By now, it is proven that diseases have caused amphibian, insect, and mammal extinctions. Disease that is causing serious problems for wildlife is a result of many factors. Read this page to discover what disease does to populations and the role that humans play in all of this. Introduced Disease: When infections are brought to an environment where the native species have not co-evolved with them, the new habitat's ecosystem has no natural defenses against the disease, and it can spread uncontrollably. A major example of an introduced disease is WNS, or White-Nose Syndrome; it has ravaged previously abundant bat populations, leaving only a few survivors in caves that used to contain hundreds of bats. This disease was first brought to the United States from a European tourist visiting a bat cave in 2007, but has now spread to about twenty-five U.S. states and five Canadian provinces. WNS has previously been manageable in Europe (in fact, bat species in Western Europe are immune to it) but here, bats are unequipped to deal with such a disease.
Lack of Diversity: As more and more species go extinct, diversity greatly goes down, allowing diseases to spread between species much more easily. It is just so much more convenient for the disease if the various creatures come in contact often and share space. In case you were wondering, this also applies to humans. Diseases first became a threat to us when we first started settling down and farming in ancient times. Before, when we were hunter-gatherers, there was little contact with other people, animals, or land that might carry disease. Now, this problem is compounded by overpopulation. We are very un-diverse, with seven billion+ of us on this planet, and a pandemic is one of the potential major threats that could strike us down. In 2014-5, Ebola thrived in Africa due to the crowdedness of areas and the amount of contact humans have. The deforestation and industrialization that we cause largely mimics the effects of civilization on us, as animals are forced to live together on small amounts of land, hence easily transmitting disease.
Identification Problems: Often times, we do not realize that species are threatened by a disease until it is too late, as diseases spread quickly, and it is hard to eliminate all sources of infection. One type of fungus, Batrachochytrium dendrobatidis (Bd for short), which is devastating to salamanders in Europe, was brought from Asia as a result of animal trade, but was not even identified until decades of extinctions had taken place. So far, two hundred species have gone extinct due to Bd. There are also major fears that the fungus could spread to the United States, a center of salamander diversity. (A fire salamander can be seen below. Bd eats away at the skin of an affected salamander)
Sources: Keim, Brandon. "Disease Can Cause Extinction of Mammals." Wired. Wired.com, 2014. Web. 8 Nov. 2014. Gorman, James. "Infection That Devastates Amphibians, Already in Europe, Could Spread to U.S." The New York Times. The New York Times, 30 Oct. 2014. Web. 01 Apr. 2015. Marcarell, Rebekah. "Skin-Eating Fungus Wiping Out Salamanders; 'It Is A Complete Mystery Why We Are Seeing This Outbreak Now'."Headlines Global News RSS. HNGN, 03 Sept. 2013. Web. 01 Apr. 2015.