nih.gov | Ivermectin has continually proved to be astonishingly safe for human use. Indeed, it is such a safe drug, with minimal side effects, that it can be administered by non-medical staff and even illiterate individuals in remote rural communities, provided that they have had some very basic, appropriate training. This fact has helped contribute to the unsurpassed beneficial impact that the drug has had on human health and welfare around the globe, especially with regard to the campaign to fight Onchocerciasis.57)
Today, ivermectin is being increasingly used worldwide to combat other diseases in humans, such as Strongyloidiasis (which infects some 35 million each year), scabies (which causes 300 million cases annually), Pediculosis, Gnathostomiasis and Myiasis—and new and promising properties and uses for ivermectin and other avermectin derivatives are continuing to be found.58) These include activity against another neglected tropical disease, Leishmaniasis.59,60) Of perhaps even greater significance is the evidence that the use of ivermectin has both direct and indirect beneficial impact on improving community health. Studies of long-term treatment with ivermectin to control Onchocerciasis have shown that use of the drug is additionally associated with significant reduction in the prevalence of infection with any soil-transmitted helminth parasites (including Ascaris, Trichuris and hookworm), most or all of which are deemed to be major causes of the morbidity arising from poor childhood nutrition and growth.61) It is also known that the prevalence of head lice is markedly reduced in children taking ivermectin tablets62) and that scabies is markedly reduced in populations taking the drug regularly.63) Above all, ivermectin has proved to be a medicine of choice for the world’s rural poor. In many underprivileged communities throughout the tropics, intestinal worms and parasitic skin diseases are extremely common and associated with significant morbidity. They usually co-exist, with many individuals infected with both ecto- and endoparasites.64,65) Mass treatment of poly-parasitized populations is deemed to be the best means of control and ivermectin is the ideal drug for such interventions. A recent study in Brazil, using locally produced ivermectin, looked at the impact on internal helminthes and parasitic skin diseases. The researchers concluded that “mass treatment with ivermectin was an effective and safe means of reducing the prevalence of most of the parasitic diseases prevalent in a poor community in North-East Brazil. The effects of treatment lasted for a prolonged period of time”. This study also represented the first published report of human medical intervention using ivermectin that had not been produced by the hitherto traditional manufacturer, Merck & Co. Inc., the patent on the drug expiring in 1997.66)
In reality, the renewed interest in fighting tropical diseases, including the involvement of the pharmaceutical industry, which has become increasingly evident over the past three decades, and which has saved lives and improved the welfare of billions of people, notably the poor and disadvantaged in the topics, can be traced back to the 1987 introduction of ivermectin for use in humans. According to a recent report, International Federation of Pharmaceutical Manufacturers & Associations (IFPMA) data show that the global pharmaceutical industry provided over $9.2 billion in health interventions (medicines and equipment) between 2000–2007 alone, benefitting 1.75 billion people worldwide.67) The hitherto unprecedented donation of ivermectin in 1987 can rightly be seen to be the origin of this philanthropic outpouring.
Since the inception of the Mectizan Donation Programme, Merck has donated well over 2.5 billion Mectizan® tablets for Onchocerciasis treatment, with in excess of 700 million treatments authorised. Currently, some 80–90 million people are taking the drug annually through MDA in Africa, Latin America and Yemen. A further 300 million total treatments have been approved for lymphatic filariasis, with around 90 million treatments being administered annually (Fig. (Fig.8 ).8 ). At present 33 countries are receiving ivermectin for Onchocerciasis and 15 for Lymphatic filariasis. Consequently, around US$4 billion worth of ivermectin tablets have been donated to date. In 2010, Ecuador became the second country in the Americas to halt River Blindness transmission. It is hoped that transmission of the disease in the Western hemisphere will be stopped by 2012—a goal that will have been achieved thanks to twice-yearly MDA with ivermectin. Lymphatic filariasis is targeted for global elimination by 2020, and, if all goes well, Onchocerciasis may well be eliminated from Africa soon thereafter.