Pacific paddlers blamed for Zika outbreak

The current Zika outbreak in Brazil may have had its origins in Polynesia, says new research speculating the virus was brought to South America by Pacific island canoeing teams competing in Rio in 2014.

The ongoing Zika outbreak in Rio de Janiero, Brazil, has been scrutinized by Brazilian and German scientists who have revealed its possible origin as well as what are classic signs of infection.

The research includes genetic analysis of several virus samples, indicating that the virus was introduced to Brazil from the Pacific.

The authors note that this finding is in line with the speculative hypothesis that Zika was introduced to Rio de Janeiro during the 6th World Sprint Championship canoe event in August 2014, which included teams from four Pacific countries – French Polynesia, New Caledonia, Cook Islands, and Easter Island – where the virus circulated during 2014.

Some reports had linked the Zika breakout to the 2014 Football World Cup tournament held the same year, but this is now thought unlikely as no infected Pacific island nations competed.

As part of the study, researchers observed 119 Brazilian patients who tested positive for Zika. None of those studied had travelled in previous months, confirming the virus was acquired locally.

Professor Michael Baker, of the University of Otago in Wellington, said the timing was plausible because of the intense outbreaks in 2014 in several Pacific countries and then a few months later that same virus in January 2015 in Rio.

“They speculate that there were quite large teams of canoers who came from Pacific specifically to Rio so it does seem like a plausible hypothesis.”

Professor Baker said although the hypothesis was speculative, it was a reminder of how easily viruses could “hitchhike” to different parts of the world.

“All that is required is for an infected person who is viraemic (has circulating virus in their blood) to be bitten by a competent vector mosquito and that could be the beginning of an outbreak in that country.

“One implication of these findings is that the large number of visitors to Rio during the Summer Olympics in August may increase the dissemination of Zika to new locations across the globe.

“This is another reason why it is important that public health officials in Rio take action to control this epidemic and visitors take measures to protect themselves from mosquito bites.”

Carried by the Aedes aegypti mosquito, Zika has spread quickly to more than 30 places in Latin America and the Caribbean since last year.

- PNC sources