Prevalence and distribution pattern of Cryptosporidium spp. among pre-weaned diarrheic calves in the Republic of Korea

Abstract

Cryptosporidium spp. are protozoan parasites that belong to subphylum apicomplexa and cause diarrhea in humans and animals worldwide. Data on the prevalence of Cryptosporidium spp. and its subtypes among calves in the Republic of Korea (KOR) are sparse. Hence, our study aimed to investigate the prevalence and association between the age of calf and the identified Cryptosporidium spp. and to determine the genotypes/subtypes of Cryptosporidium spp. in pre-weaned calves with diarrhea in the KOR. A total of 460 diarrheic fecal samples were collected from calves aged 1−60 days and screened for Cryptosporidium spp. by the 18S rRNA gene. Species identification was determined using the sequencing analysis of the 18S rRNA gene, and C. parvum-positive samples were subtyped via the sequence analysis of the 60-kDa glycoprotein (gp60) gene. Sequence analysis based on the 18S rRNA gene revealed the presence of three Cryptosporidium spp., namely, C. parvum (n = 72), C. ryanae (n = 12), and C. bovis (n = 2). Co-infection by these species was not observed. The infection rate was the highest in calves aged 11−20 days (26.1%, 95% CI 17.1−35.1), whereas the lowest rate was observed in calves aged 21−30 days (7.7%, 95% CI 0.0−16.1). The prevalence of C. parvum was detected exclusively in calves aged ≤20 days, and the highest infection rate of C. ryanae was seen in calves ≥31 days of age. The occurrence of C. parvum (χ2 = 25.300, P = 0.000) and C. ryanae (χ2 = 18.020, P = 0.001) was significantly associated with the age of the calves. Eleven different subtypes of the IIa family that belonging to C. parvum were recognized via the sequence analyses of the gp60 gene. Except for two (IIaA18G3R1 and IIaA15G2R1) subtypes, nine subtypes were first identified in calves with diarrhea in the KOR. IIaA18G3R1 was the most frequently detected subtype (72.2% of calves), followed by IIaA17G3R1 (5.6%), IIaA15G2R1 (4.2%), IIaA19G4R1 (4.2%), IIaA16G4R1 (2.8%), IIaA17G4R1 (2.8%), IIaA19G3R (2.8%), IIaA14G1R1 (1.4%), IIaA14G3R1 (1.4%), IIaA15G1R1 (1.4%), and IIaA19G1R1 (1.4%) These results suggest that the prevalence of Cryptosporidium spp. is significantly associated with calf age. Furthermore, the findings demonstrate the high genetic diversity of C. parvum and the widespread occurrence of zoonotic C. parvum in pre-weaned calves. Hence, calves are a potential source of zoonotic transmission with considerable public health implications.

First report of Cryptosporidium andersoni and risk factors associated with the occurrence of Cryptosporidium spp. in pre-weaned native Korean calves with diarrhea

“…The main reason for the difference is that past research has focused mainly on C. parvum , and the occurrence of other Cryptosporidium spp. has recently increased ( 29 – 31 , 45 , 46 ). Compared with a previous study ( 31 ), the current results showed that the occurrence of C. bovis and C. ryanae have increased noticeably in calves.…”

“…has recently increased ( 29 – 31 , 45 , 46 ). Compared with a previous study ( 31 ), the current results showed that the occurrence of C. bovis and C. ryanae have increased noticeably in calves. C. bovis, C. parvum , and C. ryanae , but not C. andersoni , were detected at similar rates in pre-weaned calves.…”

“…C. parvum is the most prevalent species infecting humans and calves worldwide, whereas C. andersoni and C. bovis are rarely found in humans ( 4 , 23 , 27 ). Recently, C. bovis and C. ryanae have been identified in pre-weaned calves ( 28 – 31 ); however, their pathogenicity and role in calf diarrhea remain unclear. According to a previous study performed by our group, C. ryanae was detected at a higher frequency in calves with diarrhea than C. bovis and has now emerged as a leading cause of diarrhea alongside C. parvum ( 31 ).…”

“…Recently, C. bovis and C. ryanae have been identified in pre-weaned calves ( 28 – 31 ); however, their pathogenicity and role in calf diarrhea remain unclear. According to a previous study performed by our group, C. ryanae was detected at a higher frequency in calves with diarrhea than C. bovis and has now emerged as a leading cause of diarrhea alongside C. parvum ( 31 ). C. parvum subtypes have been detected using the 60-kDa glycoprotein ( gp60 ) gene, and to date, at least 14 families (IIa and IIo) have been identified ( 12 , 27 ).…”

“…Additionally, family IId has been found in dairy calves in some countries ( 20 , 32 – 36 ). In contrast, pre-weaned calves with diarrhea in the Republic of Korea (ROK) are mostly infected with C. parvum , almost exclusively with family IIa, especially IIaA18G3R1 ( 31 ). C. parvum oocysts in water flowing out of stables contaminate the surrounding agricultural water or infect humans or wildlife.…”