Wildlife is considered an important factor in the emergence and spread of emerging and re-emerging infectious diseases that can ultimately impact human and animal health. It is estimated that 75% of emerging infectious diseases come from animals and more than half of these originate from wildlife. However, the study of the role of wildlife in the epidemiology of infectious diseases has been neglected in general terms. For this reason, viral ecology, an emerging field of research focused on the study of viral dynamics at the interface between wildlife, domestic animals, humans, and the environment, is gaining increasing attention.
The Dr. Santiago Mirazo’s group has been working on the Hepatitis E virus (HEV) since 2010, aiming to unravel key and intriguing aspects of viral epidemiology and molecular virology. Since then, they have reported and characterized HEV genotype 3 (HEV-3) circulation in humans, pigs, wild boars, and white-collar peccaries. Recently, the team developed an encompassing strategy to study the ecology of HEV in the field with a One Health perspective.
HEV presents a high genetic diversity and a wide and ever-expanding host range, which can lead to inter-species transmission events. For this reason, it is an excellent viral model to assess the dynamics of transmission cycles and dispersion networks in nature. Spotted deer (Axis axis) is an invasive and exotic species that was introduced to Uruguay in the early 1900s and since then an overpopulation has occurred in the country.
In the current study, conducted by MSc. Florencia Cancela and colleagues led by Dr. Santiago Mirazo, they combined serological and molecular tools within an ecological perspective with camera traps to study the HEV prevalence in axis deer and the spatiotemporal coexistence with wildlife and cattle.
In these cervids, they detected an anti-HEV seropositivity rate of 11.1% and an RNA prevalence of 68.4% among seropositive animals. Surprisingly, they found that axis deer not only can be infected by zoonotic HEV-3 but also with rare moose HEV-like strains. Additionally, based on the camera trapping analysis that allowed them to identify spots of intense interaction between wildlife and domestic animals, they could detect evidence of HEV contamination in shared water ponds.
Axis or spotted deer is an autochthonous species in India and has been successfully introduced in just a handful of countries worldwide. Interestingly, the infecting HEV-like strains identified in this work were more closely related to moose HEV variants reported once from Sweden, which clearly illustrates the complex epidemiology of this infectious disease and opens new and fascinating questions. To conclude, these novel findings suggest that HEV has an intricate dynamic in wildlife, characterized by the co-circulation of different HEV species and the existence of multiple hosts. Based on our data, the authors proposed that axis deer should be added to the list of HEV hosts/reservoirs.
This work was published in Food and Environmental Virology (2023 Aug 29). DOI: 10.1007/s12560-023-09563-2
