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Singapore scrambles to contain Zika but warns of more cases to come

Singapore has confirmed 56 cases of locally transmitted Zika virus infection, while ramping up health screenings and mosquito control efforts.

All 56 people either lived or worked in the Aljunied Crescent or Sims Drive area of Singapore and had no record of traveling to Zika-affected regions recently, according to a release by the Ministry of Health. Of the 41 people confirmed on Sunday as infected with Zika, 34 have already fully recovered.

"We expect to identify more positive cases," the official statement said. "Given that the majority of Zika cases are asymptomatic or mildly symptomatic, and mosquitoes in the affected areas may already have been infected, isolation of positive cases may have limited effect to managing the spread."

The first case was a 47-year-old Malaysian woman who developed symptoms last Thursday and tested positive for Zika on Saturday. Foreign workers at a construction site on Sims Drive comprised 36 of the cases.

"Whenever you have one local case that is not imported, you are very likely to see more cases already hiding in the community," Jasper Chan, clinical assistant professor at the University of Hong Kong's Department of Microbiology, told CNBC's "Squawk Box."

Mario Tama | Getty Images

Chan noted a couple of factors that would likely have contributed to the spread of the virus in Singapore, pointing out that the 41 infected people confirmed on Sunday had worked in the contaminated area, but also traveled home to other areas of the city-state. Moreover, he emphasized that the Zika virus, unlike Dengue fever which is also an Aedes mosquito-borne disease, can also be transmitted sexually.

Singapore's National Environment Agency has deployed more than 200 officers to inspect the affected area and conduct mosquito-eradication and mosquito-breeding prevention operations, such as thermal fogging, drain flushing and oiling. The agency will also run a public education program and distribute insect repellents.

The Ministry of Health said it would continue to screen potentially infected people at Tan Tock Seng Hospital's Communicable Disease Centre, and had alerted all medical facilities to be more vigilant in monitoring for cases of Zika.

The Zika virus is transmitted mainly by Aedes mosquitoes, and has been linked to a rare birth effect, known as microcephaly, in babies whose mothers suffered from the virus while pregnant. Symptoms include fever, skin rash, red eyes, muscle and joint pain, malaise or headaches.

There is currently no cure or vaccine to prevent Zika infection, and treatments are focused on relieving symptoms.

Singapore had reported a case of Zika in May, in a man who had been to Brazil, the country at the center of the global Zika outbreak.

Last week Hong Kong reported what was thought to be its first locally transmitted Zika case but that person has since tested negative for the virus.

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