Measles eradication still a long way off.

Abstract

Until recently, many people assumed that once polio had been eradicated, measles would be next in line. Now there are doubts about whether measles could -- or even should -- be a target for global eradication. Five years ago, an international meeting of experts sponsored by the US Centers for Disease Control and Prevention, the Pan American Health Organization, and WHO, recommended that the World Health Assembly should consider setting a target for the global eradication of measles some time between 2005 and 2010. That target date has never been set. Why not? Not because the disease no longer constitutes a major public health burden. With an annual toll of some 30 million cases and 900 000 deaths, mostly in children, it still does. Measles in fact kills more than half of the 1.6 million children who die annually from vaccine-preventable diseases. And among those who survive measles, up to 10% may suffer disabilities, such as blindness, deafness, and irreversible brain damage. Nor is it because measles fails to meet the technical criteria for eradication. It does. Humans constitute the only natural reservoir for the causative virus and there are no healthy carriers of the virus (as there are for viral hepatitis, for example). Also, an effective vaccine has been available for over three decades and today costs only USS 0.26 for a single dose, including safe injection equipment. And finally, natural immunity to the virus is of lifelong duration. There is also evidence that interrupting transmission of the virus is possible in large areas of the world -- a necessary preliminary to eradication. Several regions -- foremost among them the Americas -- have shown that it is operationally feasible to interrupt transmission of the disease. Transmission of measles virus has almost ceased in the Americas, where it is now believed to be confined to the Dominican Republic and Haiti. Two other WHO regions -- the European and Eastern Mediterranean regions -- have set targets to eliminate the disease by 2007 and 2010, respectively. Even in sub-Saharan Africa, where transmission of the virus is intensive and where over half the world's measles cases occur, a handful of countries have made remarkable progress in reducing the number of measles cases and deaths. In six southern African countries, mass vaccination campaigns during 1996-98 reduced reported measles deaths from over 300 in 1996 to only two between January 1999 and September 2000. In Malawi -- one of the world's poorest countries -- the number of measles cases plummeted from 7000 in 1997 to only two in 1999. And for the first time ever there were no measles deaths. So why is there reluctance today to make plans to eradicate the disease? One reason is the ongoing effort to eradicate polio, scheduled for 2005 (five years later than the original deadline) and now in its, hopefully, final but most difficult stage (see WHO News story p. 582). "We have to finish polio eradication before considering measles eradication," says Dr Ana-Maria Henao-Restrepo, medical officer and measles focal point within WHO's vaccine programme. "But in the meantime, we are working with countries throughout the world to reduce measles deaths through immunization plus, where needed, vitamin A administration. There is a lot we can do even before polio is eradicated." In late March this year, WHO and UNICEF issued a "global measles strategic plan" to halve measles deaths by 2005. Because measles is a highly contagious disease, the new plan calls for immunization of at least 90% of children worldwide, vs the current 74% global vaccine coverage rate. …