Snider T G, Williams J C, Karns P A, Trammell H E, Romaire T L
Am J Vet Res. 1985 Aug;46(8):1748-52.
Parasite-free 4-month-old calves were inoculated with Ostertagia ostertagi and/or Trichostrongylus axei followed 6 weeks later by increasing doses of O ostertagi for 8 weeks. Clinical signs of parasitism, fecal egg counts, and plasma pepsinogen concentrations were monitored, and gross lesions and parasite burdens were determined postmortem. Clinical signs of parasitism were not observed and weight gains were not affected in experimentally infected calves. In calves infected with O ostertagi, mean plasma pepsinogen concentrations were greater than for control calves and were diagnostically significant 4 weeks after inoculation and during the last 4 weeks of serial inoculations with O ostertagi. In calves that were given O ostertagi and T axei, abomasal pH was significantly increased, and abomasal lesions were more pronounced than in control calves or in calves inoculated with only O ostertagi or T axei. Abomasal lymph nodes were enlarged in all parasitized calves; other lymph nodes in the calves inoculated with both O ostertagi and T axei were usually smaller than in calves inoculated with only O ostertagi or T axei. Numbers of O ostertagi-inhibited larvae were small in all inoculated calves, but the percentage inhibition was significantly greater in calves inoculated with both O ostertagi and T axei. The percentage inhibition was 3.53% for the O ostertagi-inoculated calves and 7.07% for calves inoculated with both O ostertagi and T axei. These percentages indicated a synergistic effect of concurrent abomasal parasitism, whereas a synergistic effect on T axei worm burden was not observed. The low percentage of larval inhibition indicated that factors other than host resistance are involved in naturally occurring pretype II ostertagiosis.
对4月龄无寄生虫的犊牛接种奥斯特他线虫和/或艾氏毛圆线虫，6周后对其接种递增剂量的奥斯特他线虫，持续8周。监测寄生虫感染的临床症状、粪便虫卵计数和血浆胃蛋白酶原浓度，并在剖检后确定大体病变和寄生虫负荷。在实验感染的犊牛中未观察到寄生虫感染的临床症状，体重增加也未受影响。在感染奥斯特他线虫的犊牛中，平均血浆胃蛋白酶原浓度高于对照犊牛，在接种后4周以及用奥斯特他线虫连续接种的最后4周具有诊断意义。在接种奥斯特他线虫和艾氏毛圆线虫的犊牛中，皱胃pH值显著升高，皱胃病变比对照犊牛或仅接种奥斯特他线虫或艾氏毛圆线虫的犊牛更明显。所有感染寄生虫的犊牛皱胃淋巴结均肿大；同时接种奥斯特他线虫和艾氏毛圆线虫的犊牛的其他淋巴结通常比仅接种奥斯特他线虫或艾氏毛圆线虫的犊牛小。在所有接种的犊牛中，奥斯特他线虫抑制性幼虫数量较少，但同时接种奥斯特他线虫和艾氏毛圆线虫的犊牛的抑制百分比显著更高。接种奥斯特他线虫的犊牛的抑制百分比为3.53%，同时接种奥斯特他线虫和艾氏毛圆线虫的犊牛为7.07%。这些百分比表明皱胃同时寄生具有协同作用，而未观察到对艾氏毛圆线虫虫负荷的协同作用。幼虫抑制率低表明，除宿主抵抗力外，其他因素也参与了自然发生的II型前奥斯特他线虫病。
