CDC: Cases of Zika doubling in Puerto Rico weekly

(REUTERS) - The US Centres for Disease Control Director Tom Frieden told a congressional hearing on Wednesday (March 3) that cases of the Zika virus in Puerto Rico are increasing at an alarmingly fast rate.

He said it was "particularly scary" that cases in Puerto Rico were doubling every week, saying that there is a "limited window of opportunity" to take action. He compared the virus to chikungunya, adding that unless preventative measures are taken, it could spread to hundreds of thousands, and suggested that Zika could even make it on to mainland US.

Global health officials are racing to better understand the Zika virus behind a major outbreak that began in Brazil last year and has since spread to many countries in the Americas.

Zika is transmitted to people through the bite of infected female mosquitoes, primarily the Aedes aegypti mosquito, the same type that spreads dengue, chikungunya and yellow fever. The Pan American Health Organisation (Paho) said Aedes mosquitoes are found in all countries in the Americas except Canada and continental Chile, and the virus will likely reach all countries and territories of the region where Aedes mosquitoes are found.

There is no treatment or vaccine for Zika infection. Companies and scientists are racing to develop a safe and effective vaccine for Zika, but the World Health Organisation (WHO) said it would take at least 18 months to start large-scale clinical trials of potential preventative shots.