This page provides general information about this condition. Text can be revealed by clicking on the green headers. Links to press releases, results from DWHC investigations as well as other useful documents and relevant literature available on the DWHC website can be found at the bottom of the page.
In 2010, ranavirus was found for the first time in the Netherlands when a volunteer from the Dutch amphibian, reptile and fish research organisation discovered thousands of dead frogs in the Dwingelderveld National Park. Investigations carried out by the DWHC showed ranavirus to be the cause of death.
Ranavirus is a member of the Iridoviridae family of viruses. The genus contains several sorts of ranavirus including the Common Midwife Toad Virus (CMTV); this and the CMTV-like forms have been detected in the Netherlands.
Ranaviruses occur in amphibians, reptiles and fish. In the Netherlands, ranavirus has been found in all three native sorts of water frogs (the pool frog, lake frog and common water or green frog) as well as in the European common frog, common toad, spadefoot toad, common (smooth) newt and the great crested newt. In other countries ranavirus has also been found in fire salamanders, alpine salamanders and common midwife toads.
The lesions associated with ranavirus infection are skin ulceration and haemorrhages in the skin and internal organs. These lesions are, however, not unique to ranavirus and furthermore, are not seen in every case of ranavirus infection.
Ranavirus is spread via direct or indirect contact. For example ingestion of an infected animal or skin-skin contact constitute direct pathways; importantly skin damage is not necessary for infection to occur. Indirect contact could involve contact with contaminated water and sediment or materials such as boots, buckets and machinery used by researchers or people working on the waterways.
In the Netherlands, ranavirus has been found in provinces throughout the country: Friesland, Drenthe, Overijssel, Gelderland, Noord-Brabant en Limburg.
To avoid spreading the disease frogs and newts should not be relocated or released in the wild. The virus survives in soil and mud and it is, therefore, important that all equipment used in canals and ponds should be scrubbed to remove remnants of soil and then rinsed with soap and clean water. These measures can remove pathogens minimizing the chance of spread between areas. Field-researchers should, where possible, work in the direction of the current so as not to spread infection upstream. The relocation of water-plants, fish and amphibians should be avoided.