The Philippines confirmed on Monday its first case of the Zika virus this year and said it was "highly likely" it had been locally transmitted, and it expected more cases after stepping up surveillance.
A 45-year old woman who lives in the city of Iloilo in central Philippines has the virus, Dr. Eric Tayag, spokesman at the Health Ministry, told a media briefing.
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The woman is not pregnant, he said, and was recovering at her home. It was considered "highly likely" she had contracted the virus locally as she had no history of travel to any affected country in the past two weeks, Tayag said
The Philippines reported its first case of Zika in 2012. Four subsequent cases were all foreigners.
The world's current outbreak of the virus, which began last year in Brazil, is spreading in Southeast Asia.
Singaporean authorities on Sunday confirmed 27 more cases of locally transmitted Zika infections, bringing the total to 242.
The city-state announced Monday that it will no longer isolate people who test positive for Zika or are suspected of carrying it, as the number of cases has become too large.
Media have quoted the country's deputy health minister saying the virus was "here to stay".
In a statement, the Health Ministry said the presence of the Aedes aegypti mosquitoes that carry the virus, as well as the fact that most people do not display symptoms, meant isolating patients already infected would have limited effect.
"Over time, we expect Zika cases to emerge in more areas given the presence of the aedes mosquitoes here," the ministry said.
A health official in Indonesia said Monday the country cannot afford to thoroughly check for a possible Zika outbreak, as Southeast Asia's most populous country must focus on fighting dengue, a potentially fatal virus carried by the same mosquitoes.
The World Health Organisation (WHO) lists Indonesia among Asian countries with possible endemic transmission of, or evidence of, local Zika infections, but authorities in the sprawling country of 250 million people have yet to report any recent infections.
"At the moment we cannot go out there and test everybody or every suspected case for Zika because it is too costly," Muhamad Subuh, director general for disease prevention and control at Indonesia's Health Ministry, told Reuters.
"There are other priorities like dengue fever, which is more prevalent and more dangerous, and we have to allocate our resources accordingly."
Like many of its neighbours, Indonesia records thousands of dengue infections a year.
Indonesia is Southeast Asia's biggest economy but the World Bank estimates the government spends 5.7 per cent of its gross domestic product on public health, which works out to $130 per person per year, compared with $600 in Malaysia, the region's third-largest economy.
Malaysia is bracing for more Zika cases, officials said on Sunday, after detecting the first locally infected patient, which could further stretch a health system struggling with dengue, another mosquito-borne virus that can be fatal.
Malaysia reported its first Zika infection three days ago — a woman living near Kuala Lumpur who contracted the virus during a visit to Singapore.
On Saturday, Malaysian authorities said they had detected the first local infection: a 61-year-old man in the city of Kota Kinabalu, in the Malaysian part of Borneo island.
"The confirmation of the second case of Zika in Kota Kinabalu suggests that the virus is already present within our communities," Health Minister Subramaniam Sathasivam said.
"Zika is present in our country. New cases will continue to emerge," he posted on his Facebook page.
Risk to fetuses
Zika infections in pregnant women have been shown to cause microcephaly — a severe birth defect in which the head and brain are undersized — as well as other brain abnormalities.
The connection between Zika and microcephaly first came to light last fall in Brazil, which has since confirmed more than 1,800 cases of microcephaly.
There is no vaccine or treatment for Zika, which is a close cousin of dengue and chikungunya and causes mild fever, rash and red eyes.