occur bythe oral and transmammary route. N. americanus, however, requires a transpulmonarymigration phase.Life Cycle (cutaneous larval migrans):
Cutaneous larval migrans (also known as creeping eruption) is a zoonotic infection with hookworm species that donot use humans as a definitive host, the most common being A. braziliense and A. caninum. The normaldefinitive hosts for these species are dogs and cats. The cycle in the definitive host is verysimilar to the cycle for the human species. Eggs are passed in the stool , and underfavorable conditions (moisture, warmth, shade), larvae hatch in 1 to 2 days. The releasedrhabditiform larvae grow in the feces and/or the soil , and after 5 to 10 days (and twomolts) they become filariform (third-stage) larvae that are infective . These infectivelarvae can survive 3 to 4 weeks in favorable environmental conditions. On contact with theanimal host , the larvae penetrate the skin and are carried through the blood vessels tothe heart and then to the lungs. They penetrate into the pulmonary alveoli, ascend thebronchial tree to the pharynx, and are swallowed. The larvae reach the small intestine,where they reside and mature into adults. Adult worms live in the lumen of the smallintestine, where they attach to the intestinal wall. Some larvae become arrested in thetissues, and serve as source of infection for pups via transmammary (and possiblytransplacental) routes . Humans may also become infected when filariform larvae penetrate theskin . With most species, the larvae cannot mature further in the human host, and migrate aimlessly within theepidermis, sometimes as much as several centimeters a day. Some larvae may persist in deeper tissue after finishingtheir skin migration.Geographic Distribution:Hookworm is the second most common human helminthic infection (after ascariasis).Hookworm species are worldwide in distribution, mostly in areas with moist, warm climate.Both N. americanus and A. duodenale are found in Africa, Asia and the Americas. Necator
americanus predominates in the Americas and Australia, while only A. duodenale is found inthe Middle East, North Africa and southern Europe. Page 1 of 2 Life cycleHookworm life cycleSee the image for the biological life cycle of the hookworms where it thrives in warm earthwhere temperatures are over 18°C. They exist primarily in sandy or loamy soil and cannot live inclay or muck. Rainfall averages must be more than 1000 mm (40 inches) a year. Only if theseconditions exist can the eggs hatch. Infective larvae of Necator americanus can survive at highertemperatures, whereas those of Ancylostoma duodenale are better adapted to cooler climates.Generally, they live for only a few weeks at most under natural conditions, and die almostimmediately on exposure to direct sunlight or desiccation.Infection of the host is by the larvae, not the eggs. While A. duodenale can be ingested, the usualmethod of infection is through the skin; this is commonly caused by walking barefoot throughareas contaminated with fecal matter. The larvae are able to penetrate the skin of the foot, andonce inside the body, they migrate through the vascular system to the lungs, and from there upthe trachea, and are swallowed. They then pass down the esophagus and enter the digestivesystem, finishing their journey in the intestine, where the larvae mature into adult worms.Once in the host gut, Necator tends to cause a prolonged infection, generally 1–5 years (manydie within a year or two of infecting), though some adult worms have been recorded to live for15 years or more. On the other hand, Ancylostoma adults are short lived, surviving on averagefor only about 6 months. However, infection can be prolonged because dormant larvae can be"recruited" sequentially from tissue "stores" (see Pathology, above) over many years, to replaceexpired adult worms. This can give rise to seasonal fluctuations in infection prevalence andintensity (apart from normal seasonal variations in transmission).
Civilian Public Service workers built and installed 2065 outhouses for hookworm eradication inMississippi and Florida from 1943 to 1947.They mate inside the host, females laying up to 30,000 eggs per day and some 18 to 54 millioneggs during their lifetime, which pass out in feces. Because it takes 5–7 weeks for adult wormsto mature, mate and produce eggs, in the early stages of very heavy infection, acute symptomsmight occur without any eggs being detected in the patients feces. This can make diagnosis verydifficult.Summary of Biological Life CycleN. americanus and A. duodenale eggs can be found in warm, moist soil where they willeventually hatch into first stage larvae, or L1. L1, the feeding non-infective rhabditoform stage,will feed on soil microbes and eventually molt into second stage larvae, L2. L2, which is also inthe rhabditoform stage, will feed for approximately 7 days and then molt into the third stagelarvae, or L3. L3 is the filariform stage of the parasite, that is, the non-feeding infective form ofthe larvae. The L3 larvae are extremely motile and will seek higher ground to increase theirchances of penetrating the skin of a human host. The L3 larvae can survive up to 2 weekswithout finding a host. While N. americanus larvae only infect through penetration of skin, A.duodenale can infect both through penetration as well as orally. After the L3 larvae havesuccessfully entered the host, the larvae then travel through the subcutaneous venules andlymphatic vessels of the human host. Eventually, the L3 larvae enter the lungs through thepulmonary capillaries and break out into the alveoli. They will then travel up the trachea to becoughed and swallowed by the host. After being swallowed, the L3 larvae are then found in thesmall intestine where they molt into the L4, or adult worm stage. The entire process from skinpenetration to adult development takes about 5–9 weeks. The female adult worms will releaseeggs (N. Americanus about 9,000-10,000 eggs/day and A. duodenale 25,000-30,000 eggs/day)which are passed in the feces of the human host. These eggs will hatch in the environment withinseveral days and the cycle with start anew.
Incubation PeriodThe incubation period can vary between a few weeks to many months and is largely dependenton the number of Hookworm parasites an individual is infected with.