Badgers with helminth parasite infections are more likely to have tuberculosis (TB), and infection of both is more likely once either disease has been contracted, new research from Trinity College Dublin (TCD) has found.

A combination of faecal egg testing and lymph node tissue sampling was carried out on badgers that were culled under Ireland’s TB eradication programme, to investigate the relationship between helminth parasites and TB status.

The study, which is entitled An investigation of Mycobacterium bovis and helminth coinfection in the European badger Meles meles, analysed 268 fully grown badgers, 138 of which were male and 130 of which were female. Of all the badgers, 16.4% tested positive for TB.

The study found that males are more likely to have TB than females, and that badgers with hookworm infections are more likely to have TB than those without an infection.

“Males were more likely to be infected. This may be linked to behaviour as adult male badgers are more likely to show bite-wounding than adult females and biting is an efficient way of transmitting,” it states.

Prof. Nicola Marples, from TCD’s School of Natural Sciences, said that the findings of the study will be important for policymakers that are trying to manage TB infection within cattle.

“If animals have parasites, such as helminth worms, they are more likely to catch illnesses like TB because the immune system can’t do everything at once.

“If it’s busy fighting helminth worms it has fewer resources available to protect against bacterial infections, like TB, which require a different immune pathway.

“And it’s true the other way round too; if an animal has a bacterial infection, it is more susceptible to parasites,” Marples said.

She said that cattle are routinely tested for helminths but badgers are not, which led those involved in the research to develop a hypothesis that if badgers are living with a lot of worms, they may be more likely to catch and transmit TB to local herds.

“Our discovery has implications for TB management strategies and expands our understanding of the plight of badgers in the Irish environment.

“As we cannot treat wild badgers for helminth worms, it is important to consider that this will make them more susceptible to carrying TB,” she concluded.