BANGKOK, THAILAND – Thai health authorities confirmed the presence of the Nipah virus in local fruit bats but said the greater risk came from infected travelers arriving from outbreak countries.
Lower viral load found in Thai fruit bats
Deputy permanent secretary at the Ministry of Public Health Dr Sophon Iamsirithaworn said Nipah virus had been detected in fruit bats in Thailand, but the viral load was lower than in countries with active outbreaks. To prevent transmission, pig farms were banned in areas where virus had been found in bats to stop potential spread from bats to pigs and then to humans.
“There has not been any confirmed case in Thailand so far,”
said Dr Sophon, noting concern instead about cases in other countries,
“especially in Bangladesh and the Indian state of West Bengal.”
said Dr Sophon, deputy permanent secretary.
Screening of passengers on direct flights
Despite the distance from current hotspots, Thailand remained vigilant because of direct flights from those regions to Suvarnabhumi and Don Mueang airports in Bangkok as well as Phuket.
“Surveillance was necessary because there were direct connections,”
said Dr Sophon, deputy permanent secretary. At these airports, screening of arrivals from affected countries continued, focusing on passengers with fever or respiratory symptoms and people who had been in an outbreak area within the previous 21 days.
Bangladesh strain identified in Thai bats
According to Dr Sophon, the virus detected in Thai bats was the Bangladesh variant of Nipah. Disease Control Department spokesperson Dr Jurai Wongsawat explained there were Bangladesh and Malaysia strains, and
“The Bangladesh strain is more dangerous, the mortality rate is quite high and it causes respiratory symptoms,”
said Dr Jurai, spokesperson. She stressed that the illness had to be taken very seriously 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, as infection required direct contact with body fluids from an infected person. Studies of Thai fruit bats showed only 10% of samples tested positive for Nipah, compared with 40 to 50% in India, and there was no evidence in Thailand that bats had passed the virus to pigs or humans. Detection of the virus in Thai fruit bats typically peaked in April and May.
Pigs could act as amplifying hosts
Director-general of the Department of Medical Services Dr Nattapong Wongwiwat said fruit bats were the main host of Nipah virus, though it could also occur in other bat species. He warned that pigs could act as amplifying hosts if they became infected from bats. Human mortality ranged from 40 to 75%, depending on the virus variant and the level of medical care, he added.
Heightened risk for young 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 obvious than in adults, but disease progression could be very severe and Nipah could cause serious encephalitis. The illness typically began with fever, headache, muscle pain, vomiting, sore throat and dizziness, followed by drowsiness that could lead to confusion, seizures, unconsciousness, pneumonia, acute respiratory failure and encephalitis.
Long-term consequences after infection
In the long term, infected young children faced the risk of delayed development, learning difficulties and epilepsy, Dr Arkom said. He called for close monitoring of symptoms in children who might have been exposed, given the absence of a vaccine and the high mortality associated with the Bangladesh strain.