Sarcocystis spp. microcysts in dairy water buffaloes (Bubalus bubalis) from Argentina

GUAL, I.; LLADA, I.; SCIOLI, M.V.; FIORANI, F.; SCIOLI, A.; MORRELL, E.; ODRIOZOLA, E.R.; MORÉ, G.; CANTÓN, G.; MOORE, D. P.

La Plata

Seminario; XI Reunión Argentina de Patología Veterinaria (RAPAVE 2018), 12ª Seminario de la Fundación CL Davis-SW Thompson en Argentina; 2018

RAPAVE

Water buffaloes are intermediate host of four different Sarcocystis species that form cysts in skeletal and/or cardiac muscle: S. levinei, S. dubeyi, S. buffalonis and S. fusiformis. Although non-pathogenic, Sarcocystis macrocysts in bubaline meat can be a cause of carcass rejection. In addition, the role of bubaline sarcocysts as a zoonotic disease is still unknown. The dog is the definitive host of S. levinei, whereas the cat is the definitive host of S. dubeyi, S. buffalonis and S. fusiformis. Although light microscopy is useful to characterize the cysts, in order to confirm the identity of Sarcocystis species, both electron microscopy and PCR are the appropriate diagnostic tools. S. levinei and S. dubeyi cysts are microscopic, but using light microscopy they can be confused with immature forms of the macrocyst-forming species (S. buffalonis and S. fusiformis). The cyst wall thickness is an important feature used to differentiate Sarcocystis species: S. buffalonis and S. dubeyi have a thick cyst wall, whereas S. levinei and S. fusiformis have a thin one. The aim of this work is to describe microscopic sarcocysts in water buffaloes from Buenos Aires Province, Argentina. Formalin-fixed tissue samples of adult dairy female water buffaloes with different health problems were received at the Specialized Veterinary Diagnostic Service of INTA EEA Balcarce for histopathological studies using hematoxylin and eosin stain. Twenty cardiac muscle sections of approx. 1 cm2, from 6 water buffaloes and 17 skeletal muscle sections of the same area, from 2 water buffaloes were analyzed. Fourteen thin-walled cysts (< 1 µm) were found in the cardiac muscle of 5 water buffaloes; whereas 15 thin-walled cysts and one thick-walled cyst (> 1.5 µm) were found in the skeletal muscle of both water buffaloes. The cysts found in the cardiac muscle measured 78-163 (mean: 113) µm long × 54-93 (mean: 72) µm wide, whereas the ones found in the skeletal muscle measured 130-451 (mean: 260) µm long × 53-301 (mean: 131) µm wide. Skeletal muscle cysts were longer than the ones in the cardiac muscle (p< 0.01). All of the sarcocysts were intracellular and had hundreds of bradyzoites inside. Being S. levinei the only species described in buffaloes cardiac muscle, the microcysts found in myocardium belong presumably to this species. Unfortunately, electron microscopy and PCR could not be performed, thus, the identification of the sarcocysts could not be achieved. Nonetheless, the finding of sarcocysts in water buffaloes in Argentina is reported here for the first time. Further investigations are needed in order to confirm the etiology of sarcocysts in muscles of water buffalos by employing electron microscopy and PCR.