BEJAR , MALAIKAG A B A L DON, V A N ES S A CEL I N E PD2F
WHAT IS DENGUE? Dengue fever is a disease caused by a family of viruses ( genus Flavivirus, family Flaviviridae) that are transmitted by mosquitoes ( Aedes aegypti). It is an acute illness of sudden onset that usually follows a benign course with symptoms such as headache, fever, exhaustion, severe muscle and joint pain, swollen glands (lymphadenopathy), and rash.
CAUSES OF DENGUE There are four Dengue viruses (DENV) that cause Dengue fever, all of which are spread by a species of mosquito known as the Aedes aegypti mosquito, and more rarely by the Aedes albopictus mosquito. Aedes aegypti originated in Africa, but nowadays is found in all the tropical areas around the world and prospers in and close to areas of human population. The virus is transmitted from an infected mosquito to human. The process begins when a person who is infected with the Dengue virus is bitten by a mosquito, the virus is then passed on when someone else is then bitten by the infected mosquito.
Signs and SymptomsMild Dengue Fever - symptoms can appear up toseven days after the mosquito carrying the virusbites, and usually disappear after a week. This form of thedisease hardly ever results in serious or fatalcomplications. The symptoms of mild dengue fever are: Aching muscles and joints Body rashes that can disappear and then reappear High fever Intense headache Pain behind the eyes Vomiting and feeling nauseous
Dengue hemorrhagic fever(DHF) - symptoms during onset may be mild, butgradually worsen after a number of days. DHF canresult in death if not treated in time. Mild denguefever symptoms may occur in DHF, as well as theones listed below:•Bleeding from your mouth/gums•Nosebleeds•Clammy skin•Considerably damaged lymph and blood vessels•Internal bleeding, which can result in black vomit and feces (stools)•Lower number of platelets in blood - these are the cells that helpclot your blood•Sensitive stomach
Dengue shock syndrome This is the worst form of dengue which canalso result in death, again mild dengue fever symptoms may appear, but others likely to appear are: •Intense stomach pain •Disorientation •Sudden hypotension (fast drop in blood pressure) •Heavy bleeding •Regular vomiting •Blood vessels leaking fluid •Death
MODE OF TRANSMISSIONBites from infected females ofcertain Aedes mosquito species. Ae. aegypti is themajor vector of dengue; Aedes albopictus can alsotransmit DENV, but much less efficiently than Ae.aegypti .Ae. aegypti is a very domesticated, urban mosquitofound in the tropics and subtropics, and in Australiais currently confined to Queensland; it usually breedsin man-made containers and prefersindoor, sheltered, dark resting sites. Humans are thepreferred source of blood meals for female Ae.aegypti ; they are day-biting mosquitoes.
Ae. albopictus is a peri-domestic mosquitofound not only in the tropics and subtropicsbut also some temperate regions. It is anaggressive coloniser, but in Australia iscurrently confined to the Torres Strait. Itbreeds not only in artificial containers butalso in some naturally occurring sites suchas tree holes and coconut shells. Adultsprefer heavily-shaded outdoor resting sites;the female takes blood from a wide range ofmammals. It is an aggressive day -bitingmosquito.
PERIOD OF COMMUNICABILITY, RESISTANCE AND SUSCEPTIBILITYA human case is infective to mosquitoes fromshortly before, until the end of the period ofsymptomatic viraemia; usually 4 - 5 days, butcan be longer.For public health purposes, the duration ofviraemia is assumed to be from one day beforeuntil 12 days after the onset of symptoms .
There is no direct person to persontransmission, but transfusionrelated cases can occur.Susceptibility to primary infectionappears universal. Recovery frominfection with one DENV serotypeprovides lifelong immunity againstthat serotype, but only short-termprotection against other serotypes.
Antibody dependent enhancement (ADE) isan immunological phenomenon believed tobe responsible for the pathogenesis ofplasma leakage, a potentially severemanifestation of dengue. In brief, followinginfection with a particular DENVserotype, the cross-protection against otherserotypes wanes after several months; atsome point the previously protected personhas, through ADE, an increased risk ofdeveloping severe dengue following asecondary infection (from another DENVserotype).
It is hypothesized that ADE occurs inthe secondary infection when pre-existing, but no longerprotective, antibodies enhance thebinding of the (secondary) virus tomacrophages and monocytes, leading toincreased virus replication in thesecells. This, in turn, leads to complementactivation and the release of variouscytokines that target vascularendothelial cells, resulting in the leakof plasma and protein.
Treatment for Dengue There is no tested and approved vaccine for the dengue flavivirus. There is no specific medicine or antibiotic to treat it. For typical dengue, the treatment is purely concerned with relief of the symptoms (symptomatic). Close monitoring of vital signs in the critical period
Rest and fluid intake for adequate hydration is important. Supplementation with intravenous fluids may be necessary to prevent dehydration and significant concentration of the blood if the patient is unable to maintain oral intake. Acetaminophen (Tylenol) and codeine may be given for severe headache and for the joint and muscle pain (myalgia)
Platelettransfusion may be indicated if the platelet level drops significantly (below 20,000) or if there is significant bleeding The presence of melena may indicate internal gastrointestinal bleeding requiring platelet and/or red blood cell transfusion. Aspirinand non-steroidal inflammatory drugs should be avoided as these drugs may worsen the bleeding tendency
METHODS OF CONTROL•preventing mosquitoes from accessing egg-laying habitats by environmentalmanagement and modification;•disposing of solid waste properly andremoving artificial man-made habitats;•covering, emptying and cleaning ofdomestic water storage containers on aweekly basis;•applying appropriate insecticides to waterstorage outdoor containers;
• using of personal household protection such as window screens, long-sleeved clothes, insecticide treated materials, coils and vaporizers;• improving community participation and mobilization for sustained vector control;• applying insecticides as space spraying during outbreaks as one of the emergency vector control measures;• active monitoring and surveillance of vectors should be carried out to determine effectiveness of control interventions.
PROGENY FOR PREVENTION Clothing - your chances of being bitten are significantly reduced if you expose as little skin as possible. When in an area with mosquitoes, be sure to wear long trousers/pants, long sleeved shirts, and socks. For further protection, tuck your pant legs into your shoes or socks. Wear a hat. Mosquito repellants - be sure to use one with at least 10% concentration of DEET, you will need a higher concentration the longer you need the protection, avoid using DEET on young children. Use mosquito traps and nets - studies have shown that the risk of being bitten by mosquitoes is considerably reduced if you use a mosquito net when you go to sleep Smell - Avoid wearing heavily scented soaps and perfumes.
Windows- use structural barriers, such as window screens or netting. Camping - if you are camping, treat clothes, shoes and camping gear with permethrin. There are clothes which have been treated with permethrin. Certaintimes of day - try to avoid being outside at dawn, dusk and early evening. Stagnant water - the Aedes mosquito prefers to breed in clean, stagnant water. It is important to frequently check and remove stagnant water in your home/premises.