|
|
In-depth investigations by the Institute of Zoology in London revealed
the cause of previously unexplained amphibian deaths to be an iridovirus
belonging to the genus ranavirus.
Ranaviruses can infect fish,
amphibians and reptiles and while some strains of the disease affect just
one life-stage, others have been shown to kill spawn and
tadpoles as well as adult amphibians.
You may have heard the term 'red-leg' used in relation to ranaviral disease, but it is a rather misleading name.
One of the many symptoms of ranavirus is a reddening of the
skin, though the majority or frogs affected by the disease do
not display this symptom. In addition, frogs may develop red
skin through other infections, not associated with ranavirus and
some healthy frogs naturally have red skin. During the breeding
season females will sometimes develop a red, pink or orange
colouring.
Rigorous post mortem examinations were carried out on bodies
collected from the gardens of FMP reporters. As a result, two
overlapping disease syndromes were identified; the first
characterised by ulcers, the other by widespread
haemorrhaging. Interestingly, ‘red-leg’ disease symptoms were
associated with the presence of the ranavirus and not a species
of bacterium (Aeromonas hydrophila) previously thought
to cause this condition.
 |