Combined Campylobacter jejuni and Campylobacter coli Rapid Testing and Molecular Epidemiology in Conventional Broiler Flocks

Campylobacter spp. are important causes of bacterial zoonosis, most often transmitted by contaminated poultry meat. From an epidemiological and risk assessment perspective, further knowledge should be obtained on Campylobacter prevalence and genotype distribution in primary production. Consequently, 15 Austrian broiler flocks were surveyed in summer for their thermophilic Campylobacter spp. contamination status. Chicken droppings, dust and drinking water samples were collected from each flock at three separate sampling periods. Isolates were confirmed by PCR and subtyped. We also compared three alternative methods (culture‐based enrichment in Bolton broth, culture‐independent real‐time PCR and a lateral‐flow test) for their applicability in chicken droppings. Twelve flocks were found to be positive for thermophilic Campylobacter spp. during the entire sampling period. Seven flocks (46.6%) were contaminated with both, C. jejuni and C. coli, five flocks harboured solely one species. We observed to a majority flock‐specific C. jejuni and C. coli genotypes, which dominated the respective flock. Flocks within a distance <2 km shared the same C. jejuni genotypes indicating a cross‐contamination event via the environment or personnel vectors. Multilocus sequence typing (MLST) of C. jejuni revealed that the majority of isolates were assigned to globally distributed clonal complexes or had a strong link to the human interface (CC ST‐446 and ST4373). The combination of techniques poses an advantage over risk assessment studies based on cultures alone, as, in the case of Campylobacter, occurrence of a high variety of genotypes might be present among a broiler flock. We suggest applying the lateral‐flow test under field conditions to identify ‘high‐shedding’ broiler flocks at the farm level. Consequently, poultry farmers and veterinarians could improve hygiene measurements and direct sanitation activities, especially during the thinning period. Ultimately, real‐time PCR could be applied to quantify Campylobacter spp. directly from chicken droppings and avoid non‐interpretable results achieved by culture‐dependent methods.     

Sensitivity of test strategies used in the Voluntary Johne's Disease Herd Status Program for detection of Mycobacterium paratuberculosis infection in dairy cattle herds

OBJECTIVE: To evaluate sensitivities at the herd level of test strategies used in the Voluntary Johne's Disease Herd Status Program (VJDHSP) and alternative test strategies for detecting dairy cattle herds infected with Mycobacterium paratuberculosis. DESIGN: Nonrandom cross-sectional study. SAMPLE POPULATION: 64 dairy herds from Pennsylvania, Minnesota, Colorado, Ohio, and Wisconsin. Fifty-six herds had at least 1 cow shedding M. paratuberculosis in feces; the other 8 herds were free from paratuberculosis. PROCEDURE: For all adult cows in each herd, serum samples were tested for antibodies to M. paratuberculosis with an ELISA, and fecal samples were submitted for bacterial culture for M. paratuberculosis. Sensitivities at the herd level (probability of detecting infected herd) of various testing strategies were then evaluated. RESULTS: Sensitivity at the herd level of the testing strategy used in level 1 of the VJDHSP (use of the ELISA to test samples from 30 cows followed by confirmatory bacterial culture of feces from cows with positive ELISA result) ranged from 33 to 84% for infected herds, depending on percentage of cows in the herd with positive bacterial culture results. If follow-up bacterial culture was not used to confirm positive ELISA results, sensitivity ranged from 70 to 93%, but probability of identifying uninfected herds as infected was 89%. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the testing strategy used in the VJDHSP will fail to identify as infected most dairy herds with a low prevalence of paratuberculosis. A higher percentage of infected herds was detected if follow-up bacterial culture was not used, but this test strategy was associated with a high probability of misclassifying uninfected herds.     

SPONTANEOUS RESOLUTION OF A PSEUDOANEURYSM IN A HORSE FOLLOWING ANGIOGRAPHIC DIAGNOSIS

Angiography in a horse was used to confirm a pseudoaneurysm of the dorsal metatarsal artery originating from trauma. Gradual clinical resolution of the pseudoaneurysm occurred within days following the procedure. A follow-up angiogram confirmed the clinical impression. An etiology of the spontaneous resolution is presented. Probable influences included technical factors of the injection procedure that caused prolonged presence of the contrast medium within the aneurysmal sac and factors that enhance thrombus formation during angiography.     

In this issue – June 2011

Computer model predictions and field observations of anthelmintic resistance in sheep · Dangers of off‐label use of barium selenate · Elbow luxation in dogs and cats · Prognosis of joint infections in adult horses · Omentalisation for mediastinal abscess in a dog · Adenoviruses in lizards     

Babesia odocoilei infection in elk

Two male North American elk from a commercial herd were evaluated because of a sudden onset of lethargy, anorexia, and voiding of red urine. These 2 elk were kept in the same pen as 4 other male elk that had died during the preceding 2 months. Laboratory analyses revealed anemia and intraerythrocytic parasites, later confirmed as Babesia odocoilei (a protozoal hemoparasite of cervids). Of the 240 elk remaining in the herd, 59 were screened for B odocoilei by microscopic evaluation of blood smears, protozoal culture of blood, and immunofluorescent antibody testing of serum. Of those 59 elk, 34 (58%) were infected with B odocoilei. Babesia odocoilei infection in elk can be fatal and should be considered in cases of sudden death or acute hemolytic anemia. Familiarity with the disease in elk is essential for practitioners because of the increasing popularity of commercial elk farming.     

An initial survey of the cattle grub Dermatobia hominis (L. Jr.) in Nicaragua

After the civil war and the Hurricane-Mitch disaster, cattlemen in Nicaragua were forced to transport their cattle from lowland areas to higher, dryer areas of the country. These areas are natural ecological niches for the cattle grub Dermatobia hominis (L. Jr.) (Diptera: Cuterebridae). To determine the importance of this infestation, the Agricultural and Livestock-Forestry Ministry selected a central area of Nicaragua to run a pioneer survey program to acquire information about hosts involved, number of cases, treatments applied and general knowledge of 42 farmers about the life cycle of the parasite. The subjects were either farm owners or farm managers. Ninety-five percentage of the farms indicated cases of D. hominis infestation in their animals, with cattle being the most affected host (100% of the affected farms). There was poor understanding of the D. hominis life cycle, vectors and control methods. A misuse of insecticides for the treatment of larval infestation by D. hominis was indicated.     

Interferon-gamma, interleukin-4 and interleukin-10 production by T helper cells reveals intact Th1 and regulatory TR1 cell activation and a delay of the Th2 cell response in equine neonates and foals

Cytokines produced by T helper (Th) cells are important in orchestrating the immune response during health and disease. Recent reports indicated that cytokine mRNA expression in foals is often quantitatively lower than that of adult horses suggesting that foal T cells are not fully mature. Here, peripheral blood mononuclear cells from foals and adult horses were stimulated with phorbol 12-myristate 13-acetate and analyzed for intracellular interferon-gamma (IFN-γ), interleukin-4 (IL-4) and IL-10 production, representing the Th1, Th2 and regulatory T_R1 cell phenotypes respectively, by flow cytometry. In agreement with previous reports, all three cytokines were quantitatively reduced in foals compared to adults. However, the balance between Th1 and Th2 cytokines (IFN-γ/IL-4 ratio) showed a clear Th1-biased response in foals by 6 and 12 weeks of life, while similar IFN-γ/IL-10 ratios were found in foals and adult horses. By day 5 after birth, intracellular IFN-γ production by foal CD4⁺ and CD8⁺ T cells resembled that in adults. Overall, IL-4 production was low in foals. IL-4⁺ cells peaked at day 5 of age when IL-4 was mainly produced by IgE⁺ cells. Relative percentages of IL-4⁺ Th2 cells were significantly lower in foals at all time points. The data suggested that equine neonates and young foals have an impaired Th2 response, that the immune response of foals is Th1 biased, that IFN-γ production by Th and cytotoxic T cells is qualitatively similar to adult horses, and regulatory IL-10 production by T cells is developmentally mature in foals during the first three months of life.     

Effect of surgical technique on limb function after surgery for rupture of the cranial cruciate ligament in dogs

OBJECTIVE: To determine the outcome and effect of surgical technique on limb function after surgery for rupture of the cranial cruciate ligament (RCCL) and injury to the medial meniscus in Labrador Retrievers. STUDY DESIGN: Prospective clinical study. ANIMALS: 131 Labrador Retrievers with unilateral RCCL and injury to the medial meniscus and 17 clinically normal Labrador Retrievers. PROCEDURE: Affected dogs had partial or complete medial meniscectomy and lateral suture stabilization (LSS), intracapsular stabilization (ICS), or tibial plateau leveling osteotomy (TPLO). Limb function was measured before surgery and 2 and 6 months after surgery. Treated dogs were evaluated to determine the probability that they could be differentiated from clinically normal dogs and tested to determine the likelihood that they achieved improvement. RESULTS: No difference was found between LSS or TPLO groups, but dogs treated with ICS had significantly lower ground reaction forces at 2 and 6 months. Compared with clinically normal dogs only, 14.9% of LSS-, 15% of ICS-, and 10.9% of TPLO-treated dogs had normal limb function. Improvement was seen in only 15% of dogs treated via ICS, 34% treated via TPLO, and 40% treated via LSS. CONCLUSIONS AND CLINICAL RELEVANCE: Surgical technique can influence limb function after surgery. Labrador Retrievers treated via LSS, ICS, or TPLO for repair for of RCCL and medial meniscal injury managed with partial or complete meniscectomy infrequently achieve normal function. Results of LSS and TPLO are similar and superior to ICS.