[Study on the seasonal distribution of human rabies in different regions of China]

Using simple quantitative methods to describe the seasonal distribution of rabies in different provinces of China and to analyze how it was influenced by geographical settings, to provide evidence for risk assessment and prediction of potential epidemics of rabies.

A total number of 17 800 clinical and laboratory confirmed rabies cases, reported by 29 provinces, from 2005 to 2011 and related data were collected from National Disease Reporting Information System. Data on related latitudes and longitudes of different provinces were obtained from the National Geographic Information Center. Excel 2003 was used to draw the national and provincial seasonal distribution curves while SPSS 18.0 was used to calculate parameters as P(25), P(50), P(75), inter-quartile range Q and kurtosis so as analyze the linear correlation between P(25), kurtosis and the latitude of different provinces respectively.

The nation-wide incidence of rabies was low in February. The peaks fell in summer and autumn, especially in August. Seasonal distribution curves of P(25), P(50), P(75), inter-quartile range (Q) and kurtosis were different among provinces. Compared to the low latitude areas, high latitude areas had higher P(25), smaller Q and higher kurtosis. In 9 provinces where the annual reported number of cases more than 100, the related coefficients (r) between latitude and both P(25), kurtosis were 0.9342 and 0.8528 respectively (P < 0.05).

There was a distinct seasonality of rabies occurrence in China which was correlated to the geographical settings which was more obvious in the higher latitude areas.