Economic analysis of bovine brucellosis control in the Rondônia state, Brazil.

Bovine brucellosis, mainly caused by Brucella abortus, is a worldwide distribution anthropozoonosis that causes great economic losses. In 2001, Brazil launched the National Program for the Control and Eradication of Brucellosis and Tuberculosis (PNCEBT). Contemporaneously, a great effort to characterize the epidemiology of the disease in Brazilian states was started. In the state of Rondônia, a first epidemiological study was carried out in 2004, revealing a prevalence of 35.2% of infected herds and 6.22% of seropositive females. In 2014, after a successful heifer vaccination program with strain 19 (S19), a second study detected a reduction in the prevalence of infected herds to 12.3% and of seropositive females to 1.9%. The present study aimed to quantify and compare the costs and benefits related to the control of bovine brucellosis in the state through an accounting analysis. Vaccinating heifers and performing serological tests to move animals were computed as private costs. The expenditures of the state official veterinary service for brucellosis control were considered public cost. The considered benefits of lowering prevalence were decreased cow replacement, decreased abortions, decreased perinatal and cow mortality, and increased milk production. Considering private and public costs, the net present value (NPV) was estimated at US$ 18.3 million, the internal rate of return (IRR) was calculated at 23%, and the benefit-cost ratio (BCR) was 1.7. When considering only the private costs, the NPV was US$34.9 million, the IRR was 49%, and the BCR was 3.0, meaning that the bovine producer had a return of 3 for each unit of currency invested. The results showed that the bovine brucellosis control measures implemented in the state of Rondônia, which had as its main strategy the vaccination of heifers with S19, produced highly advantageous economic results. The state should continue with its vaccination program, stimulating the use of the RB51 vaccine in addition to S19, to achieve further reductions in prevalence at low cost.

Seroprevalence and risk factors for bovine brucellosis in the state of Paraná, Brazil: an analysis after 18 years of ongoing control measures.

Seroprevalence and risk factors of bovine brucellosis (Brucella abortus) in herds and cattle were estimated by a cross-sectional study in the state of Paraná, Brazil. The state was divided into seven regions and a random, two-stage sampling was performed on properties and cattle from each region between 2018 and 2019. Serum samples were collected from 11,592 cows over 24 months from 1,757 properties and a questionnaire was applied to identify potential risk factors. As recommended by the National Program for the Control and Eradication of Animal Brucellosis and Tuberculosis (PNCEBT), serological testing for the detection of anti-Brucella antibodies included the buffered plate agglutination test (screening test) and the fluorescence polarization assay (confirmatory test). The seroprevalence of bovine brucellosis on properties and in cattle was 4.87% (95% confidence interval [CI]: 3.98-5.93%) and 2.24% (95% CI: 1.47-3.41%), respectively. Multiple logistic regression analysis identified larger herd size and failure to test for brucellosis as risk factors for the presence of anti-B. abortus antibodies. These results demonstrate no change in the prevalence when comparing initial studies conducted in 2002. Given our findings, it is recommended that policies for brucellosis control include a widespread vaccination program for higher prevalence areas and eradication approach to lower prevalence areas. All steps related to correct immunization of the herds should be verified and improved by training and education. Health education action must be carried out informing farmers about the risks of introducing animals not tested for brucellosis into their herds and the benefits of testing their herds regularly.

Immunoproteomics of Brucella abortus reveals potential of recombinant antigens for discriminating vaccinated from naturally infected cattle.

Brucellosis serodiagnosis is still a challenge and vaccination is the main measure used to control bovine brucellosis, being S19 and RB51 the most currently used vaccines. So, in order to contribute to brucellosis control, a bidimensional (2D) immunoblot-based approach was used to find immunogenic proteins to be used in serodiagnosis, particularly with ability to be employed in DIVA (Differentiating Infected from Vaccinated Animals) strategy. Immunoproteomic profile of Brucella abortus 2308 was analyzed in 2D western blotting using pooled sera from S19 vaccinated animals, RB51 vaccinated animals, B. abortus naturally infected animals and non-vaccinated seronegative animals. Evaluation of the antigens differentially immunoreactive against the groups of sera showed three proteins of particular importance: MDH (malate dehydrogenase) immunoreactive for S19-vaccinated animals, SOD (superoxide dismutase) reactive for infected animals and ABC transporter (multispecies sugar ABC transporter) reactive against sera from vaccinated animals (S19 and RB51). These three proteins were produced in E. coli and tested in an indirect ELISA (I-ELISA). For MDH, comparison between the vaccinated animals (independent of the vaccine used) and the seropositive and seronegative animals in I-ELISA showed significant differences. Data on the I-ELISA using SOD showed that sera from non-vaccinated naturally infected animals exhibited significant difference in comparison with all other groups. Otherwise, sera from vaccinated animals (S19 and RB51) and from non-vaccinated naturally infected animals did not show significant difference in OD values, but they were all significant different from non-vaccinated seronegative animals using ABC transporter as antigen in I-ELISA. In conclusion, together the 2D western blot analysis and the preliminary I-ELISA results suggest that the combined use of MDH and SOD could be successful employed in a LPS-free protein based serodiagnosis approach to detect bovine brucellosis and to discriminate vaccinated from naturally infected animals, in early post-vaccination stages.

Differential expression of cytokines in PBMC of Bos indicus and Bos taurus × Bos indicus cattle due to Brucella abortus S19 antigen.

Brucellosis is the most dreadful disease among bovines, although breed differences have been observed in prevalence of disease, worldwide. In present study, antibody response and relative expression of proinflammatory cytokines was compared in Bos indicus (zebu) and Bos taurus × Bos indicus (crossbred) cattle vaccinated by live attenuated Brucella abortus S19 antigen. Six female calves (4-6 months age) of both groups were vaccinated with B.abortus S19 strain. Blood samples were collected before vaccination (0d) and 7th (7d), 14th (14d) and 28th (28d) days after vaccination. Indirect ELISA showed high (p < .05) anti-Brucella antibody level after vaccination; with no significant difference between the groups. During Real-time expression, IFNγ, TNFα, IL6 and IL10 genes initially showed down regulation followed by upregulation in both the groups; however, the trend was much prominent in crossbreds. The expressions of IFNγ, TNFα and IL6, proinflammatory molecules important for initial containment of the Brucella were significantly (p < .01) higher in crossbred. The study showed that the Sahiwal cattle were less responsive to B.abortus S19 antigen than crossbreds, indicating its lower sensitivity to the Brucella, comparatively. In contrary, higher expression of the proinflammatory molecules in crossbreds could be important for containment of the organism during initial stage of infection.

Brucellosis in India: results of a collaborative workshop to define One Health priorities.

Brucellosis is an important zoonosis worldwide. In livestock, it frequently causes chronic disease with reproductive failures that contribute to production losses, and in humans, it causes an often-chronic febrile illness that is frequently underdiagnosed in many low- and middle-income countries, including India. India has one of the largest ruminant populations in the world, and brucellosis is endemic in the country in both humans and animals. In November 2017, the International Livestock Research Institute invited experts from government, national research institutes, universities, and different international organizations to a one-day meeting to set priorities towards a "One Health" control strategy for brucellosis in India. Using a risk prioritization exercise followed by discussions, the meeting agreed on the following priorities: collaboration (transboundary and transdisciplinary); collection of more epidemiological evidence in humans, cattle, and in small ruminants (which have been neglected in past research); Economic impact studies, including cost effectiveness of control programmes; livestock vaccination, including national facilities for securing vaccines for the cattle population; management of infected animals (with the ban on bovine slaughter, alternatives such as sanctuaries must be explored); laboratory capacities and diagnostics (quality must be assured and better rapid tests developed); and increased awareness, making farmers, health workers, and the general public more aware of risks of brucellosis and zoonoses in general. Overall, the meeting participants agreed that brucellosis control will be challenging in India, but with collaboration to address the priority areas listed here, it could be possible.

Risk factors for new bovine brucellosis infections in Colombian herds.

BACKGROUND: Bovine brucellosis is a zoonotic disease that causes substantial economic losses and has a strong impact on public health. The main objective of this paper is to determine the risk factors for new infections of Brucella abortus on Colombian cattle farms previously certified as being free of brucellosis. A case-control study was conducted by comparing 98 cases (farms certified as brucellosis-free for three or more years but became infected) with 93 controls (farms that remained brucellosis-free during at least the previous three years). The farms were matched by herd size and geographical location (municipality). Information was obtained via a questionnaire completed by veterinary officers through a personal interview with the herd owners. RESULTS: Two-thirds of the herds (67%) were dairy herds, 16% were beef herds, and 17% were dual-purpose (beef and milk) herds. After exploratory univariate analysis, all explanatory variables with a p-value of ≤0.20 were included in a logistic regression model using the forward stepwise method to select the model with the best goodness of fit. The significant risk factors were the replacement of animals from farms not certified as brucellosis-free compared to replacement from certified brucellosis-free farms (OR = 4.84, p-value < 0.001) and beef cattle farms compared to dairy cattle farms (OR = 3.61, p-value = 0.017). When herds with and without artificial insemination were compared, it was observed that farms that used natural breeding with bulls from non-certified herds had a higher risk than farms using artificial insemination (OR = 2.45, p-value = 0.037), but when the bulls came from brucellosis-free farms, farms with natural breeding were less affected (OR = 0.30, p-value = 0.004) than farms using artificial insemination, whether with frozen semen from certified brucellosis-free herds or fresh semen from uncontrolled herds. The latter is commonly sold to neighbouring farms. CONCLUSIONS: The government should make efforts to inform farmers about the risks involved in the introduction of semen and replacement heifers from farms that are not certified as brucellosis-free and to establish measures to control these practices.

Analysis of domestic animal movements in Colombia (2006-2014) and their possible influence on the bovine brucellosis spread.

Bovine brucellosis is a zoonotic disease that causes great economic losses. The disease is endemic in Colombia and animal movements from infected herds carry a risk of introduction to other herds. With the objective of analyzing the animal movements and determining their relationship with bovine brucellosis, we performed a descriptive analysis of the space-time movement of livestock in Colombia between 2006 and 2014. Multiple linear regression models (MLR) were employed to determine the relationship between brucellosis status and animal movements at the province level. The prevalence of bovine brucellosis in cattle was the dependent variable, and a total of 14 independent variables related to location, year, census, and animal movements were included. The prevalence of bovine brucellosis was significantly affected by the province (F = 3.42; P < 0.001), the year (F = 9.03; P < 0.001), and bovine (F = 5.45; P = 0.02) and equine movements (F = 3.8; P = 0.053). Fewer cattle and more horses entered provinces with high prevalence than those with low prevalence, indicating the possible relationship between the animal movements and the brucellosis infection in the country.

Evolution of bovine brucellosis in Colombia over a 7-year period (2006-2012).

Bovine brucellosis is endemic in Colombia, and is a mandatory notifiable disease, subjected to a control program based on four surveillance procedures: passive surveillance, test-and-remove, certification of disease-free farms, and animal movements. The objective of this study is to estimate the evolution of bovine brucellosis in Colombia over a 7-year period (2006-2012) using data from the official control program. A total of 58 epidemiologic variables were analyzed for each year at the department level. Univariate descriptive analysis and principal components analysis (PCA) were performed to ascertain the behavior of the variables. These programs covered 3% of the census in 2006, increasing to 15% in 2012. The percentage of positive farms averaged 22% in 2006 and 23% in 2012. The highest proportion of positive farms was in the Orinoquía region (24.6 to 49.6%); the lowest was in the Amazon region, (17.9 to 32.7%). The percentage of positive animals presented certain differences between years but without any clear trend (4.7% in 2006 and 4.6% in 2012), indicating that the brucellosis control program had a low impact in Colombia in these years. The results for each surveillance procedure were 6.8% for passive surveillance, 5.9% for test-and-remove, and 4.4% both in disease-free farms and in animal movement tests. The results obtained by PCA led to finding three different clusters: geographic areas with low bovine production and low bovine brucellosis surveillance, areas with medium bovine production and medium surveillance for bovine brucellosis, and areas with a predominant bovine production, applying sanitary measures to control bovine brucellosis.

Brucella abortus 2308ΔNodVΔNodW double-mutant is highly attenuated and confers protection against wild-type challenge in BALB/c mice.

Brucellosis is an important zoonotic disease of worldwide distribution, which causes animal and human disease. However, the current Brucella abortus (B. abortus) vaccines (S19 and RB51) have several drawbacks, including residual virulence for animals and humans. Moreover, S19 cannot allow serological differentiation between infected and vaccinated animals. We constructed double deletion (ΔNodVΔNodW) mutant from virulent B. abortus 2308 (S2308) by deleting the genes encoding two-component regulatory system (TCS) in chromosome II in S2308.2308ΔNodVΔNodW was significantly reduced survival in murine macrophages (RAW 264.7) and BALB/c mice. Moreover, the inoculated mice showed no splenomegaly. The mutant induced high protective immunity in BALB/c mice against challenge with S2308, and elicited an anti-Brucella-specific immunoglobulin G (IgG) response and induced the secretion of gamma interferon (IFN-γ) and interleukin-4 (IL-4). Moreover, NODV and NODW antigens would allow the serological differentiation between infected and vaccinated animals. These results suggest that 2308ΔNodVΔNodW mutant is a potential live attenuated vaccine candidate and can be used effectively against bovine brucellosis.

Characterization of Brucella abortus mutant strain Δ22915, a potential vaccine candidate.

Brucellosis, caused by Brucella spp., is an important zoonosis worldwide. Vaccination is an effective strategy for protection against Brucella infection in livestock in developing countries and in wildlife in developed countries. However, current vaccine strains including S19 and RB51 are pathogenic to humans and pregnant animals, limiting their use. In this study, we constructed the Brucella abortus (B. abortus) S2308 mutant strain Δ22915, in which the putative lytic transglycosylase gene BAB_RS22915 was deleted. The biological properties of mutant strain Δ22915 were characterized and protection of mice against virulent S2308 challenge was evaluated. The mutant strain Δ22915 showed reduced survival within RAW264.7 cells and survival in vivo in mice. In addition, the mutant strain Δ22915 failed to escape fusion with lysosomes within host cells, and caused no observable pathological damage. RNA-seq analysis indicated that four genes associated with amino acid/nucleotide transport and metabolism were significantly upregulated in mutant strain Δ22915. Furthermore, inoculation of ∆22915 at 105 colony forming units induced effective host immune responses and long-term protection of BALB/c mice. Therefore, mutant strain ∆22915 could be used as a novel vaccine candidate in the future to protect animals against B. abortus infection.

Methodology for the assessment of brucellosis management practices and its vaccination campaign: example in two Argentine districts.

BACKGROUND: In Argentina, vaccination with Brucella abortus Strain 19 vaccine is mandatory. The objective of the study was to develop and test a method for evaluating, in an innovative way, some farmers' and veterinarians' management practices in relation to brucellosis and to assess the vaccination campaign and coverage. The work took place in Brandsen and Navarro districts. Four questionnaires were designed (for officials from Local Sanitary Entities, vaccinators, vet practitioners and farmers). Responses were coded as "ideal" (0) and "not ideal" (1). To assess the relative weight of each question ("item"), experts ranked the items according to their impact on management practices and vaccination. A weighted score was then calculated. A higher weighted score was assigned to the worse practices. Farmers obtaining a global weighted score above the third quartile were classified as "inappropriately managed farms", to be compared per type of production system and district. To assess the immunization coverage, female calves were sampled 30 to 50 days post vaccination; they were expected to react positively to serological diagnostic tests (DT+). RESULTS: There were significantly more inappropriately managed farms and higher global scores among beef farmers and in Brandsen. Eighty three percent (83%) of female calves were DT+, significantly under the ideal immunization coverage (95%). Only 48% of farms were considered well vaccinated. DT+ results were positively associated with the Brandsen district (OR = 25.94 [4.60-1146.21] and with the farms having more than 200 cow heads ((OR = 78.34 [4.09-1500.00]). On the contrary, DT+ were less associated with vaccinators being veterinary practitioners (OR = 0.07 [0.006-0.78]). Farmers are well advised by their veterinary practitioners but they should improve some management practices. CONCLUSIONS: The vaccination campaign is globally well implemented, but the immunization coverage and some vaccinators' practices should be improved. This study leads to a better understanding of the most common used management and control practices regarding brucellosis, which affect its epidemiology. Any vaccination campaign should be periodically assessed to highlight possible fails. The described methodology can be extrapolated to other countries and different contexts.

Study of knowledge about bovine brucellosis among people involved in the cattle supply chain in the province of Manabí, Ecuador. / Estudio del nivel de conocimiento de la brucelosis bovina entre personas vinculadas a la cadena de producción bovina en la provincia de Manabí, Ecuador.

A cross-sectional study was conducted to determine the level of knowledge about brucellosis among livestock farmers and their families, veterinary personnel, food processors and other people involved in the cattle supply chain in the province of Manabí. A voluntary, open-ended survey of participants was conducted in seven cantons in Manabí province selected at random: Bolívar, Chone, El Carmen, Jama, Junín, Sucre and Tosagua. Of the 500 people who responded to the survey, only 30% said they knew the disease. Greater knowledge about the disease was observed among people with a higher educational level, veterinarians, livestock farmers/traders and men. For all the aspects surveyed, only a small percentage of respondents (ranging from 0.6% to 30.2%) indicated that they had knowledge of that aspect of the disease. Only 29.8% of the respondents stated that they knew the clinical signs of the disease in cattle, which could jeopardise the brucellosis surveillance system. Only 7.6% of respondents knew the measures for reducing the risk of contracting brucellosis, leading to widespread high-risk practices when working with animals. The conclusion is that there is a low level of knowledge about the disease among people involved in the cattle supply chain in the province under study.

Une enquête transversale a été menée en vue de déterminer le niveau de connaissances sur la brucellose parmi les éleveurs et leurs familles, le personnel vétérinaire, les entreprises de transformation des aliments et d'autres personnels travaillant en lien avec la filière bovine dans la province de Manabí (Équateur). Les participants volontaires de sept cantons de la province choisis au hasard (Chone, El Carmen, Sucre, Jama, Bolívar, Tosagua et Junín), ont répondu à un questionnaire ouvert. Parmi les 500 personnes interrogées, 30 % seulement ont déclaré connaître la maladie. Le niveau de connaissance de la maladie était proportionnellement plus élevé chez les personnes possédant un bon niveau d'instruction, chez les vétérinaires et chez les éleveurs commerciaux, ainsi que chez les hommes. Le niveau de connaissance était bas pour l'ensemble des aspects étudiés, oscillant entre 0,6 et 30,2 % suivant les aspects. Seuls 29,8 % des participants ont déclaré connaître les signes cliniques de la maladie chez les bovins, ce qui compromet l'efficacité du système de surveillance de la brucellose. Au total, 7,6 % seulement des personnes interrogées connaissaient les mesures permettant de réduire les risques de contracter la brucellose, ce qui se traduit par une fréquence élevée de pratiques à haut risque dans le travail avec les animaux. L'étude conclut à un niveau faible de connaissance de la brucellose chez les personnels liées à la filière bovine dans la région étudiée.

Se realizó un estudio transversal con el objetivo de determinar el nivel de conocimiento de la brucelosis entre los ganaderos y sus familias, el personal veterinario, los procesadores de alimentos y demás personal vinculado a la cadena de producción bovina de la provincia de Manabí. Se realizó a los participantes una encuesta abierta de carácter voluntario en siete cantones de la provincia seleccionados al azar: Chone, El Carmen, Sucre, Jama, Bolívar, Tosagua y Junín. De los 500 encuestados, solo el 30% respondió que conocía la enfermedad. Se observó un mayor conocimiento de la misma en las personas de mayor nivel educacional, en los veterinarios y ganaderos que realizan actividades comerciales, así como entre los varones. Se halló un bajo nivel de conocimientos respecto a todos los aspectos encuestados, que osciló entre el 0,6 y el 30,2%. Solo el 29,8% de los participantes indicó que conocía los signos clínicos de la enfermedad en el ganado bovino, lo cual puede dar al traste con el sistema de vigilancia de la misma. Solo el 7,6% de los encuestados conocía las medidas para reducir el riesgo de contraer brucelosis, lo cual se manifiesta con la alta frecuencia de prácticas de alto riesgo en el trabajo con los animales. Se concluye que existe un bajo nivel de conocimiento de la enfermedad entre las personas vinculadas a la cadena de producción bovina en la provincia estudiada.

Safety of vaccination against brucellosis with the rough strain in pregnant cattle.

Brucellosis is an infectious and contagious disease that profoundly impacts public health. However, in many countries, disease prevention is restricted to the vaccination of calves, and there is no prophylactic strategy for pregnant heifers and cows. The aim of this study was to evaluate the safety of the rough strain vaccine against brucellosis in pregnant cattle. Crossbred cows (N = 96) at three gestational periods (early, mid, or late pregnancy) were randomly allocated into the vaccine treatment group or to the control group. We then compared the percentage of pregnancies reaching full term, live calves 60 days after delivery, and seropositive calves. There was no effect of vaccination in any of the gestational periods on the evaluation endpoints. In conclusion, vaccination against brucellosis with the rough strain is safe for pregnant cattle at all gestational periods.

Brucella abortus mutants lacking ATP-binding cassette transporter proteins are highly attenuated in virulence and confer protective immunity against virulent B. abortus challenge in BALB/c mice.

Brucella abortus RB51 is an attenuated vaccine strain that has been most frequently used for bovine brucellosis. Although it is known to provide good protection in cattle, it still has some drawbacks including resistance to rifampicin, residual virulence and pathogenicity in humans. Thus, there has been a continuous interest on new safe and effective bovine vaccine candidates. In the present study, we have constructed unmarked mutants by deleting singly cydD and cydC genes, which encode ATP-binding cassette transporter proteins, from the chromosome of the virulent Brucella abortus isolate from Korean cow (referred to as IVK15). Both IVK15ΔcydD and ΔcydC mutants showed increased sensitivity to metal ions, hydrogen peroxide and acidic pH, which are mimic to intracellular environment during host infection. Additionally, the mutants exhibited a significant growth defect in RAW264.7 cells and greatly attenuated in mice. Vaccination of mice with either IVK15ΔcydC or IVK15ΔcydD mutant could elicit an anti-Brucella specific immunoglobulin G (IgG) and IgG subclass responses as well as enhance the secretion of interferon-gamma, and provided better protection against challenge with B. abortus strain 2308 than with the commercial B. abortus strain RB51 vaccine. Collectively, these results suggest that both IVK15ΔcydC and IVK15ΔcydD mutants could be an attenuated vaccine candidate against B. abortus.

Screening Brucella spp. in bovine raw milk by real-time quantitative PCR and conventional methods in a pilot region of vaccination, Edirne, Turkey.

Brucellosis is a worldwide zoonotic disease transmitted to humans by consumption of contaminated milk and milk products. Brucellosis is endemic in Turkey, and Edirne has a high Brucella prevalence. Brucellosis is prevented by live-attenuated vaccines for animals and the vaccination program has been in place since 1984 in Turkey. Thrace is the pilot region for this vaccination program. The gold standard diagnostic technique for brucellosis is still the isolation of suspicious bacterial colonies followed by bacteriological identification, but it is very time consuming and laborious. In many studies, Brucella has been investigated by PCR techniques. However, PCR-based methods cannot differentiate between the vaccine strain and the virulent strain; thus, the vaccine strain may interfere with the virulent strain and causes false-positive reactions. To monitor brucellosis control programs effectively, it is important to distinguish vaccine and field strains of Brucella spp. In this study, raw milk samples were collected from 99 cows at 12 different barns in 5 villages of Edirne (Turkey). Bacteriological analyses and real-time quantitative (q)PCR experiments were applied to all samples. The DNA was isolated using Biospeedy DNA-Tricky Purification Kit (Bioeksen, Istanbul, Turkey). For all reactions, Roche Light Cycler Nano (Roche Diagnostics, Mannheim, Germany) instrument and Biospeedy EvaGreen qPCR Pre-Mix (Bioeksen) were used. The data were analyzed using Roche LightCycler NanoSoftware 1.0. For samples that were negative by bacteriological analyses and positive by qPCR, we developed a novel qPCR-based method to differentiate the virulent B. abortus strains and B. abortus S19 vaccine strain. We designed qPCR primers targeting the outer membrane protein of B. abortus. The qPCR products were sequenced using the ABI Prism Big Dye Terminator Cycle Sequencing Ready Reaction Kit on an ABI Prism 377 DNA sequencer (Applied Biosystems, Foster City, CA). In total, 2.02% of the samples were Brucella positive, by both bacteriological method and the novel qPCR method. We concluded that, to obtain true-positive results in Brucella spp. screening studies for milk, differentiating the virulent and vaccine strain should not be disregarded.

Brucella abortus surveillance of cattle in Fiji, Papua New Guinea, Vanuatu, the Solomon Islands and a case for active disease surveillance as a training tool.

There have been no surveys of the cattle population for brucellosis in the Pacific Island Countries and Territories (PICTs) for more than 15 years. This study used disease surveillance as a capacity building training tool and to examine some of the constraints that impede surveillance in PICTs. The study also developed and implemented a series of surveys for detecting antibodies to B. abortus in cattle in Fiji, Papua New Guinea, Vanuatu and the Solomon Islands contributing to OIE requirements. The findings indicated lack of funds, lack of technical capacity, shortage of veterinarians, high turnover of in-country officials and lack of awareness on the impacts of animal diseases on public health that were constraining active disease surveillance. During the development and implementation of the surveys, constraints highlighted were outdated census data on farm numbers and cattle population, lack of funds for mobilisation of officials to carry out the surveys, lack of equipment for collecting and processing samples, lack of staff knowledge on blood sampling, geographical difficulties and security in accessing farms. Some of the reasons why these were constraints are discussed with likely solutions presented. The detection surveys had the objectives of building capacity for the country officials and demonstrating freedom from brucellosis in cattle for PNG, Vanuatu and the Solomon Islands. PNG, Vanuatu and the Solomon Islands all demonstrated freedom from bovine brucellosis in the areas surveyed using the indirect ELISA test. Fiji had an outbreak of brucellosis, and the objective was to determine its distribution and prevalence on untested farms. The Muaniweni district surveyed during the training had a 95 % confidence interval for true prevalence between 1.66 and 5.45 %. The study showed that active disease surveillance could be used as a tool for training officials thus, improves surveillance capacity in resource poor countries.

Recent advances in Brucella abortus vaccines.

Brucella abortus vaccines play a central role in bovine brucellosis control/eradication programs and have been successfully used worldwide for decades. Strain 19 and RB51 are the approved B. abortus vaccines strains most commonly used to protect cattle against infection and abortion. However, due to some drawbacks shown by these vaccines much effort has been undertaken for the development of new vaccines, safer and more effective, that could also be used in other susceptible species of animals. In this paper, we present a review of the main aspects of the vaccines that have been used in the brucellosis control over the years and the current research advances in the development of new B. abortus vaccines.

Vaccination of adult animals with a reduced dose of Brucella abortus S19 vaccine to control brucellosis on dairy farms in endemic areas of India.

Bovine brucellosis is an economically important disease which seriously affects dairy farming by causing colossal losses. It can be controlled by practicing vaccination of animals with Brucella abortus S19 vaccine (S19 vaccine). In the present study, adult bovines were vaccinated on seven dairy farms with a reduced dose of S19 vaccine to control brucellosis. Serological screening of adult animals (N = 1,082) by Rose Bengal test (RBT) and ELISA prior to vaccination revealed the presence and absence of brucellosis on five and two farms, respectively. The positive animals (N = 171) were segregated and those which tested negative (N = 911) were vaccinated by conjunctival route with a booster after 4 months. The conjunctival vaccination induced weak antibody response in animals, which vanished within a period of 9 to 12 weeks. Abortion in 12 animals at various stages of pregnancy and post-vaccination was recorded, but none was attributed to S19 vaccine. However, virulent B. abortus was incriminated in six heifers, and the cause of abortion could not be established in six animals. The six aborted heifers perhaps acquired infection through in utero transmission or from the environment which remained undetected until abortion. These findings suggested that vaccination of adult animals with a reduced dose of S19 vaccine by conjunctival route did not produce adverse effects like abortion in pregnant animals and persistent vaccinal antibody titers, which are the major disadvantages of subcutaneous vaccination of adult animals.

Milk yield and reproductive performance of brucellosis-vaccinated but seropositive Holstein cows.

The aim of this research was to study if seropositivity for brucellosis in vaccinated cows against this disease hampers reproductive performance and milk production in high-yielding Holstein cows. For this purpose 1,026 healthy cows and 372 cows seropositive for brucellosis were enrolled in this study. Cows positive to card test and subsequently to the rivanol test were further subjected to the radial immunodiffusion (RID) test. It was found that only 11% of the presumably infected cows by brucellosis screening tests were really infected with this disease. The reproductive performance of the group of cows with 11% Brucella-infected animals was not impaired; overall pregnancy rate did not differ between seropositive and healthy cows (30.9 vs. 29.6%). The abortion rates were similar between seropositive cows (5.3%) and seronegative animals (6.9%). Cows in the herd with 11% Brucella-infected animals produced significantly more milk than unaffected cows over a 305-day lactation (10,684 ± 1,720 vs. 10,345 ± 1,736; mean ± SD; P < 0.05). It was concluded that in dairy herds vaccinated against brucellosis with both 19 and RB51 strains, supplemental tests such as RID need to be conducted on all reactors in order to maintain diagnostic accuracy. These results also indicate that 11% animal prevalence of brucellosis did not exert a detrimental effect on 305-day milk yield and reproductive performance in high milk-yielding Holstein cows.