While many factors play into the development of a viral or bacterial outbreak, including herd immunity and preexisting healthcare practices, current outbreaks of the Ebola virus and the measles have many wondering exactly what's causing the reemergence of such lethal diseases. Well, the obvious answers of vaccinations and poor sanitation conditions are readily available, but many may not consider an even more significant culprit-climate change.
Though it may not immediately seem like an obvious factor, changes in the global climate significantly alter the emergence and spread of diseases by altering the habitable zones for many pathogen vectors, like bats that carry ebola and even rats, whose fleas can carry the plague. In a new study published this week in the journal Philosophical Transactions of the Royal Society B, two zoologists studying parasites in the Arctic and in the tropics reveal that as climate conditions change across the globe, their studies became frighteningly similar.
Over the course of 30 years of research, the two researchers discovered that as habitats shifted and changed, the parasites that became the focal point of their studies would simply jump from one species to another - - an observation that challenges what evolutionary biologists believe to be a classic example of co-evolution.
"Even though I was in the tropics and [zoologist Eric Hoberg] was in the Arctic, we could see something was happening" coauthor of the study and zoologist with the University of Nebraska, Lincoln, Daniel Brooks says. "While 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."
In fact, the new species acting as hosts may be even better subjects for their parasitic friends. Since the new hosts will not yet have developed resistance to species-jumping parasites, they may face far greater risks of infection, which would have drastic ramifications on the development of epidemics.
The researchers say that public health agencies must certainly take changing habitat ranges into consideration when tracking diseases, however, in spite of valiant efforts we're likely to see a lot more outbreaks of even rarer diseases. And as human communities move farther into wildlife habitat, with ever-growing populations, in conjunction with major changes in global climate, the rate of epidemics no matter what the disease can be expected to increase.
"It's not that there's going to be one Andromeda Strain that will wipe everybody out on the planet" Brooks says. "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."
