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We have evaluated the endemicity of the onchocerciasis in two villages of the district of Amou in Togo, Okpahoué et Onglo. We have studied 294 subjects including 136 males and 158 females representing the quarter of the population of the two villages (clinical investigation and exsanguine cutaneous biopsy): 111 persons are parasited by Onchocerca volvulus that means a prevalence rate of 37.7%. We can therefore say that the villages are in a state of "meso-endemicity". We have been able to find nodules by 20 persons among the 111 that give a percentage of 6.8 of the examined persons. Among children of 3 to 9 years old, the prevalence and the average microfilaremia are respectively 8.86 and 3.54%. Among the persons of 50 or older than 50, we found a prevalence rate of 65.95% and an average microfilaremia of 28.37.

The microtest ELISA has been used for human Onchocerciasis serological study. The antigens employed were adult Onchocerca volvulus extracts, collected from dissected nodules, delipidized and cleared from human proteins by affinity Chromatography. Under the circumstances, the positivity limit of the test seems excellent (maximum )D: 0,23) defined with 171 negative sera, 66 of them taken from Africans. Specificity controls were studied with 56 heterologous sera; cross-reactions occurred with hydatidosis and especially wit various nematode infections, in particular loasis. With reagents and technical conditions used, the specificity limit of the test corresponds to an OD of 0,4 (measured with a 3 mm optical course). The diagnosis value of the test was verified by studying sera from 90 individuals wit a positive skin biopsy and with sera from 233 adults living in endemic areas. For all the infected people, the global percentage of positivity with ELISA is not greater than that with indirect immunofluorescent antibody test (85%). On the other hand, the micro-test ELISA seems slightly more sensitive in detection of high serological positivities. We did not find any statistically relationship presence and quantity of microfilarial worms in skin biopsy and positivity with the microtest ELISA. Likewise, in some polyinfested patients (with Onchocerca volvulus and Dipetalonema perstans or Wuchereria bancrofti), we did not observe any correlation between the results given the microtest ELISA and the quantity of microfilariae in the blood stream.

In a survey dealing with the frequency of onchocerciasis in leprous environments in the Marchoux Institute in Bamako (Mali) evidence is given that 43% of the leprous persons hospitalized there were touched in addition by onchocerciasis whereas, only 14% of the consultants in dermatology have proved to be also onchocercian. This last frequency is consistent with the overall estimation usually recognized for Mali. No difference was shown between leprous and non-leprous persons for snip. In contrast, 33% of microfilariae bearing leprousians showed no positive reaction to diethylcarbamazine whereas no more than 5% of non-leprous persons displayed similar negative response. Similarly leprousian blood yielded most often the microfilariae of Onchocerca volvulus. Surprisingly, hypereosinophilia has proved to be normal or null in 37% of microfilariae bearing leprosians. Though aware of the occurrence of numerous real or possible biases in such an approach the authors wonder what meaning such a difference between leprous populations and non-leprous ones in Mali can have. If a relation is definitely borne out in the future between both pathologies, they further wonder whether leprosy is the bed of onchocerciasis or vice versa.

Microfilaria of Onchocerca volvulus are localized in superficial dermis. However, they are sometimes noticed in the blood and urines, when there is an important infestation. Diethylcarbamazine (DEC) bring on an increase of microfilaria, successively in the blood and after, in the urines. This study of 30 patients, treated in double blind by placebo, DEC and ivermectin, a new molecule with spectacular action on this filariasis, allowed to compare effect of each one on apparition of microfilariae in the blood and urines. Ivermectin bring on very important increase of microfilaremia without microfilaruria, unlike diethylcarbamazine. This establishment bring to discuss very different physiologic mechanisms between them. It should have an incidence on diagnosis and treatment of this dangerous parasite.