Seroepidemiologic Survey of Potential Pathogens in Obligate and Facultative Scavenging Avian Species in California

Straub, Mary H.; Kelly, Terra R.; Rideout, Bruce A.; Eng, Curtis; Wynne, Janna; Braun, Josephine; Johnson, Christine K.

In the multivariable regression model, original release location and rearing site were significantly associated with WNV serologic status (Table 3 ). Even after adjusting for age, the condors released in Southern California were over seven times as likely as those released in Big Sur to have a positive WNV titer (P = 0.008), and birds reared at the LAZ were over ten times as likely as birds reared in the wild to have a positive WNV titer (P = 0.038). The model demonstrated good fit (Hosmer Lemeshow test; P = 0.47). In the univariable logistic regression models, age was significantly associated with WNV serostatus in both the Big Sur and Southern California condors with the odds of seropositivity increasing with increasing age of the condor (P = 0.040 and = 0.007, respectively). In addition, time since vaccination was also associated with WNV serostatus in all condors, with individuals that were vaccinated greater than three years prior to sample collection more likely to be seropositive compared to condors that had never been vaccinated (P = 0.003). However, age and time since vaccination were not significant in the multivariable logistic regression model. An increasing number of previous vaccinations was positively associated with WNV seropositivity in the univariable models, though the association was not statistically significant (P = 0.194). Number of previous vaccinations was not included in the final model because it was significantly correlated with time since vaccination (ρ = 0.493, P < 0.001) and inclusion of the variable in the model did not improve model fit. In the bivariate analyses, age and time since vaccination were correlated (ρ = 0.392, P < 0.001).