The deaths of 72 tigers in two tourist parks in Thailand were caused by a virus that should not be a public health concern, officials have said.
The tigers died at parks in Mae Taeng and Mae Rim in Chiang Mai province in north Thailand between 8 to 18 February.
Their deaths had sparked fears of an outbreak of bird flu, amid a resurgence of the virus in Asia. Authorities say it was not responsible, and that the tigers were killed by a virus not known to affect humans.
On Friday, the Chiang Mai regional livestock office had said autopsies of the animals found genetic material of canine distemper virus, or CDV, and traces of bacterial infection.
But Visit Arsaithamkul, a veterinarian who took part in the tiger analysis, expressed concern that the origins of the infections remained unclear without further investigation.
In a Facebook post, he said that he suspected that as the two parks were located just 18 miles apart, the cause of infection could be food the tigers were fed that came from the same source.
He declined to elaborate when contacted by The Associated Press.
No-one has shown any symptoms so far, but authorities are continuing to monitor the health of people who had recently come into contact with the animals.
“There has not been an animal-to-human infection case,” public health minister Pattana Promphat said at a news conference at Government House in Bangkok.
Monthien Khanasawat, director-general of the Public Health Ministry’s Disease Control Department, said: “If we detect any sick persons, we will prepare for a nationwide monitoring measure.
“This will include contact tracing and treatment as necessary.”
Both parks, run under the name of Tiger Kingdom, remain closed. The operators did not immediately respond when contacted for comment.
Bird flu has been resurgent in parts of Asia in recent years, and Thai authorities have been on alert.
Thailand saw 17 deaths out of 25 infected patients from poultry-caused influenza between 2004 to 2007, according to the Public Health Ministry.
CDV, which is infectious to both dogs and felines, can cause stronger symptoms in cats and tigers and can be transmitted through bodily fluids and air.
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Thai authorities said that tigers in confined environments could be particularly vulnerable to the viral infection, especially when compounded by stress and inbreeding conditions.
The remains of the tigers were cremated and buried, officials said.
The carcasses were disinfected, photographed and discarded to prevent any further use, Livestock Development Department director-general Somchuan Rattanamangklanan said.
The first animal-to-human transmission of bird flu was discovered in Hong Kong in 1997 before a pandemic brokeout in Asia in 2003.
Mr Monthien urged Thais to be careful around their consumption of poultry after a man in a neighbouring country, which he didn’t name, was found infected with bird flu.