Parasitic diseases onchocerciasis

A fortunate fallout of the avermectin work was the finding that Ivermectin has activity against the black fly vector of human onchocerciasis ( river blindness ). It interferes with transmission of the filarial nematode. Onchocerca volvulus, to the human population. Since 40 million people are affected by this disease, the decision by Merck to supply ivermectin free of charge to the World Health Organization, for use in humans in the tropics, was met with great enthusiasm and hope for conquering this parasitic disease. 

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. 

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. 

Another important class of anti-infective natural products introduced in recent years is the avermectins, polyketide-derived macrolides that were originally isolated from several species of Streptomyces. The major drug in this class, ivermectin, was originally developed to treat and control nematodes and parasites in livestock. In recent years, however, the potential of ivermectin for the treatment of human disease has also been realized, and it is now used to treat onchocerciasis (river blindness), a disease that afflicts 40 million people worldwide (De Smet, 1997). 

There are urgent economic reasons for trying to control predation in Africa by biting, sucking flies and acarines (ticks and mites). Among them are identified the vectors of mammalian parasitic and virus diseases such as trypanosomiasis (sleeping sickness), filariasis such as onchocerciasis (river blindness), leishmaniasis, malaria, Dengue fever and East Coast fever (Theileriosis) (ECF). 

Onchocerciasis is a blinding disease caused by infection with the filarial nematode parasite. Onchocerca volvulus. This disease is endemic in many parts of the tropics, particularly... 

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