The Times Australia
The Times World News

.
Beatbot

.

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

  • Written by Kaya Klop-Toker, Conservation Biology Researcher, University of Newcastle
The world's worst animal disease is killing frogs worldwide. A testing breakthrough could help save them

For the past 40 years, a devastating fungal disease has been ravaging frog populations around the world, wiping out 90 species. Unlike the global COVID-19 pandemic, you may not even be aware of this “panzootic” – a pandemic in the animal world. Yet it’s the world’s worst wildlife disease.

Recently published in the journal Transboundary and Emerging Diseases[1], a multinational study has now developed a method to detect all known strains of this disease, caused by the amphibian chytrid fungus. This breakthrough will advance our ability to detect and research this disease, working towards a widely available cure.

An extreme mortality rate

Chytridiomycosis[2], or “chytrid” for short, has driven severe declines in over 500 frog species and caused 90 extinctions, including seven in Australia.

The extreme rate of mortality, and the high number of species affected, makes chytrid unequivocally the deadliest animal disease known to date[3].

Chytrid infects frogs by reproducing in their skin. The single-celled fungus enters a skin cell, multiplies, then breaks back out onto the surface of the animal. This damage to the skin affects the frog’s ability to balance water and salt levels, and eventually leads to death if infection levels are high enough.

Read more: Before The Last of Us, I was part of an international team to chart the threat of killer fungi. This is what we found[4]

Chytrid originated[5] in Asia. It’s believed that global travel and trade in amphibians led to the disease being unwittingly spread to other continents.

Frogs in regions such as Australia and the Americas did not have the evolutionary history with chytrid that could grant them resistance. So, when they were exposed to this new pathogen, the results were devastating.

Many species’ immune systems were simply not equipped to defend against the disease, and mass mortalities ensued. In the 1980s, amphibian biologists began to notice sharp population declines, and in 1998, the chytrid fungal pathogen was finally recognised as the culprit[6].

Since then, much research has focused on infection trends and how to protect vulnerable frog species. To track such trends, we need a reliable way to detect chytrid in the first place.

A dead white frog floating in water with the belly up and legs splayed
Chytrid infections have an extremely high mortality rate, decimating not just entire populations, but even entire species of frog. Shutterstock[7]

An imperfect swab

To find out if a frog is carrying chytrid, researchers swab the animal and run the same type of test you might recognise from COVID-19 testing – a qPCR. It stands for quantitative polymerase chain reaction, and simply put, is a way to measure the volume of DNA from a species of interest. The test was developed at CSIRO in 2004[8]; unlike a COVID test, however, scientists swab the frog’s skin, not the nose.

Because this test was developed from chytrid in Australia, decades after the pathogen’s arrival in the country, a divergence between the Australian and Asian strains meant this test could not detect chytrid in its region of origin. This has been a major limitation to the past two decades of chytrid research.

Read more: 'Vaccinating' frogs may or may not protect them against a pandemic – but it does provide another option for conservation[9]

Over the past several years, a team led by researchers at the Council of Scientific and Industrial Research – Centre for Cellular and Molecular Biology in India has been working on a new qPCR test that can detect strains of chytrid from Asia. In collaboration with researchers in Australia and Panama, we have now verified the new test also reliably detects chytrid in these countries.

Furthermore, the test can detect another closely related species of chytrid that infects salamanders. The test is also more sensitive, meaning it can detect very low infection levels – thereby broadening the scope of species we can study.

A black and yellow salamander swimming in clear creek water Salamanders are another group of animals at risk of widespread chytrid fungal disease. Shutterstock[10]

Natural immunity?

The most puzzling thing about chytrid is that some amphibian species – even those that have not evolved with the pathogen – don’t become sick when they carry the fungus. These species have some form of natural immune resistance.

However, frog immunity[11] is extremely complex. Immunity might come from anti-microbial chemicals within the skin, symbiotic bacteria on the skin, white blood cells and antibodies in the blood, or combinations of these mechanisms.

So far, no clear trend has been found between resistance and immune function. To make matters more complicated, there is also evidence chytrid can suppress a host’s immune response.

Because there haven’t been any observed chytrid declines in Asia, and because detecting chytrid in Asia has been difficult, Asia is lagging behind the rest of the world in chytrid research. Yet the new qPCR test detected high levels of chytrid in a range of amphibian species across India.

Having the ability to study chytrid in its region of origin may help us understand how Asian species evolved resistance – research that may hold a key to help researchers develop a cure for those species in Australia, North and South America, and Europe that are now on the brink.

While the new qPCR test was successful at detecting chytrid in samples from India, Australia, and Panama, we will need to validate and promote the method so it becomes the new gold standard for chytrid testing. Future work will involve using the test to analyse samples from Europe, and samples from Brazil where genetic studies show that chytrid has diverged.

In time, this new way to detect chytrid could be the first step in helping to save frogs – the hidden gems of our forests and wetlands.

Read more https://theconversation.com/the-worlds-worst-animal-disease-is-killing-frogs-worldwide-a-testing-breakthrough-could-help-save-them-205872

The Times Features

Evaluating Costs and Benefits of DIY Plumbing vs. Professional Services in Newcastle

Plumbing is an essential service for homes and businesses in Newcastle, ensuring the smooth flow of water and sanitation facilities. As residents and businesses strive to maintai...

Tasting Australia welcomes Journey Beyond as new presenting partner

One of the country’s longest running food and beverage festivals, Tasting Australia has announced Journey Beyond as the festival’s new presenting partner for 2025 and beyond. Th...

There are 2 main ways to stretch – the one you should choose depends on what you want your body to do

Picture this: you’ve just woken up and rolled out of bed. Your feet hit the floor, and your legs buckle. They are in absolute agony – that run yesterday has really come back to...

Chef Tom Walton shares three top tips to create budget-friendly meals without compromising on flavour

Feeding the family on a budget doesn’t need to mean sacrificing flavour. Chef Tom Walton shares his top three tips for creating delicious and cost-effective meals. Here’s how y...

Mosquito-borne diseases are on the rise. Here’s how collecting mozzies in your backyard can help science

Warm weather is here and mosquitoes are on the rise in Australia. Unseasonably large swarms are causing problems in some parts of Sydney already[1]. Health authorities track m...

HOYTS Gift Cards are coming in hot this festive season

With a hot selection of blockbuster movies coming to the big screen this summer, avoid the crowds and enjoy some movie magic at HOYTS with discounted gift cards—perfect for stuff...

Times Magazine

Beet Pulp as a Holistic Treatment for Horse Ulcers

Equine ulcers are a common problem in horses that can cause a lack of stomach acid protection resulting in erosive damage to the stomach lining. Stressful situations such as competition, travel, changes in diet and environment, illness and injury c...

Protected Trees in NSW: What You Need to Know

If you live in New South Wales, you might already have heard that some trees are protected by law. Maybe you discovered this when you contacted someone for a quote to remove them, or maybe you learned the hard way by getting a fine for removing a...

Understanding Chemical Storage Cabinets: Importance, Types, and Best Practices

Chemical storage cabinets are essential components in laboratories, industrial facilities, and workplaces that handle hazardous materials. These cabinets are designed to safely store chemicals, minimizing the risk of accidents, spills, and exposure...

Pros and Cons of Using A Microphone with Noise Cancellation

Different types of microphones have different applications. Some are better for live performances, while others are better for recording. But what if you need a microphone that can do both? The best option, in this case, would be a microphone wit...

Unleash the Fun: Why Interactive Toys Are Essential for Your Cat

Cats are playfully inclined animals with their curiosity being heightened by their natural drive to play. However, the act of having to find ways and means of keeping them occupied indoors eventually could be a daunting task. Thus, even using frequ...

In-Depth Guides to Mobility Scooters

Electric scooters play a very important role in the daily needs of many people. They are ideal for the elderly, injured, and disabled who want to regain their independence when it comes to going from one place to another. Learn about the history ...