Wolf Is Back: A Novel Sensitive Sentinel Rejoins the Trichinella Cycle in the Western Alps

SIMPLE SUMMARY: Trichinellosis is a foodborne disease caused by the nematode Trichinella. Human trichinellosis represents a public health hazard with a great socioeconomic impact in food safety, and it occurs by consumption of raw or undercooked infected meat. As apex predators, wolves may represent important actors in maintaining this parasite, although to date, there is a lack of information on Trichinella prevalence in the Western Alps where wolves have recently made return. The main aim of this study was to investigate the occurrence of Trichinella infection in grey wolves and discuss the epidemiological role played by this apex predator in the early phases of their return. During the period 2017–2022, we analyzed 130 muscle samples from individual wolves found dead in the Western Alps. Trichinella larvae were found in 15 wolves. Results suggest that, after recolonization of Northern Italy, the wolf has rejoined the Trichinella cycle and already plays a sensitive sentinel role for this zoonotic pathogen. The possible role played as new maintenance host is discussed and knowledge gaps are highlighted. ABSTRACT: Trichinella is a foodborne parasite whose wildlife reservoirs are represented by carnivores and omnivores with predatory and scavenger behavior. The aim of the present study was to investigate the occurrence of Trichinella infection in grey wolves (Canis lupus) that recolonized the Western Alps from the end of the past century, and discuss the epidemiological role played by this apex predator in the early phases of its return. During the period 2017–2022, diaphragm samples were obtained from 130 individuals collected in the frame of a wolf mortality survey. Trichinella larvae were found in 15 wolves (11.53%) with a parasite intensity of 11.74 larvae per gram. Trichinella britovi was the only species identified. This is the first prevalence survey of Trichinella in wolves recolonizing the Alps. Results suggest that, in this particular biotope, the wolf has rejoined the Trichinella cycle and has the potential to play an increasingly important role as maintenance host. Arguments in favor and against this perspective are discussed and knowledge gaps highlighted. The calculated Trichinella larval biomass in the estimated wolf population roaming in Northwest Italy will serve as baseline value to explore possible shifts in the relative importance of wolves as Trichinella reservoir within the regional carnivore community. Finally, wolves re-colonizing the Alps already appear as sensitive sentinels to monitor the risk of Trichinella zoonotic transmission by infected wild boar meat.