The relationship between the Southern Oscillation Index, rainfall and the occurrence of canine tick paralysis, feline tick paralysis and canine parvovirus in Australia

- More than 13,000 parvovirus and tick paralysis cases in dogs and cats were reported from 2010 to 2013 in Australia.
- The Southern Oscillation Index was not a predictor of disease reports.
- Reported disease cases were moderately to strongly correlated with rainfall.
- Reduced rainfall 4-6 months previously predicted the occurrence of canine parvovirus disease.
- Increased rainfall 6-10 months previously predicted the occurrence of cases of tick paralysis in dogs and cats.

The aim of this study was to describe the association between climate, weather and the occurrence of canine tick paralysis, feline tick paralysis and canine parvovirus in Australia. The Southern Oscillation Index (SOI) and monthly average rainfall (mm) data were used as indices for climate and weather, respectively. Case data were extracted from a voluntary national companion animal disease surveillance resource. Climate and weather data were obtained from the Australian Government Bureau of Meteorology. During the 4-year study period (January 2010-December 2013), a total of 4742 canine parvovirus cases and 8417 tick paralysis cases were reported.No significant (P ≥ 0.05) correlations were found between the SOI and parvovirus, canine tick paralysis or feline tick paralysis. A significant (P < 0.05) positive cross-correlation was found between parvovirus occurrence and rainfall in the same month (0.28), and significant negative cross-correlations (−0.26 to −0.36) between parvovirus occurrence and rainfall 4-6 months previously. Significant (P < 0.05) negative cross-correlations (−0.34 to −0.39) were found between canine tick paralysis occurrence and rainfall 1-3 months previously, and significant positive cross-correlations (0.29-0.47) between canine tick paralysis occurrence and rainfall 7-10 months previously. Significant positive cross-correlations (0.37-0.68) were found between cases of feline tick paralysis and rainfall 6-10 months previously.These findings may offer a useful tool for the management and prevention of tick paralysis and canine parvovirus, by providing an evidence base supporting the recommendations of veterinarians to clients thus reducing the impact of these diseases.