Ivermectin onchocerciasis

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. 

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

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. 

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 It has been replaced by ivermectin for the treatment of onchocerciasis.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. 

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

Ivermectin (Mectizan, Stromectol) is the primary treatment for filarial nematode infections (onchocerciasis) that invade ocular tissues and cause loss of vision (river blindness). Ivermectin may also be used in filarial infections in other tissues (lymphatics, skin). This drug is a secondary agent for treating intestinal nematodes such as strongyloidosis. 

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). 

Ivermectin also now plays a key role in onchocerciasis control. Annual mass treatments have led to major reductions in disease transmission. 

Unfortunately, protozoan flagellates like trypanosomes are unaffected by ivermectin (21) but, at least, the animals that take up the ivermectin (with coccidiostat) will be rid of most gastrointestinal nematodes and ectoparasites. Gxtraintestinal filariasis can also be treated for example, microfilarial dermatitis in horses (22) and even onchocerciasis in humans (23). which is transmitted by the bite of infected black flies (Slmulium spp.). However, the doses required (30 - 50 pg/kg) in the latter case were not without short term side effects. 

Onchocerciasis Fluke infections Ivermectin 150 mg/kg once, repeat every 6-12 months ... 

Goa KL, McTavish D, Clissold SP. Ivermectin. A review of its antifilarial activity, pharmacokinetic properties and clinical efficacy in onchocerciasis. Drugs 1991 42 640-658. 

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. 

Onchocerciasis (river bNndnossJ ivermectin Cures with single dose. Suppressive treatment a I... 

Awadzi K, Opoku NO, Attah SK, Addy ET, Duke BO, Nyame PK, Kshirsagar NA. The safety and efficacy of amocarzine in African onchocerciasis and the influence of ivermectin on the clinical and parasitological response to treatment. Ann Trop Med Parasitol 1997 91(3) 281-96. 

Over a number of years, ivermectin has shown excellent results in the treatment of onchocerciasis, both in controlled studies and in the field, including use in the WHO-sponsored program of treatment. This experience has provided a thorough picture of its adverse effects. The effective dosage is of the order of 50-200 micrograms/kg. After a single oral dose, skin microfilariae remain at low levels for up to 9 months. 

The impact of 5 years of annual community treatment with ivermectin on the prevalence of onchocerciasis and onchocerciasis-associated morbidity in the village of Garni (Central African Republic) has been assessed (8). Pruritus, onchocercal nodules, and impaired vision were all significantly reduced by annual treatment with ivermectin. 

Although adverse reactions after ivermectin in onchocerciasis are usually less severe than after diethylcarbamazine, they still affect a significant number of patients with onchocerciasis after the first dose. With snbseqnent treatments, these reactions become less freqnent and... 

---