Introduction

Sarcocytosis is an important disease of livestock and man caused by Sarcocystis, an intracellular protozoan parasite with a two-host life cycle. The definitive hosts (carnivores) become infected by ingesting sarcocysts encysted in the tissues of an intermediate (herbivores) host and sporocysts are shed in the faeces of an infected definitive host (Giannetto et al., 2005; Sayed et al., 2008). This disease poses as a threat to the livestock industry due to its economic losses through condemnation of carcasses at meat inspection and abortions (Fayer et al., 1976). Sarcocystis cruzi, Sarcocystis hirsuta and Sarcocystis hominis are the only three species that are of significance in bovine, with Sarcocystis cruzi being the most common and most significant (Heydorn et al., 1975). There is no effective treatment for infection, either in the definitive or in the intermediate host. Where an out break occurs in cattle, Amprolium is the only compound that is recommended for prophylaxis against Sarcocystocis (Leek and Fayer, 1980).

Very little or no literature is available stressing on the need to carry out routine histopathology on cases of Cysticercosis. Therefore, the main objective of this case report was to stress on the significance of carrying out routine histopathological examination on cases suspected to be Cysticercosis based on parasitological examination in order to rule out Sarcocystocis.

Case History

Visceral organs of an adult cow were presented to the School of Veterinary Medicine Pathology Laboratory for examination. The postmortem findings included generalized nodules on the heart, liver, kidney, diaphragm and thigh muscles. The cow was reported to be lethargic, salivating, anorexic, not producing milk for her calf, reluctance to move, recumbent and finally death. It was the only cow affected from a herd of 5 cattle which are free range (100% grazing). The farmer also keeps dogs and chickens at the farm.

Materials and Methods

Tissue samples were obtained for histopathological examination, fixed in 10% neutral buffered formalin, and stained using Haematoxylin and eosin stain (H & E). The sections were mounted and examined under a light microscope before being photographed.

Results

Macroscopic findings revealed presence of nodular growths on the heart (Figure 1), liver and kidneys. There was presence of endocardial hemorrhages too (Figure 2). The cysts were calcified, thus no fluid was coming out on cutting surface. Microscopic findings showed a spindle-shaped sarcocystis cyst, measuring 250µm in length and surrounded by variable numbers of inflammatory cells, with presence of muscular degeneration. The cyst had a thin wall with numerous bradyzoites inside (Figure 3 and 4).

Discussion

Sarcocystosis is usually of no clinical significance in nonhuman primates and findings are normally incidental on histologic examination of skeletal and/or cardiac muscles from nonhuman primates, although myositis or myocaditis are rare sequelae of heavy Sarcocystis infection (Klumpp et al., 1994). The pathogenicity and economic importance in food animals includes loss of weight, anorexia, decreased milk production, anemia, and prostration often culminating in death, while during

Figure 1: Nodular cysts on the cardiac muscles (green arrow). Figure 2: Nodular cysts on the cardiac muscles with endocardial hemorrhages (green arrow).

Figure 3: Spindle-shaped sarcocystis parasite

(White arrow) in the cardiac muscles, x400 (H&E stain).

Schizogonic proliferation, changes such as lymphadenopathy, hydrothorax, hydropericardium, ascites, petechial hemorrhages in heart, brain, alimentary and urinary tracts have been reported (Dafedar et al., 2008). In the present case, the clinical signs were lethargy, salivation, anorexia, reluctance to move and finally recumbent. Death was probably due to heart and respiratory failure resulting from severe diaphragmatic and cardiac muscles degeneration, which could have interfered with the contractile function of these important organs.

This case was erroneously diagnosed as Bovine Cysticercosis caused by Ternia sarginata based on macroscopic parasitological examination. However, histopathology which was done out of curiosity resulted into correct diagnosis of Bovine Sarcocystosis. Ewing et al., 2002 also incidentally diagnosed a case of sarcocystocis in a Stranded Atlantic white-sided dolphin. This therefore indicates that incidental findings of sarcocystocis are common, and thus most cases may probably go undiagnosed if we only rely on macroscopic diagnosis. This case report therefore emphasizes on the need to carryout routine histopathology on cases suspected to be Cysticercosis based on parasitological findings.

Sarcocystosis can be confused with cysticercosis during meat inspection. It is of public health significance, as many human cases have been documented in various parts of the world (Beaver et al., 1979; Fayer, 2004). Therefore, correct identification of the disease on meat inspection is very cardinal in order to prevent the effect of the disease to the public. However, despite its public health significance and economic impacts to the cattle and pig industry, its prevalence in Zambia is not known as compared to Bovine Cysticercosis which has a prevalence of 6.1% (Dorny et al., 2002). Authors suggest that Sarcocystocis should be included in the differential diagnosis of cases suspected to be Cysticercosis and further studies be directed towards assessment of the prevalence of sarcocystocis in Zambia which has a thriving beef and pig industry. To the knowledge of the authors, this is the first time that a case of Bovine Sarcocytosis is being put on record in Zambia.

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