Occurrence of Coxiella burnetii in Polish dairy cattle herds based on serological and PCR tests

The aim of the research was to assess the prevalence of antibodies to Coxiella burnetii in dairy cattle herds in Poland and to compare the results of real-time PCR and ELISA tests performed on bulk tank milk (BTM) samples. In total, 2635 serum samples collected from 969 dairy cattle herds from all provinces were tested using ELISA. Additionally, BTM specimens from 101 herds were analysed by ELISA and real-time PCR targeting IS1111 element. Presence of anti-C. burnetii antibodies was confirmed in 25.39% of serum samples in 237 herds (24.46%) and the herd-level seroprevalence in Voivodeships varied from 2.5% to 61.4%. Moreover, 46 (45.5%) of analysed bulk tank milk samples gave postive result in ELISA and microbial DNA was detected in 40 (39.6%) of tested herds. The comparative analysis of ELISA and real-time PCR results obtained for BTM samples using the chi-square test showed statistically significant relationship between results of both methods.     

Schmallenberg virus in Dutch dairy herds: Potential risk factors for high within-herd seroprevalence and malformations in calves,and its impact on productivity

In November 2011, the new orthobunyavirus Schmallenberg virus (SBV) was identified in dairy cows that had induced fever, drop in milk production and diarrhoea in the Netherlands (Muskens et al., 2012. Tijdschrift voor Diergeneeskunde 137, 112–115) and a drop in milk production in cows in Northwestern Germany (Hoffmann et al., 2012. Emerging Infectious Diseases 18 (3), 469–472), in August/September 2011. This study aimed at quantifying risk factors for high within-herd prevalence of SBV and SBV-induced malformations in newborn calves in dairy herds in the Netherlands. Additionally, the within-herd impact of SBV infection on mortality rates and milk production was estimated.A case-control design was used, including 75 clinically affected case herds and 74 control herds. Control herds were selected based on absence of malformations in newborn calves and anomalies in reproductive performance. SBV-specific within-herd seroprevalences were estimated. Risk factors for high within-herd SBV seroprevalence (>50%) and the probability of malformed newborn calves in a herd were quantified. In addition, within-herd impact of SBV with regard to milk production and mortality was estimated.Animal-level seroprevalence was 84.4% (95% confidence interval (CI): 70.8–92.3) in case herds and 75.8% (95% CI: 67.5–82.5) in control herds. Control herds that were completely free from SBV were not present in the study. Herds that were grazed in 2011 had an increased odds (OR 9.9; 95% CI: 2.4–41.2)) of a high seroprevalence (>50%) compared to herds that were kept indoors. Also, when grazing was applied in 2011, the odds of malformations in newborn calves tended to be 2.6 times higher compared to herds in which cattle were kept indoors. Incidence of malformations in newborn calves at herd level was associated with both within-herd seroprevalence and clinical expression of the disease in adult cattle.The rate of vertical transmission of SBV to the fetus once a dam gets infected seemed low. A total of 146 stillborn or malformed calves were submitted by 65 farmers during the study period, of which 19 were diagnosed as SBV-positive based on pathological investigation and/or RT-qPCR testing of brain tissue. Based on these results combined with calving data from these herds we roughly estimated that at least 0.5% of the calves born between February and September 2012 have been infected by SBV.A drop in milk production was observed between the end of August 2011 and the first half of September (week 35–36), indicating the acute phase of the epidemic. During a 4-week period in which SBV infection was expected to have occurred, the total loss in milk production in affected dairy herds was around 30–51 kg per cow. SBV had no or limited impact on mortality rates which was as expected given the relatively mild expression of SBV in adult cows and the low incidence of malformations in newborn calves.     

Vaccination using phase I vaccine is effective to control Coxiella burnetii shedding in infected dairy cattle herds

The effectiveness of the vaccination of dairy cows combined or not with antibiotics (i.e. oxytetracycline) to control Coxiella burnetii (Cb) shedding at herd level was investigated in 77 Q fever clinically affected herds. In addition to nulliparous heifers’ vaccination, one out of the four following medical strategies was randomly assigned to dairy cows in each herd: vaccination (using a phase I vaccine) alone, vaccination combined with oxytetracycline, oxytetracycline alone or nothing. Their effectiveness to reduce Cb load in quarterly samples of bulk tank milk (BTM) and of pooled milk of primiparous (MP) was assessed through logistic hierarchical models. A significant reduction in Cb load was observed in herds where the vaccination of ≥80% of dairy cows was implemented; whereas the use of antibiotics was uneffective. Our findings support the interest of a whole vaccination strategy and provide evidence for decreasing the use of antibiotics in dairy cattle herds.     

Prevalence of Coxiella burnetii in Central and Eastern European dairy herds

The aim of the present study was to assess the prevalence of Coxiella burnetii in dairy herds in Central and Eastern European countries based on ELISA and PCR tests. A total of 370 bulk tank milk samples were collected in 2019 originating from Croatia (n = 13), Czech Republic (n = 138), Hungary (n = 126), Serbia (n = 24), Slovakia (n = 53) and Slovenia (n = 16). Prevalence of C. burnetii differed according to the country of origin with Croatia showing 100.00%, the Czech Republic 98.55%, Hungary 97.61%, Serbia 70.83%, Slovakia 90.56% and Slovenia showing 62.50% average percentages of the positive herds. C. burnetii specific ELISA showed 100.00% positivity in all examined countries if herds consisted of equal or above 250 milking cows. The growing number of farms managing large number of animals, where cattle density is high correlates with the increasing prevalence of C. burnetii in the region.     

Risk factors for Coxiella burnetii antibodies in bulk tank milk from Danish dairy herds

The aim was to identify risk factors associated with Coxiella burnetii antibody positivity in bulk tank milk (BTM) samples from 100 randomly selected Danish dairy cattle herds. Antibody levels were measured by an enzyme-linked immuno-sorbent assay. Before testing the herds, the farm managers were interviewed about hired labour, biosecurity, housing and herd health during the 12 months prior to the study. Variables considered important for C. burnetii antibody positivity in multivariable logistic regression analysis included the sharing of machines between farms (OR = 3.6), human contacts (OR = 4.2), artificial insemination by other people than artificial insemination technicians (OR = 7.7), routine herd health contract with the veterinarian (OR = 4.3) and hygiene precautions taken by veterinarians (OR = 5). In addition, herd size, hired labour, trading of cattle between farms, quarantine and use of calving and disease pens also showed significant association in univariable analysis. This study demonstrates that strict biosecurity is important for the prevention of infections with C. burnetii.     

Influence of modifiable risk factors on the incidence of stillbirth/perinatal mortality in dairy cattle

Bovine perinatal mortality is defined as the death of a full-term calf before, during or up to 48 h after calving. Recent studies indicate that the prevalence of bovine perinatal mortality is increasing, particularly in Holstein primiparae. Factors leading to a greater incidence of dystocia are the most important modifiable variables influencing the risk of perinatal mortality. Modifiable predictors are largely (age at first calving, breeding method, sire, calving management, feto-maternal health status and gestational nutrition) or moderately (calf breed, sex, gestation length) under the control of the dairy farm manager. Unlike non-modifiable risk factors, such as primiparity and fetal plurality, these factors can be manipulated to reduce the incidence of perinatal mortality.     

Prevalence and risk factors of Coxiella burnetii seropositivity in Danish beef and dairy cattle at slaughter adjusted for test uncertainty

Antibodies to Coxiella burnetii have been found in the Danish dairy cattle population with high levels of herd and within herd seroprevalences. However, the prevalence of antibodies to C. burnetii in Danish beef cattle remains unknown. The objectives of this study were to (1) estimate the prevalence and (2) identify risk factors associated with C. burnetii seropositivity in Danish beef and dairy cattle based on sampling at slaughter.     

Tuberculosis and brucellosis prevalence survey on dairy cattle in Mbarara milk basin (Uganda)

We determined the prevalence of tuberculosis and brucellosis reactors in the dairy herds in the Mbarara district of Uganda in 2002. This is one of the most important dairy-production areas of the country and includes both pastoral and agro-pastoral zones. A total of 340 (of 11,995) randomly selected herds were tested for tuberculosis, using the intradermal tuberculosis-skin test and 315 (of 10,562) herds tested for brucellosis using the serum Rose Bengal test.

The herd prevalence for tuberculosis reactors was 74.1% (95% confidence intervals 69, 78), the individual-animal prevalence was of 6.0% (5.6, 6.5) and within-herd range was 1–50% (up to 100% if suspicious reactors were included).

The herd prevalence for brucellosis was 55.6% (50, 61.2) individual-animal prevalence 15.8% (14.8, 16.7) and within-herd range 1–90%.

The reactor prevalence increased with the age of the animals for both tuberculosis and brucellosis.

Tuberculosis reactor prevalences were higher in animals from the agro-pastoral zone. However, the individual-animal and herd prevalences of brucellosis seroprevalences were higher in the pastoral zone.     

Prevalence of Coxiella burnetii infection in Dutch dairy herds based on testing bulk tank milk and individual samples by PCR and ELISA

A study using an ELISA and a real-time PCR assay based on the detection of the repetitive transposon-like gene of Coxiella burnetii revealed that infection with the bacterium was widespread among Dutch dairy herds, with antibodies detected in bulk tank milk (BTM) from 268 of 341 herds (78.6 per cent) and bacterial DNA detected in 193 of 341 herds (56.6 per cent). The BTM samples were taken in November and December 2007. Serological and molecular studies in young and adult cattle selected from 100 herds showed that antibodies were present in the blood of 470 of 2936 (16.0 per cent) lactating cows but only in 19 of 1831 (1.0 per cent) young animals. Bacterial DNA was detected in the milk of 254 of 2925 (8.7 per cent) lactating cows; bacterial DNA was not detected in any of the faecal samples obtained from youngstock. The blood and milk samples were taken from the cattle in the period January to April 2008.     

Prevalence of Bovine Viral Diarrhoea Virus antibodies among the industrial dairy cattle herds in suburb of Mashhad-Iran

Mashhad is a major dairy production in Iran. The subject of this study was to survey the seroprevalence of Bovine Viral Diarrhea Virus (BVDV) infection using an indirect Enzyme-linked immunosorbent assay (ELISA) test in industrial dairy cattle herds in suburb of Mashhad-Iran. Totally, 141 serum samples were tested. None of the herds had been vaccinated against BVDV. Commercial indirect ELISA kit was used. The herds divided to 3 sizes as cow population. They were included: small, medium and large herds. Data were analyzed using Chi-square test. Ninety-seven (68.79%) cows were ELISA seropositive. However, the true BVDV seroprevalence was 72.25%. All of the herds were antibody positive against BVDV. The prevalence ranged from 66 to 100% within the herds. There were no significant differences between the presence of antibodies to BVDV and the herd size (P > 0.05). The prevalence in animals lower than 2 years old differed significantly with cows higher than 2 years old (P < 0.05). According to the results, it is concluded that it is likely the presence of persistently infection (PI) animal(s) within the herds in suburb of Mashhad-Iran, which is responsible for the presence antibody.     

Apparent prevalence of antibodies to Coxiella burnetii (Q fever) in bulk tank milk from dairy herds in southern Belgium

In 2006, a cross-sectional survey was carried out in 206 herds in southern Belgium to estimate the proportion of herds with Q fever-seropositive bulk tank milk (BTM), i.e. herds with an intra-herd seroprevalence >10%. Of the tested herds, 119 (57.8%; 95% CI: 51.1-64.4%) were seropositive. Most had a low antibody titre. Of these herds, 50 were randomly subjected to a real time Coxiella burnetii PCR analysis. The proportion of herds excreting Coxiella in BTM was 30.0% with only 2.0% of herds having a high level of shedding. An additional questionnaire and logistical regression identified some factors which increased the risk of BTM seroconversion (in heifers, drinking water from watercourse or well water) and some which decreased it (in heifers, tie- and free-stalling, and animals of all age in the same shed; in heifers and cows, shed disinfection).     

Prevalence and associated management factors of Cryptosporidium shedding in 50 Swedish dairy herds

Cryptosporidium parvum is a protozoan parasite causing diarrhoea in young calves. This cross-sectional study was performed to estimate the prevalence of Cryptosporidium infected herds in a sample of Swedish dairy herds and to identify potential risk factors associated with shedding of oocysts. Fifty dairy herds, selected by stratified random sampling, were included. The herds were visited once during the indoor seasons of 2005–2006 and 2006–2007. Faecal samples were collected from 10 calves, 10 young stock and 5 cows in each herd. Clinical observations of sampled animals and environmental status were recorded, and farmers were interviewed about management procedures. Faecal samples were cleaned by sodium chloride flotation and detection of oocysts was made by epifluorescence microscopy. Cryptosporidium parvum-like oocysts were found in 96% of the herds. Prevalence was 52% in calves, 29% in young stock and 5.6% in cows. Three two-day-old calves shed oocysts. Cryptosporidium andersoni was found in seven animals from four different herds. Factors associated with prevalence of shedders among sampled animals in a herd were age at weaning, cleaning of single calf pens, placing of young stock, system for moving young stock, and year of sampling. Factors associated with shedding in calves were age, placing of young stock, routines for moving young stock and time calf stays with the cow. The only significant factor in young stock was age. In cows, number of calves in the herd and type of farming (organic vs. conventional) affected shedding.     

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, ≥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.     

Prevalence and risk factors associated with bovine viral diarrhea virus infection in dairy herds in Jordan

A cross-sectional study was carried out to determine the seroprevalence and to identify risk factors associated with bovine viral diarrhea virus (BVDV) infection in 62 non-vaccinated dairy herds (671 cows) in Jordan between January and June 2007. Information regarding herd management was recorded through a personal interview with farmers. Antibodies against BVDV were detected using an indirect ELISA test. Chi-square analysis and multivariable logistic regression model were used to identify risk factors for BVDV seropositivity. The true prevalence of antibodies against BVDV in individual cows and cattle herds was 31.6% and 80.7%, respectively. The seroprevalence of BVDV in medium and large size herds was significantly higher than that in smaller herds. There was no significant difference in BVD seroprevalence between different age groups. Random-effects logistic regression model revealed two major factors associated with seropositivity to BVDV; exchange of visits between adjacent farm workers and not isolating newly purchased animals before addition to the herd. The seroprevalence of BVDV in cows located in the northern Jordanian governorates was significantly higher than that in other studied governorates. Results of this study indicated that BVDV is highly prevalent in Jordan and BVDV infection could be controlled by livestock-trade control, and applying strict biosecurity measures in the dairy farms.     

Prevalence of antibodies to Coxiella burnetii (Q fever) in bulk tank milk in England and Wales.

In the United Kingdom, the infection of people with Coxiella burnetii, the causative agent of Q fever, is of significant public health importance and is associated with contact with dairy cattle. An ELISA was developed for the detection of IgG antibodies against C burnetii in bulk tank milk, and in a survey of randomly selected samples from dairy herds in England and Wales, 21 per cent showed serological evidence of C burnetii infection.     

Farm management factors associated with bulk tank total bacterial count in Irish dairy herds during 2006/07

Research has shown that total bacterial count (TBC), which is the bacterial growth per ml of milk over a fixed period of time, can be decreased by good hygiene and farm management practices. The objective of the current study was to quantify the associations between herd management factors and bulk tank TBC in Irish spring calving, grass-based dairy herds. The relationship between bulk tank TBC and farm management and infrastructure was examined using data from 400 randomly selected Irish dairy farms where the basal diet was grazed grass. Herd management factors associated with bulk tank TBC were identified using linear models with herd annual total bacterial score (i.e., arithmetic mean of the natural logarithm of bulk tank TBC) included as the dependent variable. All herd management factors were individually analysed in a separate regression model, that included an adjustment for geographical location of the farm. A multiple stepwise regression model was subsequently developed. Median bulk tank TBC for the sample herds was 18,483 cells/ml ranging from 10,441 to 130,458 cells/ml. Results from the multivariate analysis indicated that the following management practices were associated with low TBC; use of heated water in the milking parlour; participation in a milk recording scheme; and tail clipping of cows at a frequency greater than once per year. Increased level of hygiene of the parlour and cubicles were also associated with lower TBC. Herd management factors associated with bulk tank TBC in Irish grazing herds were generally in agreement with most previous studies from confinement systems of milk production.     

Prevalence and risk factors of Campylobacter infection in broiler flocks from southern Spain

An extensive epidemiological study was performed to determine the prevalence and risk factors of Campylobacter infection in broiler farms in Andalusia (southern Spain). A total of 2221 cloacal swabs and 747 environmental swabs from 291 broiler flocks were screened between April 2010 and May 2012. The prevalence of Campylobacter in individual animals was 38.1%, and the flock prevalence was 62.9%. Flocks were predominantly infected by C. jejuni and C. coli but were also infected by untyped Campylobacter spp., and mixed-species infection could be found. Risk factors for Campylobacter infection were assessed from direct interview of the farmers. The number of positive samples by flock was modelled assuming a binomial distribution. Analysis indicated five factors associated with increased intra-flock prevalence: presence of dogs or cats on the farm, older age of the broiler flock, the application of thinning of flocks, the presence of windows with canvas blinds, and the presence of rodents in the poultry house. Two factors were associated with decreased intra-flock prevalence: the treatment of drinking water and having an entrance room for access into the poultry house. This is the first study performed on broilers farms from Spain reporting the risk factors of Campylobacter infection and is the largest study on the prevalence of Campylobacter infection.     

Risk factors for culling and deaths in eight dairy herds

Objectives To identify risk factors for culling of dairy cows from eight New South Wales dairy herds.
Design A longitudinal population study of dairy cow culling in eight non-seasonally calving dairy herds in the Camden district of New South Wales. Cox's proportional hazards model was used to evaluate various risk factors for culling for a specific reason (sales, deaths, reproductive failure, disorders of the udder and low milk production).
Results Age at first calving was not a significant risk factor for culling. Milk production in the first lactation greater than the population mean did not influence length of productive life overall, but was associated with a greater hazard of removal for disorders of the udder. Risk of culling for reproductive failure differed significantly between farms, and was not related to events in the previous lactation such as calving-to-first service interval or calving-to-conception interval. Shorter calving intervals were associated with increased risk of removal for low milk production and disorders of the udder.
Conclusion Longitudinal surveys to accurately identify reasons for removal from a wide range of herds, identification of herds with low culling rates (especially for reproductive failure and udder disorders), and the identification of practices associated with these culling rates would be worthwhile to the Australian dairy industry.