China may be at risk of being affected by the mosquito-borne Zika virus, which is spreading in the Americas, but the possibility of it spreading here is low as there are fewer mosquitoes in winter and spring, the country's top health authority said on Friday.

Since 2014, cases of Zika virus, which is thought to be linked with severe birth defects, have been reported in various American countries, and the cases quickly increased in recent months.

No Zika virus cases have been seen on the Chinese mainland, but the country does face a risk that the virus could be imported from other countries and regions, the Chinese Center for Disease Control and Prevention said on Friday.

The center advised that people should remain alert.

China is closely cooperating with other countries and the World Health Organization, exchanging medical information and staying briefed on the virus situation to be prepared for any risks, it said.

Experts have been summoned to determine the risk of the virus and how it might spread in China, and their reports have gone to various agencies to coordinate their eventual response efforts.

Moreover, the center has already developed the detection reagent using nucleic acid, "which allows the researchers to test and confirm whether the suspected patients are indeed infected", He Xiong, deputy director of the Beijing Center for Disease Control and Prevention, said on Friday.

The national health authority planned to train the researchers and doctors at provincial disease control centers to be fully prepared.

"China has made huge progress in technologies and acts more swiftly in response to any outbreak of infectious disease 12 years after the SARS outbreak," He said.

International cooperation with other countries has become smoother and more effective, the deputy head said.

The mosquito-borne Zika virus is thought to lead to birth defects when a pregnant woman is infected, and is thought to have caused a recent rash of infants born with microcephaly in Brazil.

Thirty-one cases of Zika virus have been identified in the United States, Xinhua reported on Friday.

The World Health Organization has estimated that as many as 4 million people could be affected by the virus as it spreads in Latin America and the Caribbean to North America in the coming months.

zhengjinran@chinadaily.com.cn