Khallaayoune K, Stromberg B E, Dakkak A, Malone J B
Départment de Parasitologie et Maladies Parasitaires, Institut Agronomique et Vétérinaire Hassan II, Rabat-Instituts, Morocco.
Int J Parasitol. 1991 Jun;21(3):307-14. doi: 10.1016/0020-7519(91)90032-3.
Seasonal transmission of Fasciola hepatica was observed in sentinel sheep and the dynamics of the snail intermediate host, Lymnaea truncatula, was followed over a 3-year study period in the Middle-Atlas mountains in Morocco. High fluke burdens were recorded in both lambs and ewes in the fall and winter, suggesting that transmission occurred in late spring. Fluke burdens ranged from one to 302 in ewes and from one to 345 in lambs. Infections with 200 or more flukes were always fatal. A unique feature of this study was the annual cyclical fluctuation of the fluke burdens. Burdens reached maximum levels during the winter and then declined to low numbers by late spring and summer. This suggested self-regulation which may be dependent on breed resistance or may be related to forage factors, including lack of forage (nutritional stress). Snail populations were cyclical and correlated with fluke transmission as observed in the sentinel sheep. The weather was observed to affect the snail populations which in turn limited fluke transmission.
在摩洛哥中阿特拉斯山脉进行的为期3年的研究中，在哨兵羊中观察到肝片吸虫的季节性传播，并跟踪了中间宿主截形椎实螺的动态变化。秋季和冬季，羔羊和母羊体内均记录到大量吸虫，表明传播发生在晚春。母羊体内的吸虫数量在1至302条之间，羔羊体内的吸虫数量在1至345条之间。感染200条或更多吸虫通常是致命的。这项研究的一个独特之处是吸虫数量的年度周期性波动。冬季吸虫数量达到最高水平，然后在晚春和夏季降至低水平。这表明可能存在自我调节，这可能取决于品种抗性，也可能与饲料因素有关，包括缺乏饲料（营养应激）。正如在哨兵羊中观察到的那样，螺类种群呈周期性变化，且与吸虫传播相关。观察到天气会影响螺类种群，进而限制吸虫传播。
