Mathematical modeling and control of brucellosis in El Oued province, Algeria.

Abstract

Brucellosis is an endemic zoonotic disease responsible for enormous losses in animal industry and public health in Algeria. Therefore, designing a control/eradication policy adjusted to epidemiological and socioeconomic conditions appeared to be a requisite. In this context, the present PhD project aimed to simulate different control strategies over 20 years in order to predict the optimum approach to eradicate the brucellosis in small ruminant in El Oued district. Therefore, a cross sectional study was carried out among small ruminant flocks to determine the herd and individual true prevalence. Six hundred and twelve (612) sera samples were screened for anti-Brucella spp. antibodies using Rose Bengal test (RBT), and indirect enzymelinked immunosorbent assay (iELISA) in parallel and complement fixation test (CFT) for confirmation. Afterward, a deterministic mathematical model of the dynamic spread of brucellosis in small ruminant using compartmental model and a deterministic simulation agentbased-model (ABM) of different control strategies were developed. Indispensable data in relation to Brucella melitensis, characteristics of animal population in the study area, vaccination, and the performance of serological tests were collected meticulously. True herd prevalence was 27.95% (95% CI: 17.18–42.01) and true individual prevalence was 3.98% (95% CI: 2.51–6.03). Sampling of 50% of adults to be culled and slaughtered after positive reaction to RBT and CFT used in serial testing revealed to be the optimum strategy to eradicate the disease for about 18-19 years in the study area. Combining vaccination of young animals may enhance slightly the effectiveness of the eradication policy, but would not be cost-effective for a long-term program. Based on our findings, the adoption of test-and- slaughter strategy in order to eliminate the disease in El Oued district is strongly advised. However, cooperation and willingness of all stakeholders is vital for the adopted program to be effective and fruitful. Similar studies in distinct ecological areas and unified epidemiological conditions are highly recommended to draw up an optimal control/eradication plan.