New threat to the brown hare: Iberian myxoma virus variant detected in Germany for the first time

An increasing number of seriously ill or dead brown hares (Lepus europaeus) are currently being observed in North Rhine-Westphalia, Germany. The animals showed typical signs of myxomatosis (rabbit plague) such as swollen eyelids, genital mucous membranes and inflammation of the nose and lips, as well as apathy and loss of the natural flight instinct. Myxomatosis is caused by the myxoma virus (family: Poxviridae; species: Leporipoxvirus myxoma), a member of the poxvirus family, and is transmitted by direct contact between animals, contaminated feed or other inanimate vectors, and by biting blood-sucking insects (mosquitoes, fleas). However, the myxoma virus is harmless to humans. While myxoma viruses circulating in Germany to date have repeatedly led to outbreaks with high mortality rates, particularly in wild rabbits (Oryctolagus cuniculus), the increased occurrence of infected wild hares is atypical. Using modern molecular techniques such as genome sequencing and real-time PCR, a variant of the myxoma virus has now been identified in German brown hares for the first time. This myxoma virus variant was first detected in Iberian hares (Lepus granatensis) in Spain and Portugal in 2018 and represents a natural recombination of the classical myxoma virus and a yet unidentified poxvirus. Further investigations into the spread and characterisation of this variant and its host range are currently underway, coordinated by the Research Centre for Hunting and Prevention of Damage caused by Game (LANUV) between the Chemical and Veterinary Investigation Offices and the Friedrich-Loeffler-Institut.