Relationships between health and weight loss during lactation and between health and ability to return to oestrus after weaning in primiparous sows

Escherichia coli O157:H7: animal reservoir and sources of human infection

This review surveys the literature on carriage and transmission of enterohemorrhagic Escherichia coli (EHEC) O157:H7 in the context of virulence factors and sampling/culture technique. EHEC of the O157:H7 serotype are worldwide zoonotic pathogens responsible for the majority of severe cases of human EHEC disease. EHEC O157:H7 strains are carried primarily by healthy cattle and other ruminants, but most of the bovine strains are not transmitted to people, and do not exhibit virulence factors associated with human disease. Prevalence of EHEC O157:H7 is probably underestimated. Carriage of EHEC O157:H7 by individual animals is typically short-lived, but pen and farm prevalence of specific isolates may extend for months or years and some carriers, designated as supershedders, may harbor high intestinal numbers of the pathogen for extended periods. The prevalence of EHEC O157:H7 in cattle peaks in the summer and is higher in postweaned calves and heifers than in younger and older animals. Virulent strains of EHEC O157:H7 are rarely harbored by pigs or chickens, but are found in turkeys. The bacteria rarely occur in wildlife with the exception of deer and are only sporadically carried by domestic animals and synanthropic rodents and birds. EHEC O157:H7 occur in amphibian, fish, and invertebrate carriers, and can colonize plant surfaces and tissues via attachment mechanisms different from those mediating intestinal attachment. Strains of EHEC O157:H7 exhibit high genetic variability but typically a small number of genetic types predominate in groups of cattle and a farm environment. Transmission to people occurs primarily via ingestion of inadequately processed contaminated food or water and less frequently through contact with manure, animals, or infected people.

Detection of verocytotoxin-producing Escherichia coli serogroups 0157 and 026 in the cecal content and lymphatic tissue of cattle at slaughter in Italy

Verocytotoxin-producing Escherichia coli (VTEC) has emerged as a foodborne pathogen that can cause severe and potentially fatal illnesses, such as hemorrhagic colitis or the hemolytic uremic syndrome. In this study, 182 cattle at slaughter (119 dairy cows and 63 feedlot cattle) were randomly selected and tested for the presence of VTEC serogroups O26, O103, O111, O145, and O157 in their cecal content and lymphatic tissue (tonsils or mesenteric lymph nodes). A total of 364 samples were evaluated with an immunomagnetic separation technique followed by slide agglutination. Presumptive VTEC 026, O103, O111, O145, and O157 isolates were tested by Vero cell assay for verocytotoxin production and by multiplex PCR assay for the detection of vtxl, vtx2, eae, and E-hlyA genes. VTEC O157 was detected in 6 (3.3%) of 182 animals, and VTEC 026 was detected in 1 (0.5%) of 182 animals. No VTEC O103, VTEC O111, or VTEC O145 isolates were found in cattle feces, but one VTEC O91:H- vtx2+, eae-, E-hlyA+ strain nonspecifically cross-reacted with the VTEC O103 type. The prevalence of VTEC O157 in the lymphatic tissue of cattle was 1.1% in both tonsils (1 of 93 samples) and mesenteric lymph nodes (1 of 89 samples). Lymphatic tissue contamination was observed only in VTEC O157 intestinal carriers; two (33.3%) of six fecal carriers were simultaneously VTEC O157 lymphatic carriers. This finding suggests that VTEC O157 contamination of meat does not necessarily come from feces or the environment. No other VTEC serogroups were detected in the lymphatic tissue of slaughtered cattle.

Evaluation of environmental and management-related risk factors associated with chronic mastitis in sows

OBJECTIVE

To evaluate environmental and management-related risk factors associated with chronic mastitis in sows.

ANIMALS

1,254 sows from 76 herds.

PROCEDURE

Prevalence of chronic mastitis was determined by a veterinarian who performed clinical examinations at the time of weaning and approximately 1 week later in a sample of the sow population on each farm. Information concerning environmental factors and management practices was collected. In addition, the herd veterinarian made an assessment of the farmer's skills in swine production.

RESULTS

Use of partly slatted floors in the farrowing pens, use of disinfectants between batches in the farrowing and breeding areas, feeding lactating sows whey, and avoiding cutting or grinding of the piglets' teeth were significantly associated with a decreased risk of chronic mastitis. A high hygienic standard on the farm, as determined by the herd veterinarian, was associated with a significant reduction in the prevalence of mastitis.

CONCLUSIONS AND CLINICAL RELEVANCE

Chronic mastitis in sows is a common disease that has a negative influence on productivity. Results indicate that certain management practices and environmental factors influenced the development of mastitis, which may contribute to the development of methods useful for controlling the disease.

Fecal shedding of Escherichia coli O157, Salmonella, and Campylobacter in Swiss cattle at slaughter

Fecal samples from 2,930 slaughtered healthy cattle were examined with the following goals: (i) to monitor the shedding of Escherichia coli O157, Salmonella, and Campylobacter in cattle; and (ii) to further characterize the isolated strains. The percentage of the 2,930 samples that tested positive for E. coli O157 by PCR was 1.6%. Thirty-eight strains from different animals that agglutinated with Wellcolex E. coli O157 were isolated. Of the six sorbitol-negative strains, five tested positive for stx2 genes (two times for stx2c and three times for stx2), and one strain tested positive for stx1 and stx2c genes. All sorbitol-negative strains belonged to the serotypes O157:H7- and O157:H7 and harbored the eae type gamma 1 and ehxA genes. The 32 sorbitol-positive strains tested negative for stx genes and belonged to the serotypes O157:H2, O157:H7, O157:H8, O157:H12, O157:H19, O157:H25, O157:H27, O157:H38, O157:H43, O157:H45, and O157:H-. All O157:H45 strains harbored the eae subtype alpha 1 and therefore seem to be atypical enteropathogenic E. coli strains. Whereas none of 1,000 examined samples was positive for Salmonella, 95 of 935 (10.2%) samples were positive for Campylobacter, and all strains were identified as C. jejuni. Sixteen Campylobacter strains were resistant to tetracycline, five were resistant to nalidixic acid/ciprofloxacin, four were resistant to streptomycin, and one was resistant to nalidixic acid/ciprofloxacin and streptomycin. Fecal shedding of zoonotic pathogens in slaughter animals is strongly correlated with the hazard of carcass contamination. Therefore, the maintenance of slaughter hygiene is of crucial importance.

The prevalence and spread of Escherichia coli O157:H7 at a commercial beef abattoir

AIMS

To investigate the prevalence and virulence characteristics of Escherichia coli O157:H7 after a number of beef process operations at a commercial Irish abattoir.

METHODS AND RESULTS

Two 12-month studies were carried out. The first study (study 1) examined the prevalence of E. coli O157:H7 at up to six sites on carcasses at eight stages of the dressing, washing, chilling and boning process. The second study (study 2) examined the prevalence of E. coli O157:H7 in bovine faeces and rumen contents post-slaughter and on dressed, washed carcasses. Isolates from both studies were phage-typed and the presence of genes encoding verocytotoxin, enterohaemolysin and intimin production was determined. E. coli O157:H7 was isolated from four of 36 carcasses in study 1. E. coli O157:H7 was detected during hide removal and was detected at multiple carcass sites and multiple process stages, including boning. On two carcasses, contamination was first detected at the bung following its freeing and tying. All isolates from study 1 were phage type (PT) 2, eaeAO157 and ehlyA positive, but were verocytotoxin 1 (VT1) and verocytotoxin 2 (VT2) negative. In study 2, E. coli O157:H7 was isolated from 2.4% of faecal, 0.8% of rumen and 3.2% of carcass samples. In some cases, isolates recovered from the faeces of a particular animal, the resulting carcass and adjacent carcasses on the line had the same phage typing and virulence characteristic profile patterns. All isolates from study 2 were eaeAO157 and ehlyA positive and only one isolate was VT1 and VT2 negative. Most isolates were PT 32. A higher frequency of positive isolations was noted from samples taken during spring and late summer.

CONCLUSION

These studies show that in a typical Irish beef abattoir, carcass contamination with E. coli O157:H7 can occur during hide removal and bung tying and this contamination can remain on the carcass during subsequent processing.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides data that is necessary for the understanding of how E. coli O157:H7 contamination of beef occurs.

Clinical characteristics, prevalence, influence on sow performance, and assessment of sow-related risk factors for granulomatous mastitis in sows

OBJECTIVE

To determine the prevalence and clinical appearance of granulomatous mastitis in sows, to identify sow-related risk factors for development of granulomatous mastitis, and to explore the manner in which the disease influences sow performance.

ANIMALS

1,254 sows from 76 herds.

PROCEDURE

A clinical examination was performed at time of weaning and 7 days later. In addition, some sows were reexamined at time of weaning in the subsequent lactation. Data were collected on sow performance.

RESULTS

At time of weaning, 205 of 1,254 (16%) sows had granulomatous mastitis, and 7 days later, the prevalence was 19%. Variation between herds was large (0 to 50%). In most of the affected sows (156/205 176%]), only 1 mammary gland was affected. Parity, duration of lactation, and number of teat wounds were identified as risk factors for development of the disease. In 264 of 559 (47%) sows (38/104 [37%] mammary glands), a granuloma recurred in the subsequent lactation. Risk for recurrence was related granuloma appearing in multiple form but not to granuloma size. Affected glands were less distended in the subsequent lactation, suggesting lower milk production. Litter size appeared to be negatively affected by the disease.

CONCLUSIONS AND CLINICAL RELEVANCE

Granu lomatous mastitis is a common disease in sow herds maintained on straw bedding and in group housing, and it has negative effects on sow productivity. A thorough description of the clinical appearance of the disease and the identification of risk factors should contribute to development of relevant control measures.