BANGKOK, THAILAND – Thai health authorities confirmed the presence of the Nipah virus in local fruit bats but said the main threat came from infected travelers arriving from outbreak countries.
Low viral load in Thai bats, no human cases
Deputy permanent secretary for public health Dr Sophon Iamsirithaworn said the Nipah virus had been detected in fruit bats in Thailand, but with a lower viral load than in countries experiencing active outbreaks. To prevent transmission, pig farms were prohibited in areas where the virus had been found in bats, aiming to stop bats from spreading the virus to humans via pigs.
“There has not yet been a confirmed case in Thailand,”
said Dr Sophon, adding that concerns instead focused on other countries,
“especially Bangladesh and the Indian state of West Bengal.”
Screening tightened on direct flights
Despite the distance to current hotspots, Thailand remained alert because of direct flights from affected regions to Suvarnabhumi, Don Mueang and Phuket airports.
“Surveillance was necessary because there were direct connections,”
said Dr Sophon. These airports continued screening arriving passengers from affected countries, concentrating on travelers with fever or respiratory symptoms and those who had been in an outbreak area within the previous 21 days.
More dangerous Bangladesh strain detected
According to Dr Sophon, the virus found in Thai bats was the Bangladesh variant of Nipah. Disease Control Department spokesperson Dr Jurai Wongsawat explained that there were Bangladesh and Malaysia strains of the virus.
“The Bangladesh strain is more dangerous, the mortality is quite high and it causes respiratory symptoms,”
said Dr Jurai. The illness had to be taken very seriously, she noted, because it could lead to severe pneumonia and there was neither a vaccine nor specific medication.
Limited transmission but severe outcomes
Dr Jurai said it was positive that the transmission rate was relatively low, with infection requiring direct contact with body fluids of infected persons. Studies on Thai fruit bats showed only 10% of samples tested positive for Nipah, compared with 40–50% in India. In Thailand there was so far no indication that bats had passed the virus to pigs or humans locally, and detection in bats typically peaked in April and May.
Pigs as potential amplifiers
Director-general of the Department of Medical Services Dr Nattapong Wongwiwat stressed that fruit bats were the main host of the virus, though it could also occur in other bat species. He warned that pigs could act as amplifiers if they became infected from bats. The human fatality rate ranged from 40 to 75%, depending on the virus variant and the level of medical care.
High risk for small children
Director of the Queen Sirikit National Institute of Child Health Dr Arkom Chaiwerawattana highlighted the vulnerability of young children. Their symptoms were often less conspicuous than in adults, but the disease was very severe and could cause serious encephalitis. The illness typically began with fever, headache, muscle pain, vomiting, sore throat and dizziness, followed by drowsiness, which could progress to impaired consciousness, seizures, coma, pneumonia, acute respiratory failure and encephalitis.
In the long term, infected small children faced the risk of delayed development, learning difficulties and epilepsy, Dr Arkom said.