Twenty new patients in four provinces have contracted the mosquito-borne Zika virus, but the situation remains under control, according to the Public Health Ministry.
The new patients have prompted health authorities to keep Chiang Mai, Phetchabun, Bung Kan and Chanthaburi -- where new confirmed cases were reported to the ministry over the past week -- under close watch, said permanent secretary for public health Sopon Mekthon on Monday.
On average, four or five patients were found in each of the four provinces.
He said health officials were aware of the situation although people should not be too concerned about the number of new cases.
"I don't want the cases to spark panic because they are sparse."
More patients have been found due to better procedures to identify and screen those infected with Zika, according to Dr Sopon.
In the case of Zika, patients usually suffer mild effects and will recover within one week, he said.
However, pregnant women who develop Zika have a chance of giving birth to babies with microcephaly and other brain defects.
In Chiang Mai's San Sai district, two infected women, who are six and eight months pregnant, are being closely monitored by medical staff, Chiang Mai public health official Phaisan Thanyawinitchakun said.
Health officials are monitoring some 30 pregnant women living in high-risk Zika areas but who are not infected. Six of them have already delivered strong and healthy babies, Dr Sopon said.
Many Zika-control measures are being carried out in San Sai district, where several Zika patients have been found.
Provincial officials have implemented steps to eradicate mosquitoes within a designated radius of the homes of Zika-infected patients and will follow up on the health of people who came in contact with the patients for at least 14 days.
Health authorities in Malaysia and Singapore have also reported Zika patients with confirmed cases in Singapore already reaching 242.