The mysterious deaths and illness took place on three fishing trawlers while they were fishing in the Indian Ocean hence they were sent back ashore to Ranong. Five fishing boat crewmembers remained at Ranong Hospital, one of them seriously.

Citing an initial examination result by Ranong public health official Dr Chaiyaporn Suchatsunthorn, Piyasakol said the disease investigating team initially found the victims suffered from a severe form of vitamin B1 deficit.

Besides the autopsy on six dead bodies, the blood samples from 23 patients – before and after vitamin B1 injection – were sent for a lab test at Chulalongkorn University’s Faculty of Medical Science to confirm the vitamin deficit.

The lab test result should be known in three days, he said.

They also submitted 18 samples of food and water from the two trawlers on which the victims died to the lab to test for toxins at Surat Thani’s Medical Science Centre. The results should be available in 2-3 weeks, he added.

Piyasakol said such a vitamin B1 deficit could be prevented if they stored supplementary food such as brown rice and multi-coarse grains for consumption at sea.

To prevent re-occurrence, public health offices at provinces with fisheries business operators were told to ask provincial fisheries offices and associations to have trawlers equipped with such vitamin B1 supplements before sailing out.

Chaiyaporn yesterday said the initial examinations were carried out on 115 crewmembers of six trawlers, including 64 Thais, after the December-January deaths of six workers (one Thai and five Cambodians).

Most of the fatal cases reported sudden loss of muscle power on limps, swollen limps, numbness and cramp, chest tightness and respiratory difficulty 2-7 days prior to deaths.

As all ill 25 patients required the vitamin B1 injection, the discharged 20 patients were also required to either take daily vitamin shots for a week or have it orally for two weeks.