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

Description of the helminth community structure from two populations of Plains Viscacha (Rodentia: Chinchillidae) in semi-captive and wild conditions

“…Previous surveys had reported a total of 15 endoparasite species in Plains Viscacha, 11 helminths (2 in SCHP and 11 in WHP), and 4 coccidians (1 in SCHP and 3 in WHP) (Canova et al, 2021;Couch et al, 2001;Cwirenbaum et al, 2021;Ferreyra et al, 2007;Foster et al, 2002;Martínez, 1988;Railliet & Henry, 1909;Rossanigo et al, 1986;Schuurmans-Stekhoven, 1951;Sutton & Durette-Desset, 1987, 1995. In the present study, Strongyloides sp.…”

Survey and Molecular Characterization of Sarcocystidae protozoa in Wild Cricetid Rodents from Central and Southern Chile

“…and B. jellisoni-like cysts in the reproductive tissue of adult rodents, and in the fetal tissues of Lagostomus maximus (Chinchillidae) and Dipodomys sp. (Heteromyidae), suggesting vertical transmission [4,44], as also occurs in other Toxoplasmatinae, e.g., T. gondii and N. caninum [46][47][48]. Future studies should consider sampling additional tissues, such as those mentioned above, and should not only target Besnoitia, but also identify other sarcocystids that may invade these tissues.…”

“…and B. jellisoni -like cysts in the reproductive tissue of adult rodents, and in the fetal tissues of Lagostomus maximus (Chinchillidae) and Dipodomys sp. (Heteromyidae), suggesting vertical transmission [ 4 , 44 ], as also occurs in other Toxoplasmatinae, e.g., T . gondii and N .…”

“…The subfamily Sarcocystinae, represented by genus Sarcocystis , encompasses three clades: B, which mostly infects birds; C, which infects humans, felids, and canids; and D, which infects snakes as definitive hosts [ 1 , 3 ]. In South America, parasites of the Sarcocystidae family have been detected in rodents and marsupials from Argentina, Brazil, and Peru [ 4 , 5 , 6 , 7 , 8 , 9 ].…”