Observations on environmental factors in connection with avian botulism outbreaks in a Hungarian wetland habitat.

In this study, the relationship between five water-quality parameters (water temperature, pH, conductivity, water-soluble oxygen (WSO) and organic matter content (chemical oxygen demand-COD)) and avian botulism cases were examined using statistical methods. Five-five sampling points, located in high and low avian botulism risk (HR and LR) areas of Lake 'Kis-Balaton' were chosen, respectively. Data from 5 HR and 5 LR years were processed. In some cases, significant (P<0.05) differences were discovered in water temperature, pH, WSO and COD values between HR and LR sites and years. Discriminant analysis verified positive relationship between the occurrence of avian botulism outbreaks and characteristics of the sampling sites in 16/20 cases (80.0%). In the remaining instances, the role of other, not examined factors could be also important.