Variability in Seroprevalence of Rabies Virus Neutralizing Antibodies and Associated Factors in a Colorado Population of Big Brown Bats (Eptesicus fuscus)

Abstract

In 2001–2005 we sampled permanently marked big brown bats (Eptesicus fuscus) at summer roosts in buildings at Fort Collins, Colorado, for rabies virus neutralizing antibodies (RVNA). Seroprevalence was higher in adult females (17.9%, n = 2,332) than males (9.4%, n = 128; P = 0.007) or volant juveniles (10.2%, n = 738; P<0.0001). Seroprevalence was lowest in a drought year with local insecticide use and highest in the year with normal conditions, suggesting that environmental stress may suppress RVNA production in big brown bats. Seroprevalence also increased with age of bat, and varied from 6.2 to 26.7% among adult females at five roosts sampled each year for five years. Seroprevalence of adult females at 17 other roosts sampled for 1 to 4 years ranged from 0.0 to 47.1%. Using logistic regression, the only ranking model in our candidate set of explanatory variables for serological status at first sampling included year, day of season, and a year by day of season interaction that varied with relative drought conditions. The presence or absence of antibodies in individual bats showed temporal variability. Year alone provided the best model to explain the likelihood of adult female bats showing a transition to seronegative from a previously seropositive state. Day of the season was the only competitive model to explain the likelihood of a transition from seronegative to seropositive, which increased as the season progressed. We found no rabies viral RNA in oropharyngeal secretions of 261 seropositive bats or in organs of 13 euthanized seropositive bats. Survival of seropositive and seronegative bats did not differ. The presence of RVNA in serum of bats should not be interpreted as evidence for ongoing rabies infection.

Longitudinal survey of two serotine bat (Eptesicus serotinus) maternity colonies exposed to EBLV-1 (European Bat Lyssavirus type 1): Assessment of survival and serological status variations using capture-recapture models

“…This supports previous observations that bats could harbor exposure events without any impact on their mortality rate. These results are indeed comparable to the survival analysis computed for big brown bats ( Eptesicus fuscus ) affected by RABV in the United States [ 77 ] and for a Myotis myotis colony affected by EBLV-1 in Spain [ 73 ].…”

“…In a previous study, female serotine bats were shown to be more exposed to EBLV-1 than males, probably due to their gregarious social behavior, males being more solitary [ 88 ]. Similar findings were also highlighted in the framework of RABV transmission in Brazilian free-tailed bats [ 89 ] big brown bats [ 77 ] and in vampire bats [ 90 ]. In our study, occurring in breeding colonies, only females were assessed and we have shown evidence from site B that seroreversions were significantly more frequent than seroconversions.…”

Geographical Analysis for Detecting High-Risk Areas for Bovine/Human Rabies Transmitted by the Common Hematophagous Bat in the Amazon Region, Brazil

“…Given that the spread of rabies outbreaks may be favored by the interchange of bats between colonies [ 59 ], populations with infected individuals that are easily accessible may promote outbreaks of the disease more efficiently and over a shorter time scale. It is also important to note that, as found in previous studies, infection rates in a population may be related to specific characteristics, such as genetic diversity, the physiological condition of individuals [ 60 , 61 ], and immunity levels [ 6 , 62 ]. In this case, some D .…”

Comparative analysis of serologic cross-reactivity using convalescent sera from filovirus-experimentally infected fruit bats

“…"Natural" boosting of virus-specific IgG antibody levels in ERBs that had been previously infected with Marburg virus was observed during a recent experimental transmission study shortly after documenting virus infection and seroconversion in naïve contact bats 36 . Others have reported periodic boosting of rabies virus neutralizing antibody titers in a wild colony of big brown bats (Eptesicus fuscus) 47 . Second, we used a goat anti-bat IgG conjugated to horseradish peroxidase as the secondary antibody in our system.…”