Zika: The cost of neglect

Abstract

The Zika virus is vectored by mosquito species of the genus Aedes, particularly the yellow fever mosquito, Aedes aegypti and, very likely, the Asian tiger mosquito, Ae. albopictus. These species also vector a host of other viral diseases including dengue and chikungunya all of which are “neglected tropical diseases” (NTDs) because of the lack of attention given to them. NTDs are diseases of poverty: They have lacked due attention because they typically affect the poorest populations of the world and at the same time they are not common enough to be profitably exploited by the pharmaceutical industry. We argue that the depth of the current Zika crisis is because of the extent of neglect for NTDs: First, in spite of yellow fever, dengue, chikungunya and other diseases vectored by Aedes mosquitoes, insufficient efforts have been directed towards their population control. Second, specific drugs for combating yellow fever, dengue, or chikungunya do not exist. For the last two, vaccines are yet to be developed (though some trials are finally taking place for one for dengue). Thus the pharmaceutical knowledge base for tackling related viral diseases is lacking. Third, thanks to the neglect even the epidemiological, sociopolitical and economic data required to make credible and timely risk assessments are not available. For instance, in the case of Zika, it would be useful to have a global risk map based on projected travel to and from Brazil for the 2016 Summer Olympics in Rio de Janeiro. Yet, projected travel volumes for chartered flights for the summer of 2016 are not publicly accessible, preventing the creation of credible risk maps. In addition, there is a severe lack of publicly available case data, especially in countries of the South where NTDs have the largest impact. Without reliable and comprehensive outbreak data, risk models necessary for outbreak prediction cannot be validated. Zika has only drawn attention to these problems because of the likelihood of its spread into the affluent North. It is high time that all NTDs are rescued from their dangerous oblivion.