DENGUE FEVER FACT SHEET DENGUE FEVER Dengue fever is a relatively common problem that periodically reaches epidemic The most useful laboratory test in suspected DHF is the estimation of proportions, usually every 4-5 years. Dengue occurs due to infection by a FLAVIVIRUS, thrombocytes (platelets) which will be very low. In contrast to uncomplicated which is transmitted by the bite of the Aedes aegypti mosquito. It is very rarely fatal in dengue fever the white cell count is more often high in patients with DHF. healthy and fit individuals. The patient is often left debilitated and requires considerable convalescence. Dengue is not transmitted from person to person. PREVENTIVE MEASURES AGAINST MOSQUITOS Recurrent infections with Dengue fever, especially when they are from different strains of All varieties of mosquitoes breed in or near water that is stagnant or slow moving. the Flavivirus, are associated with a higher risk of complications, in particular Dengue The importance of mosquitoes in transmission of disease makes adequate control Haemorrhagic shock syndrome (covered later in this bulletin). of mosquito-breeding sites very important, especially those close to human habitation. Personal protective measures can greatly reduce the risk of being bitten. 1. The use of mosquito deterrents in bedrooms is effective to reduce the number of mosquitoes in the room, but it does not prevent mosquito bites all together. The chemical deterrent is released through an electronically heated impregnated pad or gel, and its effectiveness depends largely on the size and ventilation of the room. 2. Correct use of mosquito nets (essential if accommodation is not air- conditioned). For added protection for up to 3 months or longer, mosquito nets can be soaked in 1 % solution of PERMETHRIN (or other repellent / insecticide). If resident in a dengue or malaria affected areas, curtains can be treated in a similar manner. Windows can be closed with fine insect SYMPTOMS screens, which may or may not be treated with PERMETHRIN, to keep Following an incubation period of 2 - 14 days (usually 4 - 8), the onset of symptoms is mosquito away from bedrooms. usually abrupt with chills, headache, backache, weakness and pain behind the eyes. The 3. Use of mosquito coils and "knockdown spray" (containing pyrethoids) - joint and back pains can be very bad indeed; hence the older name 'backbone fever'. The spray insecticide in cool dark places where mosquitoes lurk. After spraying temperature rapidly rises, often to 40°C (104°F), and there is a low heart rate (compared do not enter the room and keep all doors and windows closed. to the other causes of high fever). The blood pressure is often also low. 4. Avoid use of dark coloured clothing, perfumes and colognes as all these attract mosquitoes, especially at night. 5. Use of an effective mosquito repellent on exposed skin and clothing if you are sitting outside. DEET (diethylmethylbenzamide) is still an effective safe The rash is component of good repellents. The actual concentration of DEET varies made up of widely between different manufacturers, and can be as high as 90% (too small red high for safety). Choose a repellent with between 30-45% DEET and take dots the following precautions against adverse reactions: a. apply sparingly and only to exposed skin b. never apply high concentrations to skin (use those for clothing) c. do not inhale / swallow repellent or get in eyes or mucous membranes d. do not apply to hands that may touch eyes or mouth After 2 - 4 days, a temporary improvement can occur with a sudden drop in temperature e. do not apply to wounds, rashes, or abrasions and subjective improvement, usually for 24 hours until there is a second rapid f. wash repellent off after coming indoors to stay temperature rise, and the appearance of a characteristic rash on the trunk, limbs, palms g. if skin starts to burn, wash repellent off and seek medical advice and soles especially. The skin in these areas turns bright red (the rash is usually a series 6. DEET-based repellents should last for up to 4 hours. of dots) and may peel. (This second phase of fever does not always occur). Thereafter there is slow improvement. An attack produces immunity for a year or more, but only to DESTROY MOSQUITOES AND THEIR LARVAE (YOUNG). the one of the four FLAVIVIRUS strains responsible. • Clear the neighbourhood of ponds & pits. • Cover all water containers and any objects that can trap rain water (tires, CONFIRMING THE DIAGNOSIS pots, rubbish piles) There are no immediate useful tests for diagnosing dengue fever. The white blood cell • Filling or drain areas of stagnant water except for swimming pools and count is often low unlike in bacterial causes of fever. The dengue antibody test can give ornamental pools if they are aerated by a pump or fountain or similar. both false positive and false negative results, especially in the first week of the disease. • Use of mosquito larvicides (ABATE) or mosquito larvae-eating fish in waters The diagnosis will, in a large proportion of cases, be based on clinical presentation and a that cannot be drained. characteristic drop of platelets in the blood. • Installation of mosquito screens on doors and windows and mosquito nets on Convalescence can take weeks, and bed rest and fever lowering medications are required. beds. Do not use Asprin. • Change water in flower pots once a week and wash them thoroughly. Do not let plants stand in trays containing water. Scrub trays weekly to get rid of any DENGUE HAEMORRHAGIC FEVER (DHF) mosquito eggs. A rare complication of dengue fever, dengue haemorrhagic fever, can occur, most often in • Cover all water containers and eliminate objects that can trap rainwater. This small children and elderly adults. This can sometimes be a serious illness. If DHF occurs includes areas underneath elevated walkways and accommodations. it will usually do so by day 3-5 of the fever. • Avoid the uncontrolled use of residual and space insecticides, and the use of toxic materials. It has been suggested that DHF is more likely if the patient has previously had an attack of dengue within the last calendar year, and that the occurrence of DHF relates to this • Fogging is effective to kill mosquitoes but does not kill larvae. Fogging will not previous exposure. The relationship between DHF and previous dengue infection is not stop mosquitoes entering your premises, however, it may deter them from this clear-cut, however previous exposure does raise the incidence of subsequent DHF, in establishing breeding grounds at premises where fogging is performed. particular when this involves different strains of the virus. Do not allow indiscriminate use of insecticides unless possible risks of their use SYMPTOMS OF DHF are clearly understood. Know what you are doing and / or what chemical is being Uncontrolled bleeding distinguishes this from uncomplicated dengue fever. Bleeding can used. occur from the gums, nose, intestine, or under the skin as bruises or spots of blood especially under a tourniquet - this test should be employed if there is any suspicion. The Dr. Uwe Stocker, liver is often enlarged. Medical Advisor Patients can have rapid onset of marked drowsiness, lethargy or restlessness or the International SOS, Jakarta presence of shock as manifested by a rapid and weak pulse, low blood pressure and cold clammy skin. Such patients should be immediately referred to a good hospital for further Should you wish to arrange a briefing on Dengue Fever for your management. DHF shock can be a mortal illness and requires rapid and careful in- company employees and/or families, please contact the Sales and hospital management with replacement of fluid, electrolytes, plasma and sometimes fresh Marketing department at International SOS on (21) 750 5973 blood / platelet transfusions. (Jakarta) or (361) 710 505 (Bali) to arrange a quotation. The briefing can be provided in Bahasa Indonesia or English.