India is a potential hotspot for a Zika outbreak, scientists have predicted amid a spate of infections in Singapore where nearly 190 people have caught the mosquito-borne virus identified as a serious threat to pregnant women.
13 of those infected in Singapore are Indians.
Scientists analysed travel, climate and mosquito patterns in Asia and Africa to identify the highly vulnerable countries such as India, China, Pakistan and Bangladesh, where the Aedes aegypti mosquito that spreads Zika also causes seasonal outbreaks of dengue, chikungunya and yellow fever.
The study was published online on Thursday in the journal, Lancet.
Official sources said the 13 Indian nationals in Singapore have been admitted to hospital, where they will stay until they test negative for the virus. The Indian High Commission in Singapore will be informed when they are fit enough to leave hospital and travel to India.
Zika causes only mild symptoms for most people, with symptoms of fever, rash, conjunctivitis, fatigue and joint pain for two days to a week. But in pregnant women, it can cause microcephaly, a deformation in which babies are born with abnormally small brains and heads.
The disease has also been linked to a potentially fatal disorder known as Guillain-Barre syndrome, which can lead to nervous system problems such as weakness and paralysis.
Though mosquitoes are the main vector, Zika can also be spread through sexual contact and blood transfusions. There is no treatment or vaccine for Zika infection, yet.
With 26 million babies born in India every year and 80% of people infected not developing symptoms, the risk to babies in the womb is very high, experts here said.
Thousands of Indians travel to Singapore annually either on business or for onward journey to countries like Australia, US and other South East Asian countries.
Though the United States, Australia and other countries have added Singapore to agrowing list of places that pregnant women or those trying to conceive have been warned to avoid, India is yet to announce a travel advisory for its citizens.
Experts caution that the study may overestimate the number of people at risk because Zika may have had infected populations in some of these countries in the past, which would have led to people developing immunity against the virus.
In February, the World Health Organisation declared Zika a global emergency after its link with microcephaly in babies was established. Since then, it has affected more than 70 countries.
To figure out where Zika might gain a future foothold, researchers used dengue as a model to examine patterns of people travelling from infected regions in the Americas to Africa and Asia and combined that with an assessment of local conditions, including mosquito populations.
“No one has ever looked, so we don’t know if there is any pre-existing immunity to the virus,” said Dr Abraham Goorhuis of the University of Amsterdam, an author of a commentary that accompanies the Lancet study. The virus in the Americas is an Asian strain that was responsible for a large outbreak in French Polynesia and other Pacific Islands in 2013 and 2014.
“If there was broad circulation of this virus in Asia, then it could be that the risk of Zika spreading to Asia won’t be as bad as we think,” Goorhuis said. Another unknown was whether people exposed to the African strain of Zika are protected once the slightly different Asian version arrives.
Goorhuis also noted it was possible Zika might eventually burn itself out after about a year or so of circulation, the way a related virus, chikungunya, recently did.