Age, geographic, and temporal distribution of fecal shedding of Cryptosporidium parvum oocysts in cow-calf herds

OBJECTIVE: To evaluate fecal shedding of Cryptosporidium parvum from California cow-calf herds with respect to age, geographic region, temporal effects, and association with watery feces. ANIMALS: Cows and calves from 38 beef cow-calf operations. PROCEDURE: Fecal specimens were collected and examined for C parvum oocysts, using immunofluorescent microscopy. Associations between age, geographic region, month of collection, watery feces, and likelihood of shedding C parvum were evaluated. RESULTS: 3.9% of cattle were shedding C parvum oocysts. Prevalence of shedding among calves ranged from 0 to 13%, and was 0.6% among cattle > or = 12 months old. The odds of shedding C parvum among 2-month-old calves were 41 times greater than among cattle > 4 months old. The odds of shedding C parvum among cattle tested in May were 8.7 times greater than among cattle tested during June, July, or August. The odds of infected individuals having watery feces were 3 to 4 times greater than for noninfected individuals, but the etiologic fraction was only 8 to 9%. CONCLUSIONS AND CLINICAL RELEVANCE: Substantial fecal shedding of C parvum by cow-calf herds was limited to calves 1 to 4 months old, with low prevalence detected in older animals. Risk of contamination of watersheds with C parvum was limited to those periods when young calves were in the herd. Although the odds of having watery feces were greater for animals infected with C parvum than for noninfected animals, the low etiologic fraction suggests that most calves with watery feces were not infected with C parvum.     

Association of fecal shedding of mycobacteria with high ELISA-determined seroprevalence for paratuberculosis in beef herds

OBJECTIVE: To evaluate the seroprevalence of paratuberculosis by use of 2 commercial ELISAs in association with prevalence of fecal shedding of mycobacteria within beef cattle herds. DESIGN: Cross-sectional field study. ANIMALS: Six beef herds (affected herds; 522 cattle) with and 3 geographically matched herds (181 cattle) without high seroprevalence of paratuberculosis. PROCEDURES: Blood and fecal samples were collected from adult cattle and assessed for serum anti-Mycobacterium avium subsp paratuberculosis (MAP) antibodies with 2 commercial ELISA kits and submitted for bacterial culture for MAP and environmental bacteria (termed environmental mycobacteria) via a radiometric method, respectively. Species of mycobacterial isolates were identified, and sensitivities and specificities of the 2 ELISAs were compared. RESULTS: Compared with comparison cattle, cattle from affected herds were 9.4 times as likely to have environmental mycobacteria isolated from feces. Among the 6 affected and 3 comparison herds, the proportions of cattle shedding environmental mycobacteria were 0.225 (range, 0.1 to 0.72) and 0.04 (range, 0 to 0.06), respectively. Although relative MAP- detection specificities (compared with bacterial culture of feces) were different between the 2 ELISAs, sensitivities were not. Nine environmental mycobacterial species were identified from participating herds. All affected herds apparently had > or = 1 bovid infected with MAP, although MAP was not isolated from any cattle in comparison herds. CONCLUSIONS AND CLINICAL RELEVANCE: In beef herds with persistently high rates of false- positive ELISA results, which may be associated with recovery of environmental myco- bacteria from feces, organism detection via bacterial culture of feces or PCR assay should direct paratuberculosis control measures.     

Detection of Cryptosporidium parvum oocysts in environmental water in Hokkaido, Japan

Control of cryptosporidiosis is important in public health. Rivers that are polluted with Cryptosporidium and drinking water that is treated for drinking water production from polluted rivers could result in the waterborne disease of cryptosporidiosis. We carried out an epidemiological study of natural water supplies in Hokkaido, one of the largest dairy prefectures in Japan. To detect Cryptosporidium oocysts in environmental water, the filtration method was used for 28 samples, which were collected from 10 rivers. A method adapted from the United States Environmental Protection Agency (U.S. EPA) filtration method using a cartridge filter has been used for the collection of samples. Oocysts were separated from a pellet by discontinuous sucrose gradient method. Twelve samples were collected from 10 rivers and parasites were purified by iron (III) flocculation method. Cryptosporidium parvum oocysts were identified with the immunofluorescence antibody technique using DIF kit (Cellabs Pty. Ltd., Sydney/Australia). We detected Cryptosporidium oocysts in 6 out of 10 rivers sampled. Fifty percentage (14/28) of the samples were Cryptosporidium-positive. The average number of Cryptosporidium oocysts was 16.73/100 L (max. 80/100 L).     

Prevalence and risk factors associated with Cryptosporidium oocysts shedding in pigs in Central Vietnam

We investigated the prevalence and risk factors associated with Cryptosporidium oocysts shedding in pigs in Central Vietnam. A total of 740 single fecal samples collected from diarrheic and non-diarrheic pigs on 89 farms were screened by the modified Ziehl-Neelsen staining method. Prevalence at the animal and the farm levels were 18.1% (134/740) and 71.9% (64/89), respectively. Risk factors for the infection were identified using univariate and multivariate logistic regression analysis. The results revealed that age, sanitary condition and topography were significantly associated with oocyst shedding (P<0.05). Pre-weaned piglets were at the highest risk for infection, followed by post-weaners, sows and finishing pigs. Good sanitary conditions showed positive effects in decreasing oocysts shedding. Topographically, Cryptosporidium was more common in mountainous zone than that in coastal delta zone. There was an association between the occurrence of diarrhea and the level of Cryptosporidium oocyst excretion within infected pigs. This is the first epidemiological investigation of prevalence and risk factors of Cryptosporidium in pigs in Vietnam.     

Fecal shedding of Cryptosporidium oocysts in healthy alpaca crias and their dams

Objective-To determine the apparent prevalence of shedding of Cryptosporidium spp in healthy alpaca crias and their dams on 14 farms in New York and 1 farm in Pennsylvania. Design-Cross-sectional study. Animals-110 alpaca crias and their 110 dams. Procedures-Fecal samples were obtained from 220 alpacas at 14 alpaca farms in New York and 1 farm in Pennsylvania. For each animal, age, sex, and health condition were recorded. A fecal score (1 = normally formed; 2 = soft or loose; 3 = diarrhetic) was recorded for each cria. Cryptosporidium oocysts were identified in fecal samples by a direct immunofluorescence assay. Results-Apparent prevalence of fecal shedding of Cryptosporidium oocysts was 8% (95% confidence interval, 4% to 15%) in dams and was 7% (95% confidence interval, 3% to 13%) in crias. There was no significant difference in age between dams with positive fecal test results for Cryptosporidium oocysts (median age, 4 years; range, 3 to 8 years) and dams with negative results (median age, 4 years; range, 2.5 to 19 years). No significant difference was found in age between crias with positive fecal test results (median age, 20 days; range, 7 to 53 days) and those with negative results (median, 36 days; range, 2 to 111 days). No significant difference in fecal scores was found between crias with positive versus negative fecal test results. Conclusions and Clinical Relevance-A higher than previously reported apparent prevalence of fecal shedding of Cryptosporidium oocysts in healthy alpacas was found. A zoonotic risk should be considered, especially for Cryptosporidium parvum.     

Viability and infectivity of Cryptosporidium parvum oocysts detected in river water in Hokkaido,Japan

The viability and infectivity of Cryptosporidium parvum (C. parvum) oocysts, detected in water samples collected from river water in Hokkaido, were investigated using Severe Combined Immunodeficient (SCID) mice. The water samples collected from September 27 through October 10, 2001 by filtration using Cuno cartridge filters were purified and concentrated by the discontinuous centrifugal flotation method. From 1.2 x 10 (5) liters of the raw river water, approximately 2 x 10(4) oocysts were obtained and designated as Hokkaido river water 1 isolate (HRW-1). Oocyst identification was carried out using microscopic and immunological methods. Six 8-week-old female SCID mice were each inoculated orally with 1 x 10 (3) oocysts. Infection was successfully induced, resulting in fecal oocyst shedding. Oocysts were then maintained by sub-inoculation into SCID mice every 3 months. Infectivity was evaluated by making comparisons with two known C. parvum stocks, HNJ-1 and TK-1, which were bovine genotypes detected in fecal samples from a cryptosporidiosis patient and young cattle raised in Tokachi, Hokkaido respectively. The oocyst genotypes were determined from a small subunit ribosomal RNA (SSU-rRNA) gene by polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) analysis. No significant differences were observed in the average number of oocysts per gram of feces (OPG) in any of the isolates. Our data indicates that the C. parvum oocysts detected in the sampled river water were of C. parvum genotype 2. Moreover, our data on the continued isolation, detection and identification of the C. parvum isolates is consistent with the available epidemiological data for the Tokachi area.     

Association between management practices and within-herd prevalence of Cryptosporidium parvum shedding on dairy farms in southern Ontario

To identify management practices associated with an increased within-herd prevalence of Cryptosporidium parvum shedding on dairy farms in southern Ontario, fecal samples were taken from 1089 calves aged 7-28 days, from 119 herds. Information on management practices was obtained by administering a questionnaire compiled using a modified Delphi technique. Data were analyzed using univariable and multivariable negative binomial regression. Overall, 30% of the calves in the study were shedding C. parvum oocysts, with at least one positive calf detected in 77% of herds. Within-herd prevalence ranged from 0 to 80%. Predictors significantly associated with an increased prevalence of shedding in multivariable modelling were the use of calf scour prophylaxis in cows (risk ratio [RR] 1.70, P<0.01) and calves (RR 1.38, P=0.02) and the feeding of milk replacer in the first week of life (RR 1.40, P=0.02). In contrast, the presence of concrete flooring in calf housing areas (RR 0.59, P<0.01) and the use of soap or detergent when washing calf feeding utensils (RR 0.61, P<0.01) appeared to be protective.     

Relationship of strain 19 calfhood vaccination in beef herds and brucellosis reactor rates, duration of quarantine, and number of herd tests

Initial and cumulative reactor rates for strain 19 vaccinates and nonvaccinates were significantly (P less than 0.001) lower for beef herds containing variable proportions of vaccinates, compared with reactor rates in nonvaccinated herds. In addition, significant (P less than 0.005) reduction in cumulative incidence was observed in nonvaccinated and strain 19-vaccinated cattle as the proportion of vaccinates within the herd increased from 1 to 19%, 20 to 39%, 40 to 59%, and 60 to 100%. Duration of quarantine and number of herd tests were not reduced in herds with strain 19-vaccinated cattle. In herds released from quarantine, duration of quarantine and number of tests were positively correlated to proportion of the herd vaccinated. In nonvaccinated herds released from quarantine, effect of herd size was documented by strong positive (P = 0.042) correlation with duration of quarantine and slightly weaker correlation (P = 0.095) with number of tests.     

Factors associated with shedding of Cryptosporidium parvum versus Cryptosporidium bovis among dairy cattle in New York State

OBJECTIVE: To isolate and speciate Cryptosporidium DNA from fecal samples obtained from dairy cattle in New York State and identify factors associated with whether cattle were shedding Cryptosporidium parvum versus Cryptosporidium bovis. DESIGN: Cross-sectional study. SAMPLE POPULATION: 115 fecal samples positive for DNA coding for the Cryptosporidium 18S rRNA gene from dairy cattle in New York State. PROCEDURES: A PCR assay was used to amplify DNA from fecal samples; amplification products were submitted for bidirectional DNA sequencing. Logistic regression was used to test for associations between various host factors and Cryptosporidium spp. RESULTS: 70 of the 115 (61%) fecal samples were found to have C parvum DNA, 42 (37%) were determined to have C bovis DNA, and 3 (3%) were found to have C parvum deer-type DNA. The presence of diarrhea at the time of fecal sample collection, oocyst count, and breed were associated with whether cattle were infected with C parvum or C bovis, with animals more likely to be infected with C parvum if they had diarrhea, had a high oocyst count, or were Holsteins. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that C parvum and C bovis can be isolated from dairy cattle in New York State and that various factors affect whether cattle infected with Cryptosporidium spp are infected with C parvum or C bovis. Findings also lend credence to the theory that C bovis may be more host adapted and thus less pathogenic to dairy cattle than C parvum.     

Temporal changes in the prevalence and shedding patterns of Giardia duodenalis cysts and Cryptosporidium spp. oocysts in a herd of dairy calves in Ontario

Giardia duodenalis and Cryptosporidium spp. infections, and the patterns of cyst and oocyst shedding, were observed in a herd of dairy calves in Ontario over a period of 3 mo. Cysts and oocysts were detected and enumerated in fecal samples using immunofluorescence microscopy; Giardia and Cryptosporidium DNA was detected using the polymerase chain reaction. The prevalence of G. duodenalis increased during the course of the study, reaching a peak of 93.1% when calves were 43 to 54 d old, and then decreased. Conversely, Cryptosporidium spp. prevalence was highest (75.9%) when calves were 11 to 22 d old, and subsequently decreased. The numbers of cysts and oocysts shed per gram of feces were positively correlated over time with the respective prevalence rates. Along with genotyping data, temporal changes in prevalence and shedding patterns should be considered when testing dairy calves for the presence and concentrations of cysts and oocysts, and when considering the potential for zoonotic transmission.     

Prevalence and pathogenicity of Cryptosporidium andersoni in one herd of beef cattle

Over a 35-week period from January to July 2002, a breed of Hereford beef cattle (H) and their hybrids were monitored. Five hundred and ninety-nine individual fecal samples from calves and 96 samples from their mothers were examined. First excretion of Cryptosporidium andersoni oocysts in calves was found in the 9th week after the start of calving (a calf 63-day old). The prevalence of C. andersoni in calves ranged from 11.1 to 92.9% depending on age. The mean prevalence in their mothers was found to be 43.8%. The size of oocysts was 8.48 +/- 0.78 x 6.41 +/- 0.59 microm. Infection intensity in calves ranged from 32 000 to 4 375 000 oocysts per gram (OPG) and in mothers from 78 000 to 2 552 000 OPG. Three cases of abomasal cryptosporidiosis slaughtered at the age of 81, 157 and 236 days were examined histologically and ultrastructurally [transmission electron microscopy (TEM) and scanning electron microscopy (SEM)]. Cryptosporidium infection of the abomasum was located in the upper half of the mucosal glands in the plicae spirales of the fundus, corpus and near the ostium omasoabomasicum. Cryptosporidia were not located in the glandular epithelium of the pars pylorica in the abomasum minimally 10 cm from pylorus. Histopathological changes in the site of cryptosporidial infection in the abomasum had a non-inflammatory character and included distinctive dilatation of infected parts of the glands with atrophy and metaplasia of the glandular epithelial cells, goblet cell activation and mucus hyperproduction. The TEM revealed a relatively small number of Cryptosporidium life cycle stages attached to glandular epithelial cells. In SEM the inner mucosal abomasal surface appeared swollen but was never infected by cryptosporidia.     

Prevalence of Cryptosporidium parvum infection and pattern of oocyst shedding in calves in Japan

Cryptosporidium parvum infection and the pattern of oocyst shedding were observed in calves. A total of 480 fecal samples were collected from 30 calves (age, < or =30 days) over a period of 10 months from June 1998 to March 1999. A sucrose centrifugal flotation technique revealed 28/30 (93%) calves were passing Cryptosporidium oocysts. Oocyst shedding was first detected on the sixth day after birth, with 8% of the calves testing positive. This rate increased day by day and reached approximately 80% by day 15. Oocyst shedding varied from 1 to 13 days, with a mean of 7 days. Calves infected with C. parvum had a significantly higher rate of diarrhea (33%) than non-infected calves (8%) (P<0.05), suggesting C. parvum infection as the likely cause. The mean number of oocysts excreted by calves < or =30 days old was approximately 6x10(7) per gram of feces. These results indicated that one calf would excrete some 6x10(11) oocysts in the first month after birth, taking both the quantity of feces in a day and the period of excretion into consideration. Accordingly, it is clear that calves are important in the spread of cryptosporidiosis to calves and humans.     

Detection of rotavirus and coronavirus shedding in two beef cow herds in Idaho

Fecal samples were taken at the time of pregnancy examinations and at parturition from two beef herds. They were also taken from sick calves at the onset of disease, and from 25% of the healthy calves at 15 days of age. All fecal samples were examined by electron microscopy for viruses.

Four cows in herd A were detected excreting coronavirus, one at the time of the pregnancy examinations and three at parturition. The first cow was removed from the herd and the others calved at the end of the season. There were no sick calves.

No cows in herd B were detected excreting virus at the time of pregnancy checks, but fourteen coronavirus and two rotavirus carrier cows were found at parturition. All but two calves sampled had large numbers of virus particles in their feces. Clinical illness was associated with dams shedding virus and with nightly low temperatures.

     

Modelling spring and autumn calving systems in beef herds of the Salado region of Argentina

Spring calving is recommended for beef herds in the Salado region of Argentina, but autumn calving is an alternative being used by some farmers. This study explored the biological and economic feasibility of autumn calving in cow–calf systems and their long-term performance compared with spring calving. Reproduction and calf performance data were collected from an autumn calving herd (1999–2005) and from a spring calving herd (1966–1995) at the INTA-Balcarce Research Station (37°45′ S; 58°18′ W). Similar data were obtained from a commercial farm which practiced both autumn and spring calving (1998–2003). These data showed that autumn calving is feasible in the region, provided that cows calve with a high condition score. This is a major difference with spring calving, where cows can normally gain weight during breeding. A climatically driven computer model was used to compare, at farm level, the effect of calving season across a range of combinations of weaning dates and stocking rates. Spring calving systems had greater production potential (15–20%) and profitability (17–28%) at high stocking rates. However, at low to moderate stocking rates, calving season had little effect on expected production and risk efficiency. This suggests that autumn calving could be a suitable alternative for the Salado region of Argentina. To exploit its potential, however, calf weaning age should be greater than with spring calving.     

Influence of calving season and stocking rate on birth weight and weaning weight of Simmental-sired calves from Brahman-Hereford F1 dams.

Braham-Hereford F1 dams have been used to evaluate the influence of grazing pressure on forage attributes and animal performance at the Texas A&M University Agricultural Research Center at Overton. Data for this study were compiled from 1,909 records of Simmental-sired calves born to Braham-Hereford F1 cows from 1975 to 1990. Birth weight and weaning weight were analyzed independently to estimate the influence of year, season of birth, dam age, weaning age, and sex of calf. The effect of stocking rate as represented by levels of forage availability on weaning weights and subsequent birth weights was measured. Within the fall and winter calving seasons, lactating dams grazing at a high stocking rate produced calves with the lowest subsequent birth weights. Lactating dams assigned to creep-fed treatments had calves with the heaviest subsequent birth weights. Although dams that were less than 3.5 yr of age had calves with the lightest birth weights, there was no apparent decline in birth weight of calves from dams 12 to 17 yr old. Year, sex of calf, age of dam, stocking rate, season of birth, age at weaning, and birth weight were significant factors affecting weaning weight (P less than .01). Fall-born calves grazing cool-season annual pastures were heavier at weaning (267.6 kg) than either winter- (252.0 kg) or spring-born calves (240.9 kg). A stocking rate x season-of-birth interaction was observed for birth weight and weaning weight (P less than .05). Differences in weaning weight from low- vs high-stocked pastures were greater for fall-born calves (61.6 kg) than for winter-born calves (48.7).(ABSTRACT TRUNCATED AT 250 WORDS)     

Calf-level risk factors for neonatal diarrhea and shedding of Cryptosporidium parvum in Ontario dairy calves

This work was conducted to investigate calf-level factors that influence the risk of neonatal diarrhea and shedding of Cryptosporidium parvum oocysts in calves, on dairy farms in Ontario with histories of calf diarrhea or cryptosporidiosis. Fecal samples were collected weekly for 4 weeks from each of 1045 calves under 30 days of age on 11 dairy farms in south-western Ontario during the summer of 2003 and the winter of 2004. A questionnaire designed to gather information on calf-level management factors was administered on farm for each calf in the study. Samples were examined for C. parvum oocysts by microscopy, and a subset of specimens was also tested for enterotoxigenic Escherichia coli, Salmonella, bovine rotavirus and bovine coronavirus. The consistency of each sample was scored and recorded at the time of collection in order to assess the presence or absence of diarrhea. In addition, a blood sample was taken from each calf upon enrollment in the study, for assessment of maternal antibody transfer and for polymerase chain reaction testing for persistent bovine viral diarrhea virus infection. Using the GLLAMM function in Stata 9.0, multilevel regression techniques were employed to investigate associations between management practices and the risk of C. parvum shedding or diarrhea. C. parvum oocysts were detected in the feces of 78% of the 919 calves from which all four fecal samples had been collected. Furthermore, 73% of the 846 calves for which all four fecal consistency scores had been recorded were diarrheic at the time of collection of at least one sample. Significant predictors of the calf-level risk of C. parvum shedding included the use of calf diarrhea prophylaxis in pregnant cows, and the type of maternity facilities in which the calves were born. Factors associated with an increased risk of diarrhea were leaving the calf with the dam for more than an hour after birth, and the birth of a calf in the summer as opposed to winter. Calves shedding C. parvum oocysts had 5.3 (95% CI 4.4, 6.4) times the odds of diarrhea than non-shedding calves, controlling for other factors included in the final multivariable model. Furthermore, infected calves shedding more than 2.2 x 10(5) oocysts per gram of feces were more likely to scour than infected calves shedding lower numbers of oocysts (OR= 6.1, 95% CI 4.8, 7.8). The odds of diarrhea in calves shedding oocysts that had been allowed to remain with their dams for more than an hour were higher than the odds of diarrhea in shedding calves that had been separated from their dams within an hour after birth.     

Comparison of viability and infectivity of Cryptosporidium parvum oocysts stored in potassium dichromate solution and chlorinated tap water

The present study was undertaken to compare the viability and infectivity of Cryptosporidium parvum oocysts that had been stored for 1, 4, 7, 10, 13, 16, 20, 25 and 30 months at 4 degrees C in 2.5% potassium dichromate (Cr) or chlorinated tap water, respectively. An excystation protocol was performed in vitro to evaluate viability. One hundred and eighty female BABL/c mice were used to evaluate the infectivity of oocysts by investigating the prepatent period of C. parvum infection, the quantity of oocysts excreted, and the number of parasites that colonized the villi of the ileum. The results showed that C. parvum oocysts preserved in Cr for 1-16 months or in water for 1-13 months were capable of excystation in vitro and infection of mice. The excystation rates of oocysts and the prepatent periods in mice infected by oocysts stored in Cr and water were not significantly different (p>0.05), and there was a strong correlation between prepatent period and duration of oocyst storage (Cr: R2=0.92; water: R2=0.98). There were no significant differences in oocyst shedding from feces or parasitism of the terminal ilea of mice by Cryptosporidia between the two storage media (p>0.05). In conclusion, C. parvum oocysts may be stored at 4 degrees C in water instead of Cr for the purposes of laboratory research. However, the presence of viable C. parvum oocysts in water is a severe challenge to the drinking water treatment industry.     

Age-related and housing-dependence of Cryptosporidium infection of calves from dairy and beef herds in South Bohemia, Czech Republic

Data of the prevalence, age-related and housing-dependence of naturally acquired cryptosporidiosis on 11 dairy and 11 beef farms in South Bohemia (Czech Republic) were collected. The farms were visited over four consecutive years (from 2002 to 2005). The prevalence of Cryptosporidium in pre-weaned (animals until second month of age) and post-weaned (animals from the third month of age) calves was determined. A total of 7001 faecal samples were collected, concentrated by Sheather's floatation method and stained by aniline-carbol-methyl violet. All samples were examined by light microscopy. Cryptosporidium parvum and C. andersoni oocysts were differentiated on morphological criteria. Of the 7021 specimens, 1814 (25.8%) were positive for Cryptosporidium oocysts; 561 samples (8%) for C. parvum and 1253 (17.8%) for C. andersoni. Pre-weaned dairy calves had higher infection levels of C. parvum than pre-weaned beef calves. The prevalence of C. parvum ranged from 1.4 to 56.5% on dairy farms. Only three cases of C. parvum oocysts shedding in pre-weaned calves on beef farms were found. Only one case of C. andersoni infection in pre-weaned calves was detected and no infections of C. parvum in post-weaned calves were found. The prevalence of C. andersoni reached 35.5% on dairy farms and 61.7% on beef farms. Calves that were on pasture all year long, had a lower probability of C. andersoni infection than those calves kept in a cowshed during the winter season.     

A novel multiplex polymerase chain reaction approach for detection of four human infective Cryptosporidium isolates: Cryptosporidium parvum, types H and C, Cryptosporidium canis, and Cryptosporidium felis in fecal and soil samples.

A nested multiplex polymerase chain reaction (PCR) approach was adopted for the simultaneous detection of 4 human infective genotypes of the protozoan parasite Cryptosporidium. Specific PCR primers were designed for the heat shock protein 70 gene of 2 genotypes of Cryptosporidium parvum (human and bovine types), Cryptosporidium canis, and Cryptosporidium felis. These 4 genotypes have all been found in human fecal samples. The primers amplified DNA fragments of specific sizes, each representing a unique genotype. The limit of detection of the method was found to vary between 10 and 100 oocysts per 1 ml fecal material. There appeared to be no cross-reactivity with other organisms commonly present in feces and soil, and the approach has a high specificity. The rapid identification of various human infective Cryptosporidium isolates is a part of the authors' long-term aim of determining the routes of infection with oocysts and thereby increase their epidemiological understanding of Cryptosporidium infection in humans and animals.     

Prevalence of Giardia sp. Cryptosporidium parvum and Cryptosporidium andersoni (syn. C. muris) [correction of Cryptosporidium parvum and Cryptosporidium muris (C. andersoni)] in 109 dairy herds in five counties of southeastern New York

A cross-sectional study was undertaken to determine the prevalence of Giardia sp. (G. duodenalis group), Cryptosporidium parvum and Cryptosporidium andersoni (C. muris) [corrected] in dairy cattle in three different age groups, and to evaluate the association of age and season with prevalence. One hundred and nine dairy farms, from a total of 212 farms, in five counties of southeastern New York volunteered to participate. On these farms, 2943 fecal samples were collected from three defined age groups. The farms were randomly assigned for sampling within the four seasons of the year. Each farm was visited once during the study period from March 1993 to June 1994 to collect fecal samples. Demographic data on the study population was collected at the time of sampling by interviewing the farm owner or manager. At collection, fecal samples were scored as diarrheic or non-diarrheic, and each condition was later related to positive or negative infection with these parasites. Fecal samples were processed using a quantitative centrifugation concentration flotation technique and enumerated using bright field and phase contrast microscopy. In this study, the overall population prevalence for Giardia sp. was 8.9%; C. parvum, 0.9%; and C. muris, 1.1%. When considering animals most at the risk of infection (those younger than 6 months of age) Giardia sp. and C. parvum was found in 20.1 and 2.4% of the animals, respectively. Giardia sp. and C. muris were found in all age groups. There was no significant seasonal pattern of infection for any of these parasites.