A serious disease outbreak in the northern province of Nan yesterday had Army weapons specialists and US disease investigators on full alert.

Almost 150 people in the province have been stricken with botulism, a rare yet lethal bacterial disease that could potentially be used as a biological weapon.

Health authorities have sought international assistance treating the patients.

Military biological-weapons experts have been flown into Nan, as have World Health Organisation disease specialists, said Thai Disease Control Department chief Thawat Suntharacharn.

Since March 4, 143 villagers in Nan's Ban Luang district have been diagnosed as suffering from botulism, a disease caused by toxins produced by several members of a group of bacteria known as Clostridium botulinum.

All of the patients reported having eaten dishes containing preserved bamboo shoots from the same batch at a merit-making feast in their village last week. Shortly after eating the shoots they began to suffer similar symptoms, including vomiting, diarrhoea, difficulty swallowing, dry mouths and muscle weakness, Nan chief health officer Dr Pisit Sriprasert said on Sunday. Of the 143, 33 are currently breathing with the aid of respirators, he said.

"This bacterium is among three strains that can be used as a biological warfare agent - the others are anthrax and smallpox," said Thawat. Fears of a biological attack arose because of the number of people falling ill at one time.

Thawat said there were just a few cases of botulism reported each year in Thailand, and that was why there were no stockpiles of anti-toxin serums used to treat the disease.

Just 20 doses of the anti-toxin serum arrived on Sunday from the UK, but another 10 doses from Canada and 50 from the US arrived yesterday, he said.

And while that amount of serum should suffice to initially treat the patients, Thawat said it was vital more was procured for patients that remained in a critical condition. Thawat said the bill to treat the patients could top Bt10.5 million.

Officials said that of the 70 cans of bamboo shoots in the batch thought likely to have caused the outbreak, 68 had been sold earlier.  The contents of just two of the tins likely infected the 143 patients at the merit-making feast.

Duangkamon Sajirawattanakul

The Nation