Cryptosporidium and cryptosporidiosis of tree and ground squirrels

Cryptosporidia are unicellular, single-host parasites (Apicomplexa, Cryptosporidiidae) that primarily infect the gastrointestinal, respiratory, and urogenital tracts of various vertebrates, including humans. Infection caused by members of the genus Cryptosporidium, cryptosporidiosis, is often associated with diarrheal disease of varying severity. Several species, C. parvum and C. hominis, cause cryptosporidiosis in millions of people worldwide and pose a significant threat to the lives of children under five years of age, in whom it is a leading cause of death, especially in developing countries. Economic losses due to C. parvum are frequently described in young animals of economically important ruminants, while mortality in wild animals has hardly been studied. The results of scientific work in the last decade have shown that the diversity of Cryptosporidium is much greater than previously thought. Currently, 49 valid species and many genotypes of Cryptosporidium spp. are known, exceeding 100. Most of these species and genotypes, which are most likely distinct species, are derived from wild animals. Very little is known about the biology of these species. Squirrels often share their habitat with humans and are an important reservoir of zoonotic pathogens, including Cryptosporidium spp. This Ph.D. thesis provides new insights into the occurrence, diversity, and biology of Cryptosporidium spp. parasitizing tree and ground squirrels

Cryptosporidium sciurinum n. sp. (Apicomplexa: Cryptosporidiidae) in Eurasian Red Squirrels (Sciurus vulgaris)

Cryptosporidium spp. are common protozoan pathogens in mammals. The diversity and biology of Cryptosporidium in tree squirrels are not well studied. A total of 258 Eurasian red squirrels (Sciurus vulgaris) from 25 and 15 locations in the Czech Republic and Slovakia, respectively, were examined for Cryptosporidium spp. oocysts and specific DNA at the SSU, actin, HSP70, TRAP-C1, COWP, and gp60 loci. Out of 26 positive animals, only juveniles (9/12) were microscopically positive (18,000 to 72,000 OPG), and molecular analyses revealed the presence of Cryptosporidium sp. ferret genotype in all specimens. Oocysts obtained from naturally-infected squirrels measured 5.54–5.22 μm and were not infectious for laboratory mice (BALB/c and SCID), Mongolian gerbils, Guinea pigs, Southern multimammate mice, chickens, or budgerigars. None of naturally infected squirrels showed clinical signs of disease. The frequency of occurrence of the ferret genotype in squirrels did not vary statistically based on host age, gender or country of capture. Phylogenetic analysis of sequences from six loci revealed that Cryptosporidium sp. ferret genotype is genetically distinct from the currently accepted Cryptosporidium species. Morphological and biological data from this and previous studies support the establishment of Cryptosporidium sp. ferret genotype as a new species, Cryptosporidium sciurinum n. sp

Cryptosporidium myocastoris n. sp. (Apicomplexa: Cryptosporidiidae), the Species Adapted to the Nutria (Myocastor coypus)

Cryptosporidium spp., common parasites of vertebrates, remain poorly studied in wildlife. This study describes the novel Cryptosporidium species adapted to nutrias (Myocastor coypus). A total of 150 faecal samples of feral nutria were collected from locations in the Czech Republic and Slovakia and examined for Cryptosporidium spp. oocysts and specific DNA at the SSU, actin, HSP70, and gp60 loci. Molecular analyses revealed the presence of C. parvum (n = 1), C. ubiquitum subtype family XIId (n = 5) and Cryptosporidium myocastoris n. sp. XXIIa (n = 2), and XXIIb (n = 3). Only nutrias positive for C. myocastoris shed microscopically detectable oocysts, which measured 4.8–5.2 × 4.7–5.0 µm, and oocysts were infectious for experimentally infected nutrias with a prepatent period of 5–6 days, although not for mice, gerbils, or chickens. The infection was localised in jejunum and ileum without observable macroscopic changes. The microvilli adjacent to attached stages responded by elongating. Clinical signs were not observed in naturally or experimentally infected nutrias. Phylogenetic analyses at SSU, actin, and HSP70 loci demonstrated that C. myocastoris n. sp. is distinct from other valid Cryptosporidium species

Native and introduced squirrels in Italy host different Cryptosporidium spp

The present study was undertaken to describe Cryptosporidium spp. infection in tree squirrels from 17 locations in Northern Italy. A total of 357 squirrels were examined, including species native to Europe (Sciurus vulgaris; n = 123), and species introduced from North America (Sciurus carolinensis; n = 162) and Southeast Asia (Callosciurus erythraeus; n = 72). Faecal samples of all squirrels were examined for the presence of Cryptosporidium infection by microscopy (flotation method) and PCR/sequence analysis of the Cryptosporidium 18S rRNA, actin, and gp60 genes. Despite the overlapping ranges of native and introduced tree squirrel species in the study area, they host different Cryptosporidium spp. Sciurus vulgaris were exclusively infected with Cryptosporidium ferret genotype (n = 13) belonging to three novel gp60 subtypes, VIIIb\ue2\u80\u93VIIId. Sciurus carolinensis hosted C. ubiquitum subtype XIIb (n = 2), Cryptosporidium skunk genotype subtype XVIa (n = 3), and chipmunk genotype I subtype XIVa (n = 1). Cryptosporidium chipmunk genotype I subtype XIVa was also found in two C. erythraeus. Comparing data from this and previous studies, we propose that Cryptosporidium skunk genotype and possibly C. ubiquitum subtype XIIb were introduced to Europe with eastern grey squirrels. Cryptosporidium chipmunk genotype I and ferret genotype were associated with high intensity infections, but there was no association with diarrhoea