Immunocompetence may be important in the effectiveness of Mectizan (ivermectin) in the treatment of human onchocerciasis.

Mectizan (Ivermectin) has been proved to be central to the control of onchoceriasis through self-sustainable community-based treatment. The possibility of parasitological unresponsiveness to this treatment or selection for drug resistance has emerged recently in many occasions. The reason for the reduced ability of Mectizan to maintain low levels of dermal microfilariae and early recurrent pruritus can only be speculated upon. Here, we report our own findings to address this particular issue.