A cross-sectional study of associations between herd-level calf mortality rates, compliance with legislation on calf welfare, and milk feeding management in Norwegian dairy herds.

Our aim was to investigate the associations between management factors, compliance with current legislation, and herd-level calf mortality. In a national calf welfare audit, veterinary inspectors from the Norwegian Food Safety Authority assessed compliance with current legislation on calf welfare (n = 912 herds). Nine criteria were assessed and rated as satisfactory (1) or not satisfactory (0): housing, natural behavior, single pens, colostrum feeding, feeding, water, surveillance, illness/injuries, and <5% mortality rate. In addition, a short questionnaire on milk feeding management for 3-wk-old calves was distributed to all national calf welfare audit herds, and data on mortality and disease recordings were obtained from the Norwegian Dairy Herd Recording System (NDHRS). A herd welfare compliance score (WCS) for each farm was constructed, summarizing the results for the individual criteria. Most herds had a high WCS (median 9.0, range 2-9). Fifty-six percent of the national calf welfare audit herds (508/912) responded to the questionnaire. We performed a cross-sectional study using a data set from 431 herds with available data on recorded disease and mortality events from the NDHRS, recordings from the national calf welfare audit, and the questionnaire. A mixed-effects negative binomial model with Norwegian Food Safety Authority district as the random effect was fitted to the data. Of the 416 herds with available data on calf mortality, 108 (25.9%) reported no mortality in 2016, and the median 6-mo mortality rate was 0.064 (interquartile range 0-0.11) dead calves per 6 calf-months at risk, based on NDHRS recordings. Calf mortality rates were higher in herds whose calves did not have free access to water (incidence rate ratio 1.29; 95% confidence interval 1.02-1.64) and higher in herds that had reported calf disease events (incidence rate ratio 1.31; 95% confidence interval 1.09-1.54). Neither the WCS nor any of the calf milk feeding management factors were associated with mortality, but more than half of producers (59.6%) fed less milk than currently recommended for 3-wk-old calves (8 L/d first 3 to 4 wk). These results indicate that a lack of access to water was associated with higher calf mortality rates. Herds with registered calf disease events had a higher incidence rate ratio of mortality. This finding may be linked to suboptimal calf management, leading to more calf diseases and mortality; or it may be that veterinary consultancy occurs too late or only for the worst cases. There is room for improvement in Norwegian dairy calf management, and water should be provided to young calves.

Occurrence and spread of influenza A(H1N1)pdm09 virus infection in Norwegian pig herds based on active serosurveillance from 2010 to 2014.

The incursion of influenza A(H1N1)pdm09 virus was detected by Norway's active serosurveillance of its pig population in 2009. Since then, surveillance data from 2010 to 2014 revealed that 54% of 5643 herd tests involving 1567 pig herds and 28% of 23 036 blood samples screened positive for antibodies against influenza A virus. Positive herds were confirmed to have influenza A(H1N1)pdm09 virus infection by haemagglutination inhibition test. In 50% of positive herd tests, ⩾60% of the sampled pigs in each herd had antibodies against influenza A(H1N1)pdm09 virus. This within-herd animal seroprevalence did not vary for type of production, herd size or year of test. The overall running mean of national herd seroprevalence, and annual herd incidence risks fluctuated narrowly around the means of 45% and 32%, respectively, with the highest levels recorded in the three densest pig-producing counties. The probability of a herd being seropositive varied in the five production classes, which were sow pools, multiplier herds, conventional sow herds, nucleus herds, and fattening herds in descending order of likelihood. Large herds were more likely to be seropositive. Seropositive herds were highly likely to be seropositive the following year. The study shows that influenza A(H1N1)pdm09 virus is established in the Norwegian pig population with recurrent and new herd infections every year with the national herd seroprevalence in 2014 hovering at around 43% (95% confidence interval 40-46%).

Transmission dynamics of pancreas disease (PD) in a Norwegian fjord: aspects of water transport, contact networks and infection pressure among salmon farms.

Pancreas disease (PD) in marine salmon farming is caused by salmon pancreas disease virus (SPDV). Virus survival, infection pressure and contact networks among farms influence the potential of PD to spread. The present study aims to explore contact networks and infection pressure and their ability to explain transmission dynamics of PD in a Norwegian fjord. In this study, we included all records of PD by subtype 3 (SPDV3) in the study population from the first reported in August 2006 to the last reported in November 2009. Using logistic regression analyses, we found that contact network by water transport explained better transmission of PD than contact networks defined by ownership or close distance to infected farms. Hydrodynamic modelling can be a valuable tool to forecast the spread of PD and thereby take actions to reduce the transmission. Knowing the risk of getting infected, it is important to avoid water transport from infected farms when new cohorts are transferred to sea water, and to have conscious control regarding management operations between farms.

The Norwegian Healthier Goats program--modeling lactation curves using a multilevel cubic spline regression model.

In 2001, the Norwegian Goat Health Service initiated the Healthier Goats program (HG), with the aim of eradicating caprine arthritis encephalitis, caseous lymphadenitis, and Johne's disease (caprine paratuberculosis) in Norwegian goat herds. The aim of the present study was to explore how control and eradication of the above-mentioned diseases by enrolling in HG affected milk yield by comparison with herds not enrolled in HG. Lactation curves were modeled using a multilevel cubic spline regression model where farm, goat, and lactation were included as random effect parameters. The data material contained 135,446 registrations of daily milk yield from 28,829 lactations in 43 herds. The multilevel cubic spline regression model was applied to 4 categories of data: enrolled early, control early, enrolled late, and control late. For enrolled herds, the early and late notations refer to the situation before and after enrolling in HG; for nonenrolled herds (controls), they refer to development over time, independent of HG. Total milk yield increased in the enrolled herds after eradication: the total milk yields in the fourth lactation were 634.2 and 873.3 kg in enrolled early and enrolled late herds, respectively, and 613.2 and 701.4 kg in the control early and control late herds, respectively. Day of peak yield differed between enrolled and control herds. The day of peak yield came on d 6 of lactation for the control early category for parities 2, 3, and 4, indicating an inability of the goats to further increase their milk yield from the initial level. For enrolled herds, on the other hand, peak yield came between d 49 and 56, indicating a gradual increase in milk yield after kidding. Our results indicate that enrollment in the HG disease eradication program improved the milk yield of dairy goats considerably, and that the multilevel cubic spline regression was a suitable model for exploring effects of disease control and eradication on milk yield.

Lumpy skin disease in cattle in central Ethiopia: outbreak investigation and isolation and molecular detection of the virus.

The study was a combination of two investigations into active outbreaks of lumpy skin disease (LSD) in cattle in central Ethiopia and a retrospective analysis of outbreak reports between January 2007 and December 2011 covering the entire country. Active outbreaks were investigated in four districts of central Ethiopia: Adama, Wenji, Mojo and Welenchiti. A semi-structured questionnaire was used to acquire data at individual and herd levels, and tissue samples were collected for viral isolation and characterisation. The retrospective analyses showed that, during the five-year period, a total of 1,675 outbreaks were reported, with 62,176 cases and 4,372 deaths. The highest number of outbreaks was reported in Oromia (1,066), followed by Amhara (365) and the Southern Nations, Nationalities and People's Region (123). Outbreaks were more frequently observed between September and December and the highest number of outbreaks was reported in 2010. During the period studied, a total of 2,174 local zebu cattle were clinically examined and morbidity and mortality rates of 13.61% (296) and 4.97% (108) were recorded, respectively. Analysis of the active outbreaks revealed a relatively consistent morbidity rate, with the highest observed in Adama (15.38%), followed by Wenji (10.26%). The highest mortality rates were also observed in Adama (5.89%) and Wenji (3.42%). The LSD virus was isolated from 22 samples and all tested positive in polymerase chain reaction analysis. The disease was observed in the cattle regardless of previous vaccination with Kenyan sheep- and goat-pox vaccine; thus, vaccine efficacy was assessed under field conditions and the authors' findings, together with a possible remedy, are presented in this paper.

Reproductive disorders in relation to Neospora caninum, Brucella spp. and bovine viral diarrhoea virus serostatus in breeding and dairy farms of central and southern Ethiopia.

Abortion and stillbirth are important reproductive disorders in the dairy industry and are often caused by infectious agents. This study investigated whether bovine viral diarrhoea virus (BVDV), Brucella spp., and Neospora caninum are associated with abortion and/or stillbirth in dairy cattle in Ethiopia. Dairy cattle from 99 farms were categorized as cases (n=134) or controls (n=268) according to reproductive data. Blood samples were screened for antibodies for these infectious agents. The overall proportion of cattle that were seropositive for BVDV, Brucella spp., and N. caninum was 11∙7%, 3∙2%, and 17∙2%, respectively. Seropositivity for BVDV and Brucella spp. was similar for cases and controls, but significantly more cases were seropositive for N. caninum (29∙8%) than controls (10∙8%). This is the first report demonstrating N. caninum is common in dairy cattle in Ethiopia, and is probably a greater impediment to reproductive success in Ethiopian dairy farms than either BVDV or Brucella spp.

Stochastic model for estimating the risk of transfusion-transmitted hepatitis B in Vietnam.

BACKGROUND AND OBJECTIVE: Transfusion-transmitted hepatitis B virus (HBV) infection may originate from hepatitis B surface antigen (HBsAg) false-negative blood donors, HBsAg negative and anti-HBc positive blood donors and blood donors with both tests negative. HBV DNA may be present in all these cases and blood may be infectious. The aim of the study was to estimate the risk of transfusion-transmitted HBV in Vietnam using a stochastic Monte Carlo model. METHODS: A cross-sectional study of HBV prevalence in 1200 potential blood donors in rural Vietnam is used as basis for the Monte Carlo model together with expert panel estimates of occult hepatitis B infection (OBI) prevalence in blood donors. RESULTS: With 1 000 000 blood donors running in the model, the potential OBI ranged from 658 to 747 blood units per million at 5 percentile and from 1342 to 2507 blood units per million at 95 percentile resulting in the risk of post-transfusion hepatitis ranging from 66 to 250 blood units per million assuming that risk of post-transfusion from potential OBI is 10%. Using the manufacturer's HBsAg sensitivity, the mean rate of blood units per million donations having false-negative HBsAg results was 298 (5-95 percentile: 14-893). When the test sensitivity was set lower, false-negative tests was observed at a mean of 1087 per million (5-95 percentile: 762-3220). The fraction of potential OBI donors increased with the increasing age in both genders. CONCLUSION: Current HBsAg screening in Vietnam is insufficient in eliminating the risk of transfusion-transmitted HBV infection. The major risk factors are HBsAg false-negative results and OBI. Increased test sensitivity and locally validated HBsAg assays are recommended.

Modelling salmon lice, Lepeophtheirus salmonis, reproduction on farmed Atlantic salmon, Salmo salar L.

The aim of this study was to model sea lice levels and the effect on reproduction by a stochastic simulation model and to evaluate the uncertainty of lice estimates based upon counts. Two empirical data sets were examined to parameterize the models. An overall fit of the data to the Poisson distribution was found and thus was used as the base of the stochastic models. In the model, salmon lice reproduction is not linear with the number of adult females and at low lice loads a smaller proportion of the adult female lice will reproduce. Depending on the variance structure, it was estimated that between 40% and 60% of the adult female lice will reproduce at an abundance of 0.5 adult females per fish. Lice counts, especially when examining few fish at low lice loads, are uncertain and at a true abundance of 0.1 one may count between 0 and 5 lice when examining 10 fish. Understanding the dynamics of sea lice reproduction is a key factor in the development of sustainable control strategies.

Piscine reovirus (PRV) in wild Atlantic salmon, Salmo salar L., and sea-trout, Salmo trutta L., in Norway.

This is the first comprehensive study on the occurrence and distribution of piscine reovirus (PRV) in Atlantic salmon, Salmo salar L., caught in Norwegian rivers. PRV is a newly discovered reovirus associated with heart and skeletal muscle inflammation (HSMI), a serious and commercially important disease affecting farmed Atlantic salmon in Norway. A cross-sectional survey based on real-time RT-PCR screening of head kidney samples from wild, cultivated and escaped farmed Atlantic salmon caught from 2007 to 2009 in Norwegian rivers has been conducted. In addition, anadromous trout (sea-trout), Salmo trutta L., caught from 2007 to 2010, and anadromous Arctic char, Salvelinus alpinus (L.), caught from 2007 to 2009, were tested. PRV was detected in Atlantic salmon from all counties included in the study and in 31 of 36 examined rivers. PRV was also detected in sea-trout but not in anadromous Arctic char. In this study, the mean proportion of PRV positives was 13.4% in wild Atlantic salmon, 24.0% in salmon released for stock enhancement purposes and 55.2% in escaped farmed salmon. Histopathological examination of hearts from 21 PRV-positive wild and one cultivated salmon (Ct values ranging from 17.0 to 39.8) revealed no HSMI-related lesions. Thus, it seems that PRV is widespread in Atlantic salmon returning to Norwegian rivers, and that the virus can be present in high titres without causing lesions traditionally associated with HSMI.

Seroepidemiological study of livestock brucellosis in a pastoral region.

A seroepidemiological study of Brucella infections in multiple livestock species in the Borana pastoral system of Ethiopia was performed between December 2007 and October 2008. A cross-sectional multi-stage sampling technique was employed to select 575 cattle, 1073 camels and 1248 goats from the target populations. Sera were collected from the animals, and serially tested using Rose Bengal test and complement fixation test. Overall prevalence and prevalence with respect to explanatory variables were established, and potential risk factors for seropositivity were analysed using a multivariable logistic regression. The results showed that 8·0% (95% CI 6·0-10·6), 1·8% (95% CI 1·1-2·8) and 1·6% (95% CI 1·0-2·5) of the tested cattle, camels and goats, respectively, had antibodies to Brucella antigen. Positive reactors were found in 93·8% of the villages with more frequent detection of positive cattle (93·3%) than camels (56·3%) and goats (37·5%). Risk factors identified for cattle were: keeping more livestock species at household level (OR 4·1, 95% CI 1·9-8·9), increasing age of the animal (OR 2·8, 95% CI 1·3-6·0) and wet season (OR 3·3, 95% CI 1·6-6·9). Increase in household-level species composition (OR 4·1, 95% CI 1·2-14·2) and wet season (OR 3·7, 95% CI 1·5-9·1) were found to be risk factors for seropositivity in camels and goats, respectively. Existence of more than one seroreactor animal species in most villages and association of increased livestock species composition with seropositivity may add more credence to the possibility of cross-species transmission of Brucella infections. Although no attempt to isolate Brucella spp. was made, our results suggest that cattle are more likely maintenance hosts of Brucella abortus which has spread to goats and camels. This should be substantiated by further isolation and identification of Brucella organisms to trace the source of infection and transmission dynamics in various hosts kept under mixed conditions. In conclusion, the present study suggests the need for investigating a feasible control intervention and raising public awareness on prevention methods of human exposure to brucellosis.

Factors associated with cattle cleanliness on Norwegian dairy farms.

Animal cleanliness in dairy herds is essential to ensure hygienic milk production, high microbial quality of carcasses, good hide quality, and animal welfare. The objective of this study was to identify on-farm factors associated with dairy cattle cleanliness. The study also examined differences in risk factors and preventive factors between contrasting herds regarding cattle cleanliness. In total, 60 dairy herds, selected from a national database, were visited by 2 trained assessors during the indoor feeding period in February and March 2009. In Norwegian abattoirs, cattle are assessed and categorized according to hide cleanliness, based on national guidelines, using a 3-category scale. Dirty animals result in deductions in payment to farmers. "Dirty" herds (n=30) were defined as those that had most deductions in payment registered due to dirty animals slaughtered in 2007 and 2008. "Clean" herds (n=30) were those that had similar farm characteristics, but slaughtered only clean animals during 2007 and 2008, and thus had no deductions in payments registered. The dairy farms were located in 4 different areas of Norway. Relevant information, such as housing, bedding, feeding, and management practices concerning cleaning animals and floors, was collected during farm visits. In addition, the cleanliness of each animal over 1 yr of age (4,991 animals) was assessed and scored on a 5-point scale, and later changed to a dichotomous variable during statistical analysis. Milk data (milk yield and somatic cell counts) were obtained from the Norwegian Dairy Herd Recording System. Factors associated with dirty animals in all 60 herds were, in ranked order, high air humidity, many dirty animals slaughtered during the previous 2 yr, lack of preslaughter management practices toward cleaning animals, animal type (heifers and bulls/steers), housing (freestalls and pens without bedding), manure consistency, and lack of efforts directed toward cleaning the animals throughout the year. Additional factors associated with dirty animals in the dirty herds were water leakage from drinking nipples/troughs into lying areas, bedding type, and feed type. In the clean herds, additional risk factors were water leakage from drinking nipples/troughs and low milk yield.

Risk factors for Brucella spp. infection in smallholder household herds.

Risk factors for Brucella infection, the association and impact of Brucella seropositivity on abortions were investigated in cattle (n=1291) reared in smallholder household herds (n=203) from six geographical areas of Zimbabwe between September 2004 and 2005. Data on management, abortion and herd structure were collected. Sera were tested for Brucella antibodies using the Rose Bengal test and a competitive enzyme-linked immunosorbent assay. Data were analysed by generalized estimating equation and logistic regression models. Brucella antibodies were estimated at 5·5% and 22·9% for individual cattle and herds, respectively. Abortions were reported in 3·2% of cows and 22·0% herds. The age of cows and Brucella seropositivity predicted abortion. For herds, Brucella seropositivity, geographical area, purchase of cattle and large herd size were independently associated with increased odds of abortion. Exposure to Brucella had a significant impact on abortion. These results highlight the important risk factors for Brucella spp. infection in smallholder herds. Thus, brucellosis control programmes which take these factors into consideration will be beneficial.

Dairy farmer attitudes and empathy toward animals are associated with animal welfare indicators.

Attitudes and empathy of farmers influence human-animal interaction, thereby affecting their behavior toward animals. The goal was to investigate how measures of attitude and empathy toward animals were associated with animal welfare indicators such as milk yield, mastitis incidence, fertility index, and the prevalence of skin lesions on cows. To assess empathy toward animals, a photo-based pain assessment instrument was developed depicting various conditions that could be associated with some degree of pain in cattle and included questions aimed at assessing attitudes toward animals. Photos of painful conditions are useful in eliciting measurable empathic responses to pain in humans. A total of 221 farmers were sampled via e-mail and 154 responses were obtained. In the first analysis, farmers were categorized into 2 groups according to their agreement or disagreement with the attitude statement "animals experience physical pain as humans do." In the second analysis, farmers were assigned a median pain assessment score obtained from their estimates on the visual analog scale of 21 conditions assumed painful for cattle. In the third analysis, farmers were clustered in 3 groups according to their visual analog scale responses. Three conditions were ranked as the most painful: fracture of tuber coxae, dystocia, and serious mastitis. Farmers with positive attitudes toward animals scored 2 points higher on their empathy score compared with farmers with negative attitudes. Personal experience with each additional condition resulted in a 0.09 higher score. Cluster analysis revealed 3 groups. Farmers in group 3 had the highest median pain assessment score (6.7+/-0.2), indicating a high level of empathy and a positive attitude toward animals. They had the lowest prevalence of skin lesions over the carpus (24+/-6%) and the lowest milk production (6,705+/-202 kg). The complex associations between indicators of empathy and attitudes with relevant welfare outcomes suggest that competence building to safeguard animal welfare could benefit from including both attitudes and empathy in human-animal interactions studies.

Attitudes of veterinary students to pain in cattle.

Three hundred veterinary students were divided randomly into two groups to answer a questionnaire inquiring how painful they considered 23 conditions affecting cattle (seven of which were illustrated) to be, on either a numerical rating scale (NRS) or a visual analogue scale (VAS). The individual responses were used to assess whether cluster analysis could be used to divide the population into distinct groups. The ratios of men to women in the two groups were similar. The NRS scores ranged from 1 to 10 and the VAS scores ranged from 0 to 10. The conditions that were illustrated with a picture had a wider range of scores (2.65 to 9.0 v 2.67 to 7.93) and a slightly higher mean score (5.71 v 5.34) than those without pictures. Fracture of the tuber coxae, dystocia requiring the help of two people, and serious mastitis, were scored as the most painful conditions in adult cattle. Using the median score of each student as an outcome, their sex and year of enrollment and the scoring scale were significant. Women scored 0.9 points higher than men. Cluster analysis revealed two distinct groups in both the VAS and NRS, but the distribution was more even among the students using the VAS. This group was used in further analysis, and one cluster had the most men and more students with several siblings.

Risk factors associated with bovine tuberculosis in traditional cattle of the livestock/wildlife interface areas in the Kafue basin of Zambia.

We conducted a cross-sectional study from August 2003 to February 2004 to identify risk factors for bovine tuberculosis (BTB) in the Kafue basin of Zambia. We investigated a total of 106 herds of cattle for presence of BTB using the comparative intradermal tuberculin test (CITT) while an interviewer-administered questionnaire was used to gather epidemiological data on herd structure, management and grazing strategies. BTB prevalence at herd level was estimated and possible risk factors were investigated using the multiple logistic regression model. The true herd level prevalence of BTB was estimated at 49.8% (95% CI: 37.9, 61.7%). The logistic regression model showed that cattle herd BTB status was highly associated with area and husbandry practices. When compared to Kazungula, cattle herds in Blue Lagoon were more likely to test positive for BTB when other factors such as management practices were controlled (OR=10.5). In terms of grazing strategies, transhumant herds (TH) had higher odds (OR=3.0) of being positive compared to sedentary herds (OR=1.0). The results in this study provide preliminary information about potential risk factors that were found to be associated with BTB status in cattle.

Methods for investigating patterns of mortality and quantifying cause-specific mortality in sea-farmed Atlantic salmon Salmo salar.

Methods for investigating patterns of mortality and quantifying cause-specific mortality in Atlantic salmon Salmo salar farming were developed. The methods were further used to investigate mortality and patterns of mortality for the first 3 mo after sea transfer in the 2006 year-class autumn smolts (SO) of Norwegian farmed Atlantic salmon. In the study population, which consisted of 20 pens at 10 sites, cause-specific mortality was examined by 11 fish health professionals during 8 visits to each pen. Cause-specific mortality proportions were used to convert crude mortality into cause-specific mortality. Cumulative mortality in the study period was 2.1% in the study population compared with 3.7% for the 2006 year-class SOs in the national database. Of this cumulative mortality, 73 and 59% took place in 20% of the pens in the study and the reference population, respectively. Daily mortality rates in the study population showed a variation from 0 to 2376 per 100,000 fish where the majority of mortality was observed during disease outbreaks. All study pens had periods of low baseline mortality and some pens had no increased mortality during the study period. Of 2088 dead fish examined, 92% (1929 fish) were assigned a specific cause of death, and in 97% of these 1929 fish the investigators reported the given cause of death to be likely or very likely. Ulcers were the main cause of death, accounting for 43% of the assigned mortality, and infectious agents were involved in 64% of the total mortality. The study shows that probable causes of death can be established in Atlantic salmon farming and their contribution to total mortality measured.

Association of spinal deformity and vaccine-induced abdominal lesions in harvest-sized Atlantic salmon, Salmo salar L.

Spinal deformities in Atlantic salmon, Salmo salar L., have been described as a disease of multifactorial origin for which vaccines and time of vaccination have been suggested as risk factors. A vaccine efficacy trial where spinal deformity became evident was continued by the observational study reported here. In the preharvest part of the study 17 months post-sea transfer, there was a prevalence of 11.3% spinal deformity, with deformities present only in one vaccine group indicating a strong vaccine involvement. At slaughter, the prevalence of spinal deformities was 11.7%, and deformed fish had only 62% of normal slaughter weight. Visual analogue scales (VAS) were used for continuous recordings of vaccine-induced abdominal lesions and deformity. A logistic regression model associating presence of spinal deformity with markers of abdominal lesions was developed. The odds ratio for spinal deformity was 5.7 (95% CI: 3.4-9.4) for each unit increase in adhesion score (0-6) and 4.9 (2.9-3.4) for each unit increase in melanin on abdominal organs (0-3). Lesions in the dorsal caudal part of the abdomen gave an odds ratio for spinal deformity of 2.2.

Characterisation of mycobacteria isolated from slaughter cattle in pastoral regions of Uganda.

BACKGROUND: Bovine tuberculosis is a zoonotic problem in pastoral cattle and communities in Uganda. Tuberculin tests in pastoral cattle had shown a high herd but low animal prevalence, with a high proportion of avian reactors. No work had been done to identify the mycobacterial species involved. The objective of the study was to isolate and characterise Mycobacterial species causing tuberculous lesions in slaughtered animals. Lesioned organs compatible with bovine tuberculosis in slaughtered cattle from pastoral areas in Uganda were collected and cultured to isolate mycobacteria. AccuProbe culture identification kits for the Mycobacterium tuberculosis complex, M. avium complex and M. avium were used to identify the isolates. Spoligotyping and Insertion Sequence (IS) 1311 and IS1245 Restriction Fragment Length Polymorphism analysis (RFLP) were used to further characterise the isolates. RESULTS: Of the 61 lesioned organs and tissues cultured, 19 isolates were identified as M. bovis, 3 as M. avium subsp.hominissuis, 1 as M. intracellulare, 1 as a mixed culture of M. bovis and M. avium sp. and 1 as M. avium sp. and unidentified mycobacteria. Eleven other mycobacteria outside the tuberculosis and avium complex groups were also isolated. Ten new spoligopatterns grouped into three clusters were identified from M. bovis isolates. Two of the three M. avium subsp.hominissuis isolates showed similar patterns on the IS1311 RFLP but all were different on the IS1245 RFLP. CONCLUSION: The isolation of M. bovis confirms the ongoing infection with spoligotypes unique to Uganda. Isolation of environmental mycobacteria could explain the high avian or non specific tuberculin reactor patterns commonly observed in pastoral cattle and suggests their pathogenic or opportunistic role in the infection of cattle with disseminated bovine tuberculous lesions.

Evaluation of three serological tests for brucellosis in naturally infected cattle using latent class analysis.

Serological methods are traditionally used in diagnosis of brucellosis. However, the comparative performance of these tests and their accuracy under the local environment in Zambia has not been assessed. Thus, the objective of our study was to evaluate the diagnostic performance of three serological tests for brucellosis; Rose Bengal Test (RBT), competitive ELISA (c-ELISA) and Fluorescence Polarisation Assay (FPA) in naturally infected cattle in Zambia without an appropriate reference test to classify animals into truly infected and non-infected. Serological test results from a study to determine sero-prevalence were used to compare the performance of RBT, c-ELISA and FPA in diagnosing brucellosis in traditional cattle. Since none of the tests can be seen as a perfect reference test or gold standard, their performance in a population of naturally infected cattle was evaluated using latent class analysis which allows the sensitivity (Se) and specificity (Sp) to be estimated in the absence of a gold standard. The highest Se was achieved by the c-ELISA (97%; Credible Posterior Interval (CPI)=93-100%) and the highest Sp by the FPA (93%; CPI=85-99%), conversely these tests also had the lowest Sp and Se, respectively, with the RBT performing well in both the Se (93%; CPI=84-98%) and Sp (81%; CPI=61-97).

Risk factors for brucellosis in indigenous cattle reared in livestock-wildlife interface areas of Zambia.

We conducted this cross-sectional study to investigate risk factors of Brucella seropositivity in cattle herds reared in livestock-wildlife interface areas of Blue Lagoon and Lochinvar National Parks in Zambia between August 2003 and September 2004. Sera were collected from cattle aged > or =2 years from 124 herds. Data on husbandry practices, grazing strategies, and herd structure (sex and age composition) were also collected. Sera were screened for anti-Brucella antibodies using the Rose Bengal test (RBT) as a presumptive test and a competitive-ELISA (c-ELISA) as a confirmatory test. A herd was classified as Brucella seropositive if at least one animal tested positive on both RBT and c-ELISA in series testing. Risk factors for herd-level brucellosis seropositivity were tested using multivariable logistic regression; risk factors for increases in the within-herd counts of seropositive cattle were analyzed using the negative binomial regression model with the number of seropositive animals as outcome and total number of cattle tested in a herd as the population at risk (exposure). Of the 110 herds tested, 68 (62; 95% CI: 53, 71% after adjusting for clustering by area) tested seropositive for exposure to Brucella spp. The final logistic-regression model identified geographical area, with Lochinvar (OR=3.4; CI: 0.97, 12) and Kazungula (OR=4.3; CI: 0.91, 20) recording higher odds of Brucella infections compared to Blue Lagoon. Herds coming in contact with wildlife had higher odds compared to those without contact (OR=3.4; CI: 1, 11). Similarly, the odds of Brucella infection were progressively higher in the larger herd categories (26-40 cattle, OR=2.6; CI: 0.70, 10; 41-82 cattle, OR=4.9; CI: 0.93, 26; >82 cattle, OR=9.4; CI: 1.7-51) compared to the smallest herd category (10-25). The negative binomial regression model identified geographical area, contact with wildlife, and herd size as having significant effect on counts of seropositive cattle in a herd.