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Amid outbreak, Singapore links local Zika cases to past Asian strains
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Health officials said an analysis of two locally acquired Zika virus cases in Singapore showed they are related to strains of the virus that have been circulating in Southeast Asia for decades and were not imported from South America.
Singapore is experiencing an explosive outbreak of Zika, having announced hundreds of locally acquired cases since the end of August.
Although the country has seen at least one imported case from South America, the Ministry of Health (MOH) said that sequencing completed on two local cases showed they likely evolved from strains that have been in Southeast Asia since the 1960s and are not the epidemic strain circulating in the Americas.
The MOH said there is no evidence to indicate whether the Zika virus circulating in Singapore is more or less dangerous than the virus circulating in the Americas, which has been associated with serious birth defects and other medical conditions, particularly in Brazil.
The agency has announced several clusters of cases — small areas in the city where people are being bitten by infected mosquitoes. At least one of the patients is pregnant.
Singapore is one of 69 countries to report evidence of mosquito-borne Zika transmission since 2015, according to WHO. The MOH does not keep a publicly available tally, but since Aug. 27 there have been about 300 locally acquired Zika virus cases in Singapore. By comparison, Florida reported 56 locally acquired cases between July 29 and Sept. 8.
WHO expects Zika virus to reach every country where the disease’s main vector, the Aedes aegypti mosquito, is found.
Source: James Gathany/CDC
WHO spokeswoman Nyka Alexander told Infectious Disease News it is important for other countries in the region to remain vigilant when it comes to the threat of Zika. She said WHO still expects Zika to reach every country and territory where the disease’s main vector, the Aedes aegypti mosquito, is found.
Singapore, with a population of approximately 5.5 million people living in an area of around 278 square miles, has a history of battling dengue virus — another disease spread by A. aegypti.
“The fact that there are cases in Singapore in 2016 does not change the overall global risk assessment for Zika infection, but it provides valuable information on how an effective surveillance system, such as Singapore has, can capture Zika cases,” Alexander said.
According to a recent modeling study led by researchers in Canada and the United Kingdom, Singapore was not among the countries in Africa or the Asia-Pacific region most vulnerable to local outbreaks of Zika, perhaps because of its sufficient resources.
The study, published in The Lancet Infectious Diseases, found that India, China, Indonesia, the Philippines and Thailand had both large volumes of travelers arriving from areas affected by Zika and large populations at risk for mosquito-borne infection.
The researchers said many countries in the two regions are vulnerable and that “strategic use of available health and human resources is essential to prevent or mitigate the health, economic, and social consequences of Zika virus, especially in resource-limited countries.” – by Gerard Gallagher
Reference:
Bogoch II, et al. Lancet Infect Dis. 2016;doi:10.1016/S1473-3099(16)30270-5.
Disclosure: Alexander is a spokeswoman for WHO.