JAKARTA -- Concern is growing in Asia about the spread of the Zika virus, with a recent outbreak in Singapore followed by cases in Malaysia, the Philippines, Thailand and Vietnam.
There is no vaccine or treatment for the virus, which usually causes only mild fever, rashes and red eyes in infected adults but can lead to a birth defect called microcephaly if a pregnant woman is infected. The spread of Zika in Latin America has led to about 1,800 cases of microcephaly and resulted in several prominent athletes refusing to participate in the recent Olympic Games held in Brazil. In February, the World Health Organization declared Zika, which can be spread sexually but is mostly mosquito-borne, a global public health emergency.
In Asia, the threat of the virus spreading around the region is causing concern for hundreds of millions of people already on guard against dengue, malaria and other conditions spread by the same mosquitoes that carry Zika. With almost 300 Zika cases reported in recent weeks in Singapore, a trade hub and city-state that is home to significant migrant worker populations from across Asia, the fear is that Zika will spread rapidly throughout the densely populated region.
On Monday, the Philippine Health Department confirmed the first case in the country that did not involve someone who had traveled abroad. The five previous cases in the Philippines involved foreigners who traveled to the country from affected areas. Malaysia, which shares a land border with Singapore, has reported three cases of locally transmitted Zika.
Indonesia, by far the biggest country in Southeast Asia, has not yet reported any cases. However, Oscar Primadi, a spokesman for Indonesia's health ministry, said airports and seaports are screening arrivals from affected countries.
"We've installed thermal scanners at airports and seaports through which passengers from these countries commonly enter Indonesia -- such as the airports in Jakarta, Denpasar and Surabaya, as well as the port in Batam," Primadi told the Nikkei Asian Review. Batam, an Indonesian island close to Singapore, has a ferry link to the city-state.
Thailand's official figures have not been updated since June but nonetheless show 97 cases of Zika infection so far this year. Several sources told the Nikkei Asian Review that the number has increased since June. Vichan Pawan, director of the health ministry's department for disease control, said at least 20 new cases have been confirmed in the past week.
Two pregnant women in Thailand have contracted Zika. One of them has given birth, with the baby showing no ill effects.
A 30-year-old office worker in Bangkok, who asked not to be named, said she is concerned about Zika but does not want to delay starting a family. "I am worried, because a developed country like Singapore is seeing a spread of the virus, so it seems unlikely that Thailand will be so safe," she said. "But this won't change my plans to hopefully get pregnant next year."
Pregnant women at risk
Pregnant women are described by experts as "the most important risk group" for Zika, according to the European Centre for Disease Prevention and Control (ECDC), a European Union agency. "Zika virus infection during pregnancy can be associated with intrauterine central nervous system infection, congenital malformations and fetal death," said Herve Zeller, head of the program for emerging and vector-borne diseases at the ECDC.
Meenakshi Makkar, a 38-year-old New Delhi-based lawyer who is due to deliver in November, prefers to spend most of her time at home nowadays to minimize risk. "I have read about a possible outbreak of Zika," she says. "Already there's a spike in dengue and chikungunya (another mosquito-borne virus) cases, which has left me deeply worried. In the midst of all this, it's so scary to even think of Zika."
Officials say authorities are limited in what they can do to slow the possible spread of Zika.
"We already have a strong network of personnel that are overlooking the situation, and there is not much more the government can do," said Suwannachai Wattanayingcharoen, the deputy permanent secretary at Thailand's health ministry. "The public needs to be aware of keeping their houses clean to keep the mosquitoes away."
Primadi of the Indonesian health ministry said: "We also keep carrying out preventive measures by reminding people to clean up their neighborhoods to prevent the spread of mosquitoes carrying the virus."
Similarly, Vietnam's health ministry has conducted a public information drive urging people to "kill mosquitoes, mosquito larvae for prevention against diseases caused by Zika and dengue viruses."
2 billion vulnerable
The Lancet medical journal recently published a study suggesting 2 billion people could be vulnerable to the spread of Zika, most of them in Asia and Africa. "If competent mosquito vectors become infected from these travelers in areas where environmental conditions are conducive to the virus's spread, new epidemics could occur, subject to the presence of an immunologically susceptible human population," the report said.
One of the countries at risk is India, with a population of more than 1.25 billion. India has not yet reported any Zika cases, but authorities there are on the alert. Indians have also been among those affected in Singapore.
"I can confirm that as of noon on the 30th of August, 13 Indian nationals are being treated for the Zika virus in Singapore," said Vikas Swarup, an Indian foreign ministry spokesman, adding that the Indian side is in "constant" touch with Singapore's health ministry. Airports and seaports in India have put up signboards providing information on Zika and advising travelers returning from affected countries and suffering from febrile symptoms to report to authorities.
Malaysia said it has no plan for now to make it mandatory to screen all pregnant women for Zika, despite confirming the first case of a pregnant woman with Zika on Sept. 7. Malaysia regards dengue, an occasionally fatal mosquito-borne disease, as a more pressing concern. Indonesia also says it is more concerned about dengue.
Speaking at a summit of the Association of Southeast Asian Nations in Laos, Singapore Prime Minister Lee Hsien Loong said that Southeast Asian governments should prepare for an extend campaign against Zika, and called for increased cooperation between countries in the region.
"We should prepare ourselves for a possibly extended campaign against Zika but ensure that the region remains open and connected for business and trade," Lee said.
Some public health experts suggest that there is not much more Asia's governments and health professionals can do about Zika for now. Tony Leachon, president of the Philippine College of Physicians Foundation, said he agreed with the information coming from the country's health ministry. "I think it's fairly accurate that public health communication has been done by DOH," he said.
Still being assessed
Scientists and medical professionals are still assessing Zika amid changing information on how long it can survive in an infected adult who may otherwise show no symptoms.
The WHO recommends that people who have been to any area where the virus is present should use condoms or abstain from sex for at least six months to avoid spreading the disease. Previously, it said condom use or abstention was only necessary for eight weeks, until the virus was found in the sperm of an Italian man six months after he was diagnosed.
"Mounting evidence has shown that sexual transmission of Zika virus is possible and more common than previously assumed," the WHO said on Tuesday.
"A good estimate of the situation is very challenging, as the disease is asymptomatic or mild for most cases and will tend not to trigger a visit to the doctor's, followed by testing and reporting of cases," said Herve Zeller of the ECDC.
There have not yet been any confirmed sexual transmissions of Zika in Asia, but the spread of cases and changing information are worrisome to the public. An Indonesian woman in her late 20s, who asked not to be identified, said she is not planning to have a child anytime soon but is worried that the virus could affect her later in life. "I wonder if it's a kind of virus that can stay dormant and then reawaken after years," she said.
With reporting from Nikkei staff writers Yukako Ono in Bangkok, Kim Dung Tong in Ho Chi Minh City, Kiran Sharma in New Delhi, Mikhail Flores in Manila, Erwida Maulia in Jakarta and CK Tan in Kuala Lumpur