Dengue in Brazil – Putting the heat on vaccine development and mosquito control

It’s hotter and wetter than usual in Brazil, and climate conditions are driving an early blast of a killer virus – dengue. The mosquito-borne virus is spreading earlier than ever before and affecting far more parts of the country than usual – and all at once.

Dengue’s a nasty virus. It causes pain so severe that it’s sometimes called breakbone fever. Patients often feel nauseated, develop rashes, and vomit blood. The most severe cases can cause internal bleeding. There’s no specific treatment – just fluids and rest, and watching out for signs of shock, which can kill patients within hours.

Dengue is unusual because there are four different types, known as serotypes. The first infection is often mild, but people are not immune to the other three serotypes after that first time. The second time someone gets infected, they are more likely to become seriously ill – a phenomenon called antibody-dependent enhancement. Sometimes a vaccine can cause this effect.

Brazilian authorities are keeping this in mind as they rush to roll out vaccines to fight this unusually early and widespread epidemic of dengue, says Dr. André Siqueira, principal investigator at the National Institute of Infectious Diseases Evandro Chagas at Fundação Oswaldo Cruz, also known as FioCruz, in Rio de Janeiro.

There are nowhere near enough vaccines yet – only six million doses this year, enough to protect just three million people with the two-dose regimen. Brazil’s population is more than 200 million.

Researchers at Brazil’s Butantan Institute are working to develop a new vaccine that should protect people with just one dose and, they hope, will protect against all four serotypes of dengue.

Dr. Siqueira is part of the team working on that new vaccine. Listen as he explains to One World, One Health host Maggie Fox why dengue is so bad in Brazil this year and what he and colleagues are doing to control it.