ISLAMABAD: More than two billion people live in parts of the world are at the risk of Zika virus. The Zika virus, which is spread by aedes aegypti mosquitoes, triggered a global health emergency this year. Last week the US Centres for disease control and prevention confirmed that the virus causes severe birth defects. The latest research showed mapping Zika is more complex than simply defining where the mosquito can survive. Dr Oliver Brady from the University of Oxford said that these are the first maps to come out that really use the data we have for Zika and earlier maps were based on Zika being like dengue. He said, “We are the first to add the very precise geographic and environmental conditions data we have on Zika. By learning where Zika could thrive the researchers could then predict where else may be affected”. The researchers confirmed that large areas of South America, the focus of the current outbreak are susceptible. In total, 2.2 billion people live in areas defined as being “at risk”. According to researchers, “The infection is suspected of leading to thousands of babies being born with underdeveloped brains. The “at-risk” zones in South America include long stretches of coastline as well as cities along the Amazon River and its tributaries snaking through the continent and in the US, Florida and Texas could sustain the infection when temperatures rise in summer”. Brady said, “Mosquitoes are just one condition needed for Zika to spread but there is a whole range of other ones. It needs to be warm enough for Zika to replicate inside the mosquito and for there to be a large enough human population to transmit it”. The researchers said that both Africa and Asia have large areas that could be susceptible to the virus. However, the study cannot answer why large numbers of cases have not already been reported. One possible explanation is that both the continents have already had large numbers of cases and the populations there have become largely immune to the virus.