-Nine rats (16.4%) out of 55 (Rattus norvegicus) from cattle farms were seropositive to Neospora caninum. Two of the seropositive rats were also PCR positive but all were negative by immunohistochemistry and PAS staining. The brains of all the captured rats were homogenized and initially inoculated intraperitoneally into nude mice or into SPF ICR mice, which had been immunosuppressed with prednisolone. One mouse that was inoculated with brain material from a seropositive rat became infected with N. caninum, as demonstrated by the presence of a tissue cyst in the brain and confirmed by immunohistochemistry and PCR. This is the first finding of N. caninum in naturally infected farm rats. The findings show that natural N. caninum infection occurs in wild brown rats and thus rats may serve as a reservoir for the protozoan on the cattle farm. Neospora caninum / rat / cattle farm / natural infection

ABSTRACT. Setaria digitata and S. marshalli larvae were observed in the cerebrospinal cavity of 2 paralyzed cattle in Taiwan. The 2 affected cattle showed quadriplegia and lumbar paralysis, respectively. At necropsy, which was performed 7 days after the 7-mon th-old cattle became quadriplegic, three and nineteen S. marshalli larvae as well as two female adult worms were found in the cranial cavity, spinal cavity and peritoneal cavity of the cattle, respectively. Necropsy on the other 8-month-old cattle was also performed 3 days after it showed lumbar paralysis, and ten S. digitata larvae were found in the spinal cavity. In both cattle, many mononuclear inflammatory cells mixed with a few eosinophils were seen accumulated in the connective tissue around the root of the spinal nerves. Infiltration of eosinophils and mononuclear inflammatory cells into the epidura and arachnoidea of the brain were also observed. The major inflammatory cell was lymphocytes, but neutrophils and eosinophils were also present. The number of cells in the cerebrospinal fluid collected initially from the two affected cattle were 105/0.01 ml and 143/ 0.01 ml, respectively. This is the first report of cerebrospinal setariosis in cattle associated with S. marshalli. KEY WORDS: bovine cerebrospinal setariosis, cerebrospinal fluid, Setaria digitata, Setaria marshalli, Taiwan.J. Vet. Med. Sci. 65(9): 977-983, 2003 Setaria species are filarial parasites that are commonly found in the peritoneal cavity of cattle and other ungulates. The parasites are generally considered to be nonpathogenic in their natural hosts, but transmission of infective larvae through mosquito and other arthropod vectors to non-permissive hosts such as goats, sheep, or horses, can result in serious and often fatal neuropathological disorder commonly referred to as cerebrospinal nematodiasis [1,11]. Moreover, Setaria cervi (Rudolphi, 1819) [2], S. digitata (Linstow, 1906) [18,19], S. labiatopapillosa (Alessandrini, 1848) [3,14], S. marshalli (Boulenger, 1921) [8,16,18,19], and S. leichungwingi (Chen, 1935) [7] had been reported to parasitize in the peritoneal cavity of cattle without producing clinical signs. However, larvae of S. cervi, which normally parasitized in the deer peritoneal and thoracic cavities as adult worms, had been found in the cerebrospinal cavity of deer resulting in lumbar paralysis of the host [6,15,17]. Our literature search showed that no cases of cerebrospinal setariosis with S. marshalli infection in cattle had ever been reported. We report herein the discovery of S. marshalli and S. digitata larvae from the cerebrospinal cavity of 2 paralyzed cattle in Taichung, central Taiwan. Pathological findings and inflammatory cell counts of cerebrospinal fluid (CSF) of the affected cattle are also presented. MATERIALS AND METHODS Case history:In August and September of 2001, a 7-month-old (case 1) and an 8-month-old (case 2) HolsteinFriesian strain cattle were found to have quadriplegia and lumbar paralysis, respectively, in Taichung, central T...

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ABSTRACT. Several peripheral blood microfilaria concentration methods that use Acetone (Acetone test), 2% formalin (modified Knott method), 5% Tween 20 solution, distilled water, 1% or 0.1% SDS were compared for their efficacy in detecting Setaria digitata microfilaria in cattle. The Acetone test was found to be more efficacious than the modified Knott method or the 5% Tween 20 solution test for detecting the S. digitata microfilaria in bovine blood. However, besides the Acetone test, the modified Knott method was also found to be suitable for Dirofilaria immitis microfilaria detection in dogs. SDS and distilled water were found not to be effective as hemolytic agent for the disruption of the red blood cell of both the cattle and dogs. Thus, the Acetone test is recommended for the prima ry screening of microfilaremia of S. digitata in cattle. Setaria digitata is a common filarial nematode that parasitize in the peritoneal cavities of cattle and buffalo [8], as well as causing cerebrospinal setariosis in goat [4] and cattle [7] in Taiwan. For the primarily screening of this filarial infection in cattle, the direct blood smear method is commonly used. The modified Knott method has been widely used in the diagnosis of human Bancroftian filariasis [6,9] and canine dirofilariasis [2,3,5]. When this microfilaria (mf) concentration method was applied for the detection of S. digitata microfilaremia in cattle, problems that were not seen when this method was used in dogs for Dirofilaria immitis detection, such as incomplete hemolysis of the bovine erythrocytes, were observed. Besides the direct smear method, comparative study on the use of the most optimum microfilaria concentration technique for S. digitata in cattle had not been reported. In this study, we compared the efficiency of Acetone (Acetone test), 2% formalin (modified Knott test), Tween 20 solution, distilled water, 1% SDS and 0.1% SDS as hemolytic solution for disrupting the blood cells in the microfilaria concentration method.Eleven bovine blood samples from Taichung county, Taiwan, were collected by venipuncture of the caudal vein using EDTA-containing syringe. Cattle used in this study have been suspected to be infected with S. digitata. Blood of dogs that had been confirmed to be infected with D. immitis were also collected as control. The dogs were randomly selected from animal shelters in Taichung county, Taiwan.For the Acetone mf concentration technique, one ml of the whole blood was placed into a centrifuge tube containing 9 ml of acetone hemolytic solution (5 ml acetone, 5 ml 0.5% methylene blue aqueous solution added to 90 ml of distilled water), and mixed thoroughly. After centrifuging at 160 × g for 5 min, the supernatant was discarded, and 9 ml distilled water added to the 1 ml of the residual fluid containing the microfilaria. The test-tubes were centrifuged again at 160 × g for 5 min. After decanting the supernatant, the sediments were spread onto a slide glass, covered with a cover slip of 24 × 32 mm, and examined under light microscope.In th...