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  • Author or Editor: James E: Collins x
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Abstract

Objectives—To determine the sensitivity of bacteriologic culture of pooled fecal samples in detecting Mycobacterium paratuberculosis, compared with bacteriologic culture of individual fecal samples in dairy cattle herds.

Study Design—Cross-sectional study.

Animals—24 dairy cattle herds.

Procedure—Individual and pooled fecal samples were submitted for bacteriologic culture, and results were compared between these groups.

Results—Ninety-four and 88% of pooled fecal samples that contained feces from at least 1 animal with high (mean, ≥ 50 colonies/tube) and moderate (mean, 10 to 49 colonies/tube) concentrations of M paratuberculosis, respectively, were identified by use of bacteriologic culture of pooled fecal samples. Prevalences of paratuberculosis determined by bacteriologic culture of pooled and individual fecal samples were highly correlated.

Conclusions and Clinical Relevance—Bacteriologic culture of pooled fecal samples provided a valid and cost-effective method for the detection of M paratuberculosis infection in dairy cattle herds and can be used to estimate prevalence of infection within a herd. (J Am Vet Med Assoc 2003;223:1022–1025)

Full access
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Summary

Embryonating eggs were inoculated with filtered porcine ileal mucosa containing intracellular curved rods (icr) and incubated for 4 to 6 days. Three of 12 pigs given the eggs per os developed microscopic lesions of proliferative enteritis (pe). Nonchallenge-exposed control pigs did not develop lesions of pe. Four of six positive control pigs given ileal mucosa from pigs with pe also developed microscopic lesions of pe. All of the PE lesions were found in pigs necropsied 10 to 29 days after challenge exposure. None of the swine in the study had clinical signs or gross lesions of pe.

Campylobacter spp were isolated from pigs with and without exposure to the ileal mucosa from pigs with pe. There was no relationship between Campylobacter spp isolation and development of lesions.

Deoxyribonucleic acids extracted from embryonating chicken eggs injected with the equivalent of 0.5 mg of mucosal lesions and incubated for 4 days hybridized to a dna probe specific for the icr, whereas dna extracted from 1.5 mg of mucosal homogenates of the same proliferative tissue did not hybridize with the same probe. Results of these experiments indicated that icr injected into eggs remained infective for pigs and suggest replication of icr in the first-passage eggs.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether flies can acquire porcine reproductive and respiratory syndrome virus (PRRSV) and disperse the virus throughout a designated area.

Animals—60 four-month-old pigs.

Procedure—On day 0, 28 of 60 pigs were inoculated with PRRSV MN 30-100 (index variant). On the same day, 100,000 pupae of ochre-eyed houseflies and 100,000 pupae of red-eyed (wild-type) houseflies were placed in the swine facility for a release-recapture study. Flies were recaptured at 2 locations within the swine facility, 6 locations immediately outside the facility, and 30 locations 0.4, 0.8, 1.3, 1.7, 1.9, and 2.3 km from the facility. Traps were emptied on days 2, 7, 8, 10, and 14. Samples derived from flies were tested by use of a polymerase chain reaction assay, virus DNA was sequenced, and viruses were tested for infectivity by means of a swine bioassay.

Results—PRRSV RNA homologous to the index PRRSV was detected in trapped flies collected inside and immediately outside the facility and from 9 of 48 samples collected at 0.4 km, 8 of 24 samples collected at 0.8 km, 5 of 24 samples collected at 1.3 km, and 3 of 84 samples collected at > 1.7 km from the facility. Two samples collected at 0.8 km contained genetically diverse variants of PRRSV. Swine bioassays revealed the virus in flies was infectious.

Conclusions and Clinical Relevance—Flies appeared to become contaminated with PRRSV from infected pigs and transported the virus ≥ 1.7 km. Flyborn transmission may explain how PRRSV is seasonally transported between farms. (Am J Vet Res 2004;65:1284–1292)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the influences of animal age, bacterial coinfection, and porcine reproductive and respiratory syndrome virus (PRRSV) isolate pathogenicity on virus concentration in pigs.

Animals—Twenty-one 2-month-old pigs and eighteen 6-month-old pigs.

Procedure—Pigs were grouped according to age and infected with mildly virulent or virulent isolates of PRRSV. The role of concurrent bacterial infection was assessed by infecting selected pigs with Mycoplasma hyopneumoniae 21 days prior to inoculation with PRRSV. On alternating days, blood and swab specimens of nasal secretions and oropharyngeal secretions were collected. On day 21 after inoculation with PRRSV, selected tissues were harvested. Concentrations of PRRSV were determined by use of quantitative real-time PCR and expressed in units of TCID50 per milliliter (sera and swab specimens) or TCID50 per gram (tissue specimens).

Results—Concentrations of virus were higher in blood and tonsils of pigs infected with virulent PRRSV. Pigs infected with virulent PRRSV and M hyopneumoniae had significantly higher concentrations of viral RNA in lymphoid and tonsillar tissue. Coinfection with M hyopneumoniae resulted in a higher viral load in oropharyngeal swab specimens and blood samples, independent of virulence of the PRRSV isolate. Two-month-old pigs had significantly higher viral loads in lymph nodes, lungs, and tracheal swab specimens than did 6-month-old pigs, independent of virulence of the PRRSV isolate.

Conclusions and Clinical Relevance—Multiple factors affect PRRSV concentration in pigs, including pathogenicity of the PRRSV isolate, age, and concurrent infection with M hyopneumoniae.

Full access
in American Journal of Veterinary Research

Summary

A method of extracting bacterial dna from swine feces was developed and used in a molecular assay for the presence of ileal symbiont (is) intracellularis, formerly known as the Campylobacter-like organism associated with swine with proliferative enteritis. Hybridization with a digoxigenin-labeled, is intracellularis-specific probe detected the presence of is intracellularis at a concentration of 107 organisms/g of feces. This method was sufficient to detect is intracellularis in the feces of swine with experimentally induced and naturally acquired infection. Results of the hybridization were in agreement with those from histologic postmortem examination.

Free access
in American Journal of Veterinary Research

Summary

A form of enteric Escherichia coli infection was identified in 60 calves from 59 farming operations. The E coli responsible for these infections principally colonized the colon, inducing a distinctive lesion described as attaching and effacing. Hemorrhagic enterocolitis or blood in the feces was observed on 40% of the farms. Of affected calves, 86.6% were dairy calves (average age, 11.8 days). Forty-four calves were infected concurrently with other enteropathogens (cryptosporidia, rotavirus, coronavirus, enterotoxigenic E coli, bovine viral diarrhea virus, coccidia). Verotoxin-producing E coli was recovered from 31 calves; 8 were serotype 0 111:NM isolates, 3 were serotype 05:NM, and 1 was serotype 026:NM.

Free access
in Journal of the American Veterinary Medical Association