Dreaded Chytrid Fungus
16, Jul 2018
A disease caused by a highly contagious fungus has wiped out as many as 200 species of frog worldwide since the 1970s, and pushed many more to the brink of extinction. The fungus is mostly limited to moist and cooler environments like rain forests.
- The discovery of the dreaded chytrid fungus in frogs in the Western Ghats got Indian scientists worried seven years ago. Now, a team has detected the pathogen in all major biodiversity hotspots in India.
- The pathogen is most prevalent in a family of dancing frogs (Micrixalidae) which is endemic to India, and increased with the onset of the monsoon and Bd is prevalent only at a “low level” in all the country’s hotspots.
- Is present in frogs across the Western Ghats, Eastern Ghats, Himalaya, north-eastern hill ranges, and the Andaman and Nicobar Islands.
- Genetic analyses of the pathogens showed that they are extremely diverse in India.
Chytridiomycosis is an infectious disease in amphibians caused by the chytrid fungi bactrachhochytrium dendrobatids and B.salamandrivorans a nonhyphal zoosporic fungus.
Chytridiomycosis has been linked to dramatic population decline or even extinctions of amphibian species in western North America, Central America, South America, Eastern Australia, East Africa Caribbean.
How it Affects:
It grows on a frog’s ultra-sensitive skin, disrupting the organ’s ability to absorb water and air. Sodium and potassium in the frogs blood goes down really low and they have a heart attack.” Afflicted frogs eventually die of cardiac arrest.
- No effective measure is known for control of the disease in wild populations.
- A number of options are possible for controlling this disease-causing fungus, though none has proved to be feasible on a large scale.
- To protect themselves against nasties like the chytrid fungus, frogs secrete antimicrobial peptides, essentially an immune system for the outside of the body. But this fungus is so nasty, so virulent, that it quickly overwhelms its victims, peptides be damned.
- Another strategy is to coat frogs with a solution containing a fungus-fighting bacterium, though that of course wouldn’t eradicate the fungus itself.
- Some frogs may be developing a resistance to the deadly chytrid fungus.
- Right now, researchers are fighting the fungus by capturing vulnerable frogs and bringing them into the lab for captive breeding that focuses on creating a genetically diverse population, ensuring the species doesn’t go extinct if the fungus decimates the wild population. But if you wanted to release the frogs back in the wild, it’s hard to know they’d be able to resist the fungus.
A new study suggests that changing global temperatures may be responsible for increased proliferation of chytridiomycosis. The combination of decreased daytime temperature and increased night-time temperatures may be providing optimal growth and reproduction for Chytrid fungus which has preferred temperature range between 63° and 77 °F (17° and 25 °C). The fungus dies at temperatures at and above 30 °C
The disease has been proposed as a contributing factor to a global decline in amphibian populations that apparently has affected about 30% of the amphibian species of the world. It is considered as “the worst infectious disease ever recorded among vertebrates.”