Treatment of onchocerciasis with ivermectin (Province of Bururi, Burundi): parasitologic and clinical evaluation of different periodicities of treatment.

To find out whether biannual treatments of onchocerciasis with ivermectin were necessary or whether annual treatments could suffice, parasitologic and clinical results in Burundi were compared at 12 months after a single treatment and after two treatments with an interval of six months. Adverse reactions were also compared at 12 months, after a second or third treatment, respectively. The biannual treatment resulted in a greater reduction of parasitologic parameters, had a longer-lasting effect on itching, and produced less side effects (especially itching, rash, and swellings) at 12 months than an annual treatment. Skin lesions were not significantly modified by any of the treatment schemes at 12 months. Notwithstanding this slight advantage of biannual treatment, operational constraints forced us to choose an annual distribution of ivermectin. With minimal resources, a distribution scheme was organized that was adapted to the different levels of endemicity of onchocerciasis. The results of this study may be of interest to policy makers and public health officials in areas where logistical and resource issues severely restrict the scope of treatment programs. In view of the planned activities of the African Programme of Onchocerciasis Control, the achievements in Burundi indicate that even with limited resources, an appropriate annual distribution scheme can give meaningful results. In spite of the persistence of skin lesions, their severity decreased and most patients considered that their condition had improved even after just one year.