Human movement critical in dengue spread

RIO DE JANEIRO, Nov. 11 (UPI) -- Brazilian researchers say they've determined population movement is a key factor in the spread of the dengue virus in Rio de Janeiro.

Scientists at the Oswaldo Cruz Foundation said their finding is based on data from a severe 2007-2008 dengue epidemic and contributes a new understanding of the dynamics of dengue fever, a major public health problem in many tropical regions.

The disease, transmitted most often by the mosquito Aedes aegypti, is prevalent in tropical areas of Asia and the Americas, with up to 100 million estimated cases occurring annually.

The new study combines data on dengue fever seroprevalence -- a test for the disease based on blood serum -- and recent dengue infection and vector density in three neighborhoods of Rio de Janeiro, specifically urban, suburban and slum areas. Blood serum surveys were conducted before and during the epidemic period, with weekly collections of A. aegypti eggs and adults from traps.

The scientists said their findings, that suggest significantly higher risk within areas of intense people traffic, might provide a basis for new studies that could further identify the higher risk areas and help to develop dengue-control programs.

The research is detailed in the journal PLoS Neglected Tropical Diseases.