Genetic diversity of Cryptosporidium parvum strains in cattle in Poland – a cross-sectional population study

Abstract

Cryptosporidium parvum (C. parvum) infections are reported in cattle worldwide. Ruminants are not only the reservoir of the parasite for other animal species, but they can also be a source of infection for humans. The aim of the study was an assessment of the prevalence and molecular identification of Cryptosporidium parvum subtypes circulating in the cattle population in Poland. In total, 1601 faecal samples were collected from cattle at the age of 1 week to 4 months over a period of five years (2014-2018). The animals were kept on 267 farms across 16 Polish provinces. The cattle belonged to 14 breeds, among which the most numerous was Polish Black and White Holstein Friesian (HO), mixed exclusively meat breeds (MM), Simentaler (SM) and Limousine (LM) breeds. Detection of C. parvum strains in faecal samples was performed using the 18 small subunit ribosomal RNA (SSU rRNA) PCR-RFLP method, while the parasite subtypes were determined on the basis of microsatellite sequence analysis of the GP60 gene fragment. A chi-squared (χ2) test was employed to show the relationships between C. parvum subtypes and their prevalence in cattle of different breeds, animals age (age group) and their geographical distribution in Poland. The analysis of variance (ANOVA) was conducted to assess frequency of infections in cattle caused by particular C. parvum subtypes. The overall prevalence of C. parvum in cattle from Poland was estimated at 6.2% (100/1601). The infected animals were housed in 44 (16.5%) out of 267 monitored farms. C. parvum subtypes were successfully identified for 82 out of 100 detected parasite strains, which belonged to the IIa and IId genetic families. In the genetic group IIa, the following subtypes were identified IIaA17G1R1 (n = 26), IIaA17G2R1 (n = 24), IIaA15G2R1 (n = 10), IIaA16G1R1b (n = 9), IIaA22G1R1 (n = 4), IIaA14G2R1 (n = 2), IIaA10G1R1 (n = 2), IIaA21G1R1 (n = 1), IIaA18G3R1 (n = 1) and IIaA21R1 (n = 1). The IId genetic family was only represented by IIdA24G1 subtype (n = 2). In this study, five new C. parvum subtypes (A21R1, A18G3R1, A22G1R1, A21G1R1 and A14G2R1) were detected. They have not been identified in cattle in Poland so far.