ENTO 301 –   MEDICAL & VETERINARY ENTOMOLOGY (Lectures 1-5) Dr Terry Olckers School of Biological & Conservation Sciences
Introduction <ul><li>Insects have huge impact on health of humans & domestic animals </li></ul><ul><ul><li>Irritation & di...
Introduction <ul><li>Major insect orders </li></ul><ul><ul><li>Diptera (flies) </li></ul></ul><ul><ul><li>Hemiptera (true ...
Nuisance & phobias <ul><li>Nuisance mostly related to high densities & not real hazards </li></ul><ul><ul><li>Justified in...
Blood-feeding species <ul><li>Cause major annoyance & impacts </li></ul><ul><ul><li>Humans: reduce tourism, outdoor activi...
Immunological reactions <ul><li>Caused by antigens in saliva of ectoparasites </li></ul><ul><li>Long-term exposure to bite...
Phobic responses <ul><li>Some organisms cause fear & panic in humans (snakes, spiders, insects) </li></ul><ul><li>Delusory...
Delusory parasitosis <ul><li>Sufferers seem normal & condition is difficult to diagnose </li></ul><ul><li>Symptoms mimicke...
Insect venoms <ul><li>Best known are social Hymenoptera </li></ul><ul><ul><li>Bees, wasps & ants sting in defence of nests...
Reactions to venom <ul><li>Mostly local inflammatory response </li></ul><ul><li>Systemic allergic reactions after several ...
Toxicity & fatalities <ul><li>Most fatalities caused by honey bees </li></ul><ul><ul><li>Shock from multiple stings </li><...
Other insect toxins <ul><li>Not all toxins inoculated via stings </li></ul><ul><ul><li>Physical contact with body parts, h...
Other insect toxins <ul><li>Body fluids of other beetles have potent toxins </li></ul><ul><ul><li>Certain flea beetles (Ch...
Urticating hairs <ul><li>Larvae (also pupae) of some beetles, butterflies & moths </li></ul><ul><li>Penetrate skin causing...
Venoms & discomfort levels <ul><li>Death in extreme cases </li></ul><ul><ul><li>Mostly due to hypersensitivity & anaphylax...
Arthropod allergens <ul><li>Repeated exposure to allergens (mostly proteins) causes excessive immunological reactions </li...
Arthropods & disease <ul><li>In tropics & subtropics, many arthropod-transmitted pathogens cause disease </li></ul><ul><ul...
Transfer of pathogens <ul><li>Mechanical transfer </li></ul><ul><ul><li>Occurs passively & externally from host to host </...
Transfer of pathogens <ul><li>Biological transfer </li></ul><ul><ul><li>Specific association between vector, pathogen & ho...
Disease control <ul><li>Combination of 3 approaches </li></ul><ul><ul><li>Reduce vector numbers in field (spraying program...
General disease cycles <ul><li>Biologically transferred diseases </li></ul><ul><ul><li>Blood-feeding adult arthropods tran...
Single cycles <ul><li>Pathogen completes life cycle only within vector & human host </li></ul><ul><ul><li>Human malaria (p...
Secondary cycles <ul><li>Pathogen completes life cycle within vector & animal or human host </li></ul><ul><ul><li>Non-huma...
Secondary cycles: yellow fever <ul><li>In Ugandan forests, disease has sylvan (woodland) cycle </li></ul><ul><ul><li>Reser...
Secondary cycles: leishmaniasis <ul><li>In Arabia, sand flies feed on burrowing rodents & transmit protozoan parasites </l...
Disease outbreaks <ul><li>Epidemics = outbreaks in human populations </li></ul><ul><li>Epizootics = outbreaks in animal po...
Pathogens & transmission <ul><li>Pathogens transferred by arthropods </li></ul><ul><ul><li>Viruses (arboviruses) </li></ul...
Pathogens & transmission <ul><li>Pathogens transferred during infective stage & after replication in vectors </li></ul><ul...
Major insect groups <ul><li>Most important taxa </li></ul><ul><ul><li>Order Diptera (flies) – 11 families </li></ul></ul><...
Diptera (flies) <ul><li>Large well-known group </li></ul><ul><ul><li>Thousands of important species </li></ul></ul><ul><li...
Culicidae (mosquitoes) <ul><li>Transmit several parasites </li></ul><ul><ul><li>Protozoa (malaria) </li></ul></ul><ul><ul>...
Culicidae (mosquitoes) <ul><li>Biology </li></ul><ul><ul><li>Almost all blood-sucking; only females take blood; males take...
Culicidae (mosquitoes) <ul><li>2 subfamilies </li></ul><ul><ul><li>Anophelinae </li></ul></ul><ul><ul><ul><li>Genus  Anoph...
Simuliidae (black flies) <ul><li>Females are blood-feeders </li></ul><ul><ul><li>Vicious biters & cause major distress to ...
Simuliidae (black flies) <ul><li>Identification </li></ul><ul><ul><li>Small (2-5 mm) stocky grey-black flies </li></ul></u...
Simuliidae (black flies) <ul><li>Biology </li></ul><ul><ul><li>Aquatic larvae live in fastest flowing parts of streams & r...
Psychodidae (moth flies, sand flies) <ul><li>Mostly harmless, except blood-sucking sand flies (subfamily Phlebotominae) </...
Psychodidae (sand flies) <ul><li>Biology </li></ul><ul><ul><li>Adults hide in hyrax & rat burrows during day; enter houses...
Ceratopogonidae (biting midges) <ul><li>Females of some genera ( Culicoides ) are blood-suckers; males visit flowers </li>...
Ceratopogonidae (biting midges) <ul><li>Biology </li></ul><ul><ul><li>Larvae carnivores or detritivores </li></ul></ul><ul...
Tabanidae (horse flies) <ul><li>Females are voracious blood-feeders </li></ul><ul><ul><li>Serious pests of livestock (suff...
Tabanidae (horse flies) <ul><li>Identification </li></ul><ul><ul><li>Large, stoutly built flies </li></ul></ul><ul><ul><li...
Tabanidae (horse flies) <ul><li>Biology </li></ul><ul><ul><li>Adults feed on nectar & plant juices; females take vertebrat...
Glossinidae (tsetse flies) <ul><li>Single genus ( Glossina ) </li></ul><ul><ul><li>29 species & subspecies groups = 3 ‘spe...
Glossinidae (tsetse flies) <ul><li>Identification </li></ul><ul><ul><li>Medium sized flies with very tough & leathery body...
Glossinidae (tsetse flies) <ul><li>Biology </li></ul><ul><ul><li>Adults active during day </li></ul></ul><ul><ul><li>Occup...
Muscidae (house flies) <ul><li>Large group with many common flies & some important pests </li></ul><ul><ul><li>Nuisance fl...
Muscidae (house flies) <ul><li>Muscinae </li></ul><ul><ul><li>Non-biting species – short fleshy proboscus for mopping up s...
Muscidae (house flies) <ul><li>Stomoxyinae </li></ul><ul><ul><li>Biting species – long piercing mouth parts </li></ul></ul...
Calliphoridae (blow flies) <ul><li>Identification </li></ul><ul><ul><li>Stoutly built flies </li></ul></ul><ul><ul><li>Shi...
Calliphoridae (blow flies) <ul><li>Biology </li></ul><ul><ul><li>Adults attracted to decaying flesh, carrion & faeces; lar...
Sarcophagidae (flesh flies) <ul><li>Identification </li></ul><ul><ul><li>Robust flies with grey & black colour (never meta...
Sarcophagidae (flesh flies) <ul><li>Biology </li></ul><ul><ul><li>Adults feed on decaying organic matter (mostly animal) &...
Gasterophilidae (horse bot flies) <ul><li>Identification </li></ul><ul><ul><li>Adults are dull yellow & bee-like </li></ul...
Gasterophilidae (horse bot flies) <ul><li>Biology </li></ul><ul><ul><li>Eggs laid on host’s fur; near mouth or on forelegs...
Oestridae (warble flies, bot flies) <ul><li>Identification </li></ul><ul><ul><li>Large, stout, hairy flies with large infl...
Oestridae (warble flies, bot flies) <ul><li>Biology </li></ul><ul><ul><li>Larvae are internal parasites of mammals </li></...
Hemiptera (true bugs) <ul><li>Diverse in appearance </li></ul><ul><ul><li>Piercing & sucking mouth parts </li></ul></ul><u...
Cimicidae (bed bugs) <ul><li>Identification </li></ul><ul><ul><li>Small, apricot-coloured & wingless </li></ul></ul><ul><u...
Cimicidae (bed bugs) <ul><li>Biology </li></ul><ul><ul><li>Adults & tiny nymphs hide in day </li></ul></ul><ul><ul><ul><li...
Reduviidae (assassin bugs) <ul><li>Identification </li></ul><ul><ul><li>Large robust bugs = ambush predators of arthropods...
Reduviidae (assassin bugs) <ul><li>Triatominae (kissing bugs) </li></ul><ul><ul><li>Live in woodland & forest habitats </l...
Phthiraptera (lice) <ul><li>Small, flattened & wingless </li></ul><ul><li>Short stout legs; end in strong claws </li></ul>...
Phthiraptera (lice) <ul><li>Biology </li></ul><ul><ul><li>Entire life cycle occurs on host </li></ul></ul><ul><ul><li>Eggs...
Biting lice <ul><li>Mostly associated with birds & don’t attack humans </li></ul><ul><ul><li>Feed on feathers & mostly hos...
Sucking lice  <ul><li>2 important families (attack humans) </li></ul><ul><li>Pthiridae (crab lice, public lice) </li></ul>...
Sucking lice <ul><li>Pediculidae (human lice) </li></ul><ul><ul><li>Elongated lice with abdomen longer & wider than thorax...
Sucking lice <ul><li>Head lice </li></ul><ul><ul><li>Suck blood from scalp & lay eggs on hair </li></ul></ul><ul><ul><li>C...
Siphonaptera (fleas) <ul><li>Small, laterally flattened, wingless insects </li></ul><ul><li>Large hind legs & spectacular ...
Siphonaptera (fleas) <ul><li>Biology </li></ul><ul><ul><li>Eggs are laid in host’s nest or habitat; eggs laid on host will...
Tungidae (jigger or chigger fleas) <ul><li>1 species ( Tunga penetrans ) in SA </li></ul><ul><ul><li>Introduced from South...
Tungidae (jigger or chigger fleas) <ul><li>Tungiasis </li></ul><ul><ul><li>After mating, females become permanently imbedd...
Pulicidae (common fleas) <ul><li>Large diverse family & occurs worldwide </li></ul><ul><ul><li>Most important pests (human...
Pulicidae (common fleas) <ul><li>Economic importance </li></ul><ul><ul><li>Cat flea </li></ul></ul><ul><ul><ul><li>Most co...
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ENTO 301 – MEDICAL & VETERINARY ENTOMOLOGY (Lectures 1-5) ENTO 301 – MEDICAL & VETERINARY ENTOMOLOGY (Lectures 1-5)

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ENTO 301 – MEDICAL & VETERINARY ENTOMOLOGY (Lectures 1-5) ENTO 301 – MEDICAL & VETERINARY ENTOMOLOGY (Lectures 1-5)

  1. 1. ENTO 301 – MEDICAL & VETERINARY ENTOMOLOGY (Lectures 1-5) Dr Terry Olckers School of Biological & Conservation Sciences
  2. 2. Introduction <ul><li>Insects have huge impact on health of humans & domestic animals </li></ul><ul><ul><li>Irritation & diseases </li></ul></ul><ul><li>Relatively few species involved but serious social & economic consequences </li></ul><ul><ul><li>Transmit diseases (vectors) </li></ul></ul><ul><ul><li>Inject venoms & transmit allergens </li></ul></ul><ul><ul><li>Cause wounds </li></ul></ul><ul><ul><li>Create nuisance & phobias </li></ul></ul><ul><li>Other arthropod groups also very important </li></ul>Leishmaniasis Myiasis
  3. 3. Introduction <ul><li>Major insect orders </li></ul><ul><ul><li>Diptera (flies) </li></ul></ul><ul><ul><li>Hemiptera (true bugs) </li></ul></ul><ul><ul><li>Phthiraptera (lice) </li></ul></ul><ul><ul><li>Siphonaptera (fleas) </li></ul></ul><ul><li>Diseases & causative pathogens </li></ul><ul><li>Other arthropod groups </li></ul><ul><ul><li>Acari (ticks & mites) </li></ul></ul><ul><ul><li>Araneae (spiders) </li></ul></ul><ul><ul><li>Scorpiones (scorpions) </li></ul></ul>Protozoan causing sleeping sickness
  4. 4. Nuisance & phobias <ul><li>Nuisance mostly related to high densities & not real hazards </li></ul><ul><ul><li>Justified in case of biting, venomous & filth-frequenting species </li></ul></ul><ul><li>Major causes of nuisance & irritation </li></ul><ul><ul><li>Blood-feeding species </li></ul></ul><ul><ul><li>Lachrymal-feeders </li></ul></ul><ul><ul><li>Immunological reactions </li></ul></ul><ul><ul><li>Phobic responses (delusory parasitosis) </li></ul></ul><ul><li>Large industries are focused on pest control </li></ul>Mosquito feeding frenzy
  5. 5. Blood-feeding species <ul><li>Cause major annoyance & impacts </li></ul><ul><ul><li>Humans: reduce tourism, outdoor activities, land development & land values </li></ul></ul><ul><ul><li>Domestic livestock: death via major blood loss; increases stress & grooming activities; lowers agricultural production </li></ul></ul><ul><li>Main culprits = flies, fleas, lice, bugs, ticks, mites </li></ul>Mosquito Bed bugs
  6. 6. Immunological reactions <ul><li>Caused by antigens in saliva of ectoparasites </li></ul><ul><li>Long-term exposure to bites may lead to no skin reactions </li></ul><ul><li>Host’s immune defences may be neutralized (immunosuppresion) </li></ul><ul><ul><li>Saliva contains additives to aid feeding & pathogen transmission [immunosuppressants + anticoagulants + vasodilators + pain inhibitors] </li></ul></ul><ul><ul><li>Immunosuppressants inhibit production of macrophage molecules that kill pathogens </li></ul></ul>Allergic reaction to flea bite
  7. 7. Phobic responses <ul><li>Some organisms cause fear & panic in humans (snakes, spiders, insects) </li></ul><ul><li>Delusory parasitosis (entomophobia) </li></ul><ul><ul><li>Persistent bites & skin rashes has psychological origin </li></ul></ul><ul><ul><li>Obsessive-compulsive disorder = sensation of insects crawling, biting & burrowing into skin </li></ul></ul><ul><ul><li>Sensation causes chronic itching & mental anguish & self-abuse </li></ul></ul>
  8. 8. Delusory parasitosis <ul><li>Sufferers seem normal & condition is difficult to diagnose </li></ul><ul><li>Symptoms mimicked by several conditions </li></ul><ul><ul><li>Food & skin allergies, drug abuse & medical conditions like diabetes, hepatitis etc </li></ul></ul><ul><ul><li>Infestations of parasitic insects or microscopic mites </li></ul></ul><ul><li>Condition may have genetic basis & could be drug induced </li></ul><ul><li>Treatment usually with drugs </li></ul>Symptoms can be confused with skin allergies
  9. 9. Insect venoms <ul><li>Best known are social Hymenoptera </li></ul><ul><ul><li>Bees, wasps & ants sting in defence of nests </li></ul></ul><ul><ul><li>Venom delivered via modified ovipositor </li></ul></ul><ul><ul><ul><li>Honey-bee stings are barbed & used once (sting + venom sac remain in wound) </li></ul></ul></ul><ul><ul><ul><li>Wasp & ant stings are smooth & used repeatedly </li></ul></ul></ul><ul><ul><ul><li>Some ants have reduced stings & spray venom into wound </li></ul></ul></ul><ul><ul><li>Reactions to venom </li></ul></ul><ul><ul><ul><li>Dermatitis </li></ul></ul></ul><ul><ul><ul><li>Severe neurological & cytological symptoms </li></ul></ul></ul><ul><ul><ul><li>Localized or systemic allergic reactions </li></ul></ul></ul><ul><ul><ul><li>Secondary bacterial infections </li></ul></ul></ul>
  10. 10. Reactions to venom <ul><li>Mostly local inflammatory response </li></ul><ul><li>Systemic allergic reactions after several exposures (hypersensitivity) </li></ul><ul><ul><li>Release of histamine leads to dilation of blood vessels </li></ul></ul><ul><ul><li>Effects include allergic responses, tissue swelling & respiratory problems </li></ul></ul><ul><ul><li>Immediate hypersensitivity (anaphylaxis) can be fatal </li></ul></ul>Systemic response from fire ants Local response from wasp sting
  11. 11. Toxicity & fatalities <ul><li>Most fatalities caused by honey bees </li></ul><ul><ul><li>Shock from multiple stings </li></ul></ul><ul><ul><li>Allergic response (anaphylaxis) from single sting </li></ul></ul><ul><ul><li>In non-sensitized people, LD50 varies </li></ul></ul><ul><ul><ul><li>500 stings for children </li></ul></ul></ul><ul><ul><ul><li>1100 for adult females </li></ul></ul></ul><ul><ul><ul><li>1400 for adult males </li></ul></ul></ul><ul><ul><li>Allergic people must avoid allergens & carry medication </li></ul></ul>
  12. 12. Other insect toxins <ul><li>Not all toxins inoculated via stings </li></ul><ul><ul><li>Physical contact with body parts, haemolymph, poisonous spines & defensive secretions </li></ul></ul><ul><ul><li>Blister beetles (Meloidae) release toxins (cantharidins) when crushed or handled </li></ul></ul><ul><ul><ul><li>Cause blistering of skin </li></ul></ul></ul><ul><ul><ul><li>Cause inflammation of urinary & genital tracts if taken orally (aphrodisiac ‘Spanish fly’) </li></ul></ul></ul>Blister beetle Skin blistering
  13. 13. Other insect toxins <ul><li>Body fluids of other beetles have potent toxins </li></ul><ul><ul><li>Certain flea beetles (Chrysomelidae) that feed on toxic plants are used for arrow poisons by San people </li></ul></ul><ul><ul><li>Some rove beetles of genus Paederus (Staphylinidae) have contact poisons (paederin) that cause blistering & long-lasting ulceration </li></ul></ul>Paederus beetle Ulcers from paederin
  14. 14. Urticating hairs <ul><li>Larvae (also pupae) of some beetles, butterflies & moths </li></ul><ul><li>Penetrate skin causing skin irritations (urtication) </li></ul><ul><li>Structure & function of hairs </li></ul><ul><ul><li>Hollow spines with subcutaneous venom glands </li></ul></ul><ul><ul><li>Setae (bristles & hairs) with irritating toxins </li></ul></ul><ul><li>Retain irritant properties long after being shed </li></ul><ul><ul><li>Intense burning sensation on skin </li></ul></ul><ul><ul><li>Breathing difficulties if inhaled </li></ul></ul><ul><ul><li>Inflammation of mouth & throat if ingested </li></ul></ul>Lonomia achelous
  15. 15. Venoms & discomfort levels <ul><li>Death in extreme cases </li></ul><ul><ul><li>Mostly due to hypersensitivity & anaphylaxis </li></ul></ul><ul><li>Discomfort (pain) lasts for variable periods </li></ul><ul><ul><li>Few hours if Hymenopteran stings </li></ul></ul><ul><ul><li>Few days if urtication </li></ul></ul><ul><ul><li>Few weeks if ulcerated blisters </li></ul></ul>Anaphylaxis = most serious outcome
  16. 16. Arthropod allergens <ul><li>Repeated exposure to allergens (mostly proteins) causes excessive immunological reactions </li></ul><ul><li>Many allergens are airborne & cause respiratory problems </li></ul><ul><li>Allergens found in shed cuticle, faeces, saliva & dead bodies </li></ul><ul><li>Entomologists may develop allergic reactions (rhinitis, asthma) </li></ul><ul><li>Wide diversity of arthropods implicated </li></ul><ul><ul><li>Insect cultures (e.g. mealworms, bloodworms, cockroaches etc) </li></ul></ul><ul><ul><li>Mites in stored products cause ‘baker’s itch’ or ‘grocer’s itch’ </li></ul></ul><ul><ul><li>House-dust mites cause house-dust allergy </li></ul></ul>House-dust allergy is most widespread
  17. 17. Arthropods & disease <ul><li>In tropics & subtropics, many arthropod-transmitted pathogens cause disease </li></ul><ul><ul><li>Protozoa, bacteria, viruses & nematodes </li></ul></ul><ul><li>Arthropods may be causative agent </li></ul><ul><ul><li>Human lice cause pediculosis </li></ul></ul><ul><ul><li>Skin-burrowing mites cause scabies </li></ul></ul><ul><ul><li>Fly maggots invade living flesh (as primary or secondary agents) & cause myiasis </li></ul></ul>Protozoa causing malaria Scabies caused by mites
  18. 18. Transfer of pathogens <ul><li>Mechanical transfer </li></ul><ul><ul><li>Occurs passively & externally from host to host </li></ul></ul><ul><ul><li>Pathogen does not increase inside vector </li></ul></ul><ul><ul><li>House flies & cockroaches transfer bacteria from faeces to human food (on mouthparts, legs & body) </li></ul></ul><ul><ul><li>Arthropods are one of several means; poor public & personal hygiene are main pathways </li></ul></ul>Musca domestica
  19. 19. Transfer of pathogens <ul><li>Biological transfer </li></ul><ul><ul><li>Specific association between vector, pathogen & host </li></ul></ul><ul><ul><li>All 3 components essential </li></ul></ul><ul><ul><li>Pathogen increases inside vector (close specificity between them) </li></ul></ul><ul><ul><li>Arthropod is vital link in disease transmission </li></ul></ul>Malaria cycle
  20. 20. Disease control <ul><li>Combination of 3 approaches </li></ul><ul><ul><li>Reduce vector numbers in field (spraying programmes) </li></ul></ul><ul><ul><li>Disrupt contact between vector & host (pesticides & repellents) </li></ul></ul><ul><ul><li>Attack pathogen inside host (prophylactic drugs) </li></ul></ul><ul><ul><li>Development of vaccines? </li></ul></ul><ul><li>Requires detailed knowledge of biology of vector, pathogen & host (research) </li></ul>
  21. 21. General disease cycles <ul><li>Biologically transferred diseases </li></ul><ul><ul><li>Blood-feeding adult arthropods transmit parasites </li></ul></ul><ul><ul><ul><li>Animal to animal </li></ul></ul></ul><ul><ul><ul><li>Human to human </li></ul></ul></ul><ul><ul><ul><li>Animal to human </li></ul></ul></ul><ul><ul><ul><li>Human to animal (very rare) </li></ul></ul></ul><ul><li>Human diseases have single or secondary cycles </li></ul>
  22. 22. Single cycles <ul><li>Pathogen completes life cycle only within vector & human host </li></ul><ul><ul><li>Human malaria (parasite needs Anopheles mosquitoes & humans) </li></ul></ul><ul><ul><li>Similar malaria parasites infect primates & birds but don’t affect human malaria cycle </li></ul></ul><ul><li>Few human diseases with single cycles </li></ul><ul><ul><li>Need coevolution of vector, pathogen & man </li></ul></ul><ul><ul><li>Man is of recent evolutionary origin; short time for evolution of unique insect-borne diseases that rely on man </li></ul></ul>Anopheles
  23. 23. Secondary cycles <ul><li>Pathogen completes life cycle within vector & animal or human host </li></ul><ul><ul><li>Non-human vertebrates are primary hosts </li></ul></ul><ul><ul><ul><li>Monkeys (yellow fever); rats (plague); desert rodents (leishmaniasis) etc </li></ul></ul></ul><ul><ul><li>Animal diseases that affect man = zoonoses </li></ul></ul><ul><ul><li>Human inclusion in cycle is not essential to maintain disease & animals act as disease reservoirs </li></ul></ul><ul><ul><li>Outbreaks occurs when humans spread into natural ranges of vectors & disease reservoirs </li></ul></ul>
  24. 24. Secondary cycles: yellow fever <ul><li>In Ugandan forests, disease has sylvan (woodland) cycle </li></ul><ul><ul><li>Reservoir = canopy-dwelling primates </li></ul></ul><ul><ul><li>Vector = primate-feeding mosquito ( Aedes africanus ) </li></ul></ul><ul><ul><li>Humans & monkeys coincide at banana plantations near forest </li></ul></ul><ul><ul><li>Second vector ( Aedes bromeliae ) that feeds on both humans & monkeys transmits virus to humans </li></ul></ul>
  25. 25. Secondary cycles: leishmaniasis <ul><li>In Arabia, sand flies feed on burrowing rodents & transmit protozoan parasites </li></ul><ul><ul><li>Disease affects humans when suburban expansion overlaps with rodent reservoir </li></ul></ul><ul><ul><li>No change in vector when humans enter cycle </li></ul></ul><ul><li>Animal reservoirs maintain natural disease cycles & complicate control </li></ul>
  26. 26. Disease outbreaks <ul><li>Epidemics = outbreaks in human populations </li></ul><ul><li>Epizootics = outbreaks in animal populations </li></ul><ul><li>Pandemic = worldwide epidemic </li></ul>
  27. 27. Pathogens & transmission <ul><li>Pathogens transferred by arthropods </li></ul><ul><ul><li>Viruses (arboviruses) </li></ul></ul><ul><ul><li>Bacteria (also rickettsias) </li></ul></ul><ul><ul><li>Protozoan parasites </li></ul></ul><ul><ul><li>Filarial nematode worms </li></ul></ul><ul><li>Need to replicate in vectors & hosts -> complex life cycles </li></ul><ul><li>Parasites generally don’t harm vectors </li></ul><ul><li>Pathogen presence determined by </li></ul><ul><ul><li>Dissection & microscopy </li></ul></ul><ul><ul><li>Biochemical means </li></ul></ul>Filarial nematodes West Nile virus
  28. 28. Pathogens & transmission <ul><li>Pathogens transferred during infective stage & after replication in vectors </li></ul><ul><li>Transfer from vector to host (or vice versa) occurs when blood-feeding arthropod feeds on vertebrate host </li></ul><ul><ul><li>From host to uninfected vector via parasite-infected blood </li></ul></ul><ul><ul><li>From infected vector to host via injection with anticoagulants that keep wound open during feeding </li></ul></ul><ul><li>Transfer may also be via deposition of infected faeces close to wound (gets rubbed in) </li></ul>Blood-feeding Infected faeces
  29. 29. Major insect groups <ul><li>Most important taxa </li></ul><ul><ul><li>Order Diptera (flies) – 11 families </li></ul></ul><ul><ul><li>Order Hemiptera (true bugs) – 2 families </li></ul></ul><ul><ul><li>Order Phthiraptera (lice) – 4 families </li></ul></ul><ul><ul><li>Order Siphonaptera (fleas) – 2 families </li></ul></ul><ul><li>Aspects considered </li></ul><ul><ul><li>Key taxonomic features to aid identification </li></ul></ul><ul><ul><li>General biology & life history </li></ul></ul>
  30. 30. Diptera (flies) <ul><li>Large well-known group </li></ul><ul><ul><li>Thousands of important species </li></ul></ul><ul><li>Adult features </li></ul><ul><ul><li>1 pair of membranous fore-wings </li></ul></ul><ul><ul><li>Hind wings reduced to form halteres </li></ul></ul><ul><ul><li>Mouth parts are proboscus-like for sucking fluids or piercing & sucking for penetrating tissues </li></ul></ul><ul><li>Larval features </li></ul><ul><ul><li>No conspicuous head </li></ul></ul><ul><ul><li>Legless </li></ul></ul><ul><ul><li>Slender bodies with pointed fronts which broaden towards rear </li></ul></ul>Fluid sucking Piercing
  31. 31. Culicidae (mosquitoes) <ul><li>Transmit several parasites </li></ul><ul><ul><li>Protozoa (malaria) </li></ul></ul><ul><ul><li>Filarial worms (elephantiasis) </li></ul></ul><ul><ul><li>Arboviruses (yellow fever, dengue fever, encephalitis) </li></ul></ul><ul><li>Identification </li></ul><ul><ul><li>Long & narrow wings with scales along veins & wing margin </li></ul></ul>
  32. 32. Culicidae (mosquitoes) <ul><li>Biology </li></ul><ul><ul><li>Almost all blood-sucking; only females take blood; males take nectar & plant juices </li></ul></ul><ul><ul><li>Eggs laid in flowing or still water; water collected in containers, tree cavities & leaf axils of plants </li></ul></ul><ul><ul><li>Eggs laid singly or together in floating raft </li></ul></ul><ul><ul><li>Larvae & pupae are aquatic; active swimmers & breathe via siphon tube </li></ul></ul><ul><ul><li>Adults usually close to breeding sites </li></ul></ul>Aquatic larva Blood-feeding females
  33. 33. Culicidae (mosquitoes) <ul><li>2 subfamilies </li></ul><ul><ul><li>Anophelinae </li></ul></ul><ul><ul><ul><li>Genus Anopheles (human malaria) </li></ul></ul></ul><ul><ul><ul><li>Adults rest with abdomen tilted at steep angle to substrate </li></ul></ul></ul><ul><ul><ul><li>Larvae rest horizontally on water surface </li></ul></ul></ul><ul><ul><li>Culicinae </li></ul></ul><ul><ul><ul><li>Genera Aedes & Culex (arboviruses & filarial worms) </li></ul></ul></ul><ul><ul><ul><li>Adults rest with abdomen parallel to substrate </li></ul></ul></ul><ul><ul><ul><li>Larvae hang at angle from water surface </li></ul></ul></ul>Eggs Larvae Pupae Egg raft Adults
  34. 34. Simuliidae (black flies) <ul><li>Females are blood-feeders </li></ul><ul><ul><li>Vicious biters & cause major distress to poultry, livestock & humans </li></ul></ul><ul><ul><li>Cause extreme pain, itching & local tissue swelling </li></ul></ul><ul><ul><li>Vast swarms cause livestock deaths via blood loss, suffocation & trauma </li></ul></ul><ul><ul><li>In tropical Africa, Simulium damnosum transmit filarial worms that cause river blindness in humans </li></ul></ul><ul><ul><li>Also transmit filarial worms, trypanosomes & Leucocytozon disease in poultry </li></ul></ul>
  35. 35. Simuliidae (black flies) <ul><li>Identification </li></ul><ul><ul><li>Small (2-5 mm) stocky grey-black flies </li></ul></ul><ul><ul><li>Humped thorax (buffalo gnats) </li></ul></ul><ul><ul><li>Clear wings without hairs or scales </li></ul></ul><ul><ul><li>In SA most belong to genus Simulium; S.damnosum occurs but not disease </li></ul></ul>
  36. 36. Simuliidae (black flies) <ul><li>Biology </li></ul><ul><ul><li>Aquatic larvae live in fastest flowing parts of streams & rivers </li></ul></ul><ul><ul><li>Larvae attach to rocks & vegetation (via silk & hooks) </li></ul></ul><ul><ul><li>Larvae are filter-feeders using complex labral fans on head </li></ul></ul><ul><ul><li>Pupate on rocks underwater </li></ul></ul><ul><ul><li>Adults may occur several km from water </li></ul></ul>Head fans Aquatic larva
  37. 37. Psychodidae (moth flies, sand flies) <ul><li>Mostly harmless, except blood-sucking sand flies (subfamily Phlebotominae) </li></ul><ul><ul><li>Transmit several pathogens </li></ul></ul><ul><ul><ul><li>Protozoa (leishmaniasis) </li></ul></ul></ul><ul><ul><ul><li>Arboviruses (pappataci fever) </li></ul></ul></ul><ul><ul><ul><li>Bacteria (oroya fever) </li></ul></ul></ul><ul><li>Identification </li></ul><ul><ul><li>Small cryptic flies (2-4 mm) </li></ul></ul><ul><ul><li>Very broad & hairy wings with long parallel veins </li></ul></ul><ul><ul><li>Wings held open over body </li></ul></ul>
  38. 38. Psychodidae (sand flies) <ul><li>Biology </li></ul><ul><ul><li>Adults hide in hyrax & rat burrows during day; enter houses at night to feed </li></ul></ul><ul><ul><li>Adults & larvae live near water </li></ul></ul><ul><ul><li>Larvae live in moist soil or in cracks & crevices where they survive on condensed water </li></ul></ul>
  39. 39. Ceratopogonidae (biting midges) <ul><li>Females of some genera ( Culicoides ) are blood-suckers; males visit flowers </li></ul><ul><ul><li>Painless bite is followed by intense irritation & itchiness </li></ul></ul><ul><li>Identification </li></ul><ul><ul><li>Very small flies (0.5-2mm) </li></ul></ul><ul><ul><li>Grey or yellowish bodies </li></ul></ul><ul><ul><li>Wings folded over body at rest </li></ul></ul><ul><ul><li>Wings have thick radial veins crowded close to wing margin </li></ul></ul>
  40. 40. Ceratopogonidae (biting midges) <ul><li>Biology </li></ul><ul><ul><li>Larvae carnivores or detritivores </li></ul></ul><ul><ul><li>Larvae mostly live in water bodies with high organic content; some live in moist or terrestrial habitats </li></ul></ul><ul><ul><li>Adult females transmit arboviruses in livestock </li></ul></ul><ul><ul><ul><li>Bluetongue virus in sheep </li></ul></ul></ul><ul><ul><ul><li>African horse sickness </li></ul></ul></ul><ul><ul><li>Species that bite humans may transmit filarial worms & viruses </li></ul></ul>Infestation of Culicoides
  41. 41. Tabanidae (horse flies) <ul><li>Females are voracious blood-feeders </li></ul><ul><ul><li>Serious pests of livestock (suffer weight loss) </li></ul></ul><ul><ul><li>Also bite humans </li></ul></ul><ul><ul><li>Transmit several parasites </li></ul></ul><ul><ul><ul><li>Protozoa -> surra (cattle, horses, camels) </li></ul></ul></ul><ul><ul><ul><li>Bacteria -> tularaemia & anthrax (humans) </li></ul></ul></ul><ul><ul><ul><li>Filarial worms -> loiasis (humans) </li></ul></ul></ul>
  42. 42. Tabanidae (horse flies) <ul><li>Identification </li></ul><ul><ul><li>Large, stoutly built flies </li></ul></ul><ul><ul><li>Often have irridescent eyes </li></ul></ul><ul><ul><li>Antennae have 3 segments; 3 rd segment is elongated & annulated </li></ul></ul><ul><ul><li>Wings have large calypters </li></ul></ul><ul><ul><li>Wing veins diverge at wing tip to form an open ‘V’ </li></ul></ul>
  43. 43. Tabanidae (horse flies) <ul><li>Biology </li></ul><ul><ul><li>Adults feed on nectar & plant juices; females take vertebrate blood </li></ul></ul><ul><ul><li>Larvae develop in moist habitats, often in mud at edges of water bodies </li></ul></ul><ul><ul><li>Most larvae feed on decaying plant matter; some are predaceous </li></ul></ul>
  44. 44. Glossinidae (tsetse flies) <ul><li>Single genus ( Glossina ) </li></ul><ul><ul><li>29 species & subspecies groups = 3 ‘species groups’ </li></ul></ul><ul><ul><li>Both sexes are host-specific blood-suckers (bites are painful) </li></ul></ul><ul><ul><li>Transmit protozoans (trypanosomes) </li></ul></ul><ul><ul><ul><li>Sleeping sickness (humans) </li></ul></ul></ul><ul><ul><ul><li>Nagana (livestock) </li></ul></ul></ul>Tsetse bite
  45. 45. Glossinidae (tsetse flies) <ul><li>Identification </li></ul><ul><ul><li>Medium sized flies with very tough & leathery body (survive swatting) </li></ul></ul><ul><ul><li>Flattened body & short forward-pointing proboscus </li></ul></ul><ul><ul><li>Wings folded scissor-like at rest; conceal abdomen </li></ul></ul><ul><ul><li>Wings have ‘hatchet cells’ </li></ul></ul>Hatchet cell
  46. 46. Glossinidae (tsetse flies) <ul><li>Biology </li></ul><ul><ul><li>Adults active during day </li></ul></ul><ul><ul><li>Occupy habitats with trees (e.g. grasslands & woodlands) </li></ul></ul><ul><ul><li>Both sexes feed on large mammals; humans only attacked in absence of game </li></ul></ul><ul><ul><li>Females incubate single maggot in their bodies </li></ul></ul><ul><ul><ul><li>Nourished by ‘milk gland’ </li></ul></ul></ul><ul><ul><ul><li>Larvae pupate in soil; very soon after deposited </li></ul></ul></ul>Typical tsetse habitat
  47. 47. Muscidae (house flies) <ul><li>Large group with many common flies & some important pests </li></ul><ul><ul><li>Nuisance flies </li></ul></ul><ul><ul><li>Mechanical disease transmitters </li></ul></ul><ul><li>Identification </li></ul><ul><ul><li>Thorax lightly striped </li></ul></ul><ul><ul><li>Mostly based on prescence or absence of bristles on thorax </li></ul></ul><ul><li>Biology </li></ul><ul><ul><li>Larvae live in various types of organic matter; manure, garbage, rotting vegetation </li></ul></ul><ul><li>2 important subfamilies </li></ul><ul><ul><li>Muscinae </li></ul></ul><ul><ul><li>Stomoxyinae </li></ul></ul>
  48. 48. Muscidae (house flies) <ul><li>Muscinae </li></ul><ul><ul><li>Non-biting species – short fleshy proboscus for mopping up surface liquids </li></ul></ul><ul><ul><li>Some species extract fluids from human food & faeces (e.g. house fly, Musca domestica ) </li></ul></ul><ul><ul><li>Such species mechanically transfer bacteria & viruses </li></ul></ul><ul><ul><ul><li>Cholera, poliomyelitis, leprosy, typhoid fever, dysentery etc </li></ul></ul></ul><ul><ul><li>Others feed on wounds or run off from wounds </li></ul></ul><ul><ul><li>Some involved in myiasis </li></ul></ul>
  49. 49. Muscidae (house flies) <ul><li>Stomoxyinae </li></ul><ul><ul><li>Biting species – long piercing mouth parts </li></ul></ul><ul><ul><li>Some species are aggressive & persistent blood-suckers (e.g. stable fly, Stomoxys calcitrans ) </li></ul></ul><ul><ul><li>Torment wild & domestic animals (e.g. ears of dogs) </li></ul></ul>Stomoxys calcitrans
  50. 50. Calliphoridae (blow flies) <ul><li>Identification </li></ul><ul><ul><li>Stoutly built flies </li></ul></ul><ul><ul><li>Shiny metallic (blue or green) colour </li></ul></ul><ul><ul><li>Plumose arista (at least 2/3 of length) </li></ul></ul><ul><ul><li>2-3 notopleural bristles </li></ul></ul>
  51. 51. Calliphoridae (blow flies) <ul><li>Biology </li></ul><ul><ul><li>Adults attracted to decaying flesh, carrion & faeces; larvae develop inside </li></ul></ul><ul><ul><li>Other species are involved in myiasis (genera Calliphora , Chrysomyia & Lucilia ) </li></ul></ul><ul><ul><li>Not normally involved with diseases, but may spread bacteria (e.g. anthrax) </li></ul></ul><ul><li>Postive attributes </li></ul><ul><ul><li>Key components in forensic entomology (murder cases) </li></ul></ul><ul><ul><li>Wound treatment (wartime) </li></ul></ul>Pig carcass
  52. 52. Sarcophagidae (flesh flies) <ul><li>Identification </li></ul><ul><ul><li>Robust flies with grey & black colour (never metallic) </li></ul></ul><ul><ul><li>Striped thorax & checkerboard grey pattern on abdomen </li></ul></ul><ul><ul><li>Arista plumose on basal half </li></ul></ul><ul><ul><li>4 notopleural bristles </li></ul></ul>
  53. 53. Sarcophagidae (flesh flies) <ul><li>Biology </li></ul><ul><ul><li>Adults feed on decaying organic matter (mostly animal) & faeces </li></ul></ul><ul><ul><li>Females deposit live larvae in above for further development </li></ul></ul><ul><ul><li>Also involved in myiasis & develop in skin sores of vertebrates </li></ul></ul>
  54. 54. Gasterophilidae (horse bot flies) <ul><li>Identification </li></ul><ul><ul><li>Adults are dull yellow & bee-like </li></ul></ul><ul><ul><li>Short-lived adults lack mouth parts & don’t feed; rarely seen </li></ul></ul><ul><ul><li>Genus Gasterophilus associated with myiasis </li></ul></ul><ul><ul><li>Larvae inhabit guts of large mammals </li></ul></ul><ul><ul><li>Larvae are barrel-shaped & armed with rows of spines </li></ul></ul>Gasterophilus sp.
  55. 55. Gasterophilidae (horse bot flies) <ul><li>Biology </li></ul><ul><ul><li>Eggs laid on host’s fur; near mouth or on forelegs </li></ul></ul><ul><ul><li>Larvae enter mouth of host </li></ul></ul><ul><ul><ul><li>Burrow through skin into mouth </li></ul></ul></ul><ul><ul><ul><li>Eggs are licked & swallowed by host before hatching </li></ul></ul></ul><ul><ul><li>Larvae move to stomach & attach to wall </li></ul></ul><ul><ul><ul><li>Nourished by horse’s blood </li></ul></ul></ul><ul><ul><ul><li>May damage guts & weaken animals </li></ul></ul></ul><ul><ul><li>Mature larvae pass out in faeces & pupate in soil </li></ul></ul>
  56. 56. Oestridae (warble flies, bot flies) <ul><li>Identification </li></ul><ul><ul><li>Large, stout, hairy flies with large inflated head & mottled grey colour </li></ul></ul><ul><ul><li>Adults don’t feed; short-lived & rarely seen </li></ul></ul><ul><ul><li>Larvae are involved with myiasis </li></ul></ul><ul><ul><li>Larvae are white, spiny, barrel-shaped & have black mouth parts </li></ul></ul>
  57. 57. Oestridae (warble flies, bot flies) <ul><li>Biology </li></ul><ul><ul><li>Larvae are internal parasites of mammals </li></ul></ul><ul><ul><ul><li>Nasal cavities of sheep, horses, antelope etc </li></ul></ul></ul><ul><ul><ul><li>Under skin of cattle, antelope, rodents etc </li></ul></ul></ul><ul><ul><li>Skin parasites cause pus-filled boils (warbles) that damage animal hides </li></ul></ul><ul><ul><li>Sheep nasal bot fly ( Oestrus ovis ) </li></ul></ul><ul><ul><ul><li>Living larvae deposited into nostrils; attack to sinus membrane & feed on mucous </li></ul></ul></ul><ul><ul><ul><li>Sneezed out & pupate in soil </li></ul></ul></ul><ul><ul><li>Other species of Oestrus & Gedoelstia live in pulp cavity in horns of antelope & sheep </li></ul></ul>Warbles on cattle Nasal bot larvae
  58. 58. Hemiptera (true bugs) <ul><li>Diverse in appearance </li></ul><ul><ul><li>Piercing & sucking mouth parts </li></ul></ul><ul><ul><li>When present, 2 pairs of wings (hind pair reduced) </li></ul></ul><ul><ul><li>Incomplete life cycle </li></ul></ul><ul><ul><ul><li>Immature stages = nymphs </li></ul></ul></ul><ul><ul><ul><li>Nymphs are mostly small wingless replicas of adults </li></ul></ul></ul><ul><ul><ul><li>No pupal stage </li></ul></ul></ul><ul><li>Of lesser medical importance </li></ul><ul><ul><li>Most are phytophagous or predators of arthropods </li></ul></ul><ul><ul><li>Few blood suckers = 2 families </li></ul></ul>
  59. 59. Cimicidae (bed bugs) <ul><li>Identification </li></ul><ul><ul><li>Small, apricot-coloured & wingless </li></ul></ul><ul><ul><li>Circular body & flattened extensions of prothorax behind eyes </li></ul></ul><ul><li>Medical & veterinary importance </li></ul><ul><ul><li>Most species are ectoparasitic on rodents, poultry, birds & bats </li></ul></ul><ul><ul><ul><li>3 species parasitic on humans </li></ul></ul></ul><ul><ul><ul><li>Cimex lectularius occurs worldwide </li></ul></ul></ul><ul><ul><li>Do not appear to vector any pathogens </li></ul></ul>
  60. 60. Cimicidae (bed bugs) <ul><li>Biology </li></ul><ul><ul><li>Adults & tiny nymphs hide in day </li></ul></ul><ul><ul><ul><li>Any cracks & crevices </li></ul></ul></ul><ul><ul><ul><li>Mattresses, clothing & under wallpaper </li></ul></ul></ul><ul><ul><li>Emerge at night to feed on blood </li></ul></ul><ul><ul><ul><li>Survive without food for several months, but need blood to moult & lay eggs </li></ul></ul></ul><ul><ul><li>Bites are painless; no response during sleep </li></ul></ul><ul><ul><ul><li>Many show allergic reactions (large red discs around bites; swelling & irritation for days) </li></ul></ul></ul><ul><ul><ul><li>High densities can cause anaemia in children </li></ul></ul></ul>Adult & nymphs feeding
  61. 61. Reduviidae (assassin bugs) <ul><li>Identification </li></ul><ul><ul><li>Large robust bugs = ambush predators of arthropods </li></ul></ul><ul><ul><li>Strong recurved beak for biting </li></ul></ul><ul><ul><ul><li>Inject paralytic toxin to subdue prey </li></ul></ul></ul><ul><ul><ul><li>Bite very painful to humans </li></ul></ul></ul><ul><ul><ul><li>No species in SA usually bite mammals </li></ul></ul></ul><ul><li>Medical importance </li></ul><ul><ul><li>South American subfamily Triatominae (kissing bugs) </li></ul></ul><ul><ul><ul><li>Feed on human & animal blood </li></ul></ul></ul><ul><ul><ul><li>Transmit Chagas’ disease </li></ul></ul></ul>
  62. 62. Reduviidae (assassin bugs) <ul><li>Triatominae (kissing bugs) </li></ul><ul><ul><li>Live in woodland & forest habitats </li></ul></ul><ul><ul><li>Colonized human dwellings </li></ul></ul><ul><ul><ul><li>Live in ceilings, cracks & crevices etc. </li></ul></ul></ul><ul><ul><li>Behave like bed bugs & attack humans at night </li></ul></ul><ul><ul><li>Spread protozoans which cause Chagas’s disease (American trypanosomiasis) </li></ul></ul><ul><ul><li>Most notorious species are Triatoma infestans & Rhodnius prolixus </li></ul></ul>Triatoma infestans Rhodnius prolixus
  63. 63. Phthiraptera (lice) <ul><li>Small, flattened & wingless </li></ul><ul><li>Short stout legs; end in strong claws </li></ul><ul><li>Permanent ectoparasites on birds & mammals </li></ul><ul><ul><li>Biting lice </li></ul></ul><ul><ul><ul><li>Biting & chewing mouth parts </li></ul></ul></ul><ul><ul><ul><li>Head is as wide as or wider than thorax </li></ul></ul></ul><ul><ul><ul><li>Previously Suborder Mallophaga; now 3 suborders </li></ul></ul></ul><ul><ul><ul><li>Mostly associated with birds (also mammals) </li></ul></ul></ul><ul><ul><li>Sucking lice </li></ul></ul><ul><ul><ul><li>Piercing & sucking mouth parts </li></ul></ul></ul><ul><ul><ul><li>Head generally narrower than thorax </li></ul></ul></ul><ul><ul><ul><li>Suborder Anoplura </li></ul></ul></ul><ul><ul><ul><li>Associated with mammals (also humans) </li></ul></ul></ul>↙ ↙
  64. 64. Phthiraptera (lice) <ul><li>Biology </li></ul><ul><ul><li>Entire life cycle occurs on host </li></ul></ul><ul><ul><li>Eggs (nits) are cemented onto host’s hair or feathers </li></ul></ul><ul><ul><li>All stages (nymphs & adults are blood sucking </li></ul></ul><ul><ul><li>Transmission via contact between hosts </li></ul></ul><ul><ul><li>Unable to survive for long when off hosts </li></ul></ul><ul><ul><li>Many species are host specific </li></ul></ul><ul><ul><ul><li>Attack one or few related species </li></ul></ul></ul><ul><ul><ul><li>Live in specific region of host’s body </li></ul></ul></ul><ul><ul><ul><li>Identity often indicated by host </li></ul></ul></ul><ul><ul><ul><li>Only 3 species attack humams </li></ul></ul></ul>Louse nit Adults & nymphs
  65. 65. Biting lice <ul><li>Mostly associated with birds & don’t attack humans </li></ul><ul><ul><li>Feed on feathers & mostly host specific </li></ul></ul><ul><li>2 important families </li></ul><ul><ul><li>Menoponidae (biting bird lice) </li></ul></ul><ul><ul><ul><li>Antennae fold into grooves on side of head </li></ul></ul></ul><ul><ul><li>Philopteridae (bird lice) </li></ul></ul><ul><ul><ul><li>Largest family of lice </li></ul></ul></ul><ul><ul><ul><li>Antennae not concealed in grooves in head </li></ul></ul></ul><ul><ul><li>Pests of poultry </li></ul></ul><ul><ul><ul><li>Heavily infested birds become emaciated </li></ul></ul></ul><ul><ul><li>May bite humans when infested birds nest in houses </li></ul></ul>Head of Menoponidae
  66. 66. Sucking lice <ul><li>2 important families (attack humans) </li></ul><ul><li>Pthiridae (crab lice, public lice) </li></ul><ul><ul><li>Broad, flat lice that appear crab-like </li></ul></ul><ul><ul><li>Mid & hind legs are stout with very large claws </li></ul></ul><ul><ul><li>Abdominal segments have distinct lateral lobes </li></ul></ul><ul><ul><li>Single species ( Pthirus pubus ) confined to human pubic region </li></ul></ul><ul><ul><ul><li>Bites cause irritation & typical rash </li></ul></ul></ul><ul><ul><ul><li>Spread by close body contact (usually sex) </li></ul></ul></ul><ul><ul><ul><li>No diseases </li></ul></ul></ul>Crab louse Rash caused by infestation
  67. 67. Sucking lice <ul><li>Pediculidae (human lice) </li></ul><ul><ul><li>Elongated lice with abdomen longer & wider than thorax (no lateral projections) </li></ul></ul><ul><ul><li>All 6 legs are equally strong & developed </li></ul></ul><ul><ul><li>2 species (also called subspecies) </li></ul></ul><ul><ul><ul><li>Pediculus humanus (body louse) </li></ul></ul></ul><ul><ul><ul><li>Pediculus capitis (head louse) </li></ul></ul></ul><ul><ul><ul><li>Very similar but differ in habits </li></ul></ul></ul><ul><ul><ul><li>Annoying pests </li></ul></ul></ul>Head louse Body louse
  68. 68. Sucking lice <ul><li>Head lice </li></ul><ul><ul><li>Suck blood from scalp & lay eggs on hair </li></ul></ul><ul><ul><li>Common & easily spread by close contact, sharing of combs, brushes, hats etc </li></ul></ul><ul><li>Body lice </li></ul><ul><ul><li>Suck blood from body & lay eggs on clothing </li></ul></ul><ul><ul><li>Uncommon & spread by bodily contact, sharing of clothing or bedding </li></ul></ul><ul><ul><li>Vector diseases (epidemic typhus, trench fever, relapsing fever) </li></ul></ul><ul><li>Lousiness related to sanitation </li></ul><ul><ul><li>Crowded conditions </li></ul></ul><ul><ul><li>Long periods without bathing or changing clothes </li></ul></ul>Nits on human hair
  69. 69. Siphonaptera (fleas) <ul><li>Small, laterally flattened, wingless insects </li></ul><ul><li>Large hind legs & spectacular jumps </li></ul><ul><li>Parasitic on birds & mammals </li></ul><ul><ul><li>All adults have piercing & sucking mouth parts & feed on blood </li></ul></ul><ul><ul><li>Females need blood to lay eggs </li></ul></ul><ul><ul><li>Some species are host specific, but most feed on several hosts </li></ul></ul><ul><ul><li>Annoying pests due to blood sucking, skin burrowing & transmission of diseases & parasites </li></ul></ul>
  70. 70. Siphonaptera (fleas) <ul><li>Biology </li></ul><ul><ul><li>Eggs are laid in host’s nest or habitat; eggs laid on host will drop off </li></ul></ul><ul><ul><li>Larvae are slender, whitish & legless (maggot-like) </li></ul></ul><ul><ul><ul><li>Well developed head & 2 small hooks on back end </li></ul></ul></ul><ul><ul><ul><li>Develop off host & feed on organic material in dirt or debris </li></ul></ul></ul><ul><ul><ul><li>After 3 moults, pupate in silken coccons </li></ul></ul></ul><ul><ul><li>Pupae are dormant for several months </li></ul></ul><ul><ul><ul><li>Hatch in response to vibrations from host’s movement </li></ul></ul></ul><ul><ul><li>Adults are very active </li></ul></ul><ul><ul><ul><li>Move freely on host & between hosts </li></ul></ul></ul><ul><ul><ul><li>Can survive off host for long periods </li></ul></ul></ul><ul><ul><li>2 important families (attack humans) </li></ul></ul>
  71. 71. Tungidae (jigger or chigger fleas) <ul><li>1 species ( Tunga penetrans ) in SA </li></ul><ul><ul><li>Introduced from South America in 17 th century & widespread in tropical Africa </li></ul></ul><ul><ul><li>Very small (<1 mm) </li></ul></ul><ul><ul><li>Females burrow into skin of humans & other mammals; usually on feet </li></ul></ul><ul><ul><ul><li>Soft areas between toes </li></ul></ul></ul><ul><ul><ul><li>Under toenails </li></ul></ul></ul><ul><ul><ul><li>Condition called tungiasis </li></ul></ul></ul><ul><ul><li>Males & newly emerged females live like other fleas & feed on various hosts </li></ul></ul><ul><ul><li>No diseases transmitted </li></ul></ul>
  72. 72. Tungidae (jigger or chigger fleas) <ul><li>Tungiasis </li></ul><ul><ul><li>After mating, females become permanently imbedded in skin </li></ul></ul><ul><ul><ul><li>Breathe, defecate & expel eggs through small opening at back end </li></ul></ul></ul><ul><ul><ul><li>Abdomen becomes greatly distended as eggs develop (swells to size of small pea) </li></ul></ul></ul><ul><ul><li>Host tissue becomes inflamed & swells to form boil-like sore </li></ul></ul><ul><ul><ul><li>Cause intense itching & bacterial infection </li></ul></ul></ul><ul><ul><ul><li>Sores may develop into bad lesions </li></ul></ul></ul><ul><ul><ul><li>Can cause loss of digits, septicaemia & lameness </li></ul></ul></ul><ul><ul><li>Less of problem today; many areas in South America still affected </li></ul></ul>
  73. 73. Pulicidae (common fleas) <ul><li>Large diverse family & occurs worldwide </li></ul><ul><ul><li>Most important pests (humans & animals) </li></ul></ul><ul><ul><li>Disease vectors </li></ul></ul><ul><ul><li>Mostly generalists (attack humans & animals), but often named after principle host </li></ul></ul><ul><ul><li>Many pest species occur worldwide </li></ul></ul><ul><ul><ul><li>Cat flea ( Ctenocephalides felis ) </li></ul></ul></ul><ul><ul><ul><li>Dog flea ( Ctenocephalides canis ) </li></ul></ul></ul><ul><ul><ul><li>Human flea ( Pulex irritans ) </li></ul></ul></ul><ul><ul><ul><li>Oriental rat flea ( Xenopsylla cheopis ) </li></ul></ul></ul>Flea bites Human flea
  74. 74. Pulicidae (common fleas) <ul><li>Economic importance </li></ul><ul><ul><li>Cat flea </li></ul></ul><ul><ul><ul><li>Most common in houses in SA </li></ul></ul></ul><ul><ul><li>Sticktight hen flea ( Echidnophaga gallacea ) </li></ul></ul><ul><ul><ul><li>Adults attach in tick-like manner & form dense clusters on faces & combs of chickens </li></ul></ul></ul><ul><ul><ul><li>Cause irritation & reduce growth & reproduction in bad cases </li></ul></ul></ul><ul><ul><li>Oriental rat flea </li></ul></ul><ul><ul><ul><li>Transmits bubonic plague & murine typhus to humans </li></ul></ul></ul><ul><ul><li>Dog flea </li></ul></ul><ul><ul><ul><li>Intermediate host for dog tapeworm </li></ul></ul></ul><ul><ul><li>Rabbit flea ( Spilopsyllus cuniculi ) </li></ul></ul><ul><ul><ul><li>Transmits myxoma virus which causes myxomatosis in rabbits </li></ul></ul></ul><ul><ul><ul><li>Virus used for biological control of rabbits in Australia & UK </li></ul></ul></ul>Oriental rat flea

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