Since 2009, 20 Western tourists in Thailand have died from phosphine gas poisoning

Phosphine gas likely cause of Thailand deaths of Quebec sisters: coroner – cbc.ca, March 2, 2015
…She said the Quebec coroner’s office redid all the work done by Thai medical examiners. She said her staff concluded that the DEET Thai examiners identified as the cause of death was not in concentrations high enough to kill the sisters.
Rather, Roussel said, it is likely that phosphine gas — a highly toxic pesticide used to kill bed bugs — was the culprit behind the deaths, even if it was not apparent in their blood.
Roussel said about 20 Western tourists in Thailand have died in similar circumstances since 2009…