Filariasis is a disease which causes much physical and emotional trauma , but will health authorities do the needful to eradicate it . In India , filariasis is more serious health problem , today than it was 3 decades ago and it is just next only to malaria in incidence . According to the world health organization , India alone accounts for about half of the world’s filarial patients . In India about 45 million are at risk , the disease is specially prevalent in almost all southern states , Maharastra , Madhyapradesh , orissa , West Bengal , Bihar , North eastern states and Uttar Pradesh , with incidence rates starting from 1.25 % India’s rural region records higher rates of incidence.
The disease is also one of the most neglected hidden public health and socio-economic problems , it is a fact that filariasis is a completely curable disease , like goitre, but the epidemiological situation is deteriorating year by year with the filarial infection spreading rapidly to newer parts of the country which shows failure to control the infection in the community .
In India , filariasis is caused by 2 human filarial parasites ( wuchereria bancrofti and brugia malayi ) . The wuchereria bancrofti contributes to about 95 % of filariasis which is transmitted by a mosquito culex fatigans . this disease is neglected because of the fact that it is not a fatal disease like malaria , even though lymphatic filariasis does not prove to be fatal , elephantiasis , one of the chronic manifestations causes physical , psychological and social problems . the infected larvae , following the bite of an infected mosquito , enter the skin and find their way into the lymphatic system where they grow into mature worms .
However , till the adult parasites release microfilariae into the peripheral circulation , nothing is known about their presence in the body , as no clinical symptoms are exhibited in this initial stage of infection . We do not have do not have a test to diagnose this stage of filarial infection .
In India one interesting feature of filariasis caused by wuchereria bancrofti is that the mocrofilariae released by the adults appear in peripheral circulation only at night time with peak levels between 10-12 ‘o clock at night . There fore , the diagnosis of filarial infection which is usually carried out by examination of blood films for microfilariale needs to be carried out only at night time . Diethylcarbamazine ( hetrazan )a highly effective drug is also available if the infection is detected at this stage goes undetected unless specific examination of repeated night blood smears is carried out for microfilariae
Its duration ranges from few months to few years , even in some cases , it may last life long without exhibiting any clinical symptoms , if left untreated
In 50 % cases , the circulating microfilariae slowly disappear from the peripheral circulation even without DEC treatment and after gap of one to a few years , clinical symptoms of filariasis ( for instance ,swelling of lower extremities of the body which ultimately may end up with adenolymphangitis , elephantiasis , hydrocele etc., ) will make their appearances .
It is an interesting observation that the filarial patients with clinical manifestations do not show microfilariae in their circulation and there is no way to detect adult filarial worms in the body .
Control strategies : the national filarial eradication program and world health organization have evolved several control strategies to control and finally eradicate lymphatic filariasis , which include selective and mass chemotherapies and reduction of the vector mosquito population . National health agencies have adopted various control measures which mainly include spraying of organo-phosporous compounds such as DDT and BHC in mosquito breeding and resting sites .these measures however , are becoming unpopular and ineffective because of the growing awareness of public about environmental pollution by residual pesticides and the rapid development of physiological resistances by mosquito population