Musongong G A, Chiejina S N, Fakae B B, Ikeme M M
Veterinary Research Laboratory, Wakwa Regional Centre for Agricultural Research for Development, PO Box 65, Ngaoundere, Cameroon.
J Helminthol. 2004 Sep;78(3):249-57. doi: 10.1079/joh2004236.
Clinical, parasitological and pathological responses of a tropical out-bred domestic rabbit to experimental Trichostrongylus colubriformis infection were used to evaluate its suitability as a laboratory host and model for studying the host-parasite relationships of T. colubriformis. In the first experiment, three groups each of 16, predominantly juvenile male, 8- to 10-week-old rabbits were given a single pulse infection with 500, 5000 or 25000 infective larvae (L3) of T. colubriformis, to represent low, medium and high levels of infection, respectively. A fourth group of 16 rabbits of similar age formed the uninfected controls. In the second experiment, two groups of 10 juvenile (8- to 10-week-old) and 10 adult (8- to 10-month-old) rabbits were similarly infected with 20000 L3, with appropriate naive controls. Prepatency was 14 and 16 days and peak faecal egg counts occurred on days 24 and 20 after infection in young and adult rabbits respectively. Peak worm counts occurred on day 14 in both age groups and at all levels of infection. Subsequently, parasite burdens declined in a highly significantly dose- and age-dependent manner. At low and moderate levels of infection, approximately 83-98% of worms were recovered from the first 60 cm of the small intestine. Worm fecundity was also significantly influenced by host age and larval dose. Host age also had a significant effect on worm length. Infections with T. colubriformis were associated with a highly significant loss of body weight, accompanied by anorexia, diarrhoea and 25% mortality at high dose levels during the patent period of infection. There were no significant changes in packed cell volume and eosinophil counts at all ages and levels of infection but significant lymphocytosis occurred at the high dose level between days 7 and 21. Parasite-specific serum IgG responses were not related to worm burden. Overall, data showed that this miniature, docile and relatively inexpensive breed of rabbit is a potentially valuable laboratory host for studying T. colubriformis infections. The larval dose, duration of infection and host age were major determinants of host responsiveness to primary infections in this rabbit genotype.
利用热带杂交家兔对实验性结肠毛圆线虫感染的临床、寄生虫学和病理学反应，评估其作为研究结肠毛圆线虫宿主 - 寄生虫关系的实验室宿主和模型的适用性。在第一个实验中，将三组各16只、主要为8至10周龄的幼年雄性兔子，分别单次脉冲感染500、5000或25000条结肠毛圆线虫感染性幼虫（L3），分别代表低、中、高感染水平。第四组16只年龄相似的兔子作为未感染对照。在第二个实验中，两组各10只幼年（8至10周龄）和10只成年（8至10月龄）兔子同样感染20000条L3，并设置适当的未感染对照。幼兔和成年兔的潜隐期分别为14天和16天，感染后第24天和第20天粪便虫卵计数达到峰值。两个年龄组在所有感染水平下，虫体计数峰值均出现在第14天。随后，寄生虫负荷以高度显著的剂量和年龄依赖性方式下降。在低和中等感染水平下，约83 - 98%的虫体从小肠的前60厘米处回收。虫体繁殖力也受到宿主年龄和幼虫剂量的显著影响。宿主年龄对虫体长度也有显著影响。感染结肠毛圆线虫与体重显著减轻有关，在感染的显性期，高剂量水平伴有厌食、腹泻和25%的死亡率。在所有年龄和感染水平下，红细胞压积和嗜酸性粒细胞计数均无显著变化，但在高剂量水平下，第7天至21天出现显著的淋巴细胞增多。寄生虫特异性血清IgG反应与虫体负荷无关。总体而言，数据表明这种小型、温顺且相对便宜的兔子品种是研究结肠毛圆线虫感染的潜在有价值的实验室宿主。幼虫剂量、感染持续时间和宿主年龄是该兔基因型宿主对初次感染反应性的主要决定因素。
