Wild boars have been venturing more frequently into urban areas across Spain in recent years, a trend largely driven by prolonged drought conditions. The ongoing climate challenges have led to a decline in natural vegetation, forcing the animals to search for food in towns and cities.

This growing presence has led to a number of serious issues, including a spike in road traffic accidents involving boars, damage to crops, and a potentially significant public health concern: the transmission of parasites to humans. A recent study published in the journal Veterinary Research has identified the Blastocystis parasite, found in wild boars, as a new and emerging public health challenge. This intestinal parasite can be transmitted to humans and other animals primarily through contact with contaminated faeces. 

The research, carried out by an international team of scientists (including experts from Spain and Portugal), was conducted between 2014 and 2021. In total, 459 wild boar faecal samples were analysed—360 from various regions in Spain and 99 from Portugal.

The study found that 15.3% of the Spanish wild boars were infected with Blastocystis, while the prevalence was significantly higher in Portugal, where 34.3% of the sampled boars tested positive.

Importantly, researchers identified seven different subtypes of the parasite, reflecting a notable level of genetic diversity.

All infected animals shared a specific subtype known as ST5, which appears to have adapted particularly well to the wild boar's physiology. This same subtype is commonly found in domestic pigs, suggesting a possible link between wild and domesticated animal populations in terms of disease transmission.

The scientists are now urging the implementation of broader and more systematic monitoring of wild boar populations, as well as livestock that might come into contact with them.

They recommend regular faecal sampling and genetic analysis to detect parasitic outbreaks early and minimise risk to public health.

The study emphasises the importance of incorporating Blastocystis detection and surveillance into a wider One Health strategy, an approach that recognises the interconnected nature of human, animal, and environmental health.

This model is increasingly seen as essential in tackling emerging zoonotic threats, particularly as climate change and habitat loss drive wildlife closer to human populations.

Wild boars, which are considered invasive in some regions, are known not only for their resilience and adaptability but also for their ability to thrive in peri-urban and urban landscapes.