When the freezer was inspected 2 weeks after the outbreak, the temperature of the freezer was -3.3°C, which might not have been cold enough to kill Cyclospora oocysts.
Researchers have offered various explanations for the recurring outbreaks, including temperature shifts and the changing ecology of local water bodies, but they haven't had enough evidence to nail down the cause.
Currently, new infection numbers are down due to colder temperatures (and thus, less hospitable environments for mosquitoes), but countries that experienced the biggest outbreaks last year have to deal with the aftermath of those infections, while countries that didn't experience outbreaks could find that it's their turn to grapple with a Zika outbreak as temperatures warm.
Other causal attributions – in both public discourse and the scientific literature – have linked influenza outbreaks to temperature and climatic factors [ 16].
"We can say when these organisms are going to be at risk of disease outbreaks based on temperature projections," said Mr Harvell.
In order to prevent further oyster farm outbreaks, a water temperature monitoring and shell-fish testing programme has been recommended.
The region's governor, Dmitry Kobylkin, linked the outbreak to a massive temperature spike in the region that has melted the permafrost ― a thick layer of soil and organic matter frozen year-round in the coldest areas of the planet.
Mean water temperatures increased by only 0.3°C (to 30.5°C) in the month prior to the disease outbreak in 2008, whereas temperatures increased by 1.7°C in the month prior to the 2009 outbreak and reached 31.7°C.
Another contributor to the botulism outbreak may be warming temperatures in the relatively shallow lake, whose average depth is 60 feet.
It's very, very difficult to wear those suits in hot weather," said Chikwe Ihekweazu, an epidemiologist who worked with the WHO during the 2004 outbreak in Sudan, where temperatures can soar up to 42C.
