August 13, 2012

Parasite-Caused Illnesses Affected By Unexpected Temperature Changes

redOrbit Staff & Wire Reports - Your Universe Online

Climate change could cause parasites such as tapeworms to become more infectious or malignant, researchers from Oakland University and the University of South Florida claim in a new study gauging the impact of temperature swings on frogs' fungal infection rates.

The research, which was published in Monday's edition of the journal Nature Climate Change, shows that tiny parasitic organisms likely have an easier time adapting to shifts in temperature and weather conditions than the animals they live in, Reuters reporter Alister Doyle said.

The scientists said that the reason for this phenomenon is because parasites are smaller and grow more rapidly, Doyle wrote. As a result, increases in the climatic variability would make it easier for those organisms to infect their hosts, thus exacerbating the effects of certain types of diseases, lead scientist and Oakland University researcher Thomas Raffel explained to Reuters.

Raffel and his colleagues focused their research efforts on frogs suffering from chytridiomycosis, a condition caused by the parasitic fungus batrachochytrium dendrobatidis (BD)  that has been responsible for killing amphibian species all across the world, BBC News Environmental Correspondent Richard Black said.

The scientists discovered that temperature shifts tend to make the creature's immune systems less effective against their parasitic infectious agents. Cuban treefrogs in 80 laboratory incubators were exposed to a variety of temperatures and BD infection during the experiment, Reuters reported.

Frogs that were kept in incubators at 59 degrees Fahrenheit for the entire course of the experiment were less likely to become infected with the disease than those who spent four weeks living in temperatures of 77 degrees Fahrenheit for four weeks before being moved to the cooler location.

Those who were exposed to more predictable daily temperature variations between the two, on the other hand, were better equipped to battle off the fungal infection, according to Doyle.

"I'm not convinced that the effect we've discovered could be considered responsible for declines or extinctions in the ways way that the spread of BD can be considered responsible," Raffel told Black. "It might be, however, that climate change has sped up the decline or extinction after the parasite arrived."

"There's a lot of observational evidence that climate change is leading to increased variability and unpredictability of temperature and precipitation, and it's entirely possible that the kind of effects we observed could become more important in the future," he added. "But I think it's really difficult to make extrapolations -- partly because work needs to be done with additional species, and also because we haven't done the experiments yet that would allow us to make predictive models in a quantitative way."