Temporal dynamics of European bat Lyssavirus type 1 and survival of Myotis myotis bats in natural colonies

Abstract

Many emerging RNA viruses of public health concern have recently been detected in bats. However, the dynamics of these viruses in natural bat colonies is presently unknown. Consequently, prediction of the spread of these viruses and the establishment of appropriate control measures are hindered by a lack of information. To this aim, we collected epidemiological, virological and ecological data during a twelve-year longitudinal study in two colonies of insectivorous bats (Myotis myotis) located in Spain and infected by the most common bat lyssavirus found in Europe, the European bat lyssavirus subtype 1 (EBLV-1). This active survey demonstrates that cyclic lyssavirus infections occurred with periodic oscillations in the number of susceptible, immune and infected bats. Persistence of immunity for more than one year was detected in some individuals. These data were further used to feed models to analyze the temporal dynamics of EBLV-1 and the survival rate of bats. According to these models, the infection is characterized by a predicted low basic reproductive rate (R(0) = 1.706) and a short infectious period (D = 5.1 days). In contrast to observations in most non-flying animals infected with rabies, the survival model shows no variation in mortality after EBLV-1 infection of M. myotis. These findings have considerable public health implications in terms of management of colonies where lyssavirus-positive bats have been recorded and confirm the potential risk of rabies transmission to humans. A greater understanding of the dynamics of lyssavirus in bat colonies also provides a model to study how bats contribute to the maintenance and transmission of other viruses of public health concern.

Figure 1. Temporal Variation of the Percentage of Sera and Blood Clot Positives in Bat colonies.

Percentage of seropositive (black symbols) and blood clot positive (red symbols) bats observed in M. myotis colonies 1 (A) and 2 (B) (95% confidence interval shown).

Figure 2. Temporal Pattern Model.

Temporal pattern of the number of susceptible bats X(t) in M. myotis colonies, obtained by Anderson & May (1991) model, using R₀ = 1.706 and his 95% confidence interval.