A method of accelerated eradication of bovine brucellosis in the Czech Republic

Impact of herd mobility on brucellosis seroprevalence and spread risk resulting from cross-border transhumance

BACKGROUND

Cross-border livestock mobility through transhumance is mainly practiced in West African countries for seasonal access to resources and market. Cross-border herds are involved in the dynamic of transboundary animal diseases among them brucellosis taken as model. Brucellosis is a zoonotic disease causing abortion.

OBJECTIVES

This study explores the seroprevalence of brucellosis according to mobility and infection spread between Mali and Côte d'Ivoire in the context of seasonal cross-border transhumance.

METHODS

From February to April 2021, a transversal serological survey of brucellosis was conducted on 521 cattle from 111 transhumant herds and 283 cattle from 59 sedentary herds, all from Mali.

RESULTS

The global individual seroprevalence for Brucella spp. in transhumant and sedentary cattle from Mali was 8.2% (95% CI = 6.0-10.5). At herd level, seroprevalence was 21.2% with a significant variation between transhumant (11.7%) and sedentary (39.0%) herds. For herds in transhumance, cattle seropositivity was associated with a previous infection suspected by herdsmen odds ratio (OR = 4.4; 95% CI = 1.1-18.1) and unknown abortion aetiology (OR = 4.3; 95% CI = 1.0-17.3). The departure region (coming from Sikasso) and previous brucellosis infection or unexplained abortion could be used to predict Brucella infection in transhumant herds with a probability of around 60%. The risk of brucellosis introduction in host regions was high despite the individual animal seroprevalence of 3.6% and a low sale rate in transhumant cattle.

CONCLUSIONS

The findings suggest that testing transhumant during border control and survey of cattle markets and sales could improve risk control of the spread of disease at regional scale.

A systematic review of economic assessments for brucellosis control interventions in livestock populations

Brucellosis in livestock is a disease of paramount importance to animal and human health authorities due to its socio-economic and public health consequences. Benefit cost analyses can help policymakers decide whether allocation of resources is economically beneficial to cover the costs of brucellosis control interventions in populations. One broad question of interest is: what are the consequences of acting, or failing to act, on policy options of selected intervention scenarios (e.g., vaccination, test-and-slaughter, vaccination combined with test-and-slaughter, versus a status-quo scenario). The objective of the systematic review reported here was to conduct a critical appraisal of published research reports of economic assessments of brucellosis control interventions in livestock populations. The systematic review followed standard guidelines using a Population, Intervention, Comparison, Outcome, and Context framework and Preferred Reporting Items for Systematic Review and Meta-Analysis. The review targeted research reports focused on brucellosis control interventions in livestock populations at the national or regional level. Economic outcomes of interest were benefit-cost ratio (BCR), net present value, internal rate of return, or payback period. Eleven studies conducted in Brazil, China, India, Iraq, Mexico, Mongolia, Spain, Turkey, or the USA met the inclusion criteria and were included. The baseline prevalence of brucellosis in selected study populations ranged from 1.4% in cattle in Turkey to 20% in goats in Mexico. In six studies, selected intervention scenarios of vaccination alone produced BCRs that ranged from 3.2 in yaks in China or in cattle, sheep and goats in Mongolia, to 21.3 in cattle and/or buffalo in India. In three studies, interventions of test-and-slaughter produced BCRs that ranged from - 1.2 in goats in Mexico to 0.6 in cattle in Spain. In four studies, vaccination in combination with test-and-slaughter produced BCRs that ranged from 0.2 in yaks in China to 3.7 in cattle and buffalo in India. In seven studies, using sensitivity analysis, different input parameters (prevalence of brucellosis, meat price, cashmere price, vaccination coverage, test-and-slaughter coverage, milk price, vaccination protection, abortion cost, abortion rate, or price of lamb) had an impact on economic outcomes. Vaccination alone was cost-effective, but test-and-slaughter was not, for brucellosis control in selected livestock populations in focus countries. Vaccination in combination with test-and-slaughter produced profitable or nonprofitable economic outcomes. While most studies reported the cost and benefits of implementing brucellosis control interventions, only one study explained socio-economic consequences of economic outcomes, when acting, or failing to act, on selected interventions in livestock populations.

Factors Influencing the Transborder Transmission of Brucellosis in Cattle Between Côte d'Ivoire and Mali: Evidence From Literature and Current Key Stakeholders

Brucellosis is one of the main zoonoses affecting ruminants. Cattle and small ruminants are involved in transhumance and trade between Côte d'Ivoire and Mali. The endemic nature of the disease in both countries, connected through transhumance, poses unique challenges and requires more information to facilitate disease surveillance and the development of integrated control strategies. This study aimed to assess the main factors influencing the historical and current transborder transmission of brucellosis between Côte d'Ivoire and Mali. A literature review was conducted and data collection was performed through a participatory, transdisciplinary process by holding focus group discussions and interviews with key stakeholders. Cattle breeders, herdsmen, professionals of animal and human health, border control agents and experts took part. The data was analyzed to generate essential new knowledge for transborder brucellosis transmission factors and control strategies. From the literature, the seroprevalence of brucellosis in both countries varied from 11% (1987) to 20% (2013) and 15% (1972-1973) to 5% (2012-2014) in Mali and Côte d'Ivoire, respectively. The reduction of seroprevalence in Côte d'Ivoire was the result of the annual vaccination campaigns which lowered it from 28% (1978) to 14% (1984) after an increase due to livestock policy implemented in 1976. The meta-analysis and interviews jointly showed that the cross-border mobility was associated with the livestock development policy in Côte d'Ivoire as well as the ECOWAS act on the free movement of people and goods. This act supported the seasonal transhumance of livestock for access to pasture land in southern humid zones in Côte d'Ivoire. The seasonal mobility for grazing and trade was the main risk factor for the spread of brucellosis between pastoral zones of both countries. The existing legal health framework and border control mechanism do not achieve transborder surveillance to control brucellosis. Existing sanitary regulations should be adapted at regional scale to integrate a joint surveillance of high priority zoonotic diseases like brucellosis at border controls.

Characterization and evolution of countries affected by bovine brucellosis (1996-2014)

This paper describes the global distribution and temporal evolution of bovine brucellosis due to Brucella abortus during a 19-year period (1996-2014) using the information officially reported to the World Organisation for Animal Health (OIE) by veterinary services of 156 countries. Variables that can influence the health status of bovine brucellosis (i.e., year, per capita Gross Domestic Product (GDP), continent and bovine population) were also analysed. Countries were classified into three categories of health situations: ENZOOTIC: countries infected, which may have been free of brucellosis but for periods of fewer than 3 years; NON-ENZOOTIC: countries where the disease was present but that had at least a 3-year period without the disease; and FREE: countries where the disease remained absent during the whole period. The countries free from bovine brucellosis, or in the process of eradication, were located in Oceania and Europe, while the more affected regions were Central and South America, Africa and parts of Asia. Among the Non-Enzootic countries, the results showed that a very high proportion managed to control the disease during the period of study, with a sharp decline in the percentage of infected countries from 71% in 1996 to 10% in 2014. Among the Enzootic countries, a much smaller proportion managed to control the disease, with a slight drop in the percentage of infected countries from 92% in 1996 to 80% in 2014. A relationship was found between the status of the disease and the availability of economic resources; thus, countries with a high GDP per capita tended to be free from bovine brucellosis. On the other hand, countries with a larger bovine population showed a greater probability to have the disease present. An increase in surveillance programmes and implementation of control policies were observed during the period of study.

Occurrence of oxidative stress in dairy cows seropositives for Brucella abortus

Bovine brucellosis is an important zoonotic disease caused by the bacterium Brucella abortus that leads to economic losses due to animal discard and commercial restrictions. Since positive animals for brucellosis are culled, little is known about the pathogenesis of this disease. Therefore, the aims of this study were to evaluate possible changes in the activity of deaminase adenosine (ADA) and the oxidative stress in cows seropositives for brucellosis (Experiment I), and to evaluate the seroprevalence of B. abortus in dairy cows from the Western state of Santa Catarina, Southern Brazil (Experiment II). The Experiment I evaluated 20 pregnant cows: ten seropositives for B. abortus and ten seronegatives that were used as controls. The ADA activity and markers of oxidative stress (TBARS, catalase (CAT) and superoxide dismutase (SOD)) were evaluated in these animals. A reduction in the activity of ADA and catalase enzymes in seropositive animals was observed (p < 0.001). Conversely, there was an increase in TBARS levels and superoxide dismutase activity in cows infected by B. abortus (p < 0.001). The presence of oxidative stress and a reduction of ADA might be related to the modulation of the inflammatory response. The experiment II was performed due to a high number of herds with restrictions imposed by cases of brucellosis in the state of Santa Catarina in the last two years, and thus, the seroprevalence for B. abortus was evaluated in 1242 serum samples of cows of 69 herds. The serodiagnosis was performed using two tests: buffered acidified antigen and 2-mercaptoethanol. However, none of the serum samples were positive for B. abortus. Although we did not find seropositive animals for brucellosis in our study, the disease still requires continued surveillance, due to its economic impact, and to the oxidative stress caused by it, which may have contributed to cases of abortion in three seropositive cows (Experiment I) in the final third of the gestation.