Group A rotavirus as a cause of neonatal calf enteritis in Sweden

Effects of level of social contact on dairy calf behavior and health

Housing preweaned dairy calves in pairs rather than individually has been found to positively affect behavioral responses in novel social and environmental situations, but concerns have been raised that close contact among very young animals may impair their health. In previous studies, the level of social contact permitted in individual housing has been auditory, visual, or physical contact. It is unclear how these various levels of social contact compare with each other and to pair housing, when their effects on behavior and health are considered, and whether the timing of pair housing has an effect. To investigate this, 110 Holstein calves (50 males, 60 females) in 11 blocks were paired according to birth date. Within 60 h of birth, each pair of calves was allocated to 1 of 5 treatments: individual housing with auditory contact (I), individual housing with auditory and visual contact (V), individual housing with auditory, visual, and tactile contact (T), pair housing (P), or individual housing with auditory and visual contact the first 2 wk followed by pair housing (VP). At 6 wk of age, calves were subjected to a social test and a novel environment test. In the social test, all pair-housed calves (P and VP) had a shorter latency to sniff an unfamiliar calf than did individually housed calves (I, V, and T), whereas calves with physical contact (T, P, and VP) sniffed the unfamiliar calf for longer than calves on the remaining treatments (I and V). In the novel environment test, calves with physical contact (T, P, and VP) had a lower heart rate, and more of these calves vocalized during the test compared with calves without physical contact (I and V). No effect of treatment was found for clinical scores, levels of the 5 most common pathogens in feces, or in development of serum antibodies against the 3 most common respiratory pathogens. Calves housed individually are more fearful of unfamiliar calves than are pair-housed calves. Contrary to common belief, the allowance of physical contact and pair housing had no effects on the health of the calves.

Antimicrobial resistance and virulence factors in Escherichia coli from Swedish dairy calves

Background

In Sweden, knowledge about the role of enteropathogenic Escherichia coli in neonatal calf diarrhea and the occurrence of antimicrobial resistance in E. coli from young calves is largely unknown. This has therapeutic concern and such knowledge is also required for prudent use of antimicrobials.

Methods

In a case control study Esherichia coli isolated from faecal samples from dairy calves were phenotyped by biochemical fingerprinting and analyzed for virulence genes by PCR. Antimicrobial susceptibility was tested by determination of minimum inhibitory concentration (MIC). Farm management data were collected and Fisher's exact test and univariable and multivariable logistic regression analysis were performed.

Results

Of 95 E. coli tested for antimicrobial susceptibility 61% were resistant to one or more substances and 28% were multi-resistant. The virulence gene F5 (K99) was not found in any isolate. In total, 21 out of 40 of the investigated virulence genes were not detected or rarely detected. The virulence genes espP, irp, and fyuA were more common in resistant E. coli than in fully susceptible isolates (P < 0.05). The virulence gene terZ was associated with calf diarrhea (P ≤ 0.01).

The participating 85 herds had a median herd size of 80 lactating cows. Herds with calf diarrhea problems were larger (> 55 cows; P < 0.001), had higher calf mortality (P ≤ 0.01) and calf group feeders were more in use (P < 0.05), compared to herds without calf diarrhea problems.

There was no association between calf diarrhea and diversity of enteric E. coli.

Conclusions

Antimicrobial resistance was common in E. coli from pre-weaned dairy calves, occurring particularly in calves from herds experiencing calf diarrhea problems. The results indicate that more factors than use of antimicrobials influence the epidemiology of resistant E. coli.

Enteropathogenic E. coli seems to be an uncommon cause of neonatal calf diarrhea in Swedish dairy herds. In practice, calf diarrhea should be regarded holistically in a context of infectious agents, calf immunity, management practices etc. We therefore advice against routine antimicrobial treatment and recommend that bacteriological cultures, followed by testing for antimicrobial susceptibility and for virulence factors, are used to guide decisions on such treatment.

Rotavírus bovino: fatores de risco, prevalência e caracterização antigênica de amostras em rebanhos leiteiros no estado de São Paulo

O estudo de prevalência da infecção por rotavírus em bezerros abrangeu 51 rebanhos leiteiros, escolhidos ao acaso, localizados em uma região produtora de leite do estado de São Paulo. Entre 31 de maio e 20 de outubro de 2003, foram colhidas 103 amostras de fezes de bezerros com diarreia e 308 amostras de animais sem diarreia, com idade entre um e 45 dias. As amostras foram analisadas pelas técnicas de ensaio imunoenzimático (EIE) e eletroforese em gel de poliacrilamida (PAGE). Pelo EIE foi observada prevalência de rotavírus de 21,6% (11/51) nos rebanhos e 6,7% (27/404) nos bezerros. Foram diagnosticados animais infectados por rotavírus tanto em bezerros diarreicos (18,4%; 19/103) quanto em bezerros assintomáticos (2,7%; 8/301). A maior frequência de infecção foi determinada em bezerros com idade entre um e 15 dias, sendo estabelecida uma relação inversa entre a frequência de positividade e a idade dos animais (P<0,05). Além da idade, o sistema de alimentação - fornecimento manual do leite ou bezerro com a mãe, o tipo de instalação - baias individuais ou baias coletivas - e o tamanho do rebanho -, número de matrizes foram fatores que influenciaram significativamente a frequência da infecção (P<0,05). O RNA extraído de 27 amostras pelo PAGE foi classificado em sete eletroferótipos, indicando grande diversidade genômica de rotavírus. A genotipagem das amostras positivas para rotavírus foi realizada pelo método de transcrição reversa-reação da polimerase em cadeia, destacando a presença de infecções pelos genótipos G6P[5] e G10P[11].

Cryptosporidium infection in herds with and without calf diarrhoeal problems

A case-control study was designed to investigate the role of different Cryptosporidium spp. in Swedish dairy herds with and without calf diarrhoeal problems. Faecal samples were collected from preweaned calves, young stock and cows. Cryptosporidium oocysts were detected by sodium chloride flotation and epifluorescence microscopy. Molecular diagnostics were used to identify Cryptosporidium species. Samples containing C. parvum were further analysed to determine subtypes. Calf faecal samples were also analysed for rotavirus, coronavirus and Escherichia coli F5+. Total protein was assessed in 1- to 8-day-old calves. A questionnaire was used to identify differences in management routines. Cryptosporidium infection was diagnosed in all herds, with equal prevalence in case and control herds in all three age groups. Cryptosporidium parvum, Cryptosporidium bovis, Cryptosporidium ryanae and Cryptosporidium andersoni were all identified, as were rotavirus, coronavirus and E. coli F5+. C. ryanae and C. andersoni were only detected in non-diarrhoeal samples, whereas the other pathogens were detected in both diarrhoeal and non-diarrhoeal samples. Diarrhoea was more common in case herd calves. Disinfection of single pens was more common in case herds and several other management routines seemed to differ although results were not significant.

OCORRÊNCIA DOS GENÓTIPOS G E P DE ROTAVÍRUS DO GRUPO A EM BEZERROS DE REBANHOS DE CORTE NO ESTADO DE SÃO PAULO, BRASIL

RESUMO Foi determinada a ocorrência de rotavírus do grupo A e a caracterização molecular G e P de estirpes detectadas em bezerros de rebanhos de corte em propriedades rurais do Estado de São Paulo, Brasil. Foram analisadas amostras de fezes de 649 bezerros de 14 rebanhos de corte com idade entre 1 e 60 dias, independentemente da manifestação clínica de diarréia, colhidas de julho de 2003 a julho de 2004. Por meio das técnicas de ELISA e de eletroforese em gel de poliacrilamida (PAGE), determinou-se a ocorrência de rotavírus do grupo A em 64,3% (09/14) dos rebanhos e em 6,2% (40/649) dos animais. A maior freqüência de infecção foi detectada em animais com idade entre 16 e 30 dias (10,5%). Foram diagnosticados bezerros infectados por rotavírus tanto em animais com sinais clínicos de diarréia (25,8%; 22/85) quanto naqueles assintomáticos (3,2%; 18/ 564), existindo, porém, uma correlação entre a presença da infecção e a manifestação clínica da diarréia (p < 0,01). A análise do perfil do genoma do rotavírus por PAGE identificou sete eletroferótipos distintos, indicando grande diversidade genômica dos rotavírus na região estudada. A genotipagem pela reação em cadeia da polimerase (RT-PCR) das amostras de rotavírus revelou que as estirpes circulantes nos rebanhos eram G6P[5], G6P[11], G6P[5]P[11] e G10P[11].

Rotavirus diarrhea in bovines and other domestic animals

Rotavirus diarrhea is the major cause of death of millions of children in developing countries besides causing economically significant malady in neonates of many domestic animals. In neonates, the infection is non-viremic, have very short incubation period, and manifests profuse diarrhea and severe dehydration. Concurrent infection with secondary pathogens may augment the disease severity. Diarrhea occurs due to virus-mediated destruction of absorption efficient enterocytes, activation of enteric nervous system, or due to a rotavirus enterotoxin. Diagnosis of the infection relies on conventional techniques like isolation in MA 104 cell lines, electron microscopy, electro-pherotyping, and various serological tests. Presently, diagnosis and molecular typing is performed using serotype specific RT-PCR, sequencing or genomic hybridization techniques. As the rotaviruses are known to exhibit extreme genetic diversity and outplay disinfection procedures, eradication of the pathogen is often difficult. Hence, for prevention, good management practices coupled with vaccination of dam for protecting young ones, has to be practiced. Recently, new generation prophylactic strategies including DNA vaccines, subunit vaccines, virus-like particles (VLPs) and edible vaccines have been found to induce sufficient levels of passive immunity. Aside to the infection in animals, zoonotic significance of the animal rotaviruses has to be further unearthed. In this review, efforts have been made to highlight the importance and prevalence of the disease in bovines, its pathogenesis along with preventive measures, salient features of rotaviruses and their inter-species transmission abilities, zoonotic implications, and a concise account of the infection in various domestic animals and poultry.

The studies on the aetiology of diarrhoea in neonatal calves and determination of virulence gene markers of Escherichia coli strains by multiplex PCR

The purpose of this study was to determine aetiological agents of diarrhoea in neonatal calves and to investigate virulence gene markers of Escherichia coli strains isolated from calves by multiplex polymerase chain reaction (PCR). Eighty‐two diarrhoeic calves and 18 healthy calves were used as subjects. Faeces were taken from the rectums of all the calves and were subjected to bacterial culture. Antigen enzyme‐linked immunosorbent assay (ELISA) was performed to detect rotavirus, coronavirus and E. coli K99 in faeces of all the calves. A multiplex PCR was used to characterize E. coli strains in all the calves. Escherichia coli was isolated from 37 faeces samples, Enterococcus ssp. was isolated from 22 faeces samples and Salmonella was isolated from one faeces sample in diarrhoeic calves. Furthermore, only E. coli was isolated from all 18 faeces samples of healthy calves. Of the 37 E. coli isolated from diarrhoeic calves, K99 (18.9%), F41 (18.9%), heat‐stable enterotoxin a (STa) (18.9%), Shiga toxin 1 (Stx1; 13.5%) and Shiga toxin 2 (Stx2; 5.4%) and intimin (8.1%) genes were identified by multiplex PCR. Of the 18 E. coli isolated from healthy calves, K99 (16.6%) and intimin (55.5%) genes were identified by PCR. A total of 15 rotavirus, 11 coronavirus and 11 E. coli K99 were detected in diarrhoeic calves by the antigen ELISA. As a result, this study shows that rotavirus, coronavirus, E. coli and Enterococcus ssp. were determined to play a role in the aetiology of diarrhoea in the neonatal calves. K99, F41, STa, Stx1 and Stx2 were found as the most common virulence gene markers of E. coli strains isolated from calves with diarrhoea. Multiplex PCR may be useful for characterization of E. coli isolated from calves.

Use of antimicrobial drugs in Swedish dairy calves and replacement heifers

A total of 3081 heifer calves in 122 Swedish dairy herds were monitored from birth to first calving, and all their diseases and treatments were recorded. There were 1268 cases of infectious diseases, of which 335 (26.4 per cent) were treated with antimicrobial drugs. Just over 90 per cent of the treatments were given during the first 210 days of the calves' lives, but only 61.8 per cent of the total quantity of antimicrobial drugs was consumed during this period. The most common diseases from birth until 210 days were respiratory diseases and diarrhoea; treatments for mastitis and interdigital phlegmon (foul in the foot) were more common after 420 days of age. Slightly more than 60 per cent of the treatments were given by the farmers without prior consultation with a veterinary surgeon.

Morbidity in Swedish dairy calves from birth to 90 days of age and individual calf-level risk factors for infectious diseases

The health of 3081 heifer calves born in 122 dairy herds in the south-west of Sweden from 1 January to 31 December, 1998, was monitored from birth until 90 days of age. The calves were kept either in individual pens (n=2167), in group pens, with 3-8 calves to a pen and manual feeding of milk (n=440), in group pens with 6-30 calves per pen and an automatic milk-feeding system (n=431), or with their dams (n=43). Disease incidence was recorded by farmers and project veterinarians, who clinically examined the calves and auscultated their lungs every 2-3 months. A disease was graded as 'severe' if the general loss of condition or of appetite in the calf continued for >2 days or if the animal suffered severe weight loss due to the disease. The effects of season, breed, housing, and type of colostrum feeding, and time, place and supervision of calving on the incidences of diarrhea, severe diarrhea, respiratory disease, other infectious disease and moderately to severely increased respiratory sounds, were analyzed by logistic-regression models (with herd as a random effect). The total morbidity rate was 0.081 cases per calf-month at risk. Incidence rates of arthritis, diarrhea, omphalophlebitis, respiratory disease and ringworm were 0.002, 0.035, 0.005, 0.025 and 0.009 cases per calf-months at risk, respectively. The odds ratios for diarrhea and severe diarrhea were increased in Swedish Red and Whites (OR: 1.6, 2.3) and in calves that received colostrum from first-lactation cows (OR: 1.3-1.8), and for severe diarrhea in calves born in summer or that received colostrum through suckling (OR: 1.7, 1.8). The odds ratios for respiratory disease and increased respiratory sounds were increased in calves housed in large-group pens with an automatic milk-feeding system (OR: 2.2, 2.8). Supervision of calving was associated with a decreased odds ratio for respiratory disease (OR: 0.7) and birth in individual maternity pen or tie stalls with a decreased odds ratio for increased respiratory sounds (OR: 0.5-0.6). Cross-breeds with beef breeds were associated with increased odds ratios for increased respiratory sounds (OR: 2.1-4.3) and colostrum from second-lactation cows and birth during night for other infectious disease (OR: 1.6, 1.5).

Rotavirus G-type restriction, persistence, and herd type specificity in Swedish cattle herds

G-typing of rotavirus strains enables the study of molecular epidemiology and gathering of information to promote disease prevention and control. Rotavirus strains in fecal specimens from neonatal calves in Swedish cattle herds were therefore characterized by using G1 to -4-, G6-, G8-, and G10-specific primers in reverse transcription (RT)-PCR. Fecal samples were collected from one dairy herd (herd A) for 4 consecutive years and from 41 beef and dairy herds (herd B) experiencing calf diarrhea outbreaks. Altogether, 1, 700 samples were analyzed by group A rotavirus enzyme-linked immunosorbent assay, and 98 rotavirus-positive specimens were selected for G-typing by RT-PCR. The effect of herd type, time, geographic region, and clinical symptoms on the G-type distribution was evaluated. Altogether (herds A and B), G10 was found in 59 (60. 2%) fecal specimens, G6 was found in 30 (30.6%) specimens, G3 was found in 1 (1.0%) specimen, and G8 was found in 1 (1.0%) specimen. Seven (7.1%) fecal specimens were not typeable. Herd type specificity in the G-type distribution was demonstrated in the herds in herd B. In the 6 beef suckler herds, only G6 was detected, while rotavirus strains from the 35 dairy herds were predominantly (54%) G10. The G-type distribution was restricted in herds A and B. Twenty-nine of 30 strains from herd A were characterized as G10. In the vast majority of herds in herd B, a single G-type was identified. The serotype G10 and the electropherotype persisted over time in herd A. No characteristic G-type variation in the geographic distribution of cattle herds in herd B was obvious. There was no difference in the G-type distributions between the strains from clinically and subclinically rotavirus-infected calves in dairy herd A. The results from this study strongly indicate a pronounced stability in the rotavirus G-type distribution in Swedish cattle herds, which emphasizes the importance of continuous preventive measures for control of neonatal calf diarrhea. A future bovine rotavirus vaccine in Sweden should contain G10 and G6 strains.