Detection of mortality clusters associated with highly pathogenic avian influenza in poultry: a theoretical analysis.

Rapid detection of infectious disease outbreaks is often crucial for their effective control. One example is highly pathogenic avian influenza (HPAI) such as H5N1 in commercial poultry flocks. There are no quantitative data, however, on how quickly the effects of HPAI infection in poultry flocks can be detected.

Quantification of Peyer's patches in Cheviot sheep for future scrapie pathogenesis studies.

Peyer's patches (PPs) are the most probable sites of intestinal uptake of the transmissible spongiform encephalopathy (TSE) agent. The amount of PP tissue varies considerably between different age groups of individuals, and whether this variation is related to susceptibility to TSE infection raises an intriguing possibility. The purpose of this study was to determine the surface area of PP tissue and the number of associated lymphoid follicles in different age groups of Neuropathogenesis Unit (NPU) Cheviot sheep.

Silent spread of H5N1 in vaccinated poultry.

International debate on the merits of vaccinating poultry against the H5N1 influenza A virus has raised concerns about the possibility of an increased risk of between-flock transmission before outbreaks are detected. Here we show that this 'silent spread' can occur because of incomplete protection at the flock level, even if a vaccine is effective in individual birds. The use of unvaccinated sentinels can mitigate, although not completely eliminate, the problem.

Comparative evidence for a link between Peyer's patch development and susceptibility to transmissible spongiform encephalopathies.

Background: Epidemiological analyses indicate that the age distribution of natural cases of transmissible spongiform encephalopathies (TSEs) reflect age-related risk of infection, however, the underlying mechanisms remain poorly understood. Using a comparative approach, we tested the hypothesis that, there is a significant correlation between risk of infection for scrapie, bovine spongiform encephalopathy (BSE) and variant CJD (vCJD), and the development of lymphoid tissue in the gut.

Methods: Using anatomical data and estimates of risk of infection in mathematical models (which included results from previously published studies) for sheep, cattle and humans, we calculated the Spearman's rank correlation coefficient, rs, between available measures of Peyer's patch (PP) development and the estimated risk of infection for an individual of the corresponding age.

Effect of penethamate hydriodide treatment on bacteriological cure, somatic cell count and milk production of cows and quarters with chronic subclinical Streptococcus uberis or Streptococcus dysgalactiae infection.

A randomized, controlled field trial was performed in The Netherlands to determine the therapeutic efficacy of parenteral penethamate hydriodide (Leocillin) against naturally occurring, chronic, streptococcal mastitis during lactation. Quarter milk samples were collected from subclinical cases of Streptococcus uberis or Streptococcus dysgalactiae mastitis to determine the effect of treatment on bacteriological cure and somatic cell count (SCC) at quarter level. A quarter was considered to be cured when the bacterial species, isolated prior to treatment, was not isolated from the quarter milk samples taken on days 10 and 20 post-treatment (bacteriological cure), or when a quarter milk SCC (QMSCC) was <250000 cells/ml on days 10 and 20 post-treatment (SCC cure).