The number of Zika infections detected in Thailand has increased this year, with 97 people diagnosed with the disease during the first-half of the year.

Between 2012 and 2015, an average of five people were infected with the disease each year.

Disease Control Department chief, Dr Amnuay Gajeena has sought to allay concerns about the Zika threat in Thailand, despite new infections detected in the Chiangmai, Chanthaburi, Phetchabun and Bung Kan provinces last week.

"We have implemented the strictest measures in controlling the spread of the Zika virus," he told the local media, in response to a recent report by the European Centre for Disease Prevention and Control (ECDC) on the Zika situation in Thailand.

The centre in its report has described Thailand as a "red alert" country with increasing or widespread Zika virus transmission.

Dr Amnuay said the country had not seen prolonged spread of the Zika disease in any affected area and the number of patients afflicted with the disease was not overwhelming.

Better monitoring and diagnostic system had been established, he said, which could explain the increase in Zika detection in Thailand.

"Today, we can identify the Zika virus in local labs (laboratories). We don't have to submit samples to foreign labs for test results anymore. As soon as a Zika case is detected, we have to set up emergency operation centres to control the spread at both provincial and district levels," he added.

According to Dr Amnuay, the Zika disease causes mild fever, skin rash, conjunctivitis, muscle and joint pains and headache, with recent evidence linking the virus to microcephaly and Guillain-Barre syndrome.

Pregnant women, he said, should seek prenatal care if they developed any suspicious symptom and consult the nearest doctor.

Doctors had been monitoring 20 pregnant women in areas where the Zika disease had been reported, with six having given birth to healthy babies, he said.