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Epidemiology and control of filariasis-
- 1. Epidemiology and Control ofFilariasis ABU UBAIDA FAZAA ABDULRAZZAQ DONE BY:
- 2. What is LymphaticFilariasis
- 3. What is LymphaticFilariasis Lymphatic filariasis is a vector-borne parasitic disease that is endemic in many tropical and subtropical countries. The disease is caused by thread-like, parasitic filarial worms: Wuchereria bancrofti, Brugia malayi, and Brugia timori. W. bancrofti is most widely spread and is responsible for more than 90% of the infections.
- 4. Classification Can be classifieddepending on their habitat in human tissues Lymphatic filariasis Body cavity filariasis Connective tissue filariasis
- 5. Most Important Filariae Species Geographic distribution Pathogenicity siteof infection Microfilariae (characteristics) Vector Wuchereria bancrofti Asia, Pacific, Tropical Africa, Americas Lymphangitis, fever, elephantiasis hydrocoele, and chyluria Lymphatics Found in blood, sheathed, periodicity variable Culicidae (mosquitoes) Brugia malayi South and East Asia Lymphagitis, fever, and Elephantiasis Lymphatics Found in blood, sheathed, nocturnally periodic or subperiodic Culicidae (mosquitoes)
- 6. LIFE CYCLE Theadult worms (macrofilaria) are located in the lymphatic system of the human host, where they live for 5-10 years. During their lifespan, after mating, female worms bring millions of immature microfilariae (mf) into the blood. Some of these mf may be engorged by mosquitoes taking a blood meal. Inside a mosquito, mf develop in about 12 days into L3 stage larvae (L3). These L3 are infectious to human: they can enter the human body when a mosquito takes a blood meal. Some will migrate to the lymphatic system and develop into mature worms.
- 7. LIFE CYCLE Maturationtakes 6-12 months. Mf cannot develop into adult worms without passing through the developmental stages in the mosquito. life span of mf in the human body is estimated at 6-24 months.
- 9. WHY FILARIASIS NEVERCAUSES EXPLOSIVE EPIDEMICS There are three reasons 1- The parasite does not multiply in the insect vector. 2- The infective larvae do not multiply in the human host. 3- The life cycle of the parasite is relatively long, 15 years or more. These factors favor the success of a control program.
- 10. Symptoms Most peopleinfected with Brugian or Bancroftian filariasis in endemic areas are asymptomatic, since the development of symptoms relates to the cumulative acquisition of increasing numbers of worms. The clinical course of lymphatic filariasis includes three distinct phases: 1. Asymptomatic microfilaremia. 2. Acute episodes of adenolymphangitis (ADL). Which is reversible. 3. Chronic lymphedema disease (irreversible lymphedema), which is often superimposed upon repeated episodes of ADL.
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- 12. Parasites White, slender,roundworms. Three types. the most common are: Wuchereria bancrofti. Brugia malayi. Brugia timori. Live for 5-7 years, produce millions of microfilaria.
- 13. EPIDEMIOLOGY W. bancroftioccurs in the following regions: Africa, Southeast Asia, the Indian subcontinent, many of the Pacific islands, and focal areas in Latin America. B. malayi occurs mainly in China, India, Malaysia, the Philippines, Indonesia, and various Pacific islands. B. timori is limited to the Timor Island of Indonesia.
- 14. EPIDEMIOLOGY It isestimated that more than 120 million people worldwide are infected with one of these three microfilariae. More than 90 percent of these infections are due to W. bancrofti, and the remainder are mostly due to B. malayi. Estimates suggest that more than 40 million infected individuals are seriously incapacitated and disfigured by the disease.
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- 16. Control How canthe menace of filariasis be controlled? Addition of DEC to salt for mass treatment: It is also a cheap and safe method. Common salt medicated with 1–4 g of DEC per kg. Mosquito control measures: This is achieved by spraying insecticides which are lethal to the larvae of the mosquitoes. Environmental issues in the control of filariasis: The filariasis problem largely arises as a result of poor sanitation and hygiene. The emphasis should be on improving existing sanitary conditions. In the case of Mansonia mosquitoes, breeding is best controlled by removing supporting aquatic vegetation such as the Pistia plant from all water collections and converting the ponds to fish or lotus culture. Larvicidal operations are complemented activities such as filling up of ditches and cesspools, drainage of stagnant water, adequate maintenance of septic tanks and soakage pits etc.
- 17. Control Filarial Surveys:Firstly, in order to control the disease, an estimate of the problem by conducting surveys has to be undertaken. There are many elements in the survey. The survey can either entail the examination of patients for the symptoms of filariasis, or the examination of blood samples, particularly at night time to demonstrate the parasite. Many times, the parasite is difficult to detect in the blood, and tests which measure antibodies against the parasite may have to be employed. Entomological survey: This comprises general mosquito collection from houses, dissection of female vector species for detection of developmental forms of the parasite, a study of the extent and type of breeding places. The data is assembled, analyzed and used for the compilation of certain filarial statistics.
- 18. Control Preventive measures fortravelers: Avoid outbreaks: Travelers should avoid known foci of epidemic disease transmission. Be aware of peak exposure times and places. Wear appropriate clothing: Travelers can minimize areas of exposed skin by wearing long- sleeved shirts, long pants, boots, and hats.
- 19. Control Check forticks: Travelers should inspect themselves and their clothing for ticks during outdoor activity and at the end of the day. Bed nets: Bed nets are essential in providing protection and reducing discomfort caused by biting insects. Insecticides and spatial repellents: These products, containing active ingredients that help kill the mosquitos. Optimum protection can be provided by applying the repellents to the exposed skin.
- 20. TREATMENT Diethylcarbamazine —DEC with or without corticosteroieds. Ivermectin — Studies have established that ivermectin given as a single dose in Bancroftian filariasis reduces microfilaremia by approximately 90 percent even one year after treatment. Albendazole — has also been used in filarial infections. Prolonged courses of high dose albendazole have a significant macrofilaricidal effect and result in a gradual decrease in microfilarial levels. Doxycycline — Initial studies suggested that doxycycline, which has good activity against filaria spp, leads to sterility of adult worms.
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