China's health authority has warned about the spread of the Zika virus as the weather warms up in mosquito-prone parts of the country.
State news agency Xinhua reported that National Health and Family Planning Commission spokesperson Xiong Huang told a press conference on Wednesday that China had confirmed five imported cases of the virus since its first case on February 9.
Zika has been blamed for a big spike in babies born in Latin America with microcephaly, a birth defect that causes the babies to have unusually small heads and is associated with developmental problems, after their mothers caught the virus while pregnant. The World Health Organization (WHO) has called the outbreak an international health emergency.
The virus has no vaccine or treatment, and in about 80 percent of people causes no symptoms.
The Chinese official said that the country's latest confirmed cases were a 38-year-old man and his eight-year-old son from Yiwu City in the Zhejiang Province, who were bitten by mosquitoes while visiting Fiji and Samoa. The other three people diagnosed with Zika were from the Jiangxi, Guangdong and Zhejiang provinces.
"We should be vigilant as the spread of the illness can not be ruled out in some regions where the mosquito population will increase as the weather warms," Zinhua quoted Xiong as saying. The official added that authorities would intensify efforts to quarantine infected people and reduce the number of mosquitoes.
The announcement came as the head of the that the Zika outbreak would likely worsen before nations hit by the virus got any relief.
Director-General Margaret Chan made the comments at the end of her two-day visit to Brazil, the country at the epicenter of the Zika crisis. So far the virus has mainly been found in the northeastern part of Brazil but Chan said, "Don't be surprised to see microcephaly reported in other parts of Brazil."
Brazil has confirmed more than 580 cases of the birth defect and is investigating more than 4,100 additional cases.
Chan underscored that scientists were still working to determine causality between the virus and microcephaly.
The WHO has said there is a "strongly suspected" relationship between Zika infection in pregnancy and microcephaly. Scientists are also studying a potential link between Zika infection and Guillain-Barre, a rare neurological disorder that can weaken the muscles and cause paralysis.
The U.S. Centers for Disease Control and Prevention said on Tuesday that 14 more people had caught Zika virus in the U.S. without traveling to affected zones, which was seen as evidence the virus was relatively easily transmitted via sex.
And in Australia on Wednesday, authorities sprayed houses and businesses near a hotel in the state of Queensland, where a guest with Zika had stayed. The guest had caught the virus during a visit to South America.
- Reuters contributed to this report.