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Biomedical subjects

P Willeberg

Publications and source records attributed to P Willeberg.

At least 19 recordsLinked to original sources
PubMed1994

Herd risk factors for serological evidence of Aujeszky's disease virus infection of breeding sows in northern Germany (1990-1991).

The distribution of herd risk factors with respect to serological evidence of Aujeszky's disease virus (ADV) infection in breeding sows was studied using samples collected in the early phase of an area-wide eradication programme in two districts of Northern Germany (Schleswig-Flensburg and Nordfriesland). The odds of seropositivity in breeding females were 6.5-times higher for herds that purchased replacement gilts compared with herds that introduced gilts from their own inventory. Herds in which confirmed clinical Aujeszky's disease (AD) had occurred during the 1980s had 4.2-times higher odds of seropositive test results compared with herds without clinical outbreaks of AD. The log-odds of a herd having seropositive females increased, in a curvilinear pattern, with increasing herd size. The slope of the log-transformed herd-size line suggested that wind-borne transmission may have been an important route for among-herd transmission of ADV. It was concluded that, in areas with endemically-infected swine herds, the expected level of ADV infection will be highest in regions with large herds and previous clinical outbreaks of AD. This should be taken into account in the design of future area-wide AD-eradication campaigns.

Animals↗
PubMed1991

A case-control study of risk factors in light Taenia saginata cysticercosis in Danish cattle.

Risk factors in light T. saginata cysticercosis in cattle herds were investigated in a case-control study. The case group consisted of farms from which cattle with low-grade cysticercosis had been detected at slaughter. The control group consisted of farms where no cases were detected during the same period. The major risk factor identified was allowing cattle access to drink from streams carrying effluent from sewage treatment plants (odds ratio = 3.6). Spreading of septic tank sludge through deliberate or accidental mixing with animal slurry, deposition of sewage sludge, and proximity to railways, camping sites or sewage treatment plants seemed to be of minor importance.

Animals↗
PubMed1990

EPISCOPE: computer programs in veterinary epidemiology.

Veterinary epidemiology is a rapidly developing science. However, many veterinarians are unfamiliar with the relevant techniques because veterinary schools have not introduced biostatistics as a core element of their courses or adopted epidemiology as a specific discipline. EPISCOPE, the computer software presented in this paper, covers many epidemiological principles and calculations. It can assist both the teaching of epidemiology and the analysis of field data.

Animal Diseases↗
PubMed1990

The effect of a control program for enzootic bovine leukosis. Changes in herd prevalence in Denmark, 1969-1978.

As part of the Danish control program for enzootic bovine leukosis, three hematologic screenings of all cattle herds in Denmark were performed in the period 1969-1978. Herds with multiple cases of persistent lymphocytosis and/or leukotic tumors were classified as "leukosis herds." During nationwide blood testing, 369 leukosis herds were discovered, and an additional 77 herds were found due to follow-up of tumor cases or special testing in connection with movements of cattle in 1969-1978. In the present study, the prevalence of leukosis herds in the three screening rounds is related to geographic area and herd size. By means of a statistical log-linear model, the authors show that prevalence increased proportionally with herd size. The observed number of leukosis herds per 10,000 herds tested declined during the screening program from 105 to 38 in east Denmark and from 12 to 4 in west Denmark.

Animals↗
PubMed1989

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. I. Pre-weaning diarrhoea.

The study comprised 70,796 litters in 104 sow herds, observed from 1976 through 1982. Weaning age decreased from approx. 42 days to approx. 30 days during the observation period. Diseases and symptoms were recorded together with production parameters (feeding, barn construction, economic returns etc.). The mean incidence rate of pre-weaning diarrhoea was 6.8% of litters, with considerable inter-herd differences (incidence rates from 0 to approx. 50%). There was a slight increase in incidence during the autumn (August through October). Incidence rates increased with litter size, with a peak incidence in litters of 11-13 piglets, and decreased with increasing parity of the sow. There was a positive association between occurrence of arthritis and pre-weaning diarrhoea in the litters, and litters from sows with post parturient disease (MMA complex) had 1.8 times higher risk of getting diarrhoea than litters from healthy sows. No important differences among breeds were found. Small herds (less than 200 farrowings per year) had higher incidence rates than large herds (400-499 farrowings per year). Herds with a gilt proportion above 30% had an incidence rate of 12.3%, i.e. nearly twice as high as the overall mean (6.8%). There was a trend towards a higher incidence rate in litters kept in traditional pens (i.e. large pens with solid floor and loose sows) than in intensive pens (i.e. small pens with slatted flooring and tethered sows). The overall pre-weaning mortality rate was 16.2% of pigs born, half of which was due to stillbirths (6.3%) and overlaid piglets (2.2%). In litters with pre-weaning diarrhoea, the mortality rate was 19%, compared to 13% in litters without occurrence of diarrhoea. This difference accounts for an excess loss of 0.6 piglets from birth to weaning in diarrhoeic vs. non-diarrhoeic litters. Piglets from litters with pre-weaning diarrhoea had reduced weight gain. Thus, on the average, they were 2.2 days older at 25 kg bodyweight and weighed 0.4 kg less at 30 days than piglets from non-diarrhoeic litters. Also, litters with pre-weaning diarrhoea had a significantly increased risk of post-weaning diarrhoea. The present information forms a basis for defining acceptable disease thresholds in suckling litters in intensively managed herds.

Animals↗
PubMed1989

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. II. Post-weaning diarrhoea.

This study comprised 48,931 litters in 89 sow herds. During the study (1976-82) weaning age decreased from approx. 42 days to approx. 30 days. The mean incidence of post-weaning diarrhoea was 6.0% of litters weaned, with little variation by year but with considerable variation among herds. Within the individual herd increased incidence occurred over limited periods, probably associated with specific infections. Litters with diarrhoea during the suckling period had increased risk of post-weaning diarrhoea. The incidence of post-weaning diarrhoea increased with litter size at weaning. Thus, a litter of 11-12 piglets at weaning had 1.2 times higher risk than litters with 8-10 piglets. In contrast to pre-weaning diarrhoea, there was no association between parity of the sow and diarrhoea in the litter after weaning. Litters weaned below 2 weeks of age had a 2-fold risk of developing diarrhoea after weaning and a 2.4-fold higher mortality rate than did litters weaned at 6-7 weeks. Similarly, litters weaned at an individual piglet weight below 3 kg bodyweight had a 3-fold higher risk of developing diarrhoea after weaning and a 5-fold higher mortality rate than did pigs from litters weaned at a bodyweight of 7-8 kg. The incidence of post-weaning diarrhoea decreased with increasing herd size. Piglets from litters with post-weaning diarrhoea had reduced weight gains after weaning and were 2.3 days older at 25 kg bodyweight than piglets from non-diarrhoeic litters. Likewise, diarrhoea after weaning was associated with an increased incidence of diseases of the skin and respiratory tract. Thus the risk of contracting respiratory disease was 4 times greater in diarrhoeic litters.

Animals↗
PubMed1989

Epidemiological studies of piglet diarrhoea in intensively managed Danish sow herds. III. Rotavirus infection.

The prevalence of rotavirus infection was studied in 1090 litters from 26 sow herds. Samples of normal, semifluid and watery stools were examined for rotavirus by an ELISA-test on faeces. Rotavirus was detected in 77% of the herds and in 30.5% of the litters (prevalence rates). The highest prevalence rate was seen in piglets between 21 and 41 days of age. Gilts' litters had a very high prevalence during the first week of life. Apart from this, no difference was found between litters from gilts and older sows. Rotavirus was detected more frequently in semiliquid, loose stools than in normal or watery stools, and an association between virus detection and diarrhoea could not be demonstrated. However, litters which shedded rotavirus during the suckling period had lower weight gains and higher incidence rates of respiratory diseases than virus-free litters. Litters weaned at 2 weeks in battery cages had slightly increased risk of shedding rotavirus compared to litters weaned in more traditional systems. The study revealed that rotavirus is widespread in Danish swine herds. The findings give evidence to suggest that the type of mild diarrhoea in 3-week-old piglets known as steatorrhoea or "white scours" may be associated with rotavirus infection, possibly in combination with E. coli and other agents. The high prevalence in piglets weaned at 2 weeks plus the higher morbidity and mortality among such piglets sustain the conclusion that piglets should not be weaned before 3 weeks of age or below a body weight of 6-7 kg.

Age Factors↗
PubMed1986

[Epidemiological analysis of a data bank on slaughtering pigs].

The structure and functions of the Danish Swine Slaughter Inspection System are described in the present paper. Particular attention was paid to epidemiological routine use and the use of this system for purpose of research. The former is essential to the support of the pig health care programme in Denmark. A few instances of descriptive as well as analytical studies are cited, which studies were based on a data bank, various methods of collecting data and various models of research being adopted. The importance of considering the various aspects of the validity of data with regard to each specific use is emphatically stressed.

Animal Husbandry↗
PubMed1984

The impact of terrestrial and estuarial factors on the density of environmental bacterial (Vibrionaceae) and faecal coliforms in coastal water.

A study of the densities of faecal coliforms, Vibrio anguillarum, Vibrio alginolyticus and Aeromonas hydrophila in Danish bathing areas was carried out over the period May-October, 1981 with special reference to specific terrestrial and estuarial determinants. Significant correlations were found between V. anguillarum and V. alginolyticus (r = 0.57) and A. hydrophila and faecal coliforms (r = 0.43). The densities of the Vibrios were highly influenced by temperature and distance from pollution source, while salinity was of minor importance. R2 values for V. anguillarum, V. alginolyticus and A. hydrophila of 0.54, 0.51 and 0.40, respectively, indicate that these organisms were superior to faecal coliforms (R2 = 0.21) in characterizing the local conditions. The following levels were used as relevant to characterize an environmental risk: faecal coliforms 1000/100 ml, V. anguillarum 10000/100 ml, V. alginolyticus 500/100 ml and A. hydrophila 500/100 ml. It was found that the position of sampling site, discharge with the current, and uncontrolled outlets influence the frequency of violations. At certain sites coincidence of violations for both faecal and environmental bacteria indicated a simultaneous existence of a faecal and "organic" pollution. At other sampling sites high levels of environmental bacteria only should be considered important to the evaluation of the hygienic quality of the water.

Aeromonas↗
PubMed1982

Left displacement of the abomasum: relationship to age and medical history.

The present study shows that 5 years is the numerically most frequently observed age at onset of left displacement of the abomasum (LDA) in dairy cows, and that the risk of LDA actually increases with age (Fig. 1 and 2). A high prevalence (70-75%) of other or concurrent disorders among LDA cows is observed (Tables I and II). The apparent excess risk among LDA cows of getting other diseases throughout their lives, including retained placenta (RP), disappeared when adjustments were made for age (Tables III and IV) and it is concluded that LDA cows have a higher incidence of other disorders mainly because they tend to be older cows. A negative influence of RP and LDA on reproductive performance was finally observed (Table V).

Abomasum↗
PubMed1982

Milk production and left displaced abomasum: cause and effect relationships.

In a Danish dairy herd affected with a number of cases of left displaced abomasum the milk production during the lactation periods of affected cows was retrospectively compared to that in two groups of non-affected cows. Group A contained all cows calving at the same time as the cases, and group B had one cow for each of the cases of similar age and with similar preceding production level. The average 305-days milk production was 610 kg lower among the cases than among cows in group B, as a best estimate of the amount of milk lost for each case of left displaced abomasum. The difference between mean production in groups B and A was 183 kg, indicating a higher than average production potential among cases, since matching on preceding production level had been carried out between the cases and the cows in group B, but not in group A. It may therefore be concluded that high yielding cows are at excess risk of left displaced abomasum, which in turn leads to a considerable loss of milk among affected cows.

Abomasum↗
PubMed1982

Epizootiologic patterns of diabetes mellitus in dogs.

A case-control study of spontaneous diabetes mellitus in dogs was undertaken, using 2 veterinary data bases. The Veterinary Medical Data Program (VMDP) contained records of 1,019 cases of canine diabetes from 14 university-affiliated veterinary hospitals. The Animal Medical Center (AMC), a private veterinary hospital which has not participated in the VMDP, contained records of 449 diabetes cases. Each data base was analyzed separately, control groups being chosen from all admissions, excluding diabetic animals. Summary odds ratios by sex adjusted for age and breed indicated significantly (P less than 0.05) elevated risks for entire females and neutered females compared with that for entire males. The VMDP data indicated a significantly elevated risk for castrated males, whereas the risk derived from AMC data was not significantly different from 1. Analysis of risks by breed adjusting for age and sex identified Poodles as being at significantly excess risk, and German Shepherd Dogs, Cocker Spaniels, Collies, and Boxers at significantly decreased risk in both data sets. The male-female risk ratio changed with age from 1 at less than 1 year of age to a predominance of females at older ages. In the AMC data base, diabetes was significantly associated with cataracts in dogs of both sexes combined. Diabetes was also significantly associated with benign mammary tumors in female dogs.

Age Factors↗