Stemming the tide of river blindness: the early years of ivermectin.

IN 1978, when I was a Fellow in Ophthalmology at the Johns Hopkins Hospital in Baltimore, I went to a seminar given by one of the senior faculty (Maurice Langham) about work he was doing on an unusual disease called onchocerciasis. Although I must have learnt about onchocerciasis at medical school and during my ophthalmology training, it was such an esoteric tropical disease in small print that it had made no perceptible impact on me. Actually, onchocerciasis is a fascinating disease. It is also called river blindness, as those who are affected live along rivers and streams. It affects about 20 million people; 99% of these live in Africa, with a few in Latin America (see Box 1). 1 In endemic areas, half will become blind before they die and, at any one time, some half a million people with onchocerciasis are blind. Onchocerciasis has had a devastating impact in Africa. All but the poorest of the poor have abandoned the endemic areas. In the worst affected villages, everyone is infected by the age of 14 or 15 years. 1 People go blind in their 20s and 30s, just when these subsistence-farming families are raising children. Once blind, parents often need to be led to their fields by their young children. This has a devastating effect on all aspects of the villagers' lives. There have been various attempts to treat and control onchocerciasis. During the Second World War, tens of thousands of Australian and American soldiers fighting in the Pacific islands were afflicted with lymphatic filariasis. Wartime drug development led to the discovery of diethylcar-bamazine (DEC) that would halt the progression of, and sometimes cure, filariasis. After the war, DEC was tried on some people with onchocerciasis and was found to have a temporary holding effect. 1,2 DEC was better than nothing, but its use was limited, as many infected people had a severe reaction to the treatment caused by the sudden death of billions of microfilariae, the so-called Mazzotti reaction. 3 Sleeping sickness or trypanosomiasis is almost invariably fatal. During the First World War a drug called suramin was developed in Germany that could save some people with sleeping sickness, although it was very toxic. It was tested and found to be effective against onchocerciasis, but 2%– 3% of those treated died and so it was not widely used. 4 The World Health Organization had started a major program …