Feral Wild Boar Surveillance

Report on the results of analysing blood and faecal samples taken from feral wild boar culled in the Forest of Dean.

• Faeces and serum samples collected from 91 wild boar culled in the Forest of Dean were tested for non-statutory endemic pathogens of pigs.
• Serological exposure to two types of Leptospira were detected with a combined prevalence of approximately 18%. Leptospira Bratislava was the most common and is pig adapted, it also occurs in a range of wildlife species. Prevalence was significantly higher in older pigs and the overall results suggest endemic infection across the wild boar population.
• A lower prevalence of Leptospira Javanica was reported, previous research suggests this is usually prevalent in rodents and is zoonotic.
• One adult female was positive for PRRSv antibody but there were no clinical signs of disease suggesting that although susceptible to infection, there is no evidence that wild boar act as a reservoir to infect commercial pigs.
• Infection with, or exposure to other pathogens tested was not confirmed
• No Salmonella species were detected

These results are relevant for a long established wild boar population in a forested area of England which has relatively low commercial pig density and should not be extrapolated to wild boar populations in other regions.

• The risk of disease transmission from feral wild boar to domestic pigs has been a long term concern for both animal and public health. The Forest of Dean is the site of the largest population of feral wild boar in England and limited data is available on the health status of the animals.
• A planned cull (to control wild boar population size) in the Forest of Dean presented an opportunity for diseases surveillance on prevalence of key endemic diseases that may pose a risk to domestic pigs
• Surveillance in wild boar elsewhere in Europe had indicated prevalence of some of the priority pathogens (PRRSv, Salmonella, Leptopsira and Swine influenza)
• The results would be helpful in assessing the risk of transmission of pathogens between wild boar and domestic pigs
• If these pathogens are causing disease in pigs, their presence in wild boar could cause morbidity and mortality and is likely to be of interest to those involved in wildlife disease and conservation
• There is value in holding samples from culled wild boar as an archive