It is no surprise then that Brazil has experienced the hottest year since 1998. The temperature rose by almost 1.5 degrees last year relative to previous years. The occurrence of the El Nino also did its part to help spread the disease.
The heavy rains created conducive water spots for the reproduction of the mosquito. Hotter weather is believed to make the mosquito hungrier leading it to feed on human blood more often, increasing the probability of the spread of the virus.
"With higher temperatures you have more mosquitoes feeding more frequently and having a greater chance of acquiring the infection," said Bill Reisen, an entomologist from the University of California Davis. "And then the virus replicates faster because it's hotter. Therefore, the mosquitoes can transmit earlier in their life."
Hotter conditions also help the virus grow faster, reaching its infectious stage quicker. The life cycle of the mosquito is only 12 days almost the same amount of time the virus takes to grow to its infectious stage. Most of the time without the warmer temperatures the virus would be transmitted prematurely to the human. The body would then fight the virus destroying it before it caused any harm. Scientists believe if an outbreak is to occur in the US the warmer areas will be more severely hit.