From Bluetongue disease in sheep to Rift Valley Fever in camels, researchers say that animal diseases are sparked and spread by climate change. What causes them, and what can people do to prevent them from spreading?
Sheep with swollen, bright blue tongues: it is a surreal sight only recently spotted in Germany.
Aptly dubbed Bluetongue, the deadly disease causing the coloration was previously well known in veterinary medicine as a virus specific to Africa, says Heribert Hofer, the director of the Leibniz Institute for Zoo and Wildlife Research at Free University of Berlin. It particularly occurs in sheep, cattle and goats.
Yet over the past 10 years, several cases have been reported throughout Western Europe due to an increase of the warm and wet temperatures where the disease thrives. To date, it’s killed more than 1.5 million sheep in Europe.
“Climate change makes it easier for the pathogen to spread beyond its normal places,” says Hofer. “In places where it exists already, it might become more severe.”
Bluetongue is one of a number of climate-affected diseases impacting the health of animals. Scientists such as Hofer say they will become more prevalent due to rising temperatures.
Animal diseases are a “canary in a coalmine”, or an early-warning indicator of a greater problem at hand, says Matthew Bylis, head of Liverpool University’s Climate and Infectious Diseases of Animals (LUCINDA) group. Two-thirds of human diseases originate in animals, about half of which are farm animals.
Bluetongue is transmitted by Cullicoides immitus, a tiny biting midge, similar to the way that malaria is spread by mosquitoes.
Climate change also prompts behavioral changes of animals that make them more susceptible to disease, says Baylis. For example, during periods of drought animals will cluster together more at waterholes. The close proximity will allow diseases to spread more and the animals, often in worse physical condition, will be unable to resist them.
Yet it’s not just warming, but climate fluctuations as a whole, which are sparking the spread of disease. There are a number of species of fungi, a couple of which serve as wildlife pathogens, which bode better under colder conditions.
Infectious diseases in animals will have a more profound impact on biodiversity than has previously been realized, says Hofer.
“We recognize that infectious disease pathogens are a major force shaping not only the ecology of natural ecosystems, but also the evolution of species, their ability to handle challenges, and the development of new species,” he says.
Combating these issues requires massive investment, training, and development of vaccines, says Ostfeld.
Species do move, and they can shift their positions in response to changing conditions, he adds. Yet the rate of climate change “is so fast right now”, that in many cases neither evolutionary change nor behavioral change is sufficient to keep up.
2014 Deutsche Welle