Study on method of determination of appropriate sample size of Oncomelania hupensis in marshland and lake regions / 中国血吸虫病防治杂志

ABSTRACT

Objective To explore a possible method for determining the appropriate sample size of Oncomelania hupensis in the marshland and lake regions. Methods Four bottomlands were selected randomly along the Qiupu River in Guichi District, Anhui Province. Oncomelania snails were surveyed carefully in these bottomlands and brought back to the laboratory to judge whether they were alive or not with mild water. All the data of Oncomelania hupensis were doubly input into the EpiData software and checked for the errors. Repeated sampling was performed in the four databases according to different sample sizes by using SAS software and the corresponding snail density was also calculated. According to the values of sample size and corresponding snail density, sample size-snail density absolutely changing curve and relatively changing curve were drawn to determine the appropriate sample size of snail survey. Results The appropriate sample sizes of snail survey were 40,200,100 and 200 frames in Gutan bottomland, Caizi bottomland, Qiupu bottomland and Ouyang bottomland, respectively. Conclusion Sample size-snail density absolutely changing curve and relatively changing curve could provide some instructions for choosing the appropriate sample size during the process of snail survey in the marshland and lake regions.