[Problems in the investigation of the control of Onchocerca volvulus in Mexico]

The treatment and control of onchocerciasis in Mexico has been supported only on the administration of diethylcarbamazine and the removal of adult worms, which are in the onchocercomata. These actions seems to have diminished the prevalence and incidence of blindness in those individuals who are affected by this parasitosis. However, there has not been an important impact on onchocerciasis transmission. The objective of this paper is to critically analyze and discuss subjects related to diagnosis, treatment and control of onchocerciasis transmission in Mexico. Chemical vector control has been successfully achieved in other world regions; however, in Mexico, it has not been fully accepted as part of the integral onchocerciasis control due to several causes. Moreover, there has been few scientific research activities toward the search of new options for vector control. Recently, results of research on ivermectin (a microfilaricide agent) have indicated that this drug is effective and safe for the treatment of onchocerciasis. Additionally, it has been reported that ivermectin has an effect on the onchocerciasis transmission. However, there are several unanswered questions about the efficacy of ivermectin in stopping onchocerciasis transmission. In this report, the main efforts carried out in Mexico against onchocerciasis are analysed and problems related with diagnosis, treatment and control are also discussed. Some parameters for the correct evaluation of onchocerciasis control, with entomological emphasis, are proposed.