The decline of the midwife toad: deadly diseases in the Picos de Europa


Mara Hernández

Midwife toad populations in the Picos de Europa face an increasing number of threats (being run over by vehicles, habitat fragmentation, invasive species), but in recent years there has been a worrying decline in their population due to the presence of emerging diseases, particularly ranavirus and chytridiomycosis. These diseases pose a significant risk to the diversity of the nature park and amphibians worldwide. Research is therefore essential for a better understanding of these threats and to prevent transmission between different wild animal populations, thus protecting the health of these amphibians and the integrity of ecosystems.

DIVAQUA actions

Increase in knowledge of the species distribution.

Analysis of the distribution of pathogens through the taking of environmental DNA samples.

Actions in bodies of water and creation of safety protocols.

In adults, lesions only occur on the skin.

In larvae, it produced ulcers and erosions in the oral cavity.

Dead individuals may appear without lesions.

It causes symptoms such as local bleeding, ulcers on the skin and organ necrosis.


  • Disease caused by the fungus Batrachochytrium dendrobatidis.

  • It infects amphibian larvae and adults.

  • High mortality rate.


  • Disease caused by a Ranavirus.

  • It infects amphibians, fish and

  • It affects all phases of the biological cycle.

  • Highly infectious with 100% death rate.

Transmission of pathogens

How can you help?

Do not touch or move amphibians or other wild animals.

Swimming is forbidden in the Picos de Europa. Prevent dogs from swimming in lakes and ponds and do not step in bodies of water.

Use the BSAlert app or notify the authorities of the presence of any sick or dead animals.