Brucellosis in livestock: First study on seroepidemiology, risk factors, and preventive strategies to manage the disease in Famenin, Iran

Abstract

Background and Aim: Brucellosis is an infectious disease in humans and livestock. The disease is endemic in many regions of Iran, for example, Hamedan Province. Knowledge of infection rate and associated risk factors is essential to control and prevent the disease. The study aimed to estimate the prevalence of brucellosis and associated risk factors in cattle, sheep, and goats in Famenin, Hamedan Province, West of Iran. Materials and Methods: Blood samples of 1758 animals (1470 sheep, 190 goats, and 98 cattle) were obtained in different rural regions of Famenin. The samples were evaluated to detect of Brucella-antibodies using rose Bengal plate test (RBPT), Wright standard tube agglutination test (SAT), and 2-Mercapto-Ethanol (2-ME) techniques. The risk factors associated with brucellosis such as age, gender, history of vaccination against brucellosis, and abortion history in animals were evaluated. In the sampling process, the critical gaps related to the distribution of brucellosis in the herds and regions are identified for designing the strategies to prevent and control the disease. Results: About 6.88% and 89.31% of animals had a history of abortion and vaccination against brucellosis, respectively. Most of the animals were female (92.49%) and in the range of 2–3 age old (39.8%). The antibodies to the Brucella-infection in animals were 2.73% with RBPT and 1.30% with SAT and 2-ME. The prevalence of brucellosis was detected 1.3% among individual animals and 11% among herds. This rate was 1.43% for sheep and 1.05% for goats, with no significant statistical difference. No seropositive case was detected in cattle samples using RBPT, STAT, and 2-ME. The highest rate of brucellosis (6.25%) was detected in Emamzadeh-Pirnahan region (22.2% goats and 5.6% sheep). In sheep, most cases of the disease were in 3–4 age-old group (1.92%), animals without a history of abortion (1.58%), and without a history of vaccination against brucellosis (2.80%). Furthermore, 5.94% of males and 1.11% of females were detected positive for brucellosis (p < 0.001). The chance of brucellosis in rams was 5.6 folds higher than in others (odds ratio = 5.64). Brucellosis in goats was detected 2.94% and 1.89% in the age groups <1 and 2–3 year-old. Furthermore, 1.22% of females and 1.34% of animals without a history of abortion were positive. Brucellosis was found in 0.61% of vaccinated and 3.85% of non-vaccinated goats. Except for gender in sheep, no significant statistical correlation (p > 0.05) was observed between prevalence of brucellosis and risk factors. In farmers, low level of information about the transmission and also control and preventive methods of the disease was dominant. Consumption of traditional and unpasteurized dairy products is also very common in the studied regions. Conclusion: This is a comprehensive evaluation of animal brucellosis parallel to humans' cohort study in the Famenin region for the first time. Although the rate of brucellosis in animals is low in the region, explaining the risk factors to farmers, mass vaccination, regular screening of animals, and culling the positive animals are very important for controlling and reducing the disease in the region.

Molecular Investigation of Brucella Species Belongs to Sheep and Goats in Seropositive Samples from an Endemic Area of Hamedan Province; Famenin Brucellosis Cohort Study

“…The determination of co-infection between B. abortus and B. melitensis is related to keeping various animals together, which is a risk factor that needs to be managed (16). In serology evaluation, different levels of antibodies show evidence of infection (8,13). Brucella-DNA could not be identified in three of the seropositive samples.…”

“…The present study is part of a huge project on the cohort of brucellosis in the Famenin area, Hamedan, Iran (8,13). In the first stage ( 13), the seroprevalence of brucellosis in animals was evaluated in the region.…”

“…All 1,660 sera samples (sheep=1470 and goats=190) obtained in the previous investigation were reevaluated using RBPT, SAT, and 2-ME ( 16). Twentythree positive samples (sheep=21 and goats=2) were confirmed using the Iranian Veterinary Organization (IVO) protocol (Table 1) parallel to the previous study (7,13). The sera samples of 23 seropositive animals were used for DNA extraction and molecular detection.…”

“…of Brucella in humans and animals using molecular techniques (11). Different techniques based on serology are used to identify brucellosis cases, including the Rose Bengal plate test (RBPT), Wright serum agglutination test (SAT), 2-Mercapto-Ethanol (2-ME), Enzyme-linked immunosorbent assay, and Coombs test (antihuman globulin) (13,14). In Iran, RBPT, SAT, and 2-ME tests are commonly applied to detect brucellosis in animals (7).…”

Brucellosis and One Health: Inherited and Future Challenges

“…In any case, these assays do not outperform the diagnostic sensitivity and specificity (DSe and DSp) of the classical buffered Brucella agglutination tests (Rose Bengal [RBT], Card and Buffered Plate Agglutination tests) that do not suffer from cut-off adjustment problems [ 50 ]. There are abundant examples of these problems in the recent literature [ 52 , 53 , 54 , 55 , 56 , 61 , 62 , 66 , 68 , 71 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 ].…”