A multiplex PCR test to identify four common cattle-adapted Cryptosporidium species

Molecular prevalence and associated risk factors of Cryptosporidium spp. infection in dairy cattle in Khon Kaen, Thailand

Background and Aim

Cryptosporidium spp. are important parasites in the small intestines of humans and animals, particularly cattle. The aim of this study was to estimate the molecular prevalence and associated risk factors of Cryptosporidium infection in dairy cattle in five districts of Khon Kaen province, Thailand, and to identify Cryptosporidium spp.

Materials and Methods

From July 2020 to October 2021, 296 fecal samples were collected from three groups of dairy cattle: Calves aged <3 months, calves aged 3 months-1 year, and calves aged >1 year. Cryptosporidium spp. were detected by polymerase chain reaction (PCR) amplifying the 18s RNA gene. Both genus-specific and species-specific primers were used to identify Cryptosporidium confirmed by DNA sequencing. Age, house floor type, and water trough type were evaluated as risk factors. We analyzed all associated risk factor information using the logistic regression test in the Statistical Package for the Social Sciences.

Results

PCR results showed that 40 (13.51%) out of 296 samples were positive for Cryptosporidium spp., including Cryptosporidium bovis (57.50%) and Cryptosporidium ryanae (2.50%). There was a significant association between Cryptosporidium incidence, cattle age, and house floor type (p < 0.05). National Center for Biotechnology Information Basic Local Alignment Search Tool displayed 99.48%-100% nucleotide similarity of each Cryptosporidium spp. isolate with references recorded on GenBank.

Conclusion

C. bovis and C. ryanae are commonly found in dairy cattle, especially calves, in Khon Kaen, Thailand, and the incidence was associated with age and house floor type. A molecular technique may be influential for species identification. The results of the present study would provide useful information for veterinarians and animal owners to understand better Cryptosporidium spp. and how to manage farms properly.

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.

Cryptosporidium parvum gp60 subtypes in diarrheic lambs and goat kids from Israel

Cryptosporidium parvum is the second-most prevalent Cryptosporidium species that infects humans worldwide. In European countries, it is the most prevalent species in sheep, suggesting that these animals are a source of zoonotic infection. Preweaned lambs and goats are particularly susceptible to infection by the parasite and may suffer from severe diarrhea whilst excreting large quantities of infectious oocysts. Fifty fecal samples from preweaned lambs and goats with diarrhea from 35 farms across Israel, found to be Cryptosporidium-positive by microscopy, were tested by PCR and sequence analyses to determine the infective species and subtypes. Cryptosporidium parvum DNA was detected in most samples from both lambs and goats (46/50). Cryptosporidium xiaoi DNA was detected in three samples from kids, with co-infection detected in a single sample. Eleven different C. parvum subtypes were found, 10 in lambs and 5 in goats. All subtypes were from the IIa and IId subtype families, with subtypes IIdA20G1 and IIaA15G2R1 being the most prevalent and widespread. These subtypes were previously found in calves and humans in Israel and are considered the most prevalent C. parvum subtypes in small ruminants globally. These results underline the zoonotic potential of C. parvum from small ruminants and the high subtype diversity compared to previous reports from other Middle Eastern countries. In addition, this is the first report of C. xiaoi in Israel.

Differences in virulence and oocyst shedding profiles in lambs experimentally infected with different isolates of Cryptosporidium parvum

A wide spectrum of disease severity associated with cryptosporidiosis has been described, ranging from asymptomatic to fatal in both human and animal hosts. The reasons for the variations in severity are likely to be multifactorial, involving environmental, host and parasite factors. This paper describes two experimental infection trials in lambs, a symptomatic host for the parasite, to investigate variation in the clinical manifestations following infection with two distinct isolates of Cryptosporidium parvum. In the first experiment, groups of naïve lambs were challenged with one of two isolates (CP1 or CP2) at ​< ​1 week of age, to test the effect of the isolates on disease outcome. In a second experiment one group of lambs challenged at < 1 week of age (CP1) was then re-challenged with the same isolate at 6 weeks of age (CP1), while a second group was challenged for the first time at 6 weeks of age (CP1). This experiment examined age-related disease symptoms, oocyst shedding and the effect of prior exposure to the parasite on a subsequent homologous challenge. The two isolates were associated with significant differences in the demeanour of the animals and in the numbers of oocysts shed in the faeces. There were also differences in the duration and severity of diarrhoea, though these were not significant. The age of the lamb, at the time of a primary challenge (<1 week or 6 weeks), also resulted in differences in clinical outcomes, with younger lambs showing more severe clinical disease than the older lambs (feeding profiles and presentation of diarrhoea), while older lambs showed virtually no signs of infection but still produced large numbers of oocysts.

Development and evaluation of a real-time PCR for genotyping of Cryptosporidium spp. from water monitoring slides

Cryptosporidium is an important cause of gastroenteritis globally and the main agent of waterborne outbreaks caused by protozoan parasites. Water monitoring for Cryptosporidium oocysts is by detection and enumeration using stained slide microscopy. Species identification (known as genotyping) may be undertaken post hoc and remains a specialist test, only undertaken in some laboratories. The benchmark method is nested PCR-sequencing of part of the SSU rRNA gene, but not all slides are typable and the workflow is cumbersome. We report the development, in-house validation and application of a real-time PCR-sequencing assay based on that gene, using a hydrolysis probe, for the detection and genotyping of all Cryptosporidium spp. The assay was investigated in two formats; a high volume DNA template for analysing all the DNA extracted from Cryptosporidium-positive water monitoring slides with <5 oocysts seen, and a lower volume DNA template permitting several technical replicates from slides with ≥5 oocysts seen where multiple species are more likely to be present. Each format conformed to the MIQE guidelines for amplification dynamics and was specific for Cryptosporidium spp. With high sensitivity, being capable of detecting and genotyping single oocysts by sequencing of a 435 bp amplicon. When 65 water monitoring slides with <5 oocysts seen were tested, slide typeability varied by sending laboratory (n = 9), and ranged from 22 to 60%. Typeability was 75% for slides with ≥5 oocysts seen that were submitted by a single laboratory. The laboratory workflow was improved by using real-time PCR, and decreased the time to result compared with nested PCR-sequencing. In practical application, there was no loss of typeability when the ≥5 oocysts assay was applied to all slides, irrespective of the number of oocysts present.

Cryptosporidium parvum infection and management-based risk factors of dairy calves in Taiwan

Cryptosporidiosis is one of the major causes of diarrhea in calves. Cryptosporidium parvum is considered the most important calf diarrhea pathogen in the Cryptosporidium species. Not only could infected calves spread C. parvum, but infected adult cattle could also shed oocysts. The objectives of this study were (1) to investigate the prevalence of C. parvum in dairy herds in Taiwan, including calves, the dams in delivery enclosure, the floor, and the drinking water; (2) to clarify the relationship of diarrhea, management, and C. parvum infection. Twenty dairy herds in Taiwan were selected by random sampling, including 226 calves and 198 dams, and other environmental samples were collected. A questionnaire was filled out by the farm owners to collect information regarding the management of calves and the delivery enclosure. Hierarchical logistic regression was used to analyze the risk factors for C. parvum infection. The prevalence of C. parvum infection in calves was 26.5% (60/226), while in dams, it was 19.7% (39/198). The C. parvum infection in calves increased with environmental contamination of C. parvum and clinical signs of diarrhea, while it decreased with a yard provided in the delivery enclosure. In conclusion, the management of the delivery enclosure appears to be more important for preventing cryptosporidiosis in calves in Taiwan.

Cryptosporidium parvum subtypes from diarrheic dairy calves in Israel

Cryptosporidium are protozoan parasites with worldwide distribution, infecting a wide range of terrestrial and aquatic animals, as well as humans. Cryptosporidium parvum is the most important zoonotic species and is the primary cause of cryptosporidiosis in preweaned calves, a highly prevalent, economically important disease. Extensive subtyping of C. parvum from infected humans and animals has expanded current understanding of the parasites' epidemiology. Israel has a highly developed dairy sector with intensive, zero-grazing operations. While C. parvum has been found in dairy calves throughout the country, and subtype data from human patients have also been published, subtype data from animals, and in particular preweaned ruminants, are lacking. We carried out an initial study of Cryptosporidium species and subtypes from preweaned diarrheic calves. Cryptosporidium species were determined in 71 fecal samples from 43 different dairy farms using 18S rRNA PCR, and subtyping of C. parvum based on the 60-kDa glycoprotein (gp60) sequences was done on one sample per farm. C. parvum was the only species found, with eight different subtypes belonging to the zoonotic IIa and IId families. Subtype IIaA15G2R1 was the most prevalent and widespread, found in 50% of the farms over a wide geographical distribution. Our results confirm the presence of subtypes IIaA15G2R1 and IIdA20G1, which were previously found in human patients in Israel, also in Israeli calves. In addition, subtype IIaA12G1R1 is reported here for the first time in an animal. These findings demonstrate the value of monitoring C. parvum subtypes in animal samples, and suggest that the role of calves as well as other young ruminants in the transmission of zoonotic cryptosporidiosis in Israel should be further studied.

Long-term production effects of clinical cryptosporidiosis in neonatal calves

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Cryptosporidium parvum is a major cause of enteric disease in neonatal calves.

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Clinically severe cryptosporidiosis in neonatal calves significantly reduces weight gain.

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The impact of reduced weight gain in calves is seen over a 6 month period.

Cryptosporidiosis can have a devastating effect in neonatal calves, resulting in diarrhoea, dehydration and, in severe cases, death of the animal. The disease is caused by Cryptosporidium spp. and is one of the most common causes of calf enteritis in the UK. The parasite is very difficult to remove from the farm, as the oocysts have a tough outer wall which enables the parasite to survive for several months in moist temperate environmental conditions and it is difficult to kill oocysts with common disinfectants used on a farm. If appropriate management practises are applied, the disease is usually self-limiting and most calves will recover. It has been shown, in studies with children and in lambs, that severe clinical cryptosporidiosis can result in long-term growth and cognitive impairment compared with individuals with no obvious signs of the disease. This study measured the long-term growth rate of beef calves on farm by comparing groups of animals that had suffered differing degrees of clinical severity of cryptosporidiosis as neonates. A group of 27 beef calves were enrolled in the study and monitored from birth to 6 months of age. The calves were scored for severity of cryptosporidiosis and weighed at regular intervals. The average difference in weight gain, at 6 months, between a group of calves that had severe cryptosporidiosis as neonates and a group of calves with no clinical signs of infection was 34 kg. Those calves that had experienced severe cryptosporidiosis as neonates showed a significantly reduced live weight gain compared with those calves showing no clinical signs of infection (P = 0.034). Therefore, the impact of severe cryptosporidiosis in neonatal calves has longer term effects on weight gain and production efficiency, resulting in the parasite having a greater impact on cattle production than previously thought.

A One Health Approach to Tackle Cryptosporidiosis

Cryptosporidiosis is a significant diarrhoeal disease in both people and animals across the world and is caused by several species of the protozoan parasite Cryptosporidium. Recent research has highlighted the longer-term consequences of the disease for malnourished children, involving growth stunting and cognitive deficits, and significant growth and production losses for livestock. There are no vaccines currently available to prevent the disease and few treatment options in either humans or animals, which has been a significant limiting factor in disease control to date. A One Health approach to tackle zoonotic cryptosporidiosis looking at new advances in veterinary, public, and environmental health research may offer several advantages and new options to help control the disease.

Cryptosporidium Prevalence in Calves and Geese Co-Grazing on Four Livestock Farms Surrounding Two Reservoirs Supplying Public Water to Mainland Orkney, Scotland

The parasite Cryptosporidiumparvum represents a threat to livestock health and production, water quality and public health. Cattle are known to be significant reservoirs of C. parvum, but transmission routes are complex and recent studies have implicated the potential role of wildlife in parasite transmission to cattle and water sources. On the Orkney Isles, high densities of Greylag geese (Anser anser) cause widespread faecal contamination of cattle pastures, where cryptosporidiosis is known to be the main cause of neonatal calf diarrhoea and Cryptosporidium contamination frequently occurs in two reservoirs supplying Mainland Orkney’s public water. This study aimed to determine the Cryptosporidium species and subtypes present in geese and calves co-grazing on four farms surrounding two reservoirs on Mainland Orkney. Results indicated a high level of C. parvum prevalence in calves, geese and water samples. gp60 analysis illustrated that higher genotypic diversity was present in the goose population compared with calves, but did not yield sequence results for any of the water samples. It can be concluded that the high levels of C. parvum evident in calves, geese and water samples tested represents a significant risk to water quality and public health.

Shedding of Cryptosporidium in calves and dams: evidence of re-infection and shedding of different gp60 subtypes

One of the most common causes of calf diarrhoea is the parasite Cryptosporidium parvum. Two longitudinal studies were carried out on a dairy farm Scotland to determine the prevalence of Cryptosporidium species and subtypes in a group of calves and to determine whether dams were a possible source of calfhood infection. Fecal samples were collected from 25 calves from birth to 12 months in the first year. In the second year, fecal samples were collected from pregnant cows (n = 29) and their calves (n = 30) from birth to 6 months. The samples were tested for Cryptosporidium and speciated. Cryptosporidium parvum-positive samples were subtyped by GP60 fragment analysis. All calves in both studies shed Cryptosporidium during the study period. Cryptosporidium parvum was the predominant species detected in calves ⩽6 weeks of age and at 6 months of age, C. bovis and C. ryanae were detected in calves older than 4 weeks of age but ⩽6 months of age. The prevalence of Cryptosporidium was higher in younger animals than in older animals. GP60 subtyping revealed two subtypes in calves on this farm (IIaA15G2R1 and IIaA19G2R1) that differed in frequency by age. Adult cattle also shed C. parvum, of four gp60 genotypes.

Detection of potentially human infectious assemblages of Giardia duodenalis in fecal samples from beef and dairy cattle in Scotland

This study aimed to determine the prevalence and assemblages of Giardia duodenalis present in Scottish beef and dairy cattle at different ages, to try to ascertain if cattle could play a role in the spread of zoonotic assemblages of Giardia. A total of 388 fecal samples (128 beef and 253 dairy, seven of unknown breed) were collected from 19 farms in Scotland. Samples were sub-divided by host age, 1, 2, 3, 4, 5 and 6, 7-24 and ⩾25 weeks. DNA was extracted and tested by PCR to detect G. duodenalis DNA. Of the 388 samples, 126 tested positive, giving an overall prevalence of 32.5%, with positive samples being observed in all age groups tested. The prevalence in dairy cattle was 44.7% (113/235), which was significantly higher (P &lt; 0.001) than the prevalence in beef cattle 10.1% (13/128). Sequence analysis demonstrated the presence of assemblage E (77.2%, sequence types E-S1-E-S5), assemblage B (18.2%) and assemblage A (sub-assemblages AI-AII) (4.6%). These data demonstrate that G. duodenalis is found routinely in both dairy and beef cattle throughout Scotland; the presence of assemblages A and B also indicates that cattle may play a role in the spread of potentially zoonotic assemblages of Giardia.

Bovine cryptosporidiosis: impact, host-parasite interaction and control strategies

Gastrointestinal disease caused by the apicomplexan parasite Cryptosporidium parvum is one of the most important diseases of young ruminant livestock, particularly neonatal calves. Infected animals may suffer from profuse watery diarrhoea, dehydration and in severe cases death can occur. At present, effective therapeutic and preventative measures are not available and a better understanding of the host-pathogen interactions is required. Cryptosporidium parvum is also an important zoonotic pathogen causing severe disease in people, with young children being particularly vulnerable. Our knowledge of the immune responses induced by Cryptosporidium parasites in clinically relevant hosts is very limited. This review discusses the impact of bovine cryptosporidiosis and describes how a thorough understanding of the host-pathogen interactions may help to identify novel prevention and control strategies.