Cross-sectional study of brucellosis in Jordan: Prevalence, risk factors and spatial distribution in small ruminants and cattle

• Published in: Preventive veterinary medicine 2015-03, Vol.118 (4), p.387-396
• Main Authors: Musallam, I.I., Abo-Shehada, M., Omar, M., Guitian, J.
• Format: Article
• Language: English
• Subjects: Animal Husbandry; Animals; Bacterial Vaccines - therapeutic use; Brucella; Brucellosis; Brucellosis - blood; Brucellosis - epidemiology; Brucellosis - veterinary; Brucellosis, Bovine - blood; Brucellosis, Bovine - epidemiology; Cattle; Cross-sectional; Cross-Sectional Studies; Demography; Enzyme-Linked Immunosorbent Assay - veterinary; Geography; Goat Diseases - blood; Goat Diseases - epidemiology; Goat Diseases - prevention & control; Goats; Jordan; Jordan - epidemiology; Logistic Models; Milk - microbiology; Prevalence; Risk Factors; Ruminants; Seroepidemiologic Studies; Sheep; Sheep Diseases - blood; Sheep Diseases - epidemiology; Sheep Diseases - prevention & control; Surveys and Questionnaires
• ISSN: 0167-5877; 1873-1716
• DOI: 10.1016/j.prevetmed.2014.12.020

•A cross-sectional study of ruminant brucellosis in Jordan has been carried out.•This study aimed to generate unbiased seroprevalence estimates of ruminant brucellosis.•The study identified the risk factors for seropositive status of the infection.•The study also described the spatial distribution of the infection in Jordan.•This information is hoped to inform a new phase of the brucellosis control programme in Jordan. Brucellosis is considered endemic in many Middle Eastern countries including Jordan. To determine the frequency, risk factors and spatial distribution of ruminant brucellosis in Jordan, a nationwide cross-sectional study was conducted. Small ruminant flocks (n=333) and cattle herds (n=204) were randomly selected, and their disease status was ascertained by testing individual serum samples using the Rose Bengal Test and a competitive ELISA (sheep and goats) and milk samples using an indirect ELISA (cattle). Information on putative risk factors was collected using standardized questionnaires. A logistic model with a binomial outcome was built to identify risk factors for being seropositive. The estimated true seroprevalence values were 18.1% (95% CI: 11–25.3) (cattle-only herds), 22.2% (95% CI: 16.5–28.8) (sheep flocks), 45.4% (95% CI: 30.3–61.6) (goat herds), 70.4% (95% CI: 55.5–84.9) (mixed sheep-goat flocks), 34.3% (95% CI: 28.4, 40.4) (all small ruminant flocks) and 38.5% (95% CI: 24.3–51.8) (mixed herds of cattle and small ruminants). Only 1.5% of small ruminant flocks were vaccinated. The seroprevalence was higher in northern areas, where livestock density is also higher. The logistic model fitted the data well and had a very high predictive ability. In the small ruminant model, five variables were significantly associated with a higher odds of seropositivity: lending/borrowing rams (OR=8.9, 95% CI: 3.0–26.1), feeding aborted material to dogs (OR=8.0, 95% CI: 3.5–18.1) the presence of goats (OR=6.9, 95% CI: 3.1–15.4), introducing new animals to the flock (OR=5.8, 95% CI: 2.5–13.6), and a large flock size (OR=2.2, 95% CI: 1.0–4.6). Conversely, separating newly introduced animals (OR=0.16, 95% CI: 0.05–0.47), separating animals that had aborted (OR=0.19, 95% CI: 0.08–0.46) and using disinfectants to clean pens (OR=0.37, 95% CI: 0.16–0.83) were significantly associated with a lower odds of being seropositive. The main risk factor for cattle herds being seropositive was the introduction of new animals (OR=11.7, 95% CI: 2.8–49.4); while separ