Importance of brucellosis control programs of livestock on the improvement of one health.

Brucellosis not only represents an important health restraint on livestock but also causes high economic losses in many developing countries worldwide. Despite considerable efforts made for the control of brucellosis, the disease is still spreading in many regions (such as the Middle East) where it represents one of the most important health hazards impacting both animals and humans. The present review aims to investigate the efficacy of veterinary control programs regarding brucellosis, with a special focus on current prevention, control, and eradication approaches. The reasons for unsuccessful control programs such as the absence of highly effective vaccines and non-certified bulls are also debated, to understand why the prevalence of brucellosis in livestock is not decreasing in many areas despite considerable efforts taken to date. The importance of governmental and regional investment in brucellosis control remains one of the main limiting factors owing to the limited budget allocated to tackle this disease. In this context, one health concept has generated novel comprehensive approaches with multiple economic implications across the livestock industry and public health. However, the implementation of such global preventive strategies appears to be a key issue for many endemic and low-income countries. According to the collected data, epidemiological contexts including management and trade systems along with well-defined agro-ecological zones should be evaluated in brucellosis endemic countries to improve milk production and to enhance the sustainability of the livestock sector at both national and regional levels.

Socio-economic impacts of brucellosis on livestock production and reproduction performance in Koibatek and Marigat regions, Baringo County, Kenya.

BACKGROUND: Brucellosis in Africa is caused by Brucella species transmitted through contaminated or contacts with infected animals or their carcasses. The disease reduces livestock production and reproduction performance evident by frequent episodes of abortion, still births, swollen testes, weak calves/lambs and swollen joints. However, the socio-economic impacts of these brucellosis-associated symptoms on milk, fat, meat and blood production, infertility, sale value, dowry and costs of treatment has not been evaluated extensively in developing countries. In Baringo County, Kenya, there is a continuous movement of cattle as a result of trade and grazing, which predisposes many herds to brucellosis infection. The objective of this study was to investigate the socio-economic impacts of Brucella infection on production systems for sheep, goats, cattle and camels and explore the impact of brucellosis on livestock production and reproduction performance among livestock keeping communities in Baringo County, Kenya. The study adopted a cross-sectional survey using quantitative data collection methods. RESULTS: Results demonstrated an impact on milk production in suspected brucellosis cases resulting from abortions (OR = 0.151, P < 0.0001) and swollen joints (OR = 2.881, P < 0.0001). In terms of infertility, abortion as a symptom of brucellosis (OR = 0.440, P = 0.002), still birth (OR = 0.628, P = 0.042), and weak calf or lamb (OR = 0.525, P = 0.005) had an impact on infertility. In terms of sale value, abortion (OR = 0.385, P = 0.008), weak calf/lamb (OR = 2.963, P = 0.013) had an impact on sale value. Other analyses demonstrated that for dowry, swollen testes (OR = 5.351, P = 0.032), weak calf and lambs (OR = 0.364, P = 0.019) had a likelihood of reduction of dowry value. Finally, in terms of cost of treatment, abortion (OR = 0.449, P = 0.001), still births (OR = 0.208, P = 0.015), swollen testes (OR = 0.78, P = 0.014), weak calf/lambs (OR = 0.178, P = 0.007) and swollen joints (OR = 0.217, P = 0.003) significantly increased the costs of treatments. There was no impact on fat and meat and blood production. CONCLUSION: Even though there was a huge socio-economic impact on milk production, infertility, sale value, and dowry, it was the costs of treatment that was significantly impacted on all symptoms associated with brucellosis on this community. A 'One Health' approach in tackling the brucellosis menace as a holistic approach is recommended for both humans and their livestock.

Economic and health burden of brucellosis in Kazakhstan.

Brucellosis is a widespread zoonotic disease considered as an emerging and re-emerging disease with a resulting threat of public health and animal health. Official reports document an animal incidence in Kazakhstan of about 0.6% per year, and the country still registers high number of human cases annually . The main objective of this paper was to evaluate the distribution and economic impact of brucellosis in Kazakhstan. We analysed human disease incidence data obtained from the Government Sanitary & Epidemiological Service with the aim to estimate the burden of disease in terms of disability-adjusted life years (DALYs). We also estimated the economic impact in terms of monetary losses. Additionally, we mapped the geographical distribution of the disease throughout Kazakhstan. In total, 1,334 human cases of brucellosis were registered in 2015 in Kazakhstan that resulted in 713 DALYs. Around $21 million was spent on compensation for animals that had to be slaughtered due to brucellosis, and an additional $24 million was spent on testing animals. Animal brucellosis and human brucellosis occur throughout the whole country, some trends of which are reviewed in this paper. We estimated the burden of the disease and explored possible explanation for high human incidence rates. This paper is the first to estimate the human burden of disease and the economic costs in Kazakhstan. Both of these are substantial.

Screening and identification of a human domain antibody against Brucella abortus VirB5.

Brucellosis is caused by the genus Brucella. Brucella is widely distributed in cattle, swine, sheep, goat and other mammals including human. Animal brucellosis causes severe economic losses and affects related international transportation and trade. Human brucellosis causes both acute and chronic symptoms of multi-organ dysfunction. Brucella type IV secretion system (T4SS) VirB5 was required for macrophages infection and essential for virulence in mice. VirB5 is located on the cell surface and serves as a specific adhesin targeting host cell receptors. The aim of this study was to isolate and characterize a specific human domain antibody against Brucella abortus (B. abortus) VirB5 from human single domain antibody (sdAb or VHH) phage display library. Following five rounds of screening, an sdAb named as BaV5VH4 showed the highest affinity by enzyme-linked immunosorbent assay (ELISA). Its interaction with B. abortus VirB5 was verified by binding assay, dot blot and molecular docking. These findings in this paper could greatly help elucidate the molecular mechanisms of Brucella infection, and accelerate the development of sdAbs-based vaccines and neutralizing therapeutics of brucellosis.

Evaluation of the economic impact of brucellosis in domestic yaks of Tibet.

Brucellosis is considered as an endemic disease in yaks (Bos grunniens) in China, but few economic analyses describing the cost of the disease and potential benefits of control have been reported. The aim of the study was to estimate the economic cost of brucellosis in yaks and the economic value of three control strategies: (a) vaccination; (b) test-and-slaughter; and (c) a combination of vaccination and test-and-slaughter programs in Damxung and Maizhokunggar counties and Pali township of Yadong county in Tibet. Using data from a cross-sectional seroprevalence survey conducted in 2015, combined with financial data, the predicted costs and benefits of the different control strategies were simulated over a 6-year period. The annual estimated cost of brucellosis in yaks within the study area was US$ 521,043 (95% CI: US$ 334,441; US$ 759,862), with an annual average cost per yak estimated at US$ 1.42 (95% CI: US$ 0.91, US$ 2.07). The benefit-cost analysis predicted that vaccination was the most effective control method with a benefit-cost ratio (BCR) of 3.19 (95% CI: 2.17, 4.66) and a net present value (NPV) of US$ 313,355 (95% CI: US$ 157,679, US$ 541,062) over a 6-year period. A sensitivity analysis found the NPV was most sensitive to the loss from a female yak aborting in the vaccination control program. In contrast, the price of yaks that were slaughtered had the largest influence on the NPV for both the test-and-slaughter control program and the combination control program. These estimates provide valuable information and establish a foundation for formulating and implementing cost-effective measures for controlling the disease in yaks on the Tibetan plateau, and more broadly in China.

Cost-benefit analysis of intervention policies for prevention and control of brucellosis in India.

BACKGROUND: Brucellosis is endemic in the bovine population in India and causes a loss of US$ 3·4 billion to the livestock industry besides having a significant human health impact. METHODS: We developed a stochastic simulation model to estimate the impact of three alternative vaccination strategies on the prevalence of Brucella infection in the bovine populations in India for the next two decades: (a) annual mass vaccination only for the replacement calves and (b) vaccination of both the adult and young population at the beginning of the program followed by an annual vaccination of the replacement calves and, (c) annual mass vaccination of replacements for a decade followed by a decade of a test and slaughter strategy. FINDINGS: For all interventions, our results indicate that the prevalence of Brucella infection will drop below 2% in cattle and, below 3% in buffalo after 20 years of the implementation of a disease control program. For cattle, the Net Present Value (NPV) was found to be US $ 4·16 billion for intervention (a), US $ 8·31 billion for intervention (b) and, US $ 4·26 for intervention (c). For buffalo, the corresponding NPVs were US $ 8·77 billion, US $ 13·42 and, US $ 7·66, respectively. The benefit cost ratio (BCR) for the first, second and the third intervention for cattle were 7·98, 10·62 and, 3·16, respectively. Corresponding BCR estimates for buffalo were 17·81, 21·27 and, 3·79, respectively. CONCLUSION: These results suggest that all interventions will be cost-effective with the intervention (b), i.e. the vaccination of replacements with mass vaccination at the beginning of the program, being the most cost-effective choice. Further, sensitivity analysis revealed that all interventions will be cost-effective even at the 50% of the current prevalence estimates. The results advocate for the implementation of a disease control program for brucellosis in India.

Estimation of the health and economic burden of human brucellosis in India.

High seroprevalence estimates of brucellosis in livestock species and humans in India suggest that the disease is a significant public health concern in the country. We developed an economic model and conducted an assessment of the impact of human brucellosis in India to describe the current situation to help formulate prevention and control strategies. Economic losses of human brucellosis were calculated based on the official records and the data from epidemiological surveys conducted in India. These data were used to estimate the disability adjusted life years (DALYs) due to human brucellosis. Uncertainty was incorporated in the model by applying probability distributions for certain input parameters. The analyses were further supplemented by conducting sensitivity analyses to determine which parameters had the biggest influence on the outcome of economic losses. The annual median losses due to human brucellosis were estimated to be Rs 627.5 million (uncertainty interval [95% UI] Rs 534.8-741.2 million; US $ 10.46 million) with a loss of Rs 442.3 million (95% UI 371.0-516.0; US $ 7.37 million) among adults and Rs 185.0 million (95% UI 124.0-255.0; US $ 3.08 million) among children. Human brucellosis in India caused a loss of 177 601 (95% UI 152 695-214 764) DALYs at the rate of 0.15 (95% UI 0.13-0.17) DALYs per thousand persons per year. The DALYs were found to be 0.29 (95% UI 0.08-0.70) per thousand persons per year in occupational and 0.13 (95% UI 0.06-0.18) in non-occupational adult population. This is the first systematic analysis of the health impact of human brucellosis in India and of indirect/production losses occurring due to human brucellosis anywhere in the world. The results indicate that brucellosis causes considerable economic losses and has a reasonable health impact, particularly among occupational groups. Intervention policies need to be strengthened to reduce the socio-economic impact of human brucellosis in India.

The economic efficiency and equity of government policies on brucellosis: comparative insights from Albania and the United States of America.

Brucellosis is a zoonotic bacterial disease that causes recurring febrile illness in humans, as well as reproductive failure and reduced milk production in livestock. The cost of brucellosis is equal to the sum of lost productivity of humans and animals, as well as private and public expenditures on brucellosis surveillance, prevention, control and treatment. In Albania, Brucella abortus and B. melitensis affect humans, cattle and small ruminants. In the United States, B. abortus affects cattle and wild ungulates in the Greater Yellowstone Area. These two case studies illustrate the importance of place-specific context in developing sustainable and effective brucellosis mitigation policies. Government regulations and mitigation strategies should be designed with consideration of all costs and benefits, both to public agencies and private stakeholders. Policy-makers should, for example, weigh the benefits of a regulation that increases epidemiological certainty against the costs of compliance for producers and households. The distribution of costs and benefits amongst public agencies and private individuals can have important implications for a policy's economic efficiency and equity quite apart from their total magnitude.

La brucellose est une maladie bactérienne zoonotique responsable d'épisodes fébriles récurrents chez l'être humain ainsi que d'infertilités et d'une baisse de la production de lait chez les animaux d'élevage. Le coût de la brucellose équivaut à la somme des pertes de productivité chez l'homme et chez les animaux et des dépenses privées et publiques engagées dans la surveillance, la prévention, la prophylaxie et le traitement de la brucellose. En Albanie, Brucella abortus et B. melitensis affectent aussi bien l'être humain que les bovins et les petits ruminants. Aux États-Unis d'Amérique, B. abortus affecte les bovins et les ongulés sauvages de la région du Grand Yellowstone. Les deux études de cas présentées dans cet article illustrent l'importance de prendre en compte le contexte spécifique de chaque site particulier lors de la mise en place de politiques durables et efficaces d'atténuation de la brucellose. La réglementation et les stratégies d'atténuation mises en oeuvre par les pouvoirs publics doivent être conçues en considérant l'ensemble des coûts et des bénéfices induits pour les agences gouvernementales et les intervenants privés. Par exemple, les décideurs politiques devraient évaluer les avantages induits par une réglementation basée sur un accroissement des certitudes épidémiologiques, par rapport aux coûts supportés par les producteurs et les ménages se conformant à cette réglementation. La répartition des coûts et des bénéfices entre les agences gouvernementales et les individus privés peut avoir d'importantes répercussions sur l'efficacité économique et l'équité d'une politique sanitaire, indépendamment de leur amplitude totale.

La brucelosis es una enfermedad bacteriana zoonótica que provoca dolencias febriles recurrentes en el ser humano, así como trastornos reproductores y una menor producción lechera en el ganado. Su costo es igual a la suma de las pérdidas de productividad en personas y animales, junto con el gasto público y privado dedicado a tareas de vigilancia, prevención, control y tratamiento de la enfermedad. En Albania, Brucella abortus y B. melitensis afectan a personas, ganado bovino y pequeños rumiantes. En los Estados Unidos, B. abortus afecta al ganado bovino y a ungulados salvajes de la zona del Gran Yellowstone. Los autores presentan dos estudios monográficos que ponen de relieve la importancia del contexto geográfico a la hora de definir políticas duraderas y eficaces para mitigar la brucelosis. Al elaborar tanto reglamentos como estrategias públicas de mitigación es preciso tener en cuenta la totalidad de los costos y beneficios, a la vez para los organismos oficiales y para el sector privado. Los planificadores deben, por ejemplo, sopesar los beneficios derivados de un reglamento que aporte mayor certidumbre epidemiológica en relación con los costos que entrañe su aplicación para productores y familias. La forma en que costos y beneficios se distribuyan entre organismos públicos y personas físicas puede influir sustancialmente en los niveles de eficiencia económica y equidad de una política, con independencia de su magnitud total.

Temporal Analysis and Costs of Ruminant Brucellosis Control Programme in Egypt Between 1999 and 2011.

Data for the prevalence of brucellosis in ruminants in Egypt are scarce; recent studies suggest the disease is endemic, with a high prevalence. The aim of this study was to assess the financial costs and the impact of the current control programme on the pattern of brucellosis among ruminants between 1999 and 2011. A univariate binary logistic regression model was used to compare between seropositive proportions for different years for each species. The proportion of seropositive cattle was significantly increased from 2000 to 2004 then significantly decreased from 2005 to 2011. The proportion of seropositive buffalo fluctuated year to year; however, there was a significant increase in 2008 (OR 3.13, 95% CI 2.69-3.66, P < 0.001). There was a decrease in the proportion of seropositive sheep during the study period except in 2001 and 2009 in which there was a significant increase. The proportion of seropositive goats increased in 2000 and 2001, and then decreased from 2002 to 2007. In 2008, there was a significant increase in the seropositive proportion of goats (OR 2.53, 95% CI 2.21-2.90, P < 0.001). The average annual cost for the control programme including testing and compensation was more than US$3 million. The total cost for the control programme including testing and compensation for the period (13 years) between 1999 and 2011 was more than US$40 million, from which more than 56% for cattle. Further studies are required for the effectiveness of the current control strategies and alternative strategies should be considered. The socio-economic impact of brucellosis and its control measures should be investigated.

Risk assessment and management of brucellosis in the southern greater Yellowstone area (II): Cost-benefit analysis of reducing elk brucellosis prevalence.

Recent cases of bovine brucellosis (Brucella abortus) in cattle (Bos taurus) and domestic bison (Bison bison) of the southern Greater Yellowstone Area (SGYA) have been traced back to free-ranging elk (Cervus elaphus). Several management activities have been implemented to reduce brucellosis seroprevalence in elk, including test-and-slaughter, low-density feeding at elk winter feedgrounds, and elk vaccination. It is unclear which of these activities are most cost-effective at reducing the risk of elk transmitting brucellosis to cattle. In a companion paper, a stochastic risk model was used to translate a reduction in elk seroprevalence to a reduction in the risk of transmission to cattle. Here, we use those results to estimate the expected economic benefits and costs of reducing seroprevalence in elk using three different management activities: vaccination of elk with Brucella strain 19 (S19), low-density feeding of elk, and elk test-and-slaughter. Results indicate that the three elk management activities yield negative expected net benefits, ranging from -$2983 per year for low-density feeding to -$595,471 per year for test-and-slaughter. Society's risk preferences will determine whether strategies that generate small negative net benefit, such as low-density feeding, are worth implementing. However, activities with large negative net benefits, such as test-and-slaughter and S19 vaccination, are unlikely to be economically worthwhile. Given uncertainty about various model parameters, we identify some circumstances in which individual management activities might generate positive expected net benefit.

The Price of a Neglected Zoonosis: Case-Control Study to Estimate Healthcare Utilization Costs of Human Brucellosis.

Human brucellosis has reemerged as a serious public health threat to the Bedouin population of southern Israel in recent years. Little is known about its economic implications derived from elevated healthcare utilization (HCU). Our objective was to estimate the HCU costs associated with human brucellosis from the insurer perspective. A case-control retrospective study was conducted among Clalit Health Services (CHS) enrollees. Brucellosis cases were defined as individuals that were diagnosed with brucellosis at the Clinical Microbiology Laboratory of Soroka University Medical Center in the 2010-2012 period (n = 470). Control subjects were randomly selected and matched 1:3 by age, sex, clinic, and primary physician (n = 1,410). HCU data, demographic characteristics and comorbidities were obtained from CHS computerized database. Mean±SD age of the brucellosis cases was 26.6±17.6 years. 63% were male and 85% were Bedouins. No significant difference in Charlson comorbidity index was found between brucellosis cases and controls (0.41 vs. 0.45, respectively, P = 0.391). Before diagnosis (baseline), the average total annual HCU cost of brucellosis cases was slightly yet significantly higher than that of the control group ($439 vs. $382, P<0.05), however, no significant differences were found at baseline in the predominant components of HCU, i.e. hospitalizations, diagnostic procedures, and medications. At the year following diagnosis, the average total annual HCU costs of brucellosis cases was significantly higher than that of controls ($1,327 vs. $380, respectively, P<0.001). Most of the difference stems from 7.9 times higher hospitalization costs (p<0.001). Additional elevated costs were 3.6 times higher laboratory tests (P<0.001), 2.8 times higher emergency room visits (P<0.001), 1.8 times higher medication (P<0.001) and 1.3 times higher diagnostic procedures (P<0.001). We conclude that human brucellosis is associated with elevated HCU costs. Considering these results in cost-effective analyses may be crucial for both reducing health inequities and optimal allocation of health systems' scarce resources.

Economic losses occurring due to brucellosis in Indian livestock populations.

Brucellosis is a serious public health issue in India. Estimation of economic losses occurring due to brucellosis is required to help formulate prevention and control strategies, but has not been done in India. We estimated economic losses due to brucellosis by sourcing prevalence data from epidemiological surveys conducted in India. Data for livestock populations were obtained from official records. Probability distributions were used for many of the input parameters to account for uncertainty and variability. The analysis revealed that brucellosis in livestock is responsible for a median loss of US $ 3.4 billion (5th-95th percentile 2.8-4.2 billion). The disease in cattle and buffalo accounted for 95.6% of the total losses occurring due to brucellosis in livestock populations. The disease is responsible for a loss of US $ 6.8 per cattle, US$18.2 per buffalo, US $ 0.7 per sheep, US $ 0.5 per goat and US $ 0.6 per pig. These losses are additional to the economic and social consequences of the disease in humans. The results suggest that the disease causes significant economic losses in the country and should be controlled on a priority basis.

Financial analysis of brucellosis control for small-scale goat farming in the Bajío region, Mexico.

Brucellosis is an endemic disease in small-scale goat husbandry systems in Mexico. It is a zoonosis and the economic consequences can be large, although estimates are not available for the Mexican goat sector. Our objective was to conduct a financial analysis of brucellosis control in a prominent dairy goat production area of the Bajío region, Mexico. We used three models: (1) a brucellosis transmission model at village flock level (n=1000 head), (2) a flock growth model at smallholder flock level (n=23 head) using output of model 1 and (3) cost-benefit analysis of several brucellosis control scenarios based on output of model 2. Scenarios consisted of test-and-slaughter or vaccination or a combination of both compared to the base situation (no control). The average net present values (NPV) of using vaccination over a 5-year period was 3.8 US$ (90% CI: 1.3-6.6) and 20 US$ (90% CI: 11.3-28.6) over a 10-year period per goat. The average benefit-cost ratios over a 5-year period and 10-year period were 4.3 US$ (90% CI: 2.2-6.9) and 12.3 US$ (90% CI: 7.5-17.3) per goat, respectively. For the total dairy goat population (38,462 head) of the study area (the Bajío of Jalisco and Michoacán) the NPV's over a 5-year and 10-year period were 0.15 million US$ and 0.8 million US$. However, brucellosis prevalence was predicted to remain relatively high at about 12%. Control scenarios with test-and-slaughter predicted to reduce brucellosis prevalence to less than 3%, but this produced a negative NPV over a 5-year period ranging from -31.6 to -11.1 US$ and from -31.1 to 7.5 US$ over a 10-year period. A brucellosis control campaign based on vaccination with full coverage is economically profitable for the goat dairy sector of the region although smallholders would need financial support in case test-and-slaughter is applied to reduce the prevalence more quickly.

Brucellosis in low-income and middle-income countries.

PURPOSE OF REVIEW: Human brucellosis is a neglected, underrecognized infection of widespread geographic distribution. It causes acute febrile illness and a potentially debilitating chronic infection in humans, and livestock infection has substantial socioeconomic impact. This review describes new information regarding the epidemiology of brucellosis in the developing world and advances in diagnosis and treatment. RECENT FINDINGS: The highest recorded incidence of human brucellosis occurs in the Middle East and Central Asia. Fever etiology studies demonstrate brucellosis as a cause of undifferentiated febrile illness in the developing world. Brucellosis is a rare cause of fever among returning travelers, but is more common among travelers returning from the Middle East and North Africa. Sensitive and specific rapid diagnostic tests appropriate for resource-limited settings have been validated. Randomized controlled trials demonstrate that optimal treatment for human brucellosis consists of doxycycline and an aminoglycoside. Decreasing the burden of human brucellosis requires control of animal brucellosis, but evidence to inform the design of control programs in the developing world is needed. SUMMARY: Brucellosis causes substantial morbidity in human and animal populations. While improvements in diagnostic options for resource-limited settings and stronger evidence for optimal therapy should enhance identification and treatment of human brucellosis, prevention of human disease through control in animals remains paramount.

Economics of brucellosis impact and control in low-income countries.

Most data and evidence on the economic burden of brucellosis and the benefits of its control are from high-income and middle-income countries. However, the burden of brucellosis is greatest in low-income countries. This paper focuses on estimating the economic burdens of brucellosis in low-income countries in tropical Asia and Africa. The prospects for national, technically feasible, and economically viable, national brucellosis control programmes in most low-income countries are limited. However, some targeted control programmes will be beneficial and can probably be feasibly managed and provide good economic returns. More ambitious control will require a more general strengthening of Veterinary Services and livestock-sector capacity, using risk-management-based approaches.

Modelling risk aversion to support decision-making for controlling zoonotic livestock diseases.

Zoonotic infectious livestock diseases are becoming a significant burden for both animal and human health and are rapidly gaining the attention of decision-makers who manage public health programmes. If control decisions have only monetary components, governments are generally regarded as being risk-neutral and the intervention strategy with the highest expected benefit (lowest expected net costs) should be preferred. However, preferences will differ and alternative intervention plans will prevail if (human) life and death outcomes are involved. A rational decision framework must therefore consider risk aversion in the decision-maker and controversial values related to public health. In the present study, risk aversion and its impact on both the utility for the monetary component and the utility for the non-monetary component is shown to be an important element when dealing with emerging zoonotic infectious livestock diseases and should not be ignored in the understanding and support of decision-making. The decision framework was applied to several control strategies for the reduction of human cases of brucellosis (Brucella melitensis) originating from sheep in Turkey.

Cattle producers' economic incentives for preventing bovine brucellosis under uncertainty.

Cattle in the Greater Yellowstone Ecosystem occasionally contract bovine brucellosis from free-ranging elk and bison. Cattle producers use a variety of brucellosis prevention activities to reduce their herds' risk of contracting brucellosis, such as: (1) having state agency personnel haze elk off private land, (2) fencing haystacks, (3) administering adult booster vaccination, (4) spaying heifers, (5) altering the winter-feeding schedule of cattle, (6) hiring riders to prevent cattle-elk commingling, and (7) delaying grazing on high-risk allotments. Their brucellosis prevention decisions are complicated, however, by several sources of uncertainty, including the following: a cattle herd's baseline risk of contracting brucellosis, the inherent randomness of brucellosis outbreaks, the cost of implementing prevention activities, and the activities' effectiveness. This study eliminates one source of uncertainty by estimating the cost of implementing brucellosis prevention activities on a representative cow/calf-long yearling operation in the southern GYE. It then reports the minimum level of effectiveness each prevention activity must achieve to justify investment by a risk-neutral producer. Individual producers face different levels of baseline risk, however, and the US government's brucellosis-response policy is constantly evolving. We therefore estimate breakeven levels of effectiveness for a range of baseline risks and government policies. Producers, animal health experts, and policymakers can use this study's results to determine which brucellosis prevention activities are unlikely to generate sufficient expected benefits to cover their cost of implementation. Results also demonstrate the influence of government policy on producers' incentives to prevent brucellosis. Policies that increase the magnitude of economic loss a producer incurs when their herd contracts brucellosis subsequently decrease prevention activities' breakeven levels of effectiveness, and increase producers' incentives to implement those activities. Producers' incentives to implement prevention activities also increase as activities' costs decrease. Policymakers can easily adapt the results of this analysis to help target cost-share agreements to producers and prevention activities most likely to generate positive expected net benefits. Epidemiologists can also use our results to help prioritize future research on the technical effectiveness of various brucellosis prevention activities.

Brucellosis in camels.

Camels are highly susceptible to brucellosis caused by Brucella melitensis and Brucella abortus. Difficulties can arise in diagnosis of camel brucellosis, especially as this disease provokes only few clinical signs in contrast to its clinical course in cattle. Because none of the commonly used serological test can be perceived as a perfect test for Brucella diagnosis in camel and most serological tests used for camels have been directly transposed from cattle without adequate validation, an incorrect diagnosis may occur when diagnosis is based on serology alone. Of imminent concern is the fact that brucellosis can be easily transmitted from animals or their products to humans mainly via milk. In many developing countries in the arid areas of Asia and Africa, camels are still the most important productive livestock for nomadic populations. Therefore, we reviewed the literatures on camel brucellosis to highlight the epidemiologic, economic and public health impact of camel brucellosis as a basis for designing effective control strategies.

Brucellosis: a re-emerging zoonosis.

Brucellosis, especially caused by Brucella melitensis, remains one of the most common zoonotic diseases worldwide with more than 500,000 human cases reported annually. The bacterial pathogen is classified by the CDC as a category (B) pathogen that has potential for development as a bio-weapon. Brucella spp. are considered as the most common laboratory-acquired pathogens. The geographical distribution of brucellosis is constantly changing with new foci emerging or re-emerging. The disease occurs worldwide in both animals and humans, except in those countries where bovine brucellosis has been eradicated. The worldwide economic losses due to brucellosis are extensive not only in animal production but also in human health. Although a number of successful vaccines are being used for immunization of animals, no satisfactory vaccine against human brucellosis is available. When the incidence of brucellosis is controlled in the animal reservoirs, there is a corresponding and significant decline in the incidence in humans.