Timeline of key events in the probe into multiple tourist deaths in Chiang Mai
27-28 April 2011: The DDC team and officials of the Occupational Health Office went to Hotel C again to examine environmental factors.
5 May 2011: Chiang Mai health officials performed an experiment at Hotel C to measure air toxicity. Result was that it was within acceptable standard.
8 May 2011: New Zealand TV3‚Äôs 60 Minutes programme aired an investigative report in which it swabbed the room in Hotel C where the NZ tourists stayed and found traces of chlorpyrifos, a pesticide, which its ‚Äúexperts‚Äù ruled to be the likely cause of death of one of the NZ women. Thai and foreign toxicologists, including those in New Zealand, subsequently ruled this out.
10 May 2011: Meeting of experts from multiple diciplines in Chiang Mai to review investigation progress. The DDC in Bangkok joined this meeting through video conference facilities. WHO and US CDC representatives participated in the consultation at the DDC.
12 May 2011: At 2 pm Chiang Mai authority, led by the governor, held a briefing for representatives of foreign consulates and embassies in the province, to inform them of progress in the investigation to date.
At 6 pm there was a video and teleconference consultation between Thai investigators and international toxicologists from Australia, India, Sri Lanka, the United Kingdom, the United States, the World Health Organization (WHO) and the US Centers for Disease Control and Prevention (US CDC). Hypotheses about toxin and chemical causes were discussed at this conference which was hosted by the US CDC in Bangkok.
20 May 2011: MOPH team, with a representative of the WHO, visited the hotel where the New Zealand women stayed. Additional environmental samples were collected and sent to laboratories in Thailand and overseas for further tests.
The US CDC was testing for some infectious agent in the heart muscles of all six people who died. The Thai National Institute of Health also tested for toxin/chemical from gastric samples from the New Zealand case. Result was negative.
23 May 2011: DDC wrote Update 3 in Thai and English to inform on further progress and posted it on the department‚Äôs website. But this was done only after Chiang Mai province informed relatives of the NZ case and representatives of various consulates. The media, both local and overseas, was then notified of the update.
31 May 2011: video conference hosted by US CDC‚Äôs Global Disease Detection Branch and include various subject matter experts to discuss progress of investigation.
21 June 2011: DDC wrote Update 4 in Thai and English and posted it on the web through the same procedure as Update 3 ‚Äì prior notification of relatives and consulates. Update 4 announced the formation of a panel of expert to review evidence and help the investigation team reach a conclusion on its probe.
12 July 2011: Chiang Mai Health Office held a briefing for some members of its expert panel who are new to these cases.
19 July 2011: US CDC Bangkok hosted a video conference between DDC and experts in Atlanta and WHO in Geneva to review findings so far.
3 August 2011: Chiang Mai Health Office and its expert panel go over the evidence and findings in Chiang Mai to conclude the investigation. DDC took part in the meeting through a video link from Bangkok.
16 August 2011: Investigation Committee announces findings and DDC put Update 5 and other relevant information on its website