First record of an infection by tissue cyst-forming coccidia in wild vizcachas (Lagostomus maximus, Rodentia) of Argentina

Ruth Cwirenbaum; Alejandro R Schmidt; Santiago A Cortasa; María C Corso; Alfredo D Vitullo; Verónica B Dorfman; Julia Halperin

doi:10.1016/j.ijppaw.2021.08.002

First record of an infection by tissue cyst-forming coccidia in wild vizcachas (Lagostomus maximus, Rodentia) of Argentina

Int J Parasitol Parasites Wildl. 2021 Aug 9:16:52-58. doi: 10.1016/j.ijppaw.2021.08.002. eCollection 2021 Dec.

Authors

Ruth Cwirenbaum¹, Alejandro R Schmidt^{1

2}, Santiago A Cortasa^{1

2}, María C Corso^{1

2}, Alfredo D Vitullo^{1

2}, Verónica B Dorfman^{1

2}, Julia Halperin^{1

2}

Affiliations

¹ Centro de Estudios Biomédicos Básicos, Aplicados y Desarrollo (CEBBAD) Universidad Maimónides, Hidalgo 775, C1405BCK-Buenos Aires, Argentina.
² Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina.

Abstract

Endoparasites of the Sarcocystidae family share the ability to form tissue cysts in their intermediate hosts, ultimately leading to pathogenesis in the definitive hosts that include various mammals, reptiles and birds. In our research on the endocrinology of the female vizcachas (Lagostomus maximus), we have found abnormal cystic structures in the ovaries of some individuals. So far, no cases of infection by tissue cyst-forming parasites have been reported in this species. To evaluate whether this autochthonous wild rodent is an intermediate host of an undescribed endoparasite, histological sections from various organs were examined. Pinhead-sized tissue cysts were found in the ovaries, mammary glands, uterus, pituitary, brain, adrenals and spleen, of both pregnant and non-pregnant females. The presence of cysts in the adult brain and embryonic tissue is indicative of the ability of the parasite to cross both the blood-brain and placental barriers. The infected brains exhibited a lower cyst density than that seen in other organs. Regardless of their location in superficial or deep tissue, the cysts were surrounded by a layer of connective tissue. Histologically, the cyst wall consisted of an outer layer of fibroblasts and collagen fibers, and an inner, granular-looking layer composed of host nucleated cells surrounding thousands of spindle-shaped bradyzoites. Outside the cysts, the host cellular structures showed normal appearance. The remarkable morphological similarities between the cysts studied here with those reported in naturally infected rabbits from an area neighboring the one inhabited by the vizcachas point to Besnoitia sp. as a plausible candidate. More studies will be necessary to confirm the identity of the parasite. Nevertheless, this is the first report of L. maximus as an intermediate host for a tissue cyst-forming coccidia.

Keywords: Bradyzoites; Coccidia; Intermediate host; Lagostomus maximus; Tissue cyst; Wildlife.