Barber J S, Trees A J
Veterinary Parasitology, Liverpool School of Tropical Medicine, University of Liverpool, UK.
Int J Parasitol. 1998 Jan;28(1):57-64. doi: 10.1016/s0020-7519(97)00171-9.
Vertical transmission of Neospora caninum was studied in naturally infected, privately owned dogs, using antibody detection by IFAT to identify infected individuals. Retrospective studies were undertaken in litters from six bitches of the Hamiltonstövare breed, and on litters from seven bitches of other breeds--in both cases following diagnosis of clinical disease in puppies--and prospective studies were carried out on 17 seropositive bitches of other breeds. Puppies were classified as infected if either pre-colostral sera, or serum taken at > or = 5 weeks, had a titre of > or = 1:50 in the IFAT. The frequency of putative congenital transmission was variable; three seropositive dams produced successive litters, each containing seropositive puppies; four other seropositive bitches, which each whelped twice, produced six litters in which all pups were seronegative. Bitches born to seropositive dams themselves produced litters containing seropositive pups. In the retrospective studies, 32/61 (52%) of pups tested born to 13 seropositive dams were themselves seropositive and 22/88 (25%) of all pups born developed clinical signs compatible with a diagnosis of neosporosis. However, in the prospective study, only 4/118 (3%) pups tested from 17 seropositive dams were seropositive and 4/122 (3%) of all pups born developed signs consistent with neosporosis. This difference reflected levels of IFAT titre in the two groups of bitches and overall the proportion of pups seropositive was strongly and positively correlated (r = 0.980, P < 0.05) with bitch IFAT titre. Overall, 80% of pups born to seropositive dams were not infected as determined serologically. This study shows that the frequency of vertical transmission of naturally acquired Neospora infection in dogs is variable, but much too low to sustain infection alone. Post-natal infection must occur to maintain infection at seroprevalence rates reported in dog populations.
利用间接荧光抗体试验（IFAT）检测抗体来鉴定感染个体，对自然感染的私人饲养犬进行犬新孢子虫垂直传播的研究。对汉密尔顿斯多瓦犬种6只母犬所产幼犬进行回顾性研究，以及对其他犬种7只母犬所产幼犬进行回顾性研究（两种情况均在幼犬临床疾病诊断之后），并对其他犬种17只血清学阳性母犬进行前瞻性研究。如果初乳前血清或5周及以上采集的血清在IFAT中的滴度≥1:50，则幼犬被分类为感染。假定的先天性传播频率各不相同；3只血清学阳性母犬产下的连续几窝幼犬中均有血清学阳性幼犬；另外4只血清学阳性母犬各产仔两次，所产6窝幼犬中所有幼犬血清学均为阴性。血清学阳性母犬所生的母犬自身产下的幼犬窝中含有血清学阳性幼犬。在回顾性研究中，13只血清学阳性母犬所产的61只检测幼犬中有32只（52%）血清学呈阳性，所有出生幼犬中有22只（25%）出现与新孢子虫病诊断相符的临床症状。然而，在前瞻性研究中，17只血清学阳性母犬所产的118只检测幼犬中只有4只（约3%）血清学呈阳性，所有出生幼犬中有4只（约3%）出现与新孢子虫病相符的症状。这种差异反映了两组母犬的IFAT滴度水平，总体而言，幼犬血清学阳性比例与母犬IFAT滴度呈强正相关（r = 0.980，P < 0.05）。总体而言，血清学检测确定血清学阳性母犬所生的幼犬中80%未被感染。本研究表明，犬自然感染新孢子虫的垂直传播频率各不相同，但低到无法仅靠其维持感染。必须发生产后感染才能使犬群中的血清阳性率维持在报告水平。
