# Smithsonian and Penn State link frog losses in Brazil to a fungal disease, chytridiomycosis

- Published: 2026-11-08 06:48 UTC
- Section: Planet › Ecology & recycling
- Tags: frog decline Brazil, chytridiomycosis, Batrachochytrium dendrobatidis, Boracéia biological station, amphibian museum specimens, Molecular Ecology, Smithsonian, Atlantic Forest amphibians
- URL: https://realtech.media/news/rt-d1e99c26b644a272a41c1123_smithsonian_and_penn/

**Analysis of over 370 preserved amphibians from 17 species found no infection before 1979, while more than half of those collected after the declines tested positive, the authors report.**

![Smithsonian and Penn State link frog losses in Brazil to a fungal disease, chytridiomycosis](https://realtech.media/media/2026/11/96dba24dc43acc52.jpg)
*Charles J. Sharp, Wikimedia Commons, CC BY-SA 4.0*

Researchers from the Smithsonian's National Zoo and Conservation Biology Institute and Pennsylvania State University have described evidence that a fungal disease stood behind the disappearance of frogs at the Boracéia biological station in Brazil's Atlantic Forest, tech.wp.pl reports. The study, published in Molecular Ecology, concerns amphibian populations that shrank sharply between 1979 and 1982. For almost 50 years the cause had not been explained. [1]

According to the authors, the most probable explanation is chytridiomycosis, a disease caused by the microscopic fungus Batrachochytrium dendrobatidis. [1] Earlier suggestions pointed to climate change or unusually harsh weather. The authors note that the spread of the pathogen coincided in time with the unexplained decline of amphibians in the region. [1]

## Museum specimens as data

The data came from frogs preserved in museum collections. The Smithsonian's National Museum of Natural History holds specimens collected by William Ronald Heyer during five expeditions to Boracéia: two before the main collapse of populations and three after the mass declines. [1]

The team examined samples from more than 370 preserved amphibians belonging to 17 species. They looked for traces of infection and checked how often the fungus appeared in successive years. Among specimens collected before 1979 there were no signs of infection, while more than half of those collected after the declines tested positive. [1]

The study also produced a less obvious result. Species that suffered most showed no detectable infection in preserved specimens, whereas the fungus often appeared in species whose numbers stayed more stable. [1] The authors say this does not contradict the role of the disease. In their view, some frogs may have tolerated infection better and survived, while more susceptible species may have died so quickly after infection that infected animals were not collected. [1]

## Amphibians in Boracéia today

Between 2022 and 2024, together with researchers from the University of São Paulo, the scientists visited Boracéia six times to check which amphibians live there now. They found 12 of the 17 species known from the historical collection. The presence of five was not confirmed, so their current status remains uncertain. [1]

Even so, the researchers assess that most amphibian species at Boracéia recovered after the strong declines. The fungus has not disappeared from the local environment, but some formerly sensitive species may have developed greater tolerance over time. [1]

## Sources

1. [tech.wp.pl](https://tech.wp.pl/tajemnica-znikajacych-zab-w-brazylii-po-50-latach-naukowcy-znalezli-sprawce,7347071521958336a)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-d1e99c26b644a272a41c1123_smithsonian_and_penn/