Prevalence of VTEC O157 in dairy and veal herds and risk factors for veal herds.

The aim of this study was to determine the herd prevalence of veal and dairy herds and to identify risk factors for VTEC O157 positive veal herds. The study was based on monitoring data from November 1996 through July 2005 of 1051 dairy herds and 930 veal herds. The herd level prevalence (95% CI) was 8.0% (6.4-9.6) for dairy herds and 12.6% (10.5-14.7) for veal herds. Within the population of veal herds, a prevalence of 39.8% (33.9-45.6) was found for pink veal herds (n = 269) and 1.5% (0.7-2.8) for white veal herds (n = 661). Multivariable logistic regression showed that the type of veal (pink vs. white; OR = 21.6; 95% CI: 10.4-45.0), ventilation (mechanical vs. natural; OR = 0.4; 95% CI: 0.2-0.8), time between arrival in the herd and sampling (3-5 months vs. 0-2 months: OR = 2.33; 95% CI: 1.1-5.1, > or = 6 months vs. 0-2 months: OR = 4.11; CI: 1.9-8.9), other feed than the 7 most common (yes vs. no; OR = 2.1; 95% CI: 1.2-3.7) and at least one dog present in the stable (yes vs. no; OR = 2.6; 95% CI: 1.5-4.6) were significantly (P < 0.05) associated with the presence of VTEC O157. The large difference in the VTEC O157 prevalences for pink veal and white veal production might have been caused by a very different management of these type of herds. However, this could not be studied with the data collected.

Herd management practices associated with paratuberculosis seroprevalence in Dutch dairy herds.

We describe the paratuberculosis management practices applied in dairy herds in the Netherlands. The findings from paratuberculosis seronegative and seropositive herds were compared to discover possible risk factors. In total, 370 randomly selected herds with > or =20 dairy cows were surveyed. A questionnaire was used to collect data on current and previous paratuberculosis management practices. All cattle aged > or =3 years were serologically tested for paratuberculosis using an enzyme-linked immunosorbent assay. Herds with >33 tested cattle, of which only one was seropositive, were excluded to reduce the risk of including false-positive herds in the analysis. A comparison of the management data of the seronegative herds (n = 166) and the seropositive herds (n = 143) showed that in both groups important management measures for the prevention of paratuberculosis, such as calving in a cleaned calving area, removing the calf immediately after birth, and feeding paratuberculosis non-suspect roughage to calves, were used only rarely. However, such measures should be regarded as the critical first step to control the disease and/or reduce its prevalence. Using univariable analysis, four factors were statistically different between seronegative and seropositive herds: herd size, cows with clinical signs of paratuberculosis, prompt selling of clinically diseased cattle and feeding milk replacer. Using a multivariable logistic regression model, only herd size was a significantly different factor. These results indicate that most of the paratuberculosis preventive management measures were executed on these Dutch dairy farms only to a limited extent.

Genetic variation of susceptibility to Mycobacterium avium subsp. paratuberculosis infection in dairy cattle.

Paratuberculosis is an infectious disease that is not easily amenable to classical control methods such as treatment and vaccination. Experimental animal models suggest that there could be genetic factors responsible for susceptibility or resistance to infection with the causative agent, Mycobacterium avium subsp. paratuberculosis. The aim of this study was to estimate genetic variation in susceptibility to paratuberculosis in Dutch dairy cattle. Data collected during a vaccination trial, conducted from 1984 to 1994, was used. A total of 3020 cows, with complete pedigree records and infection status at slaughter, were available for analysis. A standard polygenic statistical probit model was used to estimate heritabilities. The estimated heritability of susceptibility to M. avium. subsp. paratuberculosis infection was 0.06 for the overall population. In the subpopulation of vaccinated animals the estimated heritability was 0.09. Other calculations based on the model used in this study argue against a prominent role for vertical transmission. Because the establishment of genetic variation is one of the first steps towards the exploration of the possible use of selection for genetic improvement, the present study provides evidence for the presence of genetic variation in the susceptibility of cattle to paratuberculosis. Because the economic impact of the disease is substantial, the development and application of genetic tools, along with other control methods, could be instrumental in the eradication of paratuberculosis.

[An outbreak of keratoconjunctivitis in a dairy farm]. / Een uitbraak van kerato-conjuctivitis op een melkveebedrijf.

An outbreak of infectious kerato-conjunctivitis is described in a dairy herd during the (winter)stable period. Moraxella was isolated from lacrimation fluid from three animals. The development of the infection was possibly precipitated by a vaccination with modified live IBR virus, adenovirus type 3 and parainfluenza virus type 3. Presumably, climatological-stable conditions play an important role in the clinical manifestation of the infection.