The world’s worst animal disease is killing frogs worldwide. A testing breakthrough could help save them

Source: The post is based on the article “The world’s worst animal disease is killing frogs worldwide. A testing breakthrough could help save them” published in The Hindu on 30th May 2023

What is the News?

For the past 40 years, a devastating fungal disease, called chytridiomycosis or chytrid, has been ravaging frog populations around the world. This is a “panzootic” – a pandemic in the animal world.

What is chytridiomycosis or chytrid?

The single-celled fungus enters a skin cell, multiplies, and then breaks back out onto the surface of the animal. This affects their ability to balance water and salt levels, and eventually leading to death if infection levels are high enough.

The high mortality rate and the high number of species affected make chytrid unequivocally the deadliest animal disease known to date.

Origin: Chytrid originated in Asia and spread to other continents through global travel and trade in amphibians.

The intensity of the disease: Chytrid has been devastating frog populations for the past 40 years, wiping out 90 species, including seven in Australia, and causing severe declines in over 500 frog species.

Many species’ immune systems were simply not equipped to defend against the disease, and mass mortalities ensued.

Note: In the 1980s, amphibian biologists began to notice sharp population declines. Only in 1998, the chytrid fungal pathogen was finally recognised.

Diagnosis of Disease: Researchers use a quantitative polymerase chain reaction (qPCR) test to detect chytrid in frogs by swabbing their skin.

Note: The qPCR is a way to measure the volume of DNA from a species of interest.

Recently, Indian scientists have verified the qPCR test and reliably detects chytrid. This new qPCR test can detect strains of chytrid from Asia and another closely related species of chytrid that infects salamanders.

Immunity: So far, there is no clear trend between resistance and immune function.

Research in Asia: Asia is lagging behind the rest of the world in chytrid research.