An investigation into the mysterious deaths of five foreign tourists and a Thai tour guide in hotels in northern Thailand suggests a link to toxic chemical exposure but has failed to determine exactly what killed them, the government said Tuesday.
The victims included tourists from New Zealand, France, the United States and Britain staying at three different hotels in the popular northern Thai city of Chiang Mai. Three other tourists fell ill but recovered.
No one has been declared responsible in the spate of deaths, which came in January and February.
"The specific agents that caused the deaths and illnesses in these events cannot be identified, and it cannot be determined exactly how people were exposed to them," the Department of Disease Control said on its website.
The results were most revealing concerning a 23-year-old New Zealand woman who died Feb. 6, her two female companions who became sick but recovered, and a 47-year-old Thai woman who died Feb. 3 at the same hotel.
The four are "most likely to have the same cause of illness, probably exposure to some toxic chemical, pesticides or gas," the report states.
The deaths of a British couple in their 70s found in their hotel room Feb. 19 were "possibly related" to the those deaths "as they occurred in the same hotel," the report states.
Those deaths happened at the Downtown Inn in Chiang Mai. The hotel owner declined to comment Tuesday.
In an investigative report broadcast in May, New Zealand TV3's "60 Minutes" program said it found traces of the toxic insecticide chlorpyrifos, used to kill bedbugs, in the room where the New Zealand tourist had stayed.
The government report said the cause of death of an 33-year-old American woman who died Jan. 11 "is likely to be chemical or biotoxin in nature and it is probable that it might have been a pesticide."
She was staying in a different hotel in the same area. A 29-year-old Canadian woman traveling with her fell ill but recovered.
A 25-year-old French woman who died Jan. 19 "developed fever and other symptoms on 16 January before arriving in Chiang Mai" so her case is probably not related to the others, the report states.
The website said authorities are taking measures to reduce the risks to visitors, but did not give details.