Filariasis

The value of insecticides in controlling human and animal diseases spread by insects has been dramatic. It has been shown that between 1942 and 1952, the use of DDT in pubHc health measures to control the mosquito vectors of malaria and the human body louse vector of typhus saved five million hves and prevented 100 million illnesses (4). Insecticides have provided the means to control such important human diseases as filariasis transmitted by Culex mosquitoes and onchocerciasis transmitted by Simulium blackflies. 

Eqvalan, off-white powder, mp 4 p-g/mL water. filariasis Onchocerca 15... 

Many parasitic worms cause systemic infections outside the gastrointestinal tract. These include Strong loides stercoralis (threadworm), Trichinella spiralis Dracunculus medinensis and the several species of nematodes that cause filariasis (Mansonellaperstans and Onchocerca volvulus). 

Diethylcarbama2iae (9) (orally administered) has been successful for decades in the treatment of filariasis, eg, elephantiasis (32). It kills microfilariae in the blood of the filarial worms Wuchereria bancrofti Brugia malaji and lj)a loa. 

Diethylcarbama2iae has limited antimicrofilarial activity against Onchocerca volvulus. Adults of W. bancrofti the filarial worm causiag elephantiasis, coil in the lymph system. Here females can attain a length of 10 cm. Over the years, tissue reactions result in obstmction to lymph return. Lymph nodes, lymph vessels, and the spleen become enlarged. The condition of elephantiasis is a late and unusual complication of filariasis, where the lower extremities of the body become edematous, enlarge, and over a period of time harden with a rough nodular skin. 

Mansonellaperstans adult worms five encysted in various peritoneal tissues (eg, pericardium, pleura, and peritoneum). Af. perstans microfilariae are not affected by diethylcarbama2ine but mebenda2ole has been successful in treating Af. perstans filariasis (33). 

Two forms of lymphatic filariasis are found in India. The Bancroftian form is the most common and accounts for more than 90% of the disease whereas Bmgian filariasis accounts for the rest. In a study carried out in India (6) in 40 patients with Wuchereria Bancwfti filariasis treated with single oral doses, all of the dose levels chosen (25, 50, 100, and 200 mg/kg) were efficacious in clearing microfilariae from the blood of all patients treated. However, after three months some microfilaria recurred in the blood of most patients (Table 5). Further studies are planned and some are underway using different doses and regimens. Ivermectin still appears to hold promise as a new treatment for lymphatic filariasis. 

Table 5. Efficacy of Ivermectin in the Treatment of Wuchereria Filariasis...

Diseases which will probably be subject to control by insecticides but have not yet been adequately tested include sandfly fever, dengue, urban yellow fever, bartonellosis, cutaneous leishmaniasis, Chagas disease, filariasis, trench fever, and louse-born relapsing fever. Some of the virus encephalitides. sleeping sickness, and visceral leishmaniasis may also be susceptible of control. 

Filariasis (but not thick) in alcohol before it is sent. Send 5 ml of citrate- or EDTA-anticoa-... 

Trypanosomiasis gulated blood on ice (not frozen). Unfixed thick films may be sent in addition. Send serum for serologic tests. Send 5 ml of anticoagulated blood as for filariasis (above). 

Freedman, D.O. (1998) Immune dynamics in the pathogenesis of human lymphatic filariasis. Parasitology Today 14, 229-234. 

Harada, R., Maeda, T., Nakashima, A., Sadakata, M., Ando, M., Yonomine, K., Otsuji, Y. and Sato, H. (1970) Electron-microscopical studies on the mechanism of oogenesis in Dirofilaria immitis. In Sasa, M. (ed.) Recent Advances in Researches on Filariasis and Schistosomiasis in Japan. Baltimore University Press, Baltimore, Maryland, pp. 99-121. 

Hoerauf, A., Volkmann, L., Hamelmann, C., Adjei, O., Autenrieth, I.B., Fleischer, B. and Buttner, D.W. (2000a) Endosymbiotic bacteria in worms as targets for a novel chemotherapy in filariasis. Lancet 355, 1242-1243. 

Turner, P.F., Rockett, K.A., Ottesen, E.A., Francis, H., Awadzi, K. and Clark, I.A. (1994) Interleukin-6 and tumor necrosis factor in the pathogenesis of adverse reactions after treatment of lymphatic filariasis and onchocerciasis. Journal of Infectious Diseases 169, 1071-1075. 

Maizels, R.M., Sartono, E., Kurniawan, A, Partono, F., Selkirk, M.E. and Yazdanbash, M. (1995) T-cell activation and the balance of antibody isotypes in human lymphatic filariasis. Parasitology Today 11, 50-56. 

Freedman D.O., Nutman, T.B. and Ottensen, E.A. (1989) Protective immunity in bancroftian filariasis. Selective recognition of a 43-kDa larval stage antigen by infection-free individuals in an endemic area. Journal of Clinical Investigation 83, 14-22. 

Fuhrman, J.A. (1995a) Filariasis the role of chitinase in larval development and transmission. In Komuniecki, R. (ed.) Molecular Approaches to Parasitology. Wiley-Liss, New York, pp. 77-87. 

Fuhrman, J.A., Lane, W.S., Smith, R.F., Piessens, W.F. and Perler, F.B. (1992) Transmission-blocking antibodies recognize microfilarial chitinase in Brugian lymphatic filariasis. Proceedings of the National Academy of Sciences USA 89, 1548-1552. 

AlQaoud, KM., Fleischer, B. and Hoerauf, A. (1998) The Xid defect imparts susceptibility to experimental murine filariasis - association with a lack of antibody and IL-10 production by B cells in response to phosphorylcholine. International Immunology 10, 17—25. 

Kazura, J.W., Nutman, T.B. and Greene, B. (eds) (1993) Filariasis. Blackwell Scientific Publications, Oxford. 

King, C.L. and Nutman, T.B. (1991) Regulation of the immune response in lymphatic filariasis and onchocerciasis. Immunology Today 12, A54-58. 

Maizels, R.M. and Lawrence, R.A. (1991) Immunological tolerance the key feature in human filariasis Parasitology Today 7, 271-276. 

Arsenic effectively controls filariasis in cattle new protective uses are under investigation. The control of parasitic nematodes (Parafllaria bovicola) in cattle was successful after 30 weekly treatments in plungement dips containing 1600 mg As203/L. However, the muscle of treated cattle... 

One likely reason for the prevalence of helminths is their undoubted ability to down-regulate the host immune system at both the antigen-specific and polyclonal levels [3], In many chronic diseases, such as schistosomiasis and lymphatic filariasis, peripheral blood T cells show dramatically impaired parasite antigen-specific responsiveness [4], as discussed in more detail below. Moreover, from early reports of immunosuppression in animal models of infection, to studies in Africa linking vaccine failure to heavy helminth infection, there is clear evidence that infections can diminish reactivity to bystander antigens, particularly with increasing intensity of... 

Our perspective is thus one of general significance to chronic infection, as well as one that will provide specific pathways to novel treatments of human schistosomiasis, and lymphatic filariasis. These two diseases represent a massive public health problem with 300 million people infected in the world today. Intervention by ablating parasite-specific Tregs in these patients will solve the specific problems of schistosomiasis and filarial diseases, while at the same time proving a principle which will be applicable to chronic infections in general. 

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