Distribution of S. japonicum infections in snails in 2006 and 2007.

Note: * mean abundance is the number of cercariae genotypes per infected snail; † p is the p-value of Poisson distribution goodness-of-fit test; ‡ p is the p-value of Negative binomial distribution goodness-of-fit test; +, for one cell with an expected value less than 3 in calculation of the χ2 value under a given distribution. M, for marshland; and H, for hilly region.