Bouvry M, Rau M E
Vet Parasitol. 1986 Dec;22(3-4):267-73. doi: 10.1016/0304-4017(86)90114-7.
Seasonal changes in Fasciola hepatica egg passage were documented in 17 dairy herds in Portneuf County, Quebec (Canada). Egg passage was low or absent in spring and summer but rose in autumn to reach a peak in winter, then subsequently returned to low levels. This study suggests that there are two periods of transmission to the bovine host during the grazing season: a minor period in the spring, due to overwintered snails, and a major period in August and September due to snails that acquired the infection in May or June.
在加拿大魁北克省波特纽夫县的17个奶牛场记录了肝片吸虫虫卵排出的季节性变化。春季和夏季虫卵排出量较低或无虫卵排出，但秋季上升并在冬季达到峰值，随后又回到低水平。这项研究表明，在放牧季节向牛宿主的传播有两个时期：春季因越冬蜗牛而出现的较小传播期，以及8月和9月因在5月或6月感染的蜗牛而出现的主要传播期。
