Dubey J P, Mitchell S M, Morrow J K, Rhyan J C, Stewart L M, Granstrom D E, Romand S, Thulliez P, Saville W J, Lindsay D S
Animal Parasitic Diseases Laboratory, Animal and Natural Resources Institute, Agricultural Research Service, United States Department of Agriculture, Building 1001, Beltsville, Maryland 20705-2350, USA.
J Parasitol. 2003 Aug;89(4):716-20. doi: 10.1645/GE-66R.
Sarcocystis neurona, Neospora caninum, N. hughesi, and Toxoplasma gondii are 4 related coccidians considered to be associated with encephalomyelitis in horses. The source of infection for N. hughesi is unknown, whereas opossums, dogs, and cats are the definitive hosts for S. neurona, N. caninum, and T. gondii, respectively. Seroprevalence of these coccidians in 276 wild horses from central Wyoming outside the known range of the opossum (Didelphis virginiana) was determined. Antibodies to T. gondii were found only in 1 of 276 horses tested with the modified agglutination test using 1:25, 1:50, and 1:500 dilutions. Antibodies to N. caninum were found in 86 (31.1%) of the 276 horses tested with the Neospora agglutination test--the titers were 1:25 in 38 horses, 1:50 in 15, 1:100 in 9, 1:200 in 8, 1:400 in 4, 1:800 in 2, 1:1,600 in 2, 1:3,200 in 2, and 1:12,800 in 1. Antibodies to S. neurona were assessed with the serum immunoblot; of 276 horses tested, 18 had antibodies considered specific for S. neurona. Antibodies to S. neurona also were assessed with the S. neurona direct agglutination test (SAT). Thirty-nine of 265 horses tested had SAT antibodies--in titers of 1:50 in 26 horses and 1:100 in 13. The presence of S. neurona antibodies in horses in central Wyoming suggests that either there is cross-reactivity between S. neurona and some other infection or a definitive host other than opossum is the source of infection. In a retrospective study, S. neurona antibodies were not found by immunoblot in the sera of 243 horses from western Canada outside the range of D. virginiana.
犬新孢子虫、休氏新孢子虫、犬神经肉孢子虫和刚地弓形虫是4种相关的球虫，被认为与马的脑脊髓炎有关。休氏新孢子虫的感染源尚不清楚，而负鼠、狗和猫分别是犬神经肉孢子虫、犬新孢子虫和刚地弓形虫的终末宿主。我们测定了怀俄明州中部276匹野生马（处于负鼠已知分布范围之外）体内这些球虫的血清阳性率。在276匹用1:25、1:50和1:500稀释度的改良凝集试验检测的马中，仅1匹马检测到刚地弓形虫抗体。在用新孢子虫凝集试验检测的276匹马中，86匹（31.1%）检测到犬新孢子虫抗体——38匹马的滴度为1:25，15匹为1:50，9匹为1:100，8匹为1:200，4匹为1:400，2匹为1:800，2匹为1:1600，2匹为1:3200，1匹为1:12800。用血清免疫印迹法评估犬神经肉孢子虫抗体；在检测的276匹马中，18匹马检测到被认为对犬神经肉孢子虫具有特异性的抗体。还用犬神经肉孢子虫直接凝集试验（SAT）评估犬神经肉孢子虫抗体。在检测的265匹马中，39匹马有SAT抗体——26匹马的滴度为1:50，13匹马的滴度为1:100。怀俄明州中部的马体内存在犬神经肉孢子虫抗体，这表明要么犬神经肉孢子虫与某些其他感染之间存在交叉反应，要么除负鼠之外还有其他终末宿主是感染源。在一项回顾性研究中，在弗吉尼亚负鼠分布范围之外的加拿大西部243匹马的血清中，通过免疫印迹法未检测到犬神经肉孢子虫抗体。
