Plague Dynamics In Small Mammal Communities Of Northern New Mexico

Presentation: More than 200+ mammal species worldwide are affected by plague, and yet, the dynamics of enzootic plague and its inter-species interactions among rodents are largely unknown. Non-epizootic manifestation of the disease on nocturnal or cryptic species is difficult to quantify, and how the disease persists between epizootic events is poorly understood. Enzootic transmission cycles may be maintained in soils, or by small mammals and/or fleas acting as reservoirs for the disease. If so, the invasive plague bacterium, Yersinia pestis, may be functioning as a non-native predator, whose effects augment natural mortality. We hypothesized that enzootic plague is causing chronic mortality in wild rodent species in northern New Mexico. Our objectives included: (1) measuring survival rates of rodents protected from plague via an experimental F1 antigen vaccine; (2) measuring the effects of flea vectors on host mortality by controlling vectors through the application of a pyrethroid, DeltaDust; (3) testing the efficacy and longevity of DeltaDust by tracking flea abundance on host species; and (4) field-testing the efficacy of the F1 experimental vaccine. Preliminary data indicate that vaccine improved survival of brush mice (Peromyscus boylii) by 66% at one plot without demonstrating any benefit for brush mice at a second plot with similar treatment. Survival was higher in short-tailed Peromyscus spp. on dusted plots than non-dusted plots. Control for vectors and plague vaccinations may improve survival of small mammals and interdict plague transmission.