Densely packed slums, rampant mosquitoes and a history of rapidly spreading infections make Asia particularly vulnerable to the devastating Zika virus, posing a massive challenge for the region, health experts warn.
Thailand confirmed Tuesday that a man contracted the mosquito-borne infection, blamed for a surge in the number of brain-damaged babies in South America, while Indonesia has also reported a domestic case.
The cases in Asia come as top US health authorities confirmed this week a patient in Texas contracted the Zika virus through sexual transmission, fuelling fears the disease may spread rapidly.
Officials in India worry it could be next, noting that the Zika and dengue fever-carrying Aedes aegypti mosquito thrives in the high-density communities of its teeming cities, where sanitation is often poor.
“In India particularly there is a great threat of the Zika virus spreading quickly given the 
presence of the Aedes mosquito and favourable environment,” said Om Shrivastav, an infectious diseases specialist.
“It would definitely be a big challenge for Asian countries to control the spread of the virus… consider-ing high population in the region,” added Shrivastav, who is based in Mumbai, home to Dharavi, Asia’s biggest slum.
More than half of Mumbai’s 20 million inhabitants live in slums — at least one million reside in Dharavi alone — enduring cramped conditions, poor ventilation and a lack of toilets.
Every summer monsoon, heavy rains lash Mumbai for four months, flooding parts of the city, including the slums’ maze of alleyways, which become fertile breeding grounds for mosquitos and lead to a mas-sive spike in tropical diseases.
Soumya Swaminathan, director general of the Indian Council for Medical Research, warned against panicking but said a surge of dengue cases worldwide recently, was a cause for concern.
“(Because of) the way dengue has spread over the last several years across continents and across coun-tries, (and with) Zika being a mosquito borne illness, there is a potential for spread,” she told Indian news channel NDTV.
Zika, which was first identified in Uganda in 1947, causes relatively mild flu-like symptoms and a rash. But the World Health Organization (WHO) said it strongly.