Cryptosporidium parvum GP60 subtypes in dairy cattle from Buenos Aires, Argentina

Prevalence, risk factors and molecular epidemiology of neonatal cryptosporidiosis in calves: The Argentine perspective

Cryptosporidium spp. are enteroparasitic protozoans that cause cryptosporidiosis in newborn calves. Clinical signs of the infection are diarrhoea and dehydration leading to decreased productivity and economic losses in cattle farms around the world. Additionally, cryptosporidiosis is a relevant zoonotic disease since the ingestion of oocysts can be fatal for children under five years of age, the elderly, and/or immunocompromised adults. This review aims to integrate existing knowledge on the epidemiological situation of calf cryptosporidiosis and associated risk factors in Argentina. In addition, the GP60 subtype diversity of the pathogen was analysed and related with the global distribution of corresponding GP60 subtypes. Depending on the study region and applied diagnostics, prevalence among calves up to 20 days of age varied between 25.2% and 42.5%, while a prevalence of 16.3-25.5% was observed at the age of 1-90 days. So far, molecular studies have determined exclusively Cryptosporidium parvum in preweaned calves. In addition, C. parvum infection was reported as the major cause of calf diarrhoea, followed by rotavirus A (RVA), while enteropathogens such as coronavirus, Escherichiacoli, and Salmonella sp. played a negligible role. Calf age of 20 days or less, incidence of diarrhoea, poorly drained soils, and large farm size were identified as risk factors for C. parvum-infection in Argentina. A total of nine GP60 subtypes (IIaAxxG1R1, xx = 16 to 24) were identified, showing a stepwise increase of the trinucleotide motif TCA, and including the zoonotic subtypes IIaA16G1R1, IIaA17G1R1, IIaA18G1R1, IIaA19G1R1, and IIaA20G1R1. We found that an increase in the A16→A24 trinucleotide repeat was accompanied by a gradual decrease in the global distribution of GP60 alleles, strongly suggesting that IIaA16G1R1 represents the primordial allelic variant of this group. Since identified GP60 alleles have a similar genetic background, we hypothesize that the continuous trinucleotide repeat array has been generated by stepwise repeat expansion of A16. The information gathered and integrated in this study contributes to an improved understanding of the epidemiological characteristics of bovine cryptosporidiosis in and beyond Argentina, which in turn can help to develop control strategies for this parasitosis of veterinary and medical relevance.

Population genetics of Cryptosporidium parvum subtypes in cattle in Poland: the geographical change of strain prevalence and circulation over time

Background

Cryptosporidium parvum (C. parvum) is a cosmopolitan parasite that infects various livestock animals including cattle. Microsatellite typing tools for identification of C. parvum subtypes are currently employed to better understand the species-specific epidemiology of cattle cryptosporidiosis. The aim of this study was to analyse the population genetics of C. parvum strains infecting cattle and recognise geographical distribution and time-span correlations in subtype prevalence in Poland. In total, 1601 faecal samples were collected from 2014 to 2018 from healthy cattle from dairy, meat and mixed breeds at the age of 1 week to 4 months. The 267 farms visited were randomly selected and represented all Polish provinces. PCR–RFLP based identification of C. parvum at the 18 small subunit ribosomal RNA (SSU rRNA) locus was performed, followed by strain subtyping by GP60-PCR. 

Results

The overall prevalence of C. parvum in Polish cattle was estimated at 6.2% (100/1601). Animals below the age of 1 month were the major host for this parasite. Excluding one breed, that of dairy-meat mixed, there were no significant differences observed between breed and presence of C. parvum infections (95% TPI_{All breeds}: 1.67–73.53%; POPR = 0.05—0.95). Infected animals were detected in 15 out of 16 Polish provinces, with significant regional prevalence diffrences (Kruskal–Wallis rank sum test, Kruskal–Wallis χ² = 13.46, p < 0.001). When the population genetics of C. parvum strains were analysed, 11 parasite subtypes from the IIa and IId genetic families were identified. Compared to other parasite strains, IIaA17G1R1 and IIaA17G2R1 appeared at statistically significantly higher frequency (F-test, F = 3.39; p = 0.0003). The prevalence of C. parvum subtypes in cattle was breed-related (Chi-squared test, χ² = 143.6; p < 0.001).

Conclusions

The analysis of the population genetics of C. parvum subtypes showed that strains from the IIa subtype family predominated in the tested cattle population. However, relations in changes of subtype prevalence and circulation over time were observed. They were associated with the disappearance of some strains and emergence of new variants from the same genetic family in different geographical locations.

C. parvum subtypes from the IIa allele family predominated in the tested cattle. The prevalence of C. parvum subtypes in cattle was breed-related. Dynamicity in the population C. parvum strains circulating in cattle was shown.

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

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.

Occurrence of Cryptosporidium and other enteropathogens and their association with diarrhea in dairy calves of Buenos Aires province, Argentina

Cryptosporidiosis of neonatal dairy calves causes diarrhea, resulting in important economic losses. In Argentina, prevalence values of Cryptosporidium spp. and other enteropathogens such as group A rotavirus (RVA), bovine coronavirus (BCoV) and enterotoxigenic Escherichia coli (ETEC, endotoxin STa⁺), have been independently studied in different regions. However, an integrative epidemiological investigation on large-scale farms has not been carried out. In this study, fecal samples (n = 908) were randomly collected from diarrheic and healthy calves from 42 dairy farms, and analyzed for the presence of Cryptosporidium spp., RVA, BCoV, ETEC (STa⁺) and Salmonella spp. In all sampled dairy farms, dams had been vaccinated against rotavirus and gram-negative bacteria to protect calves against neonatal diarrhea. The proportion of calves shedding Cryptosporidium spp., RVA, and BCoV in animals younger than 20 days of age were 29.8%, 12.4% and 6.4%, and in calves aged between 21 and 90 days, 5.6%, 3.9%, and 1.8%, respectively. ETEC was absent in the younger, and occurred only sporadically in the older group (0.9%), whereas Salmonella spp. was absent in both. The observed sporadic finding or even absence of bacterial pathogens might be explained by the frequent use of parenteral antibiotics in 25.3% and 6.5% of the younger and the older group of calves, respectively, within 2 days prior to sampling and/or vaccination of dams against gram-negative bacteria. Diarrhea was observed in 28.8% (95% CI, 24.7-32.8%) of the younger calves and 11.7% (95% CI, 9.1-15.5%) of the older calves. Importantly, Cryptosporidium spp. (odds ratio (OR) = 5.7; 95% CI, 3.3-9.9; p < 0.0001) and RVA (OR = 2.5; 95% CI, 1.2-5.1; p < 0.05) were both found to be risk factors for diarrhea in calves younger than 20 days old. Based on its high prevalence and OR, our results strongly suggest that Cryptosporidium spp. is the principal causative factor for diarrhea in the group of neonatal calves, whereas RVA seems to play a secondary role in the etiology of diarrhea in the studied farms, with about three-times lower prevalence and a half as high OR. Furthermore, a coinfection rate of Cryptosporidium spp. and RVA of 3.7% was observed in the group of younger calves, which strengthens the assumption that these events are independent. In contrast, due to a low infection rate of enteropathogens in older calves, mixed infection (<< 1%) was virtually absent in this group.

Dairy Calves in Uruguay Are Reservoirs of Zoonotic Subtypes of Cryptosporidium parvum and Pose a Potential Risk of Surface Water Contamination

Cryptosporidium parvum, a major cause of diarrhea in calves, is of concern given its zoonotic potential. Numerous outbreaks of human cryptosporidiosis caused by C. parvum genetic subtypes are reported yearly worldwide, with livestock or water being frequently identified sources of infection. Although cryptosporidiosis has been reported from human patients in Uruguay, particularly children, epidemiologic information is scant and the role of cattle as reservoirs of zoonotic subtypes of C. parvum has not been explored. In this study, we aimed to (a)-identify C. parvum subtypes infecting dairy calves in Uruguay (including potentially zoonotic subtypes), (b)-assess their association with calf diarrhea, (c)-evaluate their spatial clustering, and (d)-assess the distance of infected calves to surface watercourses draining the farmlands and determine whether these watercourses flow into public water treatment plants. Feces of 255 calves that had tested positive for Cryptosporidium spp. by antigen ELISA were selected. Samples had been collected from 29 dairy farms in seven Uruguayan departments where dairy farming is concentrated and represented 170 diarrheic and 85 non-diarrheic calves. Selected samples were processed by nested PCRs targeting the 18S rRNA and gp60 genes followed by sequencing to identify C. parvum subtypes. Of seven C. parvum subtypes detected in 166 calves, five (identified in 143 calves on 28/29 farms) had been identified in humans elsewhere and have zoonotic potential. Subtype IIaA15G2R1 was the most frequent (53.6%; 89/166), followed by IIaA20G1R1 (24.1%; 40/166), IIaA22G1R1 (11.4%; 19/166), IIaA23G1R1 (3.6%; 6/166), IIaA17G2R1 (3%; 5/166), IIaA21G1R1 (2.4%; 4/166), and IIaA16G1R1 (1.8%; 3/166). There were no significant differences in the proportions of diarrheic and non-diarrheic calves infected with any of the C. parvum subtypes. Two spatial clusters were detected, one of which overlapped with Uruguay's capital city and its main water treatment plant (Aguas Corrientes), harvesting surface water to supply ~1,700,000 people. Infected calves on all farms were within 20–900 m of a natural surface watercourse draining the farmland, 10 of which flowed into six water treatment plants located 9–108 km downstream. Four watercourses flowed downstream into Aguas Corrientes. Calves are reservoirs of zoonotic C. parvum subtypes in Uruguay and pose a public health risk.

Prevalence of Cryptosporidium parvum in dairy calves and GP60 subtyping of diarrheic calves in central Argentina

Cryptosporidiosis of calves is caused by the enteroprotozoan Cryptosporidium spp. The disease results in intense diarrhea of calves associated with substantial economic losses in dairy farming worldwide. The aim of this study was to determine calf, herd, and within-herd Cryptosporidium prevalence and identify Cryptosporidium species and subtypes in calves with diarrhea in intensive dairy herds in central Argentina. A total of 1073 fecal samples were collected from 54 randomly selected dairy herds. Cryptosporidium-oocysts were isolated and concentrated from fecal samples using formol-ether and detected by light microscopy with the modified Ziehl-Neelsen technique. Overall prevalence of oocyst-excreting calves was found to be 25.5% (274/1073) (95% C.I. 22.9; 28.1%). Of the herds studied, 89% (48/54) included at least one infected calf, whereas within-herd prevalence ranged from the absence of infection to 57% (20/35). A highly significant association was found between the presence of diarrhea and C. parvum infection (χ² = 55.89, p < 0.001). For species determination, genomic DNA isolated from oocyst-positive fecal samples was subjected to PCR-RFLP of the 18S rRNA gene resulting exclusively in Cryptosporidium parvum identification. C. parvum isolates of calves displaying diarrhea and high rate of excretion of oocysts were subtyped by PCR amplification and direct sequencing of the 60 kDa glycoprotein (GP60) gene. Altogether five GP60 subtypes, designated IIaA18G1R1, IIaA20G1R1, IIaA21G1R1, IIaA22G1R1, and IIaA24G1R1 were identified. Interestingly, IIaA18G1R1 and IIaA20G1R1 were predominant in calves with diarrhea and high infection intensity. Notably, IIaA24G1R1 represents a novel, previously unrecognized C. parvum subtype. The subtype IIaA18G1R1, frequently found in this study, is strongly implicated in zoonotic transmission. These results suggest that calves might be an important source for human cryptosporidiosis in Argentina.

Multilocus fragment analysis of Cryptosporidium parvum from pre-weaned calves in Colombia

The intra-species genetic diversity of Cryptosporidium parvum in dairy cattle farms in the central area of Colombia was investigated using a multilocus fragment typing approach with nine variable-number tandem-repeat (VNTR) loci and the gp60 gene. Genomic DNA of 70 C. parvum isolates from pre-weaned calves in 32 farms was analysed. Most markers showed two (ML1, MSB, CP47, and MSC6-7) or three alleles (5B12, Cgd2_3850, and Cgd6_5400), although they exhibited a major allele accounting for more than 69% of specimens, which explains their low discriminatory index. The TP14 microsatellite was monomorphic while a total of six alleles were found at the ML2 microsatellite. The two novel allelic variants (219bp, 245bp) exhibited by more than 36% of specimens at the latter locus were a remarkable finding. The 10-markers typing tool provided a Hunter-Gaston discriminatory value of 0.940 (95% CI, 0.918 - 0.961) and differentiated 22 multilocus subtypes (MLTs). Nevertheless, the combination of the three most informative markers (ML2, gp60, and Cgd2_3850) differentiated 68% of MLTs and hardly impaired the discriminatory index. The fact that many MLTs (13/22) were distinctive for individual farms provides evidence for the endemic nature of the infection and the major role played by transmission within farms. The eBURST algorithm suggested a low degree of genetic divergence. All but three MLTs were clustered in a clonal complex with a star-like topology typical of clonal expansion, however linkage analysis did not find evidence of linkage disequilibrium. Bayesian analysis also identified a genetic structure with K = 3 being the best estimation of ancestral clusters, although a large proportion of isolates (35%) could not be allocated to a single population, which indicates their mixed origin. The results confirm the genetic distinctiveness of C. parvum in cattle farms in this geographical area. This is the first multilocus analysis on the intra-specific variability of Cryptosporidium from calves in South America.

Diversity of Cryptosporidium spp. in Apodemus spp. in Europe

The genetic diversity of Cryptosporidium spp. in Apodemus spp. (striped field mouse, yellow-necked mouse and wood mouse) from 16 European countries was examined by PCR/sequencing of isolates from 437 animals. Overall, 13.7% (60/437) of animals were positive for Cryptosporidium by PCR. Phylogenetic analysis of small-subunit rRNA, Cryptosporidium oocyst wall protein and actin gene sequences showed the presence of Cryptosporidium ditrichi (22/60), Cryptosporidium apodemi (13/60), Cryptosporidium apodemus genotype I (8/60), Cryptosporidium apodemus genotype II (9/60), Cryptosporidium parvum (2/60), Cryptosporidium microti (2/60), Cryptosporidium muris (2/60) and Cryptosporidium tyzzeri (2/60). At the gp60 locus, novel gp60 families XVIIa and XVIIIa were identified in Cryptosporidium apodemus genotype I and II, respectively, subtype IIaA16G1R1b was identified in C. parvum, and subtypes IXaA8 and IXcA6 in C. tyzzeri. Only animals infected with C. ditrichi, C. apodemi, and Cryptosporidium apodemus genotypes shed oocysts that were detectable by microscopy, with the infection intensity ranging from 2000 to 52,000 oocysts per gram of faeces. None of the faecal samples was diarrheic in the time of the sampling.

First identification of Cryptosporidium parvum subtype IIaA20G1R1 in water buffalos (Bubalus bubalis)

Cryptosporidium can infect a wide variety of vertebrate animals, including mammals, birds, amphibians, reptiles, and fish. There are few molecular characterizations of Cryptosporidium isolated from water buffalo. Thus, the present study investigated the occurrence and molecular characterization of Cryptosporidium spp. in water buffalos by nested-PCR. Non-diarrheic feces were obtained from 122 water buffalo calves. All samples were tested by nested-PCR based on the 18S rRNA gene, after which positive samples were analyzed by RFLP and genetic sequencing. Sixteen fecal (13.1%) samples were positive, and RFLP showed that fifteen presented patterns consistent with C. ryanae and one with C. parvum. Sequencing of the gp60 gene from the C. parvum positive sample indicated the subtype IIaA20G1R1. This is the first identification of the IIaA20G1R1 subtype in water buffalos.

Cryptosporidium spp. and Giardia spp. in feces and water and the associated exposure factors on dairy farms

The aims of this study were to verify the prevalence of Cryptosporidium spp. and Giardia spp. in animal feces and drinking water on dairy farms and to identify a possible relation between the exposure factors and the presence of these parasites. Fecal samples from cattle and humans and water samples were collected on dairy farms in Paraná, Brazil. Analysis of (oo)cysts in the feces was performed by the modified Ziehl-Neelsen staining and centrifugal flotation in zinc sulfate. Test-positive samples were subjected to nested PCR amplification of the 18SSU ribosomal RNA gene for identification of Cryptosporidium and Giardia and of the gp60 gene for subtyping of Cryptosporidium. Microbiological analysis of water was carried out by the multiple-tube method and by means of a chromogenic substrate, and parasitological analysis was performed on 31 samples by direct immunofluorescence and nested PCR of the genes mentioned above. Identification of the species of Cryptosporidium was performed by sequencing and PCR with analysis of restriction fragment length polymorphisms. The prevalence of Giardia and Cryptosporidium was higher in calves than in adults. Among the samples of cattle feces, Cryptosporidium parvum was identified in 41 (64%), C. ryanae in eight (12.5%), C. bovis in four (6.3%), C. andersoni in five (7.8%), and a mixed infection in 20 samples (31.3%). These parasites were not identified in the samples of human feces. Thermotolerant coliform bacteria were identified in 25 samples of water (45.5%). Giardia duodenalis and C. parvum were identified in three water samples. The gp60 gene analysis of C. parvum isolates revealed the presence of two strains (IIaA20G1R1 and IIaA17G2R2) in the fecal samples and one (IIaA17G2R1) in the water samples. The presence of coliforms was associated with the water source, structure and degradation of springs, rain, and turbidity. The prevalence of protozoa was higher in calves up to six months of age. C. parvum and G. duodenalis were identified in the water of dairy farms, as were thermotolerant coliforms; these findings point to the need for guidance on handling of animals, preservation of water sources, and water treatment.

Prevalence and risk factors for shedding of Cryptosporidium spp. oocysts in dairy calves of Buenos Aires Province, Argentina

In order to determine the prevalence and risk factors for shedding of Cryptosporidium spp. in dairy calves, a cross-sectional study was carried out in the northeastern region of Buenos Aires Province, Argentina. Fecal samples from a total of 552 calves from 27 dairy herds were collected, along with a questionnaire about management factors. Cryptosporidium spp. oocysts were detected by light microscopy using Kinyoun staining. Putative risk factors were tested for association using generalized linear mixed models (GLMMs). Oocyst shedding calves were found in 67% (CI_95% = 49–84) of herds (corresponding to a true herd prevalence of 98%) and 16% (CI_95% = 13–19) of calves (corresponding to a true calve prevalence of 8%). Within-herd prevalence ranged from 0 to 60%, with a median of 8%. Cryptosporidium spp. excretion was not associated with the type of liquid diet, gender, time the calf stayed with the dam after birth, use of antibiotics, blood presence in feces, and calving season. However, important highly significant risk factors of oocyst shedding of calves was an age of less or equal than 20 days (OR = 7.4; 95% CI_95% = 3–16; P < 0.0001) and occurrence of diarrhea (OR = 5.5; 95% CI_95% = 2–11; P < 0.0001). The observed association with young age strongly suggests an early exposure of neonatal calves to Cryptosporidium spp. oocysts in maternity pens and/or an age-related susceptibility. Association with diarrhea suggests that Cryptosporidium spp. is an important enteropathogen primarily responsible for the cause of the observed diarrheal syndrome. Results demonstrate that Cryptosporidium spp. infection is widespread in the study region. Monitoring and control of this parasitic protozoan infection in dairy herds is recommended.

Cryptosporidiosis outbreak in visitors of a UK industry-compliant petting farm caused by a rare Cryptosporidium parvum subtype: a case-control study

A case-control study was conducted to investigate an outbreak of 46 cases of cryptosporidiosis in visitors to a petting farm in England. Details of exposures on the farm were collected for 38 cases and 39 controls, recruited through snowball sampling. Multivariable logistic regression identified that cases were 5·5 times more likely than controls to have eaten without washing their hands [95% confidence interval (CI) 1·51–19·9, P = 0·01] and 10 times less likely to report being informed of risk of infection on arrival (odds ratio 0·10, 95% CI 0·01–0·71, P = 0·02). An uncommon Cryptosporidium parvum gp60 subtype (IIaA19G1R1) was identified in a lamb faecal sample and all subtyped cases (n = 22). We conclude that lack of verbal advice and non-compliance with hand washing are significantly associated with a risk of cryptosporidiosis on open farms. These findings highlight the public health importance of effectively communicating risk to petting farm visitors in order to prevent future outbreaks of zoonotic infections.

Multiple Cryptosporidium parvum subtypes detected in a unique isolate of a Chilean neonatal calf with diarrhea

To further understand the composition of population of parasite in a single host, we analyzed the GP60 gene of Cryptosporidium parvum amplified from DNA of a randomly selected isolate found in the feces of a diarrheic calf from a dairy farm in Central Chile. Direct sequencing of the amplicon yield the IIaA17G4R1 C. parvum subtype. The same amplicon was cloned in Escherichia coli (22 clones) and sequenced, yielding three different GP60 subtypes, IIaA17G4R1 (16/22), IIaA16G4R1 (1/22), and IIaA15G4R1 (1/22), and four sequences with nucleotide substitutions in the serine repeats, which subtype would be otherwise IIaA17G4R1. It is thus possible to determine allelic polymorphism using Sanger sequencing with an additional step of bacterial cloning. The results also indicate the necessity to further characterize parasite populations in a single host to better understand the dynamics of Cryptosporidium epidemiology.

Molecular characterization of Cryptosporidium parvum from two different Japanese prefectures, Okinawa and Hokkaido

Infectious diarrhea is the most frequent cause of morbidity and mortality in neonatal calves. Cryptosporidium parvum is one of the main pathogens associated with calf diarrhea. Although diarrhea is a symptom of infection with various pathogens, investigations to detect the types of pathogens have never been performed in Japan. This study investigated the prevalence of four major diarrhea-causing pathogens in calves: C. parvum, rotavirus, coronavirus, and enterotoxigenic Escherichia coli (E. coli K99). Commercial immunochromatography testing of all four pathogens and molecular analysis of C. parvum with diarrhea in calves from southernmost Okinawa and northernmost Hokkaido, Japan, were conducted. The frequencies of C. parvum, rotavirus, coronavirus, and E. coli (K99) in Okinawa were 50%, 28%, 2.3%, and 4.7%, respectively. Watery fecal stools were significantly correlated with C. parvum (p < 0.05). In oocyst calculations for C. parvum, no significant difference was observed between the single-infection cases and the mixed-infection cases with rotavirus. Interestingly, molecular analyses targeting small subunit ribosomal RNA as well as glycoprotein 60 (GP60) genes revealed that the C. parvum nucleotide sequences from the two prefectures were identical, indicating that C. parvum with a uniform characteristic is distributed throughout Japan. GP60 subtyping analysis identified C. parvum from Okinawa and Hokkaido as belonging to the IIaA15G2R1 subtype, a known zoonotic subtype. Hence, control of cryptosporidiosis is important not only for pre-weaned calves, but also for human health.

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ICT strips were used for calf diarrhea to detect four major enteric pathogens.

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C. parvum showed the highest frequency in the southernmost Okinawa prefecture, Japan.

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C. parvum from the northernmost Hokkaido prefecture was used for a comparative study.

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C. parvum from the two prefectures had a uniform character in SSUrRNA and GP60 genes.

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GP60 subtyping revealed that IIaA15G2R1, a known zoonotic subtype, was predominant.

Symptomatic and asymptomatic secondary transmission of Cryptosporidium parvum following two related outbreaks in schoolchildren

Two related outbreaks (in 2009 and 2012) of cryptosporidiosis in Norwegian schoolchildren during a stay at a remote holiday farm provided us with a natural experiment to investigate possible secondary transmission of Cryptosporidium parvum IIa A19G1R1. After the children had returned home, clinical data and stool samples were obtained from their household contacts. Samples were investigated for the presence of Cryptosporidium oocysts by immunofluorescence antibody test. We found both asymptomatic and symptomatic infections, which are likely to have been secondary transmission. Laboratory-confirmed transmission rate was 17% [4/23, 95% confidence interval (CI) 7·0–37·1] in the 2009 outbreak, and 0% (95% CI 0–16·8) in the 2012 outbreak. Using a clinical definition, the probable secondary transmission rate in the 2012 outbreak was 8% (7/83, 95% CI 4·1–16·4). These findings highlight the importance of hygienic and public health measures during outbreaks or individual cases of cryptosporidiosis. We discuss our findings in light of previous studies reporting varying secondary transmission rates of Cryptosporidium spp.