Mass treatment with ivermectin: an underutilized public health strategy.

Ivermectin was a revolutionary drug in the 1980s, the forerunner of a new group of antiparasitic agents with activity against both parasitic nematodes and arthropods. Initially it was marketed for veterinary use by Merck & Co. Inc.; it was used largely for nematode control in cattle, horses, pigs and dogs and became the standard for control of the ectoparasitic disease, scabies. The injectable cattle formulation, Ivomec, became the world’s most profitable veterinary drug (1). Merck recognized Ivermectin’s potential for human use, particularly in the control of filariasis and most notably onchocerciasis, the cause of river blindness in West Africa, in the early 1980s. In collaboration with WHO, nongovernmental organizations and affected national governments, the company initiated a drug donation programme for onchocerciasis control that subsequently became the global model for philanthropic partnerships between pharmaceutical companies and countries unable to afford the drug. Profits from the veterinary use of ivermectin supported this programme (1). Merck’s patent on ivermectin expired in 1996, though it was extended for different periods in various countries. Thus, other companies’ ivermectin preparations are now commercially available. Bioavailability of drugs depends on formulation and manufacturing processes, so the results obtained with the ivermectin manufactured by Merck may not apply to the new products. It is thus encouraging to see clinical trials evaluating new formulations of this valuable drug. Heukelbach et al. (pp.563–579) report a study that investigates changes in parasitological parameters and the occurrence of side-effects after treatment with ivermectin in a Brazilian community heavily parasitized with intestinal helminths and ectoparasites. The trial was unblinded and uncontrolled, but provided valuable information. Community members, ineligible for ivermectin, were