Prandini da Costa Reis Rodrigo, Crisman Robin, Roser Margie, Malik Richard, Šlapeta Jan
School of Life and Environmental Sciences, Faculty of Veterinary Science, McMaster Building B14, The University of Sydney, New South Wales 2006, Australia.
Kulnura Veterinary Clinic, 956 George Downes Drive, Kulnura, New South Wales 2250, Australia.
Vet Parasitol. 2016 May 15;221:134-8. doi: 10.1016/j.vetpar.2016.03.023. Epub 2016 Mar 29.
Neonatal neosporosis is a challenging disease to diagnose in neonatal and young puppies because the first signs of this condition may not be strongly suggestive of an infectious aetiology. Within two weeks of birth, three of four pups died with a subacute clinical course, some with dyspnea, some with diarrhoea and some with neurologic signs. Neosporosis was diagnosed post-mortem, but only after microscopic examination of tissues collected at necropsy. Histological findings consisted of (i) necrotizing, diffuse interstitial pneumonia associated with intralesional protozoa and (ii) necrotizing multifocal myocarditis with mineralization and intralesional protozoa. No significant alterations were found in the cerebrum or cerebellum (spinal cord was not examined). Immunohistochemistry confirmed protozoal stages and cysts were Neospora caninum. Immunohistochemistry for Toxoplasma gondii was negative. Lung and heart were the most severely affected tissues with large numbers of free zoites, BAG5 positive bradyzoites and tissue cysts of N. caninum further confirmed by N. caninum-specific quantitative real-time PCR. One affected pup which displayed knuckling, ataxia and diarrhoea were treated with trimethoprim sulfadiazine and clindamycin, and made a complete recovery. This surviving pup (at 8 weeks-of-age) and dam were both positive for N. caninum antibody (reciprocal titres 4096 and 256, respectively). Three other intact bitches on the same property were seropositive for N. caninum, suggesting horizontal transmission and a common source of infection, possibly due to consumption of infected meat. Analysis using microsatellite-10 (MS10) demonstrated that multiple strains of N. caninum were present. It was likely that all MS10 N. caninum strains were transplacentally transmitted from dam to pups. This is the first time that multiple N. caninum strains have been demonstrated to be vertically transmitted in dogs. N. caninum should be considered in the differential diagnosis for acute to subacute death in neonatal pups even when neurological signs suggestive of neosporosis are absent.
新生幼犬的新孢子虫病是一种诊断颇具挑战性的疾病，因为该病最初的症状可能并不强烈提示感染性病因。出生两周内，四只幼犬中有三只死于亚急性病程，有的出现呼吸困难，有的腹泻，还有的出现神经症状。新孢子虫病在尸检后才得以确诊，但这是在对尸检时采集的组织进行显微镜检查之后。组织学检查结果包括：（i）与病灶内原生动物相关的坏死性弥漫性间质性肺炎，以及（ii）伴有矿化和病灶内原生动物的坏死性多灶性心肌炎。大脑或小脑未发现明显病变（未检查脊髓）。免疫组织化学证实原生动物阶段和囊肿为犬新孢子虫。弓形虫免疫组织化学检测为阴性。肺和心脏是受影响最严重的组织，大量游离速殖子、BAG5阳性缓殖子和犬新孢子虫组织囊肿通过犬新孢子虫特异性定量实时PCR进一步得到证实。一只出现关节屈曲、共济失调和腹泻的患病幼犬接受了甲氧苄啶磺胺嘧啶和克林霉素治疗，并完全康复。这只存活的幼犬（8周龄）和母犬的犬新孢子虫抗体均为阳性（效价分别为4096和256）。同一养殖场的另外三只未生育母犬犬新孢子虫血清学检测呈阳性，提示存在水平传播和共同感染源，可能是由于食用了受感染的肉类。使用微卫星10（MS10）分析表明存在多种犬新孢子虫菌株。所有MS10犬新孢子虫菌株很可能是通过胎盘从母犬传播给幼犬的。这是首次证明多种犬新孢子虫菌株在犬中垂直传播。即使没有提示新孢子虫病的神经症状，在新生幼犬急性至亚急性死亡的鉴别诊断中也应考虑犬新孢子虫。
