Ranavirus in Pelophylax

What is it?

Ranavirus is a virus that affects frogs, including the North African green frog (Pelophylax saharicus). It can cause severe illness, sometimes fatal within a short time. This infection is monitored worldwide because it threatens populations of wild and captive amphibians.

It is not transmissible to humans, but it is highly contagious between frogs and can also affect other amphibians, fish, or reptiles depending on the viral strain.

Commonly observed signs

These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.

Causes and risk factors

The disease is caused by a ranavirus, a DNA virus belonging to the Iridoviridae family. Several ranavirus species exist and can affect amphibians, some fish, and some reptiles.

The virus attacks multiple internal organs at the same time (liver, kidney, spleen, digestive tract), which explains the severity and rapid progression in young or weakened animals.

Young frogs and tadpoles are generally more susceptible than adults. Stress, overcrowding in a pond or terrarium, poor water quality, and unusual temperatures favour the development of disease.

Introducing new animals without an observation period, sharing equipment between multiple ponds or terrariums, and contact with wild populations also increase the risk.

Transmission

The virus spreads through direct contact between frogs, through contaminated water, or by contact with material, mud, or objects that have touched an infected animal. Ingestion of contaminated prey or carcasses is also a route of transmission.

The virus can survive for a period of time in the environment, particularly in water and wet sediments, which facilitates its spread between water bodies if material or animals move between locations.

Diagnosis and care

Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.

Treatment

There is no established specific antiviral treatment against ranavirus. Veterinary care aims to support the affected animal: supportive care, environmental management (water, temperature), treatment of secondary infections if needed with appropriate antibiotics or antifungals.

Group management (isolation of sick animals, disinfection) is essential to limit spread to other animals.

Prevention

Possible complications

The disease can progress very rapidly to death, particularly in young animals or tadpoles. Secondary bacterial or fungal infections may develop on skin lesions.

In a population or breeding collection, infection can cause significant mortality over a short period.

When to see a veterinarian

Prognosis

The prognosis is guarded to poor in the event of declared infection, especially in young animals, as the disease often progresses rapidly. Healthy adults may sometimes survive, but remain carriers and contagious.

Early intervention and isolation measures strongly influence the outcome at the group level.

Frequently asked questions

References

WOAH — Organisation mondiale de la santé animale (ex-OIE)

OMS — Organisation mondiale de la santé

Content reviewed by the TunisieVet editorial team · Updated 28 August 2026