Risk Factors For Bovine Tuberculosis Research Articles

Prevalence and risk factors associated with bovine tuberculosis in the southern zone of Nasarawa State, north-central Nigeria

A cross-sectional study was conducted on 500 grazing cattle under a pastoral production system in the southern zone of Nasarawa state, North-Central Nigeria to determine the prevalence and risk factors associated with bovine tuberculosis using a Single intradermal Comparative Tuberculin Test (SCITT) from April 2019 to February 2020. The total number of animals with bTB was 46 (9.2%) and the results were significantly higher in older animals between 5-6years (OR: 7.4; CI: 1.54-35.4; P=0.000) and in those animals that were ≥ 7 years (OR: 5.7; CI: 1.24-25-9; P=0.00) old and likely at risk of having more bTB. Additionally, the prevalence was significantly higher in female animals (OR:3.7; CI:1.5-8.8; p=0.003), also a significant prevalence was observed as the herd size increased from 31-80 (OR:1.95; CI: 0.75-5.0; p=0.000) as well as from 81-171 (OR:5.5; CI: 2.14-14.4; p=0.000). Moreso, the prevalence was significant with the location of the animals, as areas with grazing reserves appeared to have more odds and more likely to have bTB: Awe (OR:9.6; C I:.2-4.4); Doma (OR:6.9; I:1.5-30.1; p= 0.01); Keana (OR:4.5; CI:0.96-21.6; p=0.01); Obi (OR:3.5; CI:0.7-17; p=0.01). The major risk factors for bovine tuberculosis in this study were sex, age, herd size, and location, contributing largely to the spread of bTB in the study area.

Prevalence and risk factors of bovine tuberculosis in cattle in selected districts of Fafan pastoral settings, Eastern Ethiopia

Cross-sectional study was conducted from October 2021 to August 2022 to investigate the prevalence and associated risk factors of bovine tuberculosis in cattle in selected districts of the pastoral settings of Fafan zone, Somali region, eastern Ethiopia. A comparative intradermal tuberculin test was performed using purified protein derivatives. Animal-related characteristics, and the owner's knowledge on the importance of BTB were collected using a structured questionnaire. The prevalence was 11.24 % (95 % CI, 8.61–14.35) and 43.3 % (95 % CI, 33.27–53.75) at the individual and herd levels, respectively. There were statistically significant differences in the proportions of positive reactor animals according to body condition score (P = 0.000), age (P = 0.048), seasonal migration (P = 0.038), parity number (P = 0.005), and reproductive status (P = 0.037). Animals with poor body condition scores had a significantly higher likelihood of testing positive, with their odds being 11.4 times greater (COR = 11.408, CI = 3.43–37.94, P < 0.001). In multivariate logistic regression, poor body condition score remained significantly associated with the odds of a positive reaction to tuberculosis (AOR = 0.137, CI = 0.053–0.356, P < 0.001). Similarly, the analysis showed that seasonal migration (AOR = 2.882, CI = 1.155–7.191, P = 0.023) and parity number (AOR = 11.64, CI = 1.818–74.464, P = 0.010) were significant predictors of bovine tuberculosis infection in cattle. According to the questionnaire, 14.2 % (17 of 120) and 13.3 % (16 of 120) of the respondents were knowledgeable about bovine tuberculosis and its transmission from animals to humans, and vice versa, respectively. The general judgment of herders' understanding of bovine tuberculosis transmission methods to humans was very low. The study findings showed a high prevalence of bovine tuberculosis in the study area, emphasizing the need for an effective control and prevention strategy.

Bovine Tuberculosis: Ethiopian Perspective

Bovine tuberculosis is a significant zoonotic disease affecting livestock and humans worldwide, causing substantial economic losses and posing serious public health risks. This review aims to provide an overview of bovine tuberculosis in Ethiopia, highlighting its prevalence, risk factors, transmission routes, clinical manifestations, and diagnostic methods. Mycobacterium bovis primarily causes bovine tuberculosis, which is characterized by granulomatous lesions in various organs. Transmission occurs through inhalation, ingestion of contaminated materials, and direct contact with infected animals. The age, breed, herd size, and management practices are some of the risk factors for bovine tuberculosis. In Ethiopia, the disease is prevalent but poorly controlled, lacking a national control program. Effective diagnosis relies on methods such as the tuberculin skin test, culture, and PCR. Control measures include test-and-slaughter programs, movement restrictions, biosecurity protocols, and public health education. This review underscores the urgent need for a comprehensive national control strategy, enhanced surveillance, public awareness campaigns, and investment in research to mitigate the impact of bovine tuberculosis in Ethiopia, thereby safeguarding both animal and human health.

Condemnation of bovine carcasses due to tuberculosis-gross lesions in Rio Grande do Sul, Brazil: Associated risk factors

Surveillance of bovine tuberculosis (bTB) lesions in animals at slaughterhouses is useful for controlling and eradicating the disease, besides providing epidemiological information. This study aimed to identify risk factors for bovine tuberculosis (bTB) condemnation in cattle at slaughterhouses in Rio Grande do Sul, Brazil. A logistic regression analysis was conducted using data on bTB-related condemnations. Variables examined included animal origin, number of slaughtered animals, season, inspection level (state or municipality), animal sex, and slaughterhouse location. A total of 297,817 Animal Transport Guides were evaluated, representing the transportation of 3497,521 animals. Among these, 6097 (2.05%) had at least one animal condemned due to bTB lesions. Risk factors for condemnation included larger batch sizes, female animals, slaughterhouses, and animal origin. The higher condemnation frequency in females and regions with dairy farms suggests links to milk production. Variation in condemnation rates by inspection level and slaughterhouse highlights the need for standardized procedures in identifying bTB lesions. Identifying these risk factors enables targeted interventions to enhance disease control and eradication efforts.

Prevalence, distribution, and risk factors of bovine tuberculosis in dairy cattle in central China.

Bovine tuberculosis (bTB) is one of the priority epidemic diseases in dairy cattle in China. Continuous surveillance and evaluation of the control programs will help on improving the efficiency of bTB control policy. We designed this study to investigate both animal and herd level prevalence of bTB, as well as to determine the associated factors in dairy farms in Henan and Hubei provinces. A cross-sectional study was conducted from May 2019 to September 2020 in central China (Henan and Hubei provinces). We sampled 40 herds in Henan and six herds in Hubei via stratified systematic sampling and administrated a questionnaire consisting of 35 factors. A total of 4900 whole blood samples were collected from 46 farms, including 545 calves <six months old and 4355 cows ≥six months old. This study demonstrated a high animal-(18.65%, 95% CI: 17.6-19.8) and herd-level (93.48%, 95%CI: 82.1-98.6) prevalence of bTB in dairy farms in central China. The Least Absolute Shrinkage and Selection Operator (LASSO) and negative binomial regression models showed that herd positivity was associated with the practice of introducing new animals (RR = 1.7, 95%CI: 1.0-3.0, p=0.042), and changing the disinfectant water in the wheel bath at the farm entrance every three days or less (RR = 0.4, 95%CI: 0.2-0.8, p=0.005) which reduced the odds of herd positivity. In addition, the result illustrated that testing cows with a higher age group (≥ 60 months old) (OR=1.57, 95%CI: 1.14-2.17, p=0.006) and within the early stage of lactation (DIM=60-120 days, OR=1.85, 95%CI: 1.19-2.88, p=0.006) and the later stage of lactation (DIM≥301 days, OR=2.14, 95%CI: 1.30-3.52, p=0.003) could maximize the odds of detecting seropositive animals. Our results have plenty of benefit to improve bTB surveillance strategies in China and elsewhere in the world. The LASSO and the negative binomial regression models were recommended when dealing with high herd-level prevalence and high dimensional data in questionnaire-based risk studies.

Prevalence and risk factors of bovine tuberculosis in slaughtered cattle, Malawi

Bovine tuberculosis (bTB) is an infectious disease with significant socioeconomic, animal, and public health impacts. However, the prevalence of bTB remains largely unclear in Malawi due to a paucity of information. Additionally, the existence of multiple risk factors is postulated to enhance bTB transmission in animals. A cross-sectional survey to estimate the prevalence of bTB, animal characteristics and identify associated risk factors was conducted from slaughtered cattle at three major regional abattoirs (southern, central and northern regions) in Malawi. Out of a total of 1547 cattle examined, 154 (9.95%) had bTB-like lesions in various visceral organs and lymph nodes; one sample per animal was collected, processed, and cultured in the in the BACTEC Mycobacterial growth indicator tube (MGIT) 960 system. From the 154 cattle that showed tuberculous like lesions, only 112 were positive on MGIT and 87 were confirmed to have M. bovis based on multiplex PCR. Cattle from the southern region (odds ratio (OR) = 1.96, 95% CI: 1.03–3.85) and central region (OR = 2.00, 95% CI: 1.16–3.56) were more likely presented with bTB-like lesions at slaughter than from the northern region. The risk of having bTB-like lesions was higher in females (OR = 1.51, CI: 1.00–2.29), older cattle (OR = 2.17, CI: 1.34–3.37), and crossbreeds (OR = 1.67, 95% CI: 1.12–2.47) than in males, younger animals, and Malawi Zebu breed, respectively. The high prevalence of bTB is of critical concern and necessitates active surveillance and strengthening of the current control strategies under a One Health (OH) approach at the animal-human interface.

Apparent prevalence and risk factors for bovine tuberculosis in the state of Paraná, Brazil: an assessment after 18 years since the beginning of the Brazilian program

Bovine tuberculosis (bTB) impacts considerably animal production and one health worldwide. To describe the prevalence, risk factors, and spatial pattern of the disease in the state of Paraná, Brazil, a cross-sectional study was conducted from September 2018 to February 2019. The area was divided into seven regions. Within each region, farms were randomly selected, and a predetermined number of cows was selected and tested by a comparative cervical tuberculin test. 17,210 animals were tested across 1757 farms. Herd prevalence of bTB-infected herds in Paraná was 2.5% [1.87–3.00%]. It has varied from 0.8 to 3.98% among seven regions, with clustering being detected in the west, central, and northeast areas. Animal prevalence was 0.35% [0.21–0.59%] and has varied from 0.08 to 0.6% among the pre-set regions. No major shifts in the prevalence of bTB were detected since 2007. Large-sized herds, dairy production, and feeding with whey were detected to be correlated with the presence of bTB. Exclusively among dairy herds, veterinary assistance from cooperatives, possession of self-owned equipment to cool milk, and feeding with whey were correlated with the disease. Considering these results, it is recommended that the state of Paraná seek to implement a surveillance system for the detection of bTB-infected herds transforming them into free ones, if possible, incorporating elements of risk-based surveillance. Health education is also recommended to inform farmers about the risks of introducing animals without testing and of feeding raw whey to calves.

Bovine Tuberculosis Epidemiology in Cameroon, Central Africa, Based on the Interferon-Gamma Assay.

Despite sub-Saharan Africa (SSA) accounting for ~20% of the global cattle population, prevalence estimates and related risk factors of bovine tuberculosis (bTB) are still poorly described. The increased sensitivity of the IFN-γ assay and its practical benefits suggest the test could be useful to investigate bTB epidemiology in SSA. This study used a population-based sample to estimate bTB prevalence, identify risk factors and estimate the effective reproductive rate in Cameroonian cattle populations. A cross-sectional study was conducted in the North West Region (NWR) and the Vina Division (VIN) of Cameroon in 2013. A regional stratified sampling frame of pastoral cattle herds produced a sample of 1,448 cattle from 100 herds. In addition, a smaller cross-sectional study sampled 60 dairy cattle from 46 small-holder co-operative dairy farmers in the NWR. Collected blood samples were stimulated with bovine and avian purified protein derivatives, with extracted plasma screened using the IFN-γ enzyme-linked immunosorbent assay (Prionics Bovigam®). Design-adjusted population prevalences were estimated, and multivariable mixed-effects logistic regression models using Bayesian inference techniques identified the risk factors for IFN-γ positivity. Using the IFN-γ assay, the prevalence of bTB in the dairy cattle was 21.7% (95% CI: 11.2–32.2). The design-adjusted prevalence of bTB in cattle kept by pastoralists was 11.4% (95% CI: 7.6–17.0) in the NWR and 8.0% (95% CI: 4.7–13.0) in the VIN. A within-herd prevalence estimate for pastoralist cattle also supported that the NWR had higher prevalence herds than the VIN. Additionally, the estimates of the effective reproductive rate Rt were 1.12 for the NWR and 1.06 for the VIN, suggesting different transmission rates within regional cattle populations in Cameroon. For pastoral cattle, an increased risk of IFN-γ assay positivity was associated with being male (OR = 1.89; 95% CI:1.15–3.09), increasing herd size (OR = 1.02; 95% CI:1.01–1.03), exposure to the bovine leucosis virus (OR = 2.45; 95% CI: 1.19–4.84) and paratuberculosis (OR = 9.01; 95% CI: 4.17–20.08). Decreased odds were associated with contacts at grazing, buffalo (OR = 0.20; 95% CI: 0.03–0.97) and increased contact with other herds [1–5 herds: OR = 0.16 (95% CI: 0.04–0.55); 6+ herds: OR = 0.18 (95% CI: 0.05–0.64)]. Few studies have used the IFN-γ assay to describe bTB epidemiology in SSA. This study highlights the endemic situation of bTB in Cameroon and potential public health risks from dairy herds. Further work is needed to understand the IFN-γ assay performance, particularly in the presence of co-infections, and how this information can be used to develop control strategies in the SSA contexts.

Prevalence and Associated Risk Factors of Bovine Tuberculosis in Slaughtered Cattle, Malawi

Prevalence and Associated Risk Factors of Bovine Tuberculosis in Slaughtered Cattle, Malawi

Prevalence and Risk Factors of Bovine Tuberculosis in Cattle and Dairy Farm Workers in Mirpurkhas and Badin Districts of Sindh, Pakistan

Prevalence and Risk Factors of Bovine Tuberculosis in Cattle and Dairy Farm Workers in Mirpurkhas and Badin Districts of Sindh, Pakistan

Prevalence and risk factors of bovine tuberculosis in dairy cattle farms in Egypt

Prevalence and risk factors of bovine tuberculosis in dairy cattle farms in Egypt

Distribution of seroprevalence and risk factors for bovine tuberculosis in east Algeria

Despite the difficulties and the absence of credible scientific information concerning bovine tuberculosis in Algeria, our cross-sectional and inferential study, which is estimated to be a first in Algeria, affected three major semi-intensive regions in East of Algeria, by analyzing 21 holdings which grouped 516 cattle in an intensive and semi-intensive breeding character over a period of 12 months, in order to estimate the seroprevalence and the risk factors those influence the emergence of the disease in these regions. A serological test (ELISA) was carried out on all collected sera, after a stratified two-level sampling. A generalized linear mixed model was used to identify risk factors associated with animal-level positivity. A multivariate descriptive analysis (MCA) was used to identify farm clusters associated with bTB seroprevalence. The results obtained allow us to classify Algeria on the epidemiological level in the field of bovine tuberculosis, in an intermediate situation with a seroprevalence rate of 3.49 % (95 % CI : 1,91, 507); between industrialized countries where the seroprevalence is mostly very low below 0,1% and developing countries with very high seroprevalence such as African-Asian countries. This intermediate epidemiological position is influenced by certain risk factors that are integrated into the three mechanisms commonly known by the scientific community: “contamination by the introduction of an animal”; “neighborhood contamination"; “recurrence”. But what characterizes this study is the obtaining of a “Animals purchased from a country listed as not OTF” factor that has returned as a highly protective factor and contributed to the decrease in this seroprevalence, and put Algeria in an intermediate epidemiological situation according to our study, and this is due to a purchase channeled by the state which is exclusive of the countries certified OTF by the OIE.

Study on the prevalence and risk factors of bovine tuberculosis in dairy cattle in Adama city, central Ethiopia

Bovine tuberculosis (bTB) is a serious infectious disease of cattle with significant economic impact and public health risk. It is particularly important in Ethiopia where effective control measures are lacking. This cross-sectional study was carried out between April and July 2016 on 1038 cattle selected from 206 dairy farms in Adama city located in central Ethiopia to estimate the prevalence of bTB and identify the potential risk factors using comparative intradermal tuberculin skin test. Accordingly, the individual animal level prevalence was found to be 2.1% (95% CI: 1.35 – 3.22). Of the 206 dairy farms included in the study, 7.3% (95% CI: 4.29 – 11.98) had one or more 15 cattle positive for the tuberculin test. Furthermore, 5.5% of the examined cattle were found reactive for atypical Mycobacterium. Among the risk factors considered, age and lactation status of the animals were significantly associated (p&lt; 0.05) with the prevalence of bTB. It was noted that the apparent prevalence of bTB positive reactivity was greater in young and non-lactating cattle than their counterparts. In conclusion, the present study revealed 2.1% prevalence of bTB in the dairy farms investigated and culling of positive reactors is recommended as a feasible control intervention.&#x0D; Keywords: Adama; Bovine tuberculosis; CIDT; dairy cattle; Ethiopia

Bovine tuberculosis and brucellosis in Livestock at the Greater Ruaha Ecosystem

A cross-sectional study was conducted to determine the prevalence of bovine tuberculosis (BTB) and the seroprevalence of brucellosis in livestock at the Greater Ruaha Ecosystem in Tanzania. The study further characterized the Mycobacterium spp. from the slaughtered livestock. A questionnaire survey conducted to assess potential herd-level risk factors for BTB and brucellosis revealed that the respondents’ ethnicity and herd mixing were the significant risk factors. Twenty-eight percent of 102 cattle herds had at least one positive or suspect BTB reactor. The overall prevalence of BTB infection in the cattle was 1.32% (18/1368). Forty-two percent of 93 flocks of the small ruminants had at least one brucellosis seropositive animal. The overall seroprevalence of brucellosis in the cattle and small ruminants was 6.6%. Although the prevalence of both diseases was relatively low for individual animals, herd-level prevalence was high suggesting that infection is widespread in the study area and a significant number of households are at risk. Mycobacterium bovis strain identified via polymerase chain reaction (PCR) was confirmed by spoligotyping as spoligotype SB0133. This cattle strain of M.bovis was similar to previously reported involving wild animals in adjacent protected areas. Isolation of identical M. bovis from wildlife and livestock and the demonstration of Brucella spp. seroprevalence in livestock in the same interface, strongly suggest livestock-wildlife interspecies sharing of these pathogens. Occurrence of the microorganisms poses a serious challenge to disease management strategies in pastoralist communities in the interface area

Decision tree machine learning applied to bovine tuberculosis risk factors to aid disease control decision making

Identifying and understanding the risk factors for endemic bovine tuberculosis (TB) in cattle herds is critical for the control of this disease. Exploratory machine learning techniques can uncover complex non-linear relationships and interactions within disease causation webs, and enhance our knowledge of TB risk factors and how they are interrelated. Classification tree analysis was used to reveal associations between predictors of TB in England and each of the three surveillance risk areas (High Risk, Edge, and Low Risk) in 2016, identifying the highest risk herds. The main classifying predictor for farms in England overall related to the TB prevalence in the 100 nearest cattle herds. In the High Risk and Edge areas it was the number of slaughterhouse destinations and in the Low Risk area it was the number of cattle tested in surveillance tests. How long ago the last confirmed incident was resolved was the most frequent classifier in trees; if within two years, leading to the highest risk group of herds in the High Risk and Low Risk areas. At least two different slaughterhouse destinations led to the highest risk group of herds in England, whereas in the Edge area it was a combination of no contiguous low-risk neighbours (i.e. in a 1 km radius) and a minimum proportion of 6–23 month-old cattle in November. A threshold value of prevalence in 100 nearest neighbours increased the risk in all areas, although the value was specific to each area. Having low-risk contiguous neighbours reduced the risk in the Edge and High Risk areas, whereas high-risk ones increased the risk in England overall and in the Edge area specifically. The best classification tree models informed multivariable binomial logistic regression models in each area, adding statistical inference outputs. These two approaches showed similar predictive performance although there were some disparities regarding what constituted high-risk predictors. Decision tree machine learning approaches can identify risk factors from webs of causation: information which may then be used to inform decision making for disease control purposes.

Prevalence and risk factors analysis of bovine tuberculosis in cattle raised in mixed crop-livestock farming system in Tigray region, Ethiopia.

Bovine tuberculosis (BTB) is a disease of animal and public health importance in developing countries. In rural Ethiopia, there is potential for a shift in the epidemiologic of this disease driven by transformation of dairy industry. This includes gradual change from the traditional mixed crop-livestock husbandry practice to a semi-intensification system. It is therefore, essential to document the prevalence and risk factors of BTB to continuously update the designing and implementation of control and prevention strategies. Here, we present findings of a cross-sectional study on the prevalence and associated risk factors of BTB among cattle reared under mixed crop-livestock farming system in Tigray region, Ethiopia. A multistage purposive sampling approach was used to select districts, villages, herds and individual cattle. A total of 1,357 cattle from 310 herds were examined for BTB infection using a comparative intradermal tuberculin skin test (CIDT). Questionnaires were used to gather data on herd structure and herd management practices. A multilevel logistic mixed effect model was used to determine risk factors after accounting for clustering effect at three levels (village, herd and individual animal). Overall prevalence of BTB was 4.3% (95% CI=3.4-5.6), with the highest prevalence recorded in Alamata district (5.6%) and lowest in Korem (1.6%). Multilevel logistic mixed effect model analysis identified exotic breed (OR=3, p=0.014), closed barn (OR=2.6, p=0.018), large herd size (OR=2.6, p=0.05) and purchase of cattle (OR=2.1, p=0.027) as important risk factors for BTB. Taken together, these findings suggest that the current dairy development program centred on the introduction of exotic and or crossed animals could have contributed to changing epidemiological situations of BTB in the study area.

CD14 gene polymorphisms associated with increased risk of bovine tuberculosis in Chinese Holstein cows

Cluster differentiation antigen 14 (CD14) is an important pattern recognition receptor protein in innate immunity. The aim of this study was to identify and assess the association of single-nucleotide polymorphisms (SNPs) in the CD14 gene with susceptibility to bovine tuberculosis (BTB) in Chinese Holstein cows. DNA samples from 517 Chinese Holstein cows (257 tuberculosis positive cases and 259 healthy controls) were collected from dairy farms in China. SNPs in the entire CD14 gene, including exonic regions, intronic regions and close to the 5′- and 3′-terminal untranslated regions, were detected by PCR, followed by direct sequencing. Five SNPs (−5C/T, 613G/A, 1023G/A, 1306G/A and 1326G/T) were found in the CD14 gene region. Significantly increased BTB susceptibility was evident in T allele carriers of −5C/T (P<0.001; odds ratio, OR 2.02; 95% confidence interval, CI 1.57–2.77), G allele carriers of 613G/A (P<0.001; OR 2.17, 95% CI 1.50–3.08) and TG haplotype carriers of both SNPs (P<0.001; OR 3.14, 95% CI 1.24–4.50). These results suggest that −5C/T and 613G/A are risk factors for BTB in Chinese Holstein cattle and might be used as candidate genetic markers in breeding cows with natural resistance to BTB.

Prevalence and risk factors for bovine tuberculosis in the State of Mato Grosso do Sul, Brazil

The objective of this study was to describe the epidemiological situation of bovine tuberculosis in Mato Grosso do Sul. The State was divided into three regions, Pantanal, Planalto Norte, and Planalto Sul. In each region, properties were randomly chosen and a pre-established number of animals were also randomly selected; these animals were submitted to the intradermal comparative cervical tuberculin diagnostic test. In total, 17,121 animals from 938 properties were tested. In cases of inconclusive results, the animals were retested with the same diagnostic procedure within a minimum interval of 60 days. An epidemiological questionnaire was administered in the properties sampled to investigate possible risk factors for the disease. In the State, the prevalence of infected herds was 1.3% (95% confidence interval [CI]: 0.72–2.37%) and that of infected animals was 0.035% (95% CI: 0.017–0.069%). Point estimates indicated a higher concentration of infected herds (2.61%; 95% CI: 1.31–5.15%) and infected animals (0.132%; 95% CI: 0.055–0.315%) in the Planalto Sul region, which has a predominance of dairy properties. The prevalence of herds infected with bovine tuberculosis was found to be associated with the production of milk, with technification in the mode of production represented by the use of mechanical milking. Thus, it is recommended that the State adopt strategies for the eradication of bovine tuberculosis, with the structuring of the surveillance system for detection and mitigation of infected herds, incorporating risk-based surveillance elements.

Epidemiological status of bovine tuberculosis in the Federal District of Brazil

Considering the implementation of the National Program for the Control and Eradication of Animal Brucellosis and Tuberculosis (PNCEBT) in 2001, and the need to determine the epidemiological status of animal tuberculosis for future evaluation of the effectiveness of the measures laid down, the objective of this study was to estimate the prevalence and identify risk factors of bovine tuberculosis in the Federal District (DF) of Brazil, as well as to provide an input for the strategic management of PNCEBT. Field testing and data collection was carried out from February to December 2003. The DF was considered a single epidemiological region owing to the small number of existing farms, and the absence of significant differences between the region’s farming enterprises, which would justify the stratification of the regional sample. A total of 278 farms were randomly sampled from the local registry database of bovine farms with reproductive activity, in which 2,019 adult cows were tuberculin tested. Only one sampled animal had a positive result, using the comparative cervical tuberculin test, resulting in a bovine tuberculosis prevalence of 0.05% [95% CI: 0.0-0.4%]. The herd-level prevalence of bovine tuberculosis in the DF was estimated as 0.36% [95% CI: 0-2.0%]. The analysis of risk factors was impaired by the results obtained, as the number of cases did not allow for this kind of analysis. Cattle farming in the DF is predominantly aimed at dairy production; however, it is characterized by the presence of small low milk yield herds, which may not favor the introduction and persistency of infection of Mycobacterium bovis. Health authorities from the DF perform surveillance for bovine tuberculosis and maintain the need for tests for the movement of bovines for breeding and those animals destined for any form of animal gathering, especially auctions. Therefore, it is likely that the DF has good conditions for successfully implementing the PNCEBT.

Prevalence and herd-level risk factors for bovine tuberculosis in the State of Paraná, Brazil

Bovine tuberculosis is a zoonosis with worldwide distribution. Its control has a direct impact on public health and livestock production. This study estimated the prevalence of infected herds and adult bovines and evaluated risk factors associated with the presence of tuberculosis within herds in the state of Paraná. The state was divided in seven livestock regions and independent sampling was performed. A total of 1,419 farms were sampled and 16,045 animals were tested using the intradermal comparative cervical tuberculin diagnostic test. The apparent and estimated prevalence rates in farms and adult bovine animals were 2.15% (95% CI: 1.31-3.00) and 0.42% (95% CI: 0.04-0.81), respectively. It was not possible to state with 95% confidence that the disease prevalence in any region was significantly different from that in other regions. There were no positive animals in the western region, and the prevalence of positive herds and animals in the other regions ranged from 1.03% to 3.89% and 0.17% to 1.08%, respectively. The logistic regression model identified larger herd size (OR = 2.4) and mechanical cmilking (OR = 5.18) as risk factors associated with the presence of bovine tuberculosis. The combination of low prevalence with risk factors associated to larger herds and more intensive dairy farming, renders the state of Paraná a good candidate for the implementation of industry-based free-herd accreditation schemes and makes a case for planning risk-based surveillance targeted at major dairy basins.