Onchocerciasis

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. 

The activity of ivermectin against the filarial parasite Dirofilaria immitis in dogs suggested a possible role for the control of filarial parasites of humans (20). It has been extensively tested in human onchocerciasis and is now considered to be the dmg of choice. In a single yearly oral dose, it suppresses microfilariae in the skin and eyes and, in most cases, prevents the progression of the disease to blindness. Table 4 shows the results of a 30-patient double-blind study recorded over one year. 

Skin snips may be useful in the diagnosis of microfilarial infections such as onchocerciasis in which the parasites circulate in the skin and not the blood. A small (2-mm) skin snip is taken with a needle and a knife. The needle point is stuck into the skin, and the skin is raised. With a sharp knife or razor blade, the skin is excised just below the needle. Alternatively, a scleral punch may be used. The skin snip is then placed in a small volume (0.2 ml) of saline in a tube or a microtiter well, teased, and allowed to stand for 30 min or more. The microfilariae migrate from the tissue into the saline, which is then examined microscopically to demonstrate the wiggling microfilariae. 

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. 

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

Wanni, N.O., Strote, G., Rubaale, T. and Brattig, N.W. (1997) Demonstration of immunoglobulin G antibodies against Onchocerca volvulus excretory-secretory antigens in different forms and stages of onchocerciasis. Transactions of the Royal Society of Tropical Medicine and Hygiene 91, 226-230. 

Satoguina J, Mempel M, Larbi J, et al Antigen-specific T regulatory-1 cells are associated with immunosuppression in a chronic helminth infection (onchocerciasis). Microbes Infect 2002 4 1291-1300. 

Onchocerciasis (River blindness) Onchocerca volvulus Suramin,- Diethylcarbamazine, or Ivermectin-... 

When used for the treatment of onchocerciasis a potentially fatal Mazotti reaction may occur, with severe skin reactions, tachycardia, hypotension and fever. 

The filarial worms differ from other nematodes in that they are threadlike and are found in blood and tissue. The infective larvae enter following the bite of an infected arthropod (fly or mosquito). They then enter the lymphatics and lymph nodes. Fever, lymphangitis, and lymphadenitis are associated with the early stage of the disease. Chronic infections may be characterized by elephantiasis as a result of lymphatic obstruction. Some species of filarial worms migrate in the subcutaneous tissues and produce nodules and blindness (onchocerciasis). 

For obvious reasons of structural analogy to heparinoids the focus of this review is on sulfated carbohydrate derivatives. While it is not in all cases clear that these compounds really mimic the physiological activity of heparinoids, it is even less so for non-carbohydrate sulfates or sulfonates. Examples of the latter class include suramin and the simple 1,3-propanediol disulfate. Suramin is a sulfonat-ed bis-naphthalene derivative used as a drug to treat African trypanosomiasis and onchocerciasis (a filarial infection) it was also tested in a number of other indications including adrenocortical carcinomas and AIDS. A wider use is, however, restricted by various toxic effects [66]. 1,3-Propanediol disulfate reduced inflammation-associated amyloid progression in vivo after oral administration which may be relevant to the treatment of Alzheimer s disease [67]. 

Ivermectin (9.119), a semisynthetic macrocyclic lactone, is the dmg of choice for strongyloidiasis and onchocerciasis types of helminth infestation. Ivermectin appears to paralyze the nematode, which may lead to its death but which certainly facilitates its expulsion from the body. 

Tropical eosinophllla 4-6 mg/kg BD-TDS x 7-10 days Filariasis 6-12 mg/kg OD-BD x 21 days Also used in prophylaxis offilaria. Onchocerciasis 150 pg/kg single dose. Also used in intestinal nematode infection and enterobiasis. For scabies and strongyloidiasis 200 pg/kg single dose. 

It is mainly indicated in scabies, ascariasis trichuriasis, strongyloidiasis, enterobiasis, filariasis, onchocerciasis (River blindness) and elephantiasis. It is drug of choice for onchocerciasis producing long lasting reduction in microfilaria without affecting adult worm. 

Diethylcarbamazine is a drug of choice in the treatment of filariasis, loiasis, and tropical eosinophilia. It has been replaced by ivermectin for the treatment of onchocerciasis. 

Ivermectin is the drug of choice in strongyloidiasis and onchocerciasis. It is also an alternative drug for a number of other helminthic infections. 

Ivermectin also now plays a key role in onchocerciasis control. Annual mass treatments have led to major reductions in disease transmission. However, evidence of diminished responsiveness after mass administration of ivermectin has raised concern regarding selection of drug-resistant parasites. 

Note Ivermectin is approved for use in the USA for the treatment of onchocerciasis and strongyloidiasis. See Chapter 65 for comment on the unlabeled use of drugs. 

Udall DN Recent updates on onchocerciasis Diagnosis and treatment. Clin Infect Dis 2007 44 53. 

The UNICEF/UNDP/World Bank/WHO Special Program for Research and Training in Tropical Diseases (TDR) was established in 1975 in response to appeals from countries where neglected diseases are endemic. TDR addresses ten tropical diseases African trypanosomiasis, dengue, leishmaniasis, schistosomiasis, tuberculosis, Chagas disease, leprosy, lymphatic filariasis, and onchocerciasis. Its mission is ... 

Onchocerciasis -ivermectin treatment [ANTIPARASITIC AGENTS - AVERMECTINS] (Vol 3) -pesticide control of [PESTICIDES] (Vol 18)... 

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