Zoonotic diseases present constant public health threats because of the complex interactions between humans and wildlife. The genus Orthopoxvirus contains many such zoonoses, including Akhmeta virus (AKMV) which is endemic to Georgia (country). The reservoir host(s) for AKMV remain(s) unknown, but there is evidence it could infect a wide range of mammals, including wild rodents which are likely involved in AKMV circulation.
The effects of community species diversity on disease prevalence have been studied for many pathogens including plant, fungal and animal diseases. The dilution effect hypothesis proposes that increased species diversity generally correlates with decreased disease prevalence in the host species. Here, we explore this hypothesis in the context of AKMV circulation in Georgia.
During 2015-2019, small mammals were trapped at two to four sites in each of 13 locations across Georgia. Dried blood samples were tested for the presence of anti-OPXV antibodies using ELISA. Species diversity at each site was calculated using Simpson’s diversity index. Since the specific reservoir host(s) of AKMV is unknown, all seropositive results were used to calculate OPX percent positivity at each site. Regression analyses were used to evaluate the correlation between OPX positivity and species diversity.
Results/Conclusions
A total of 2052 small mammals were caught during the five-year period representing 17 species from 10 genera. Anti-OPXV antibodies were detected in 157 individuals from 12 species in 8 genera. Simpson’s diversity indexes varied from 0.31 to 0.84 across sampling sites and OPX seropositivity ranged from 0% to 29%. Preliminary regression analyses showed R2 values ranging from 0.00053 to 0.00125 and p-values ranging from 0.8 to 0.9.
Good representation of the small mammal diversity and prevalence from ecologically diverse sites was observed across Georgia. The low number of seropositive animals indicates disease prevalence is likely low throughout most of the country with a few sites of higher positivity rates. Regression analyses indicated no significant correlation between OPX seropositivity and species diversity across Georgia. The lack of correlation between seropositivity and diversity could be due to OPXVs ability to infect a wide variety of mammal species. AKMV is no exception based on the serological evidence. Since AKMV is not dependent upon a single taxon to maintain itself in a community, disease prevalence is likely unaffected by species diversity alone. Other factors like environmental conditions that impact rodent densities may affect disease prevalence more.