Prevalence of Giardia and Cryptosporidium in dairy calves in three areas of Norway

A study was undertaken to determine the prevalences of Cryptosporidium and Giardia in dairy calves less than 6 months of age in Norway. Faecal samples were collected from a total of 1386 calves, between 3 and 183 days of age, in 136 dairy farms from three different areas of Norway. Faecal samples were examined for Cryptosporidium oocysts and Giardia cysts after concentration and immunofluorescent staining.

Giardia was found in 93% (127 out of 136) of the farms and in 49% (679 out of 1386) of the calves. Cryptosporidium was found in 53% (72 out of 136) of the farms and in 12% (167 out of 1386) of the calves. The level of Giardia and/or Cryptosporidium was low in the majority of the infected calves.

Infection peaked in the age group 2–3 months for both Cryptosporidium and Giardia. The prevalences of both parasites were higher in samples taken during winter than in samples taken during summer, and statistically significant differences were found when prevalences in different age groups of calves were compared between the three areas. A significantly lower prevalence of Cryptosporidium was found in calves housed in shared pens that were thoroughly washed more than three times a year than in calves from pens washed less often. For Giardia there was a trend for decreasing intensity of infection with increasing age in the sampled calves. For Cryptosporidium there was a trend for increasing herd prevalence with increasing number of calves in the herd, but this trend was not statistically significant. Other parameters which were investigated such as housing, feeding or management routines were not associated with prevalence or intensity of infection with either parasite.     

Prevalence and first genetic identification of Cryptosporidium spp. in cattle in central Viet Nam

We investigated the prevalence of Cryptosporidium infection in relation to age and clinical status in cattle in the central region of Viet Nam. A total of 266 fecal samples from diarrheic and non-diarrheic cattle were examined by the modified Ziehl-Neelsen staining method. Prevalence of Cryptosporidium parvum type infections, those of the Cryptosporidium andersoni type, and mixed infection of both types was 33.5% (89/266), 5.6% (15/266), and 3.4% (9/266), respectively. The infection rate of 44.3% (35/79) of C. parvum in calves less than 6 months old was significantly higher than that of 28.9% (54/187) in cattle greater than 6 months old (P < 0.01). Although no C. andersoni oocysts were detected in calves less than 3 months old, no significant difference was observed between the age groups in the prevalence of C. andersoni infection and mixed infection. The percentage of diarrheic and non-diarrheic cattle identified to be shedding C. parvum oocysts was 46.5% (74/159) and 14.0% (15/107), respectively (P < 0.0001). The risk of diarrhea was 1.7 times greater in C. parvum-infected calves than in their non-infected counterparts. DNA sequences of 18S rRNA genes of C. parvum type and C. andersoni type indicated that they were C. parvum bovine genotype and C. andersoni, respectively. This is the first genetic identification of C. parvum bovine genotype and C. andersoni from cattle in Viet Nam.     

Study of virus excretion in feces of diarrheic and asymptomatic calves infected with rotavirus

Infection of calves by rotavirus could lead to diarrhea or subclinical disease. Therein, kinetic of viral excretion from a group of asymptomatic calves, previously exposed to a virulent strain of rotavirus, is compared to that of a group the calves of which had diarrhea associated with rotavirus infection. As determined by an enzyme-linked immunosorbent assay (ELISA), duration of rotavirus shedding in feces and maximum yield of virus antigen were similar within the two groups of calves. Rotaviruses isolated from the two above groups of animals were antigenically related as shown by neutralization tests, and showed a similar RNA electrophoretic profile. In conclusion, it is likely that both asymptomatic and diarrheic calves infected by rotavirus are equally a major source of contamination to contact healthy calves.     

Prevalence and molecular characterization of Giardia duodenalis and Cryptosporidium spp. in dairy cattle in Ontario, Canada

Giardia duodenalis and Cryptosporidium spp. are intestinal protozoan parasites that infect a wide range of host species, including humans. Molecular characterization of these parasites has demonstrated that a number of genotypes and species are common to both humans and animals, and that zoonotic transmission may occur. Numerous studies have reported a high prevalence of G. duodenalis and Cryptosporidium spp. in cattle, particularly calves, and these animals are frequently associated with zoonotic transmission. In the present study, a total of 143 faecal samples from adults, heifers and calves were collected from two dairy cattle farms in eastern Ontario, Canada. The prevalence and molecular characteristics of G. duodenalis and Cryptosporidium spp. in these animals were determined in order to investigate the potential for transmission between cattle and humans in this region. Following DNA extractions from faecal samples, nested-PCR protocols were used to amplify fragments of the 16S rRNA gene and the heat-shock protein 70 (HSP-70) gene for determining the prevalence of G. duodenalis and Cryptosporidium spp. infections, respectively. Genotypes of G. duodenalis, and species of Cryptosporidium, were determined by means of DNA sequencing of amplicons, and subsequent sequence alignment. Cattle on both farms showed a high prevalence of G. duodenalis (42.0%) and Cryptosporidium spp. (27.3%). G. duodenalis infections were more prevalent in calves and heifers than in adults, and Cryptosporidium spp. infections were only observed in calves and heifers. The zoonotic genotype, G. duodenalis Assemblage B was isolated from 24.5% of the cattle tested, while G. duodenalis Assemblage E was found in 17.5% of the cattle tested. The overall prevalence of the zoonotic species Cryptosporidium parvum in the animals tested was found to be 21.7%, while only 1.4% were infected with C. bovis. These findings suggest that there is a potential risk of zoonotic and/or zooanthroponotic transmission of G. duodenalis and C. parvum infections between cattle and humans in eastern Ontario, likely by means of contaminated water or food, or through direct faecal-oral transmission in the case of farmers and veterinary staff.     

Rotavirus and concurrent infections with other enteropathogens in neonatal diarrheic dairy calves in Spain

Faeces samples from 218, one to 30 days old, diarrheic dairy calves in 65 dairy herds were screened for the presence of rotavirus and concurrent infections with coronavirus, Cryptosporidium, F5+ Escherichia coli and Salmonella spp. Calves were grouped according to their age as follows: 1-7, 8-14, 15-21 and 22-30 days. Rotavirus infection was detected in 46.9%, 45.6%, 33.8% and 48.3% of the calves in the respective age-groups. No significant differences in the detection rate of rotavirus were found among calves on the different age-groups. Rotavirus was the only enteropathogen detected in 39 of the 93 (41.9%) diarrheic calves positive to this agent. Concurrent infections with other enteropathogen(s) were detected in 31.3%, 33.3%, 20.6% and 3.4% of the rotavirus infected calves in the age-groups 1-7, 8-14, 15-21 and 22-30 d, respectively. A significant age-associated decrease in the detection rate of mixed infections (p < 0.01) was found. The detection rates of the other enteropathogens considered in calves with rotavirus infection were 20.4% for coronavirus, 85.2% for Cryptosporidium, 16.7% for F5+ E. coli and 1.8% for Salmonella.     

Determination of lactose and xylose malabsorption in preruminant diarrheic calves.

In preliminary studies feeding the poorly absorbed carbohydrate sorbitol at 2.3 g/kg body weight as an indication of maximal fermentative capacity failed to produce the expected large increase in breath hydrogen excretion but did produce a transient diarrhea in five out of six control calves. Twelve healthy control and eighteen diarrheic calves were fed lactose or D-xylose on consecutive days at 1.15 g/kg body weight and a concentration of 46 g/L. Breath and blood samples were collected at 1 h intervals from 0 to 7 h. After administration of lactose, there was a significant increase in breath hydrogen excretion in diarrheic versus control calves. The increase in plasma glucose concentrations was delayed in diarrheic calves but the area under the absorption curve was similar in control and diarrheic calves. After administration of D-xylose, breath hydrogen excretion did not increase significantly but plasma D-xylose concentrations were significantly reduced in diarrheic calves. The pathogens commonly isolated from the feces were Cryptosporidium species, rotavirus and coronavirus. The number of pathogens and the severity of the calves' acid-base deficit were not related to the severity of carbohydrate malabsorption. Decreased absorption of lactose and D-xylose may be the result of intestinal villous atrophy caused by viral or parasite infection. It was concluded that carbohydrate malabsorption rather than a specific lactose maldigestion is a significant problem in diarrheic calves. Diarrheic calves appear to digest and absorb lactose when fed in small amounts.     

Protection of colostral antibodies against bovine leukemia virus infection in calves on a California dairy.

A three-year prospective study involving 244 calves was undertaken on a California dairy to evaluate the protective role of colostral antibodies against bovine leukemia virus (BLV) infection in calves. Calves were followed from birth to the time they left their individual hutch (TLIH), at about 90 days of age. The probability of being infected at TLIH and the daily risk of infection between birth and TLIH were modelled using the logistic and the Cox models, respectively. Calves with no detectable antibodies during the first week of life were up to 2.00 and 2.75 times more likely to be infected at TLIH compared to calves with low and high concentrations of antibodies during the first week of life, respectively (p = 0.01). When the daily risk was modelled, calves without antibodies at the estimated day of infection were up to 3.4 and 11.6 times more likely to become infected than calves with low and high concentrations of antibodies on that day, respectively (p less than 0.001). Results indicated that calfhood infection may be reduced by about 45% through the feeding of colostrum with BLV antibodies. Further reduction in infection may be possible by feeding calves milk powder, milk replacer, and/or milk from noninfected cows. Results also indicated that quantification of the effect of a time-dependent risk factor, such as colostral antibody concentration, might be affected if treated as a fixed factor.     

The efficacy of colostrum from cows vaccinated with rotavirus in protecting calves to experimentally induced rotavirus infection

Calves which were continuously fed colostrum from vaccinated cows for the first ten days of life, were fully refractory to experimental infection with strain 81/36 F of bovine rotavirus. By contrast, the response to virus exposure of calves which were treated with normal colostrum was identical to that of the control calves, in that they underwent severe diarrhea and a significant slowing of the growth rate. The antibody titer in the milk of vaccinated cows tends to decline rapidly so that it no longer provides any protective effect. Two alternatives were considered feasible in improving prophylaxis for rotavirus infections: (a) the continuous feeding of calves with 1st day colostrum as part of the ration throughout the period of greatest risk (first week of life), or (b) enhancing the efficacy of the vaccine in pregnant cows to the point where antibody concentration in the milk would remain at a protective level.     

Prevalence of serotypes G6 and G10 group A rotaviruses in dairy calves in Quebec.

Fecal samples from diarrheic and nondiarrheic dairy calves (1 to 3 weeks old) from 12 regions of Quebec, collected between 1992 and 1994, were screened for group A bovine rotavirus (BRV) using a combination of 2 VP6-specific monoclonal antibodies (MAbs) in an enzyme-linked immunosorbent assay (ELISA). The overall prevalence of BRV infection was 26.4% (107/405). In diarrheic calves, BRV infection reached 74.3% (55/74), but only 15.7% (52/331) in nondiarrheic calves. BRV-positive samples were serotyped by enzyme-linked immunosorbent assay (ELISA) using G6 and G10 specific MAbs. The analysis of 107 field samples revealed that, in diarrheic calves, 34.5% (19/55) were G6, 27.2% (15/55) were G10, 9% (5/55) were G6 and G10 positive, and 29.9% (16/55) were G6 and G10 negative. In nondiarrheic calves, 19.2% (10/52) were G6, 19.2% (10/52) were G10, 7.6% (4/52) were G6 and G10 positive, and 53.6% (28/52) were G6 and G10 negative. Rotavirus dsRNA was extracted from BRV-positive samples and examined by polyacrilamide gel electrophoresis (PAGE). Of 107 samples tested, 74 (69.1%) were positive, and all the samples demonstrated a typical group A rotavirus migration pattern.     

A study on neonatal calf diarrhea induced by rotavirus

This review summarizes the results of a study on rotaviruses isolated from calves affected by neonatal diarrhea.

The results indicated that rotavirus infection is widespread and supported the evidence for an etiologic role of these viruses in neonatal diarrhea. Differences in virulence among bovine rotaviruses appeared also to be confirmed.

Conventionally reared calves were fully susceptible to the experimental infection induced by rotaviruses originating from heterologous hosts, i.e. monkeys, pigs and rabbits.

When rotavirus strains of bovine, simian and rabbit origin were compared by cross neutralization tests, it was found the simian and porcine strains were indistinguishable and both appeared to relate antigenically to the bovine strain.

Finally, it was proven that feeding newborn calves with colostrum and first milk of their dams, previously vaccinated with an inactivated adjuvanted rotavirus vaccine, could prevent the neonatal diarrhea from occurring.     

Isolation of bovine coronavirus from feces and nasal swabs of calves with diarrhea.

Fecal and nasal samples were collected from 180 calves with diarrhea and 36 clinically normal co-habitants, and tested for virus using HRT-18 cell cultures derived from human rectal adenocarcinoma. A cytopathic virus was isolated from 5 fecal and 56 nasal samples obtained from diarrheic calves. All calves in which the virus was isolated from diarrheic feces were positive for virus isolation from nasal swabs. The virus was also isolated from the nasal swabs of 10 clinically normal calves that were co-habitants with diarrheic calves. Because they were morphologically similar to coronavirus, agglutinated mouse erythrocytes and serologically identical with the Nebraska calf diarrhea coronavirus, new isolates were identified as bovine coronavirus. The demonstration of viral antigens in nasal epithelial cells by a direct immunofluorescence was in close agreement with the virus isolation in HRT-18 cell cultures. This is the first report on the isolation of bovine coronavirus from newborn calves with diarrhea in Japan. The evidence that the virus was frequently isolated from nasal swabs is of great interest for understanding the pathogenesis of bovine coronavirus infection.     

Prevalence of Cryptosporidium spp. oocysts in cattle and wildlife in Morogoro region, Tanzania

Prevalences of Cryptosporidium spp. oocysts in cattle (n = 486) on five selected farms in Morogoro municipality and three species of herbivorous wildlife (n = 87) from Mikumi National Park, Morogoro, Tanzania, were determined using the modified Ziehl-Neelsen staining technique. Of 486 bovine faecal samples, 5.3% were positive for Cryptosporidium spp. The prevalence of Cryptosporidium was higher in calves less than 3 months of age compared to weaned calves and adults. Cryptosporidium spp. oocysts were detected in both diarrhoeic and non-diarrhoeic animals, but there was a significantly higher prevalence (P < 0.001) of oocyst shedding in diarrhoeic than in non-diarrhoeic animals. Of the 87 faecal specimens from the wildlife species, 36 were from the African buffaloes (Syncerus caffer), 25 from zebra (Equus zebra) and 26 from the wildebeest (Connochaetes gnou). Cryptosporidium spp. oocysts were detected in eight (22%) buffaloes, seven (28%) zebras and seven (27%) wildebeests. Confirmation of the diagnosis was performed using anti-Cryptosporidium monoclonal antibody specific for Cryptosporidium muris, Cryptosporidium parvum and Cryptosporidium baileyi (Pathasure Cryptosporidium test kit).     

Ultrasonographic imaging of abomasal milk clotting and abomasal diameter in healthy and diarrheic calves

In case of diarrhea calves are treated with oral rehydration solutions (ORS), which are known to increase abomasal pH and inhibit milk clotting in vitro. Nevertheless, recent studies have shown that ORS with HCO₃^‐ ≤ 62 mmol/L do not interfere with abomasal milk clotting in healthy calves. However, in diarrheic calves, feeding ORS and milk simultaneously may disturb abomasal curd formation and exacerbate diarrhea due to faster abomasal passage of ingesta. Therefore, the aim of the present study was to ultrasonographically examine abomasal milk clotting and diameter after feeding milk and milk replacer (MR) with and without ORS to healthy and diarrheic calves. Abomasal curd formation and diameter in healthy and diarrheic calves were ultrasonographically imaged before and after feeding milk, MR and ORS prepared in milk or MR. Feeding mixtures of milk or MR with ORS did not cause any remarkable differences in the ultrasonographic images of abomasal content. Moreover, abomasal milk clotting was not disturbed due to diarrhea. Statistically significant differences of abomasal diameter after feeding between healthy and diarrheic calves indicated that abomasal emptying is delayed in diarrheic calves. Hence, further studies are needed to determine reasons for decelerated abomasal passage in calves suffering from diarrhea.     

Indigestion in Young Calves VI: Studies of Diarrheic Calves Fed Milk Replacers Made of Normal and Heat-Treated Skim Milk and whey Powder

Diarrhea occurred in 12 pre-ruminant calves after the introduction of milk replacers. Six of the calves were fed a replacer made of normally treated skim milk and whey powder, while the other 6 got a replacer made of heat-treated powders, although otherwise similar to that of the first group. Abomasal curd formation was deficient in calves fed for 9 or 17 days on the heat-treated replacer (4 of 6 calves). Otherwise, no clear differences between the calves given normally treated and heat-treated replacer occurred, as regards diarrhea, bacteriological, virological, and pathomorphological findings in the intestinal tract. Rotavirus and chlamydial infections were indicated and considered as the major cause of the diarrheic condition, although bacteria, including coliforms and Pseudomonas aeruginosa, may have contributed. The milk replacers may have been involved was provoking factors.Key words: heat-treatment, skim milk, whey, diarrhea, curd formation, intestinal microflora, rotavirus, chlamydia, calves     

Comparison of blood electrolyte and biochemical parameters between single infections of rotavirus and Cryptosporidium parvum in diarrheic Hanwoo calves

BackgroundNeonatal calf diarrhea is a major problem in the cattle industry worldwide. Rotavirus and Cryptosporidium parvum are the primary causative agents, especially during the first three weeks of the calf’s life.ObjectivesThis study investigated the differences in acid-base, electrolytes, and biochemical parameters of diarrheic calves with infection of either rotavirus or C. parvum.MethodsA total of 61 Korean native calves (≤ 20 days old) were divided into two groups based on rotavirus or C. parvum infections: rotavirus infection (n = 44) and C. parvum infection (n = 17). The calves with at a specific blood pH range (pH 6.92–7.25) were chosen for comparison. The acid-base, electrolyte, chemistry, and serum proteins were analyzed, Further, fecal examinations were performed.ResultsCompared to C. parvum-infected calves, the rotavirus-infected calves showed lower levels of total carbon dioxide, bicarbonate (HCO₃ ⁻), anion gap, total protein, and albumin/globulin ratio, and significantly lower levels of potassium, globulin, and α2-globulin (p < 0.05). The C. parvum-infected calves (r = 0.749) had stronger correlations between pH and HCO₃ ⁻ than the rotavirus-infected calves (r = 0.598). Compared to rotavirus-infected calves, strong correlations between globulin and α2-globulin, α2-globulin and haptoglobin were identified in C. parvum-infected calves.ConclusionsThis study is the first to investigate acid-base, electrolyte, and biochemical parameters in calves in response to infections of rotavirus and C. parvum. Although rotavirus and C. parvum cause malabsorptive and secretory diarrhea in similar-aged calves, blood parameters were different. This would help establish the diagnostic and treatment strategies.     

河北省唐山市奶犊牛病毒性腹泻流行病学调查

试验旨在掌握河北省唐山市13个县（市、区）奶牛场奶犊牛病毒性腹泻病原的流行状况,有效防控奶犊牛腹泻。采集唐山市不同地区38个奶牛场腹泻犊牛粪便样品788份,提取腹泻粪便样品中的基因组RNA。根据GenBank公布的牛病毒性腹泻病毒（Bovine viral diarrhea virus,BVDV）E2基因、牛轮状病毒（Bovine rotavirus,BRV）VP6基因、牛冠状病毒（Bovine coronavirus,BCV）N基因序列,利用Primer Premier 5.0软件分别设计特异性引物,采用PCR方法检测粪便样品中这3种基因,利用Excel 2007对不同地区、不同季节和混合感染病原检测结果进行汇总分析。在采样范围内的788份犊牛腹泻粪便样品中,BVDV、BRV和BCV阳性检出率分别为29.82%（235/788）、29.44%（232/788）和18.02%（142/788）;在所有被检地区,滦南县BVDV感染率最高,阳性检出率为45.38%（59/130）,汉沽区BRV和BCV感染率最高,阳性检出率分别为55.00%（22/40）和37.50%（15/40）;从采样季节来看,春季、夏季和秋季BRV感染率最高,阳性检出率分别为27.71%（46/166）、39.58%（114/288）和19.89%（39/196）,冬季则以BVDV感染为主,阳性检出率为52.17%（72/138）;从混合感染情况来看,以BRV＋BCV二重混合感染为主,感染率为8.37%（66/788）。河北省唐山市各地区腹泻犊牛群中均存在BVDV、BRV和BCV感染,以BVDV、BRV单一感染为主。     

A possible role for Clostridium difficile in the etiology of calf enteritis

Clostridium difficile was investigated as a possible cause of enteritis in calves. The organism and its toxins (TcdA and TcdB), respectively, were found in 25.3% and 22.9% of stool samples from diarrheic calves. Culture positive samples were more likely than culture negative samples to be toxin positive. However, toxin positive stools were more common among nondiarrheic calves, but diarrheic calves were nearly twice as likely to be culture positive. Ribotype 078 was dominant among isolates. Salmonella sp. was isolated from both diarrheic and nondiarrheic calves, but large numbers of E. coli were found more commonly in diarrheic calves than in nondiarrheic animals. Prevalence rates for coronavirus and Cryptosporidium sp. were substantially higher in nondiarrheic calves than in diarrheic, but rates of detection of rotavirus and Giardia sp. were more nearly equal between groups. Lesions in naturally infected calves included superficial mucosal erosion with associated fibrinous exudates. Neutrophils and eosinophils infiltrated lamina propria. Large Gram-positive rods morphologically compatible with C. difficile were abundant in the colonic lumen and the organism was isolated by bacteriologic culture. Toxins were found throughout the colon. Purified toxins A and B (individually and conjointly) caused comparable lesions, as well as fluid accumulation, in ligated intestinal loops. Our findings are in substantial agreement with those of others [Rodriguez-Palacios, A., Stampfli, H.R., Duffield, T., Peregrine, A.S., Trotz-Williams, L.A., Arroyo, L.G., Brazier, J.S., Weese, J.S., 2006. Clostridium difficile PCR ribotypes in calves, Canada. Emerg. Infect. Dis. 12, 1730-1736; Porter, M.C., Reggiardo, C., Bueschel, D.M., Keel, M.K., Songer, J.G., 2002. Association of Clostridium difficile with bovine neonatal diarrhea. Proc. 45th Ann. Mtg. Amer. Assoc. Vet. Lab. Diagn., St. Louis, MO, U.S.A.] and add strength to a working hypothesis that C. difficile infection and the accompanying intoxication can manifest as diarrhea in calves. It seems clear that calves serve as multiplying hosts for this organism.     

Effects of microbial and host variables on the interaction of rotavirus and Escherichia coli infections in gnotobiotic calves

Naturally occurring mixed infections with Escherichia coli and rotavirus have been associated with fatal diarrhea of calves about 1 week old. Experiments were designed to reproduce this syndrome in gnotobiotic calves. Clinical, microbiological, and pathologic data were used to assess severity of disease and mechanisms of the interaction between the 2 infections. An initial study involved 5- to 8-day-old gnotobiotic calves inoculated with a strain of enterotoxigenic E coli (ETEC) and a strain of rotavirus. Calves were observed for 2 days after they were inoculated; fatal diarrhea was not produced. In later studies, variables were tested to identify those that might contribute to fatal diarrhea. Variables which did not result in fatal or severe diarrhea or which did not cause disease that was more severe in dually inoculated calves than that in monoinoculated calves were increasing feed to 2 times base line, increasing dose of ETEC to 10 times base line, inoculating calves when they were 2 days old, using a strain of E coli that causes colisepticemia, and using a different strain of rotavirus. When the observation period was extended from 2 days to 6 days after calves were inoculated, severe, watery, fatal diarrhea occurred in 6 of 12 calves by 32 to 72 hours after dual inoculation was given. Fatal diarrhea was associated with intensive colonization by the ETEC in the caudal half of the small intestine. Microscopic lesions were similar between dually inoculated and rotavirus-monoinoculated calves, except there was more severe atrophy of ileal villi of dually inoculated calves.(ABSTRACT TRUNCATED AT 250 WORDS)     

Occurrence and characteristics of enterohemorrhagic Escherichia coli O26 and O111 in calves associated with diarrhea

The aims of this study were: (1) to examine whether or not enterohemorrhagic Escherichia coli O26 and O111 (EHEC O26 and O111) are involved in neonatal calf diarrhea; (2) to determine the specific age periods at which the calves are vulnerable to these organisms, and (3) to reveal the biochemical, genetic and cytotoxic characteristics of the isolates. The study investigated the occurrence of EHEC O26 and O111 in calves associated with or without diarrhea. A total of 442 diarrheic and non-diarrheic young calves from 115 different farms were examined. Of the 257 calves with diarrhea, 37 (14.4%) and 32 (12.5%) tested positive for EHEC O26 and EHEC O111, respectively. Of the 185 non-diarrheic calves, 14 (7.6%) and 11 (5.9%) tested positive for EHEC O26 and EHEC O111, respectively. EHEC O26 and O111 were recovered from 14/69 (20%) and 11/69 (16%) diarrheic calves <2-weeks-old, respectively, and no EHEC O26 and O111 were detected in the non-diarrheic claves of this age group, suggesting that EHEC O26 and O111 are possible causes of the disease in infected neonatal calves. However, there were similar rates of occurrence in the diarrheic and non-diarrheic calves in the older animals (particularly, aged >10 weeks). PCR analysis showed that the isolates carried various virulence genes such as Ehly, eae, stx1 and stx2, which highlight the potential importance of these attributes for the infection, colonization and the possible pathogenesis of calf diarrhea. Cytotoxicity analysis revealed that many of the EHEC isolates showed high cytotoxicity to Vero cells, re-emphasizing the potential for cattle being a direct source of EHEC infections in humans.     

Bovine cryptosporidiosis in Denmark. 2. Cryptosporidia associated with neonatal calf diarrhea

In recent years cryptosporidia have often been identified in diarrheic calves of under one month old, either as the sole pathogenic agent or in combination with other diarrhea-causing infectious agents. In 203 cases of bovine cryptosporidiosis, recorded over a period of two years, cryptosporidia were present in such great numbers that they would seem to be of causal significance. The calves were from three days to five weeks old. In 111 cases (55%) a monoinfection with cryptosporidia occurred, while in the rest of the cases mixed infections with other agents associated with calf diarrhea were demonstrated, especially rotavirus (61 cases) and coronavirus (32 cases); in addition, mixed infections with ETEC (four cases), septicaemic E. coli (two cases), salmonellosis (11 cases), and BVD and coccidiosis (one case each) were seen. In 87 (10%) of 849 4-21-day-old dead calves a massive occurrence of cryptosporidia was demonstrated. Extreme emaciation was noted in 36 of 122 autopsied calves. Most of these calves were more than 14 days old, and mono-infection with cryptosporidia was demonstrated in two thirds of them. In younger calves, more acute cases of cryptosporidiosis were commoner, often in connection with concomitant infections with rota- or coronavirus.