Researchers warned that infectious diseases popping up in new places and in new hosts is most likely a result of climate change, and the phenomenon is only going to get worse.
Daniel Brooks, a noted zoologist affiliated with the Harold W. Manter Laboratory of Parasitology at the University of Nebraska-Lincoln, said as climate change alters habitats, more animals and humans will come into contact with parasites they have never encountered in the past.
"It's not that there's going to be one 'Andromeda Strain' that will wipe everybody out on the planet," Brooks said. "There are going to be a lot of localized outbreaks putting pressure on medical and veterinary health systems. It will be the death of a thousand cuts."
Brooks and his co-author Eric Hoberg, a zoologist with the U.S. National Parasite Collection of the USDA's Agricultural Research Service, have both observed parasites invade new areas of the Arctic and tropics in their work.
"Over the last 30 years, the places we've been working have been heavily impacted by climate change," Brooks said in an interview last week, the University of Nebraska-Lincoln reported. "Even though I was in the tropics and he was in the Arctic, we could see something was happening."
As an example Brooks pointed to capuchin and spider monkeys that were hunted to extinction in regions of Costa Rica. In this scenario the parasites that once infected these species moved to howler monkeys, where they remain today. Contrary to previous belief, Brooks believes hosts and parasites become more adapted to each other over time, but even well adapted parasites have the ability to move to new hosts under the right circumstances.
"Even though a parasite might have a very specialized relationship with one particular host in one particular place, there are other hosts that may be as susceptible," Brooks said.
These new hosts could be even more susceptible to the new parasites because they have not yet developed a resistance to them. Resistances can evolve relatively quickly, but rarely completely takes care of the problem.
The researchers believe the real solution is learning which non-human species carry certain pathogens as well as the geographic distribution and behavior of these hosts. This could lead to new public health strategies aiming to minimize human contact with infected animals and insects, such as malaria-carrying mosquitos.
"We have to admit we're not winning the war against emerging diseases," Brooks said. "We're not anticipating them. We're not paying attention to their basic biology, where they might come from and the potential for new pathogens to be introduced."
The research was published recently in a special issue of the Philosophical Transactions of the Royal Society B.
