Batrachochytrium salamandrivorans (Bsal): how to spot and report the disease

Batrachochytrium salamandrivorans (Bsal) is a  fungus that causes  chytrid disease in amphibian species. It mainly affects salamanders and newts.

Bsal was first detected in wild salamanders in Europe in 2013. It was most likely introduced to Europe through trade in captive amphibians from South East Asia to Europe, where it then spread from the captive to the wild salamander population.

Since its introduction to Europe, Bsal has caused mass mortalities in wild salamanders in Belgium, Germany, the Netherlands and Spain.

Bsal can affect most western Palaearctic salamander and newt species, including the GB protected species the great crested newt. It is considered a major threat to amphibian biodiversity.

Clinical signs

Bsal is only known to cause disease in salamanders and newts, although some frogs and toads can carry the fungus without showing any clinical signs.

Chytrid disease is characterised by ulcerated skin, which may extend all over the body.

Clinical signs can include:

• excessive shedding of the skin
• anorexia
• apathy
• ataxia
• death

How is Bsal spread

Direct contact between animals, contaminated materials, such as water, equipment, soil, gravel and aquatic plants. It can also persist in the environment without amphibians for at least several weeks.

Confirmatory laboratory tests are needed to confirm the presence of Bsal - you cannot confirm from clinical signs.

Human health implications

There are no human health implications.

Disease control

For further information on prevention and control, see the Garden Wildlife Health (GWH) scheme Amphibian Disease Alert guidelines for safe disposal of wastewater and other materials from captive amphibian enclosures

For further information on the import of live amphibians of the order Caudata (salamanders and newts), read the guidance on quarantine requirements for live amphibians of the order Caudata (salamanders and newts)

Legislation

The main legislation relating to the control of Bsal is The Animal Health (Notification and Control Measures) (Miscellaneous Amendments) (Scotland) Order 2021and the Animal Health Act 1981.

Biosecurity

Biosecurity is about being aware of the ways disease can spread and taking every practical measure to minimise the risk of disease spreading. You can help prevent this disease from spreading between captive and wild populations in GB by practising good biosecurity.

If you keep or breed salamanders or newts, or are involved in amphibian fieldwork you should:

• dispose of waste water and other materials safely
• prevent the escape or release of potentially infected animals – it is an offence to release or allow to escape any non-native amphibian into the wild
• cleanse and disinfect people and equipment that have been in contact with amphibians or their habitats