Swedish veterinary authorities have identified two cases of equine parapoxvirus (EqPPV) infection in horses, marking the first documented instances of the virus in the country. The virus, which causes a contagious skin disease, was previously detected in Finland in 2021.
The affected horses, located in the Jönköping and Norrbotten counties, are exhibiting characteristic symptoms including blisters and sores on the skin of their legs, according to the Swedish Veterinary Institute (SVA). While the risk of widespread infection is currently assessed as low, officials are emphasizing the importance of preventative measures.
A Poxvirus Affecting Animals and Potentially Humans
Equine parapoxvirus belongs to the Poxvirus family, a group known to cause skin lesions in both animals and humans. The virus is transmitted through direct contact with infected animals, as well as via contaminated equipment, clothing, hands, and other objects. The SVA recommends isolating infected horses and utilizing disposable gloves and dedicated protective clothing when handling them to minimize the risk of transmission.
The emergence of this virus in Sweden follows an outbreak in Finland beginning in 2021, where it impacted several horse stables. This suggests a potential spread of the virus within the region.
Zoonotic Potential and Human Infection
A significant concern surrounding EqPPV is its potential for zoonotic transmission – the ability to spread from animals to humans. While human infections are generally rare and often mild, the possibility exists, and precautions are advised. Research published in PubMed details an outbreak in Finland where skin lesions were occasionally reported in humans, indicating potential transmission. Other parapoxviruses are known to be zoonotic, further highlighting the need for vigilance.
A study analyzing the Finnish outbreak, published in February 2025, notes that EqPPV can cause painful skin lesions in humans. The research also identified co-infections with several potentially pathogenic and zoonotic bacteria in affected horses.
Clinical Presentation and Diagnosis
The clinical signs of EqPPV infection in horses typically manifest as severe skin lesions, particularly on the pasterns (the area between the hoof and the lower leg). Approximately one-third of horses in affected stables experienced clinical dermatitis during the Finnish outbreak. Due to the lack of readily available specific tests, researchers in Finland developed a novel diagnostic PCR test for EqPPV with a high degree of sensitivity.
Analysis of viral sequences from the Finnish outbreak revealed minimal variation between samples collected in 2013 and those from 2021-2022, suggesting the virus has remained relatively stable over time.
Risk Factors and Prevention
Epidemiological surveys conducted during the Finnish outbreak identified attendance at race events as a significant risk factor for pastern dermatitis. This suggests that the virus may be spread through horse-to-horse contact at these gatherings. Differences in practices between stables that experienced cases and those that did not were also noted, indicating that biosecurity measures may play a role in preventing transmission.
The SVA is closely monitoring the situation in Sweden to prevent further spread of the virus and ensure a rapid response to any potential developments. Veterinary services are advising horse owners to remain vigilant and report any suspected cases of skin lesions to their local veterinarian.
The potential for human infection underscores the importance of practicing good hygiene when handling horses, particularly those exhibiting signs of illness. This includes thorough handwashing and the use of appropriate protective clothing.
While the current risk of widespread infection is considered low, the emergence of EqPPV in Sweden serves as a reminder of the ongoing threat posed by zoonotic diseases and the importance of proactive surveillance and preventative measures. Further research is needed to fully understand the virus’s transmission dynamics and develop effective control strategies.
research highlighted the need for early recognition, diagnostics, and disease control measures should outbreaks occur again.
