The potential for zoonotic transmission of Giardia duodenalis and Cryptosporidium spp. from beef and dairy cattle in Ontario, Canada

The objective of this study was to compare the occurrence and the genotypes and species of Giardia duodenalis and Cryptosporidium spp. in beef and dairy cattle from farms in the Regional Municipality of Waterloo, Ontario, in an effort to determine the potential for zoonotic transmission from these animals. Pooled manure samples were collected from 45 dairy cattle farms and 30 beef cattle farms. The presence of Giardia cysts and Cryptosporidium oocysts was determined by immunofluorescence microscopy, while nested-PCR and DNA sequencing were used to determine genotypes and species. The overall farm prevalence was very high for both Giardia and Cryptosporidium, and was similar for dairy cattle farms (96 and 64%, respectively) and beef cattle farms (97 and 63%, respectively). However, on dairy cattle farms, G. duodenalis and Cryptosporidium spp. were detected in 44% and 6% of total pooled pen manure samples, respectively, with the occurrence of both parasites being generally higher in calves than in older animals. Most Giardia isolates were identified as either the host-adapted genotype G. duodenalis Assemblage E or the zoonotic Assemblage B. Cryptosporidium parvum and Cryptosporidium andersoni were the most frequently identified species in dairy cattle, while the non-zoonotic species Cryptosporidium ryanae and Cryptosporidium bovis were also found. On beef cattle farms, 72% and 27% of the total pooled pen manure samples were positive for Giardia and Cryptosporidium, respectively, with no obvious correlation with age. All Giardia isolates in beef cattle were identified as G. duodenalis Assemblage E, while all Cryptosporidium isolates were identified by sequence analysis as C. andersoni, although microscopic analyses, and subsequent restriction fragment length polymorphism analyses, indicated that other Cryptosporidium species were also present. The results of this study indicate that although Giardia and Cryptosporidium were identified in a higher overall percentage of the pooled beef cattle manure samples than in dairy cattle, firmly established zoonotic genotypes and species were much more common in dairy cattle than in beef cattle in this region. Dairy cattle, and especially dairy calves, may, therefore, pose a greater risk of infection to humans than beef cattle. However, these results may also provide evidence of potential zooanthroponotic transmission (human to animal).     

Epidemiologic Survey and Species Determination of Coccidia Infection in Dairy Cattle in Yuzhong,Gansu Province

This investigation aimed to examine coccidia infection in diary cattle in Yuzhong,Gansu province.An investigation was carried out on the Holstein calves less than one year old in six large-scale dairy farms.A total of 234 fecal samples were examined,and oocysts were identified to the species level on the basis of morphological features after positive samples were mixed thoroughly with 2.5% potassium dichromate solution.The results showed that the prevalence rate of coccidia in Holstein calves reached 46.15%.The average prevalence rate of the calves under 3 months old was 52.43%,the 4 to 6 months old calves was 37.50% and the 7 to 12 months old calves was 43.37%.Seven species of Eimeria coccidians and one species Isospora sp.including Eimeria bovis,Eimeria auburnensis,Eimeria zuernii,Eimeria alabamensis,Eimeria subspherica,Eimeria ellipsoidalli,Eimeria canadensisi,were identified in the investigation,and Eimeria bovis,Eimeria auburnensis,Eimeria zuernii were the dominant species.In conclusion,the prevalence rate of coccidiosis in dairy cattles in Yuzhong,Gansu province was high.Therefore,appropriate strategies and measures should be taken to control coccidiosis prevalence in dairy cows in this region.     

甘肃榆中县奶牛球虫病流行病学调查与虫种鉴定

奶牛球虫病呈世界性分布,中国部分省市也有报道,但是甘肃省至今尚未有关于奶牛球虫病的相关调查。甘肃省榆中县是甘肃省奶牛主产区之一,为了解甘肃省榆中县奶牛球虫感染情况,对当地6个规模化奶牛养殖场1岁以内荷斯坦奶牛犊牛球虫感染情况进行了调查。试验采用显微镜下观察的方法检测了该地区的234份奶牛粪便样品,并对球虫阳性粪便进行重铬酸钾法孵化来鉴定球虫种类。结果发现,犊牛球虫总感染率达到46.15%,其中1~3月龄犊牛平均感染率为52.43%,4~6月龄犊牛平均感染率为37.50%,7~12月龄犊牛平均感染率为43.37%。经虫种鉴定,共发现7种艾美尔属球虫和1种等孢属球虫,7种艾美尔属球虫分别是牛艾美尔球虫(Eimeria bovis)、奥博艾美尔球虫(Eimeria auburnensis)、邱氏艾美尔球虫(Eimeria zuernii)、阿拉巴艾美尔球虫(Eimeria alabamensis)、亚球形艾美尔球虫(Eimeria subspherica)、椭圆艾美尔球虫(Eimeria ellipsoidalli)、加拿大艾美尔球虫(Eimeria canadensis),其中牛艾美尔球虫、奥博艾美尔球虫、邱氏艾美尔球虫为优势种。本次调查结果表明,甘肃省榆中县奶牛球虫感染情况严重,应引起相关部门重视。     

Coccidia in cows and calves on pasture in north Georgia (U.S.A.)

The prevalence and abundance of coccidian oocysts were determined in a herd of beef cows and calves on fescue pastures in the Piedmont area of Georgia during 4-consecutive grazing seasons. Twelve species of Eimeria were found in the feces of the calves and 10 species were found in the feces of the cows. Eimeria bovis was the most prevalent species found in both the calves and cows. It occurred in 72.5% of 1090 samples from the calves and 10.2% of 719 samples from cows. Eimeria bovis also comprised the majority of oocysts present in the fecal samples from the calves and cows. The greatest number of E. bovis in a sample was 45 800 oocysts per gram of feces (OPG) from a calf and 1900 OPG from a cow. No cases of clinical coccidiosis were seen in any of the animals sampled during the survey.     

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.     

2005年上海地区乳牛球虫感染的季节动态

为了解上海地区乳牛球虫感染的季节变化情况，对上海地区3个牧场乳牛抽样直肠采集粪便，检查了718头乳牛粪样。结果，查出球虫阳性牛269头，平均感染率为37．46％，其中1月龄以内牛的感染率为33．89％，1～12月龄牛的感染率为42．33％，12月龄以上牛的感染率为25．95％。平均感染率最高的4月份为44．44％，最低的8月份为28．57％。3个牧场球虫阳性牛的感染强度（OPG值）为0～169000个，平均OPG值为9477个，其中1月龄以内牛的OPG值为8270个，1～12月龄牛的OPG值为4318个，12月龄以上牛的OPG值为145个。调查发现了6种球虫，分别是牛艾美球虫（Eimeria boris）、椭圆艾美球虫（E．ellipsoidalis）、邱氏艾美球虫（E．zurnii）、怀俄明艾美球虫（E．wyomingensis）、柱状艾美球虫（E．cylindrica）、亚球形艾美球虫（E．subspherica）。结果表明，2005年上海地区乳牛球虫感染率无明显季节差异，12月龄内乳牛的球虫感染率与感染强度均明显高于12月龄以上乳牛，乳牛球虫的优势虫种为牛艾美球虫、椭圆艾美球虫、邱氏艾美球虫。     

High prevalence of Cryptosporidium bovis and the deer-like genotype in calves compared to mature cows in beef cow-calf operations

Recent studies have identified the novel, host adapted Cryptosporidium bovis and the deer-like genotype in dairy cattle from farms in the United States, China, India and Europe. This novel species and genotype appear to be more prevalent in older, post-weaned dairy cattle than previously thought. However, little information is available on their prevalence in beef cow-calf operations. In the present study, we determined the prevalence of Cryptosporidium species in 98 calves (6-8 months old) and 114 cows (>2 years old) in seven beef cow-calf herds in western North Dakota. DNA was extracted from fecal samples and Cryptosporidium spp. were identified by amplification of the 18S rRNA gene followed by sequencing or RFLP analysis. All seven herds tested positive for Cryptosporidium. Overall, 43/212 (20.3%) animals were positive. Only five of these positives were from cows. C. bovis, the deer-like genotype and C. andersoni were identified in 9.4, 6.6 and 1.4% of animals sampled, respectively. C. parvum was not identified in any of the positive samples. C. bovis, the deer-like genotype and C. andersoni were detected in 6/7, 5/7 and 2/7 herds, respectively. C. bovis and the deer-like genotype were primarily detected in calves, while C. andersoni was only detected in cows. Six isolates could not be typed. These results show a relatively high prevalence of C. bovis and the deer-like genotype in 6-8-month-old beef calves compared to cows older than 2 years in the seven herds studied.     

The recent prevalence of bovine leukemia virus (BLV) infection among Japanese cattle

A seroepidemiological survey of bovine leukemia virus (BLV) infection was conducted in Japan in 2007 using an enzyme-linked immunosorbent assay (ELISA) and an agar gel immunodiffusion (AGID) test. A total of 5420 cattle (dairy, 3966; breeding beef, 797; fattening beef, 657) from 209 farms in seven prefectures in Japan were tested. The overall prevalence of BLV infection was 28.6%. The prevalence of BLV infection in dairy cattle (34.7%) was higher than for both fattening beef cattle (7.9%) and breeding beef cattle (16.3%). Age-specific prevalence showed that BLV prevalence increased with age in all types of cattle and was notably different between dairy and beef cattle under 1 year of age. Among 207 farms, 141 herds (68.1%) had one or more positive animals. The proportion of these positive farms was significantly higher among dairy farms (79.1%) than among beef breeding farms (39.5%) and beef fattening farms (51.9%) (P < 0.001). Dairy farms (40.5%) also showed a significantly higher within-herd prevalence than beef breeding (27.4%) and fattening (14.9%) farms (P = 0.001). This study indicated that BLV is more widely spread in dairy cattle than in beef breeding cattle in Japan. Given the prevalence of BLV infection in dairy and beef cattle was 8- and 1.7-fold higher, respectively, than rates previously found in 1980–1982, BLV appears to be spreading particularly among the dairy cattle population during the last two decades. Further investigation is required to determine the risk factors necessary to control BLV infection that take into account the different farming practices that exist between dairy and beef sectors.     

Quantitative determination of coccidian oocysts in beef calves from the coastal plain area of Georgia (U.S.A.)

For two consecutive years, determinations were made of the prevalence and abundance of coccidian oocysts from crossbred beef calves raised on Bahia grass pastures in the coastal plain area of Georgia. Of the 534 fecal samples collected during the survey, 461 (86.3%) contained one or more species of coccidian oocysts. The total mean oocysts per gram of feces (OPG) was significantly different (P less than 0.10) between the two years. Thirteen species of Eimeria were found during both years of the survey. Eimeria bovis was the most prevalent species found in the survey; E. ellipsoidalis, however, had the greatest number of OPG. Eimeria bukidnonensis, E. pellita, and E. brasiliensis were the least prevalent species and also had the lowest numbers of OPG. Only one clinical case of coccidiosis was seen. A nine-month-old calf had E. zuernii coccidiosis; it excreted E. zuernii oocysts in several fecal samples before the clinical disease appeared.     

Prevalence of Cryptosporidium, Giardia and Isospora species infections in pet cats with clinical signs of gastrointestinal disease

This study reports the prevalence of Cryptosporidium, Giardia and Isospora species in cats showing signs of gastrointestinal disease. Records from a United Kingdom commercial diagnostic laboratory between December 2003 and December 2005 were reviewed. Of 1355 cats, Cryptosporidium species oocysts were found in 13 cats (1%), Giardia species trophozoites in 74 (6%), and Isospora felis oocysts in 46 (3%). In a second group of 48 cats, prevalence of Giardia species was 15% using an immunoassay for detection of antigen compared to 4% detected with microscopy. Prevalence of Giardia (9%) and Isospora (9%) species was higher in cats less than 6 months old. Gender and breed did not affect prevalence. There was a trend for Cryptosporidium and Isospora species infections to be detected in late autumn and early winter. Regional differences in prevalence were not detected. None of these organisms show a characteristic pattern of clinical signs. This study demonstrates that enteric protozoal infection is common in domestic cats showing signs of alimentary disease.     

Prevalence and genotypes of Giardia duodenalis in dairy and beef cattle in farms around Charlottetown, Prince Edward Island, Canada

Prevalence of Giardia duodenalis in dairy and beef cattle on farms around Charlottetown, Prince Edward Island (Canada) was determined by analyzing feces using direct immunofluorescence antibody microscopy. Genotypes were determined by 16S-rRNA sequencing. Fecal samples (n = 892) were collected from adult cattle in dairy tie-stall, dairy free-stall, and beef herds (10 herds each), and from calves (n = 183) from 11 dairy farms. Prevalence rates were 38% and 51% in cows and calves, respectively. Giardia duodenalis was present in all dairy herds, in 9/10 beef herds and in calves from 10/11 herds examined. Prevalence rates were 40% and 41% for cows in tie- and free-stall herds, respectively, and 27% for beef cows. Zoonotic Assemblage A was found in 12.2% of calves concomitantly infected with Assemblage E. All successfully sequenced samples (114/128) from cows corresponded to Assemblage E. Giardia duodenalis is highly prevalent in cattle herds in Prince Edward Island and Assemblage A in calves is a potential public health concern.     

Prevalence of Cryptosporidium, Giardia and Eimeria infections in post-weaned and adult cattle on three Maryland farms

The prevalence of Cryptosporidium, Giardia and Eimeria, in healthy, asymptomatic, post-weaned and mature cattle was investigated on three Maryland farms. One farm, a dairy research facility, had 150 multiparous Holstein milking cows; 24 were examined and Cryptosporidium andersoni was detected in three (12.5%) but neither Giardia nor Eimeria was detected. The second farm, a commercial dairy, had 57 multiparous Holstein milking cows and an equal number of heifers. Of 19 cows examined, C. parvum, Giardia duodenalis, and Eimeria bovis and/or E. ellipsoidalis were detected in two (10.5%), two (10.5%) and one (5.26%) cow, respectively. Of 23 heifers examined, C. parvum, Giardia, and E. bovis and E. ellipsoidalis, was detected in two (8.7%), four (17.4%), and five (21.7%), heifers, respectively. The third farm, a beef cattle breeding and genetics research facility, had 180 7- to 9-month old purebred black Angus. Of 118 examined for C. parvum and Giardia, 34 (28.8%) and 44 (37.3%) were positive, respectively, of 97 examined for E. bovis and/or E. ellipsoidalis 32 (33.0%) were positive. These findings, based on a method with a minimum detection level of 100 oocysts of C. parvum/g of feces, which underestimates the number of infected cattle, clearly demonstrate the presence of low level, asymptomatic infections in post-weaned and adult cattle in the United States and indicate the potential role of such cattle as reservoirs of infectious parasites.     

Giardia duodenalis and Cryptosporidium spp. in a veterinary college bovine teaching herd

In a preliminary study, we commonly identified Giardia duodenalis in adult dairy cattle from a veterinary college teaching herd. Therefore, the present study was carried out in order to better understand the potential of adult cattle to act as a source for G. duodenalis infections for students and staff at the veterinary college. Fecal samples were collected bi-weekly from this herd of adult cattle (n=30) over an 8-month period to determine the prevalence of G. duodenalis and Cryptosporidium spp. within the herd. Nested PCR followed by DNA sequencing was then performed on a subset of positive samples in order to better understand the zoonotic potential of these infections. Every cow was sampled between 11 and 18 times, depending on the date the animal joined the teaching herd. In total, 507 fecal samples were collected from 30 different cows and examined for cysts and oocysts using epifluorescence microscopy. G. duodenalis prevalence during the course of the study ranged from 37% (11/30) to 64% (18/28), with a mean of 49%. Cumulative G. duodenalis prevalence was 73% (22/30). Zoonotic G. duodenalis assemblage A genotype was identified in 43% (6/14) of the G. duodenalis-positive samples on which PCR and genetic sequencing were successfully performed. G. duodenalis assemblage E was identified in 57% (8/14) of these samples. Cryptosporidium spp. oocysts were not detected in the feces of any cows during the study period. The presence of the zoonotic G. duodenalis assemblage A in 43% of the sequenced samples indicates that there is a potential risk of infection for students and staff at this research and teaching facility, although the roles of cows as sources of giardiasis in humans remain uncertain. Furthermore, due to the large amount of feces they produce, adult cattle may serve as important sources for G. duodenalis infections in young cattle, or other animals in the facility, despite relatively low numbers of cysts excreted per gram of feces. In contrast, the results of this study indicate that this herd posed a negligible risk of transmitting Cryptosporidium parvum infections to humans.     

Canine isosporosis - epidemiology of field and experimental infections

Isospora spp. are the causative agents of canine isosporosis. Of the 3590 diagnostic samples from Austrian dogs (< or = 2 years old), 8.7% contained Isospora oocysts, 78% of which from dogs up to 4 months of age. Non-haemorrhagic and haemorrhagic diarrhoea were significantly more prevalent in Isospora-infected animals than in coccidia-negative ones. Twelve of 15 litters from a large commercial dog breeding unit (examined from the third to the 10th week of life) also excreted Isospora (average prevalence: 36.4%) in intensities from 333 to 35,000 oocysts per gram of faeces (opg). In experimental trials 26 3-week-old Beagle puppies were infected with low (600-6000), medium (10,000) or high (20,000) dose of Isospora ohioensis-group or Isospora canis field isolates. Additionally 21 puppies were infected as above and treated with a symmetrical triazintrione. Parasitological and clinical parameters were examined. The two Isospora species differed significantly concerning intensity and duration of excretion. The pre-patent period was 6-7 days for I. ohioensis and 10-12 days for I. canis. The latter species showed significantly longer excretion and higher opg. This was not influenced by simultaneous infections with both species. Individual patterns of faecal consistency were very variable, irrespective of the infection dose. Treatment significantly reduced both the intensity and the duration of oocysts excretion as well as diarrhoea in comparison with the infected, untreated group and thus proved to be effective against coccidiosis in experimental infections.     

Prevalence and age-dependent occurrence of intestinal protozoan infections in suckling piglets

A cross-sectional survey was performed on 20 pig breeding farms in southern Hesse, central Germany, to evaluate the prevalence and age-dependent occurrence of intestinal protozoan parasites in unweaned piglets. Faecal samples of 514 clinically unaffected piglets of different age (< 1 to 5-7 weeks) were examined using the sodium acetate-acetic acid-formalin (SAF) concentration technique. Infections with the following protozoan species were detected: Balantidium coli (16 of 20 farms), Entamoeba sp. (15), Jodamoeba sp. (14), Isospora (I.) suis (9), Chilomastix sp. (6) and Eimeria spp. (6). The protozoan species differed in the start and course of (oo)cyst excretion. I. suis oocysts and Jodamoeba cysts were detected already in the first week of life whereas shedding of the other parasites started later on. The prevalence of Isospora oocyst excretion increased to a maximum (18%) in 2-3 weeks old animals followed by a sharp decline. The proportion of Balantidium, Entamoeba or Jodamoeba positive suckling piglets continously increased until the age of 5-7 weeks to 60%, 52% and 22%, respectively, whereas that of Chilomastix positive animals remained on a low level of 8-12% independent of the age. Eimeria oocysts were found transiently in the faeces of 1-4 weeks old piglets.     

Dynamics of Eimeria oocyst excretion in dairy calves in the Province of Buenos Aires (Argentina), during their first 2 months of age

Clinical coccidiosis is associated with high fecal contamination and stress situations, mainly in animals under 1 year of age. Artificially fed dairy calves are one of the categories most prone to suffer from this parasitic disease. The study was carried out in a commercial dairy farm. Feces samples of heifer calves between 2 and 8 weeks old were taken monthly for oocyst counts and Eimeria spp. identification. Of the 862 feces samples analyzed, 48% presented oocysts. When grouping the results of monthly samplings of each age group, it was observed that this percentage increased in the group of calves between 20 and 40 days of life, reaching the peak average of 85% of infection prevalence in the group with between 26 and 30 days of age. The discharge of oocysts observed between 21 and 35 days of age was superior to the rest (p<0.05). This trend appeared every month throughout the whole year. However, during March, April, June, September and November, the curves in the group categories were higher than in the remaining months (p<0.05). Twelve Eimeria species were identified, being E. ellipsoidalis, E. bovis, E. zuernii and E. auburnensis those in highest numbers. E. ellipsoidalis had an important predominance in the opg composition, >75% up to 25 days of life (p<0.05). E. bovis reached peak values in the 26 and 30 days group (p<0.05), remaining without significant variations in the last stage of the artificial milk feeding period (approximately 60 days of life), when the oocyst counts were significantly low. Oocysts of E. auburnensis appeared in great proportion (46%) in the cultures later than the previous species (p<0.05), in calves of the age groups of between 46 and 50 days of age. Oocysts of E. zuernii showed no trend associated with age. The highest prevalence of infection and of oocyst values appeared during the periods with better environmental conditions for sporulation, survival and dispersion of oocysts (spring and autumn), coincident with the highest birth rates and an elevated number of calves in the paddock. Calves developed a process of natural "vaccination" against coccidiosis. This was demonstrated by the decrease in the quantity of animals shedding oocysts and in the number of oocysts eliminated at the end of the artificial milk feeding period.     

陕西省某羊场简阳大耳山羊球虫感染情况调查及种类鉴定

为了解陕西省某简阳大耳山羊场球虫种类和感染情况,采集不同年龄段简阳大耳山羊新鲜粪便55份,用形态学方法并结合麦克马斯特虫卵计数法(McMaster's method)对该场简阳大耳山羊球虫进行种类鉴定和感染情况调查。结果表明,大耳山羊球虫总感染率为92.7%,其中3月龄~7月龄、10月龄~12月龄、3岁山羊球虫检出率分别为100%、90%和86.7%,各年龄段平均OPG值为3 300、1 050、854。共鉴定出8种山羊球虫,其中阿氏艾美耳球虫(Eimeria arloingi)、雅氏艾美耳球虫(E.ninakohlyakimovae)和艾氏艾美耳球虫(E.alijevi)为该羊场优势虫种。     

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.     

Giardia and Cryptosporidium in dairy calves in British Columbia.

A study was undertaken to determine the prevalence of Giardia infections in dairy calves and to compare Giardia and Cryptosporidium infections in calves of different ages. Fresh fecal samples were collected from 386 male and female Holstein calves (newborn to 24 wk) in 20 dairies located in the lower Fraser river valley area of British Columbia. Giardia intestinalis, Cryptosporidium parvum, and Cryptosporidium muris were enumerated in each sample after concentration by sucrose gradient centrifugation and immunofluorescent staining. Giardia was identified at all farm locations. The overall prevalence of Giardia in calves was 73% with a geometric mean cyst count of 1180 cysts per gram of feces (CI, 41 to 5014). Cryptosporidium parvum and C. muris were identified in 80% and 40% of the farms, respectively. The prevalence of C. parvum was 59%, and the geometric mean for oocysts was 457 oocysts per gram of feces (CI, 18 to 160). The prevalence of C. muris was only 2% and the mean oocyst counts were 54 oocysts per gram of feces. Giardiasis was not age dependent, and approximately 80% of the calves from 2 to 24 wk were infected. In contrast, C. parvum infections were predominant in calves 2 to 4 wk, while C. muris was demonstrated in calves older than 4 wk. Fourty-seven percent of calves with diarrhea had high numbers of Giardia cysts in their feces. Giardia infections are highly prevalent in dairy calves and should be considered in animals with diarrhea or failure to thrive.     

Internal parasites of Washington cattle.

The occurrence of internal parasites in Washinton cattle was estimated. During the survey period in 1972 and 1973, more than 3,700 fecal samples from 29 herds and 4 feedlots, and viscera from 55 cattle were examined. The percentage of fecal samples with parasite eggs or oocysts from herds was as follows: oocysts, 77%; "strongyline" eggs, 44%; Nematodirus eggs, 3%; Moniezia eggs, 3%; Fasciola eggs, 2%; Trichuris eggs, 2%; and Dictyocaulus larvae, 1%. The fecal samples from feedlots contained principally strongyline eggs which varied markedly in numbers among groups of cattle in the lots. The predominant parasite in viscera was Ostertagia spp, which was recovered from all of the cattle examined. Other parasites identified in the survey were found less frequently in these examinations. Cattle in dairy and beef operations utilizing irrigated pastures were particularly prone to Fasciola infections, and more strongyline eggs were observed there than in fecal samples from other management systems. Seasonal fluctuations in numbers of strongyline and Fasciola eggs were pronounced.