Infectious disease causes long-term changes to frog's microbiome

February 10, 2021

Just as beneficial microbes in the human gut can be affected by antibiotics, diet interventions and other disturbances, the microbiomes of other animals can also be upset. In a rare study published this week, Andrea Jani, a researcher with the University of Hawai'i at Mānoa School of Ocean and Earth Science and Technology (SOEST), determined the skin microbiome of an endangered frog was altered when the frogs were infected by a specific fungus, and it didn't recover to its initial state even when the frog was cured of the infection.

All animals host symbiotic microbes--many of which are beneficial--within and on their bodies. For optimal health, this microbial community needs to remain robust and fairly stable, either by resisting change or by recovering effectively after a disruption. Some infectious diseases disrupt the microbiome, but very little is known about what happens after the host is cleared of infection.


Batrachochytrium dendrobatidis (Bd) is a fungus that infects the skin of amphibians and since its discovery just over two decades ago, Bd has emerged as a global threat to amphibians. This pathogen has affected hundreds of species and driven massive population declines, including 90 presumed species extinctions--representing the greatest known disease-induced biodiversity loss.

Jani led a team of researchers from the San Francisco Zoological Society, Sequoia and Kings Canyon National Parks, USDA Forest Service and the University of California to study the skin microbiome of the mountain yellow-legged frog (Rana muscosa), an endangered species in the Sierra Nevada in California.

"Many populations of these frogs have been wiped out by Bd infection, and the fate of remaining populations will depend largely on their ability to survive despite the presence of the pathogen," said Jani.


Researchers and conservation managers have tested immunization as a method to protect the frogs. Frogs were taken into captivity, deliberately infected with the pathogen, and then cleared of their infections using antifungal drugs, in an attempt to train their immune systems to recognize and fight the pathogen. The frogs are then released back to the wild.

During one of these trials, Jani sampled the skin microbiomes of the frogs before they were exposed to the pathogen, after they were infected, and again after they had been cleared of infection. She then used genetic sequencing technologies to identify the bacteria present.

"We found that Bd infection disturbed the frog microbiome by altering the relative abundances of core bacterial species, just as we had observed in previous research," said Jani. "But surprisingly, when the frogs were cleared their infections, their microbiomes did not recover. In other words, removing the cause of the microbiome disturbance was not enough to bring about recovery from the disturbance."


Establishing whether the microbiome can be resilient after disease is important to a basic understanding of microbiome dynamics, as well as the effects of infectious diseases.

Bacteria inhabiting the skin of amphibians have the potential to provide some resistance to disease conditions. Some researchers are exploring whether probiotics can protect wild amphibians, especially endangered species.

"We would hope that the microbiome can act as a 'body guard,' but that possibility may be compromised if a Bd infection can change the microbiome itself," said Jani.

"Among the key unanswered questions are whether and how the disturbance to the microbiome affects the functions it provides for the host," she added. "In our recent study, we found that greater shifts in the microbiome were linked to greater weight loss by the frogs, which suggests--but doesn't prove--that microbiome change may have been detrimental. As with many microbiome studies, it can be very difficult to tease apart cause and effect."


Hawai'i is home to a wealth of endemic biodiversity, but also has one of the highest extinction rates on the planet. Although Hawai'i has no native amphibians, infectious diseases have decimated and continue to threaten Hawaiian species, such as the iconic O'hia and several forest bird species.

"Conservation of Hawaiian species will require understanding of how infectious diseases affect Hawaiian wildlife, including effects on associated microbiomes," said Jani. "Hawaiian species' microbiome sensitivity and resilience to infectious disease is not well understood, but a broad understanding of these processes in other species may provide initial insights and guide future research with Hawaiian species."

With a wide variety of microbiome research being conducted in Hawai'i, the UH Mānoa Center for Microbiome Analysis through Island Knowledge and Investigation (CMAIKI) connects microbiome scientists, including Jani, across the islands, furthering collaboration and facilitating new discoveries related to environmental and human health.

University of Hawaii at Manoa

Related Infectious Diseases Articles from Brightsurf:

Understanding the spread of infectious diseases
Physicists at Münster University (Germany) have shown in model simulations that the COVID-19 infection rates decrease significantly through social distancing.

Forecasting elections with a model of infectious diseases
Election forecasting is an innately challenging endeavor, with results that can be difficult to interpret and may leave many questions unanswered after close races unfold.

COVID-19 a reminder of the challenge of emerging infectious diseases
The emergence and rapid increase in cases of coronavirus disease 2019 (COVID-19), a respiratory illness caused by a novel coronavirus, pose complex challenges to the global public health, research and medical communities, write federal scientists from NIH's National Institute of Allergy and Infectious Diseases (NIAID) and from the Centers for Disease Control and Prevention (CDC).

Certain antidepressants could provide treatment for multiple infectious diseases
Some antidepressants could potentially be used to treat a wide range of diseases caused by bacteria living within cells, according to work by researchers in the Virginia Commonwealth University School of Medicine and collaborators at other institutions.

Opioid epidemic is increasing rates of some infectious diseases
The US faces a public health crisis as the opioid epidemic fuels growing rates of certain infectious diseases, including HIV/AIDS, hepatitis, heart infections, and skin and soft tissue infections.

Infectious diseases could be diagnosed with smartphones in sub-Saharan Africa
A new Imperial-led review has outlined how health workers could use existing phones to predict and curb the spread of infectious diseases.

The Lancet Infectious Diseases: Experts warn of a surge in vector-borne diseases as humanitarian crisis in Venezuela worsens
The ongoing humanitarian crisis in Venezuela is accelerating the re-emergence of vector-borne diseases such as malaria, Chagas disease, dengue, and Zika virus, and threatens to jeopardize public health gains in the country over the past two decades, warn leading public health experts.

Glow-in-the-dark paper as a rapid test for infectious diseases
Researchers from Eindhoven University of Technology (The Netherlands) and Keio University (Japan) present a practicable and reliable way to test for infectious diseases.

Math shows how human behavior spreads infectious diseases
Mathematics can help public health workers better understand and influence human behaviors that lead to the spread of infectious disease, according to a study from the University of Waterloo.

Many Americans say infectious and emerging diseases in other countries will threaten the US
An overwhelming majority of Americans (95%) think infectious and emerging diseases facing other countries will pose a 'major' or 'minor' threat to the U.S. in the next few years, but more than half (61%) say they are confident the federal government can prevent a major infectious disease outbreak in the US, according to a new national public opinion survey commissioned by Research!America and the American Society for Microbiology.

Read More: Infectious Diseases News and Infectious Diseases Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to