Environmental degradation promotes infectious diseases

SARS, HIV, and Ebola: human behaviour apparently assists in the creation of these and further infectious diseases. Biologists Simone Sommer and Marco Tschapka from the University of Ulm are searching for the causes in Central American rainforests. During their quest in Panama, they were accompanied by a television camera team from the German ZDF. Their programme about disease-causing zoonoses, transmitted from animals to humans, will be televised on Sunday 8. November at 14:50 in the series planet e.
costa rica
Viruses are omnipresent components of natural ecosystems. Most pathogens are limited to a small group of animals, on which they normally have a minimal effect. However, if conditions worsen, for example through the destruction of their habitat by humans, these animals experience stress. Their immune systems can no longer combat the viruses, and symptoms of disease increase. As the pathogens proliferate, the rate of mutation rises. This also increases the probability of the virus being transmitted to humans. Famous cases include the infectious diseases AIDS – where the pathogen was transmitted from monkeys – and Ebola, transmitted by bats.

Viral reservoirs

Since 2013, the biologists from Ulm have been researching the complex ecological relationships between alterations of the rainforest through humans and the health of small mammals and bats. These communities can play an important role as “viral reservoirs” in human infectious diseases. Their fieldwork, in cooperation with the Smithsonian Tropical Research Institute, focussed on rodents, opossums, and bats around the Panama Canal.

“Amidst the harsh conditions of the rainforest, with extreme heat, mud, and tropical downpour, it was a real challenge to preserve blood and stool samples from the animals without contamination,” explain Sommer and Tschapka. The samples were later analysed in special laboratories at the Universities of Ulm and Bonn. “First results show clear connections between the degree of infection of individual species and the respective environmental conditions,” the researchers explain.

Protect nature, prevent diseases

The protection of natural environments is therefore not only important for the survival of animals, but also in preventing an excessive proliferation of viruses and subsequent rise in transmission to humans. Hence, environmental protection could help prevent infectious diseases like Ebola.

Photo credit: Kim Seng, flickr/Creative Commons

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