ABSTRACT
Objective: The aim of the present work was to raise awareness of Brucella infection and emphasize the use of serological tests for screening and confirmation of the presence of the infection in different localities in the Dhofar region in the Sultanate of Oman. Methods: A seroprevalence of Brucella infection in naturally infected livestock was undertaken in 50 farms (a total of 434 sera, 207 goats, 84 sheep, 54 cattle, and 89 camels) from different wilayat of the Dhofar region in the southern part of Oman. Rose Bengal (RBT), complement fixation (CFT), and indirect enzyme-linked immunosorbent assay (I-ELISA) tests were used to determine the presence of Brucella antibodies. Statistical analysis (Pearson chi-square, binary logistic regression, and univariate logistic regression) was used to investigate the significance between the prevalence and the categorical risk factors individually, with two or more levels (animal species, animal condition, and or location). Results: Our results show that the overall seroprevalence based on CFT, RBT, and I-ELISA was 3% (13/424, CI: 1.8-5.1%), 4.8% (21/434, CI: 3.1-7.3%), and 8% (35/434, CI: 5.8-10.9%), respectively. The highest seroprevalence was reported in goats (13% (27/207)) and animals from East Jabal (13% (21/161)), whereas the lowest was recorded in camels (3.4% (3/89)) and animals from deserts (1.4% (1/69)). Parameters such as the positive predictive value (PPV) and the negative predictive value (NPV) showed that the sensitivity of I-ELISA and CFT based on the RBT test was 61.9% and 57.1%, respectively, whereas the specificity of I-ELISA (94.6%) was less than that of CFT (97.33%). Conclusion: We concluded that three tests are confirmatory for the presence of Brucella infection.
ABSTRACT
The original article [1] incorrectly presents final author, Eugene H. Johnson's name incorrectly whereby middle initial, 'H.' is mistakenly presented as a Family Name.
ABSTRACT
BACKGROUND: The objective of this study was to investigate Brucella infection in farm animals in Saham, Oman, with reference to a survey carried out by the Ministry of Agriculture & Fisheries (MAF) for Brucellosis during the period of May to July 2016 in Saham, following an outbreak of human brucellosis. We wanted to apply different serological, bacteriological and molecular tests in a time frame (phase 1, 2 & 3) with reference to the pivotal time of a human brucellosis outbreak to ascertain the status of the disease in Saham area where the MAF survey was conducted. Blood samples were collected from farm animals and sera were screened in parallel for Brucella antibodies using different serological tests. RESULTS: Using the RBT test, phase 1 sera showed seropositivity in sheep at 2.6%, (95% CI: 0.5-13.5%), in camel (5.9%, 1.1-27.0%), but not in sera from goats and cattle (0%). Using I-ELISA, seropositivity in goat was 3.1% (0.6-15.8%), with no positive sheep and cattle. Using c-ELISA for camel we found a seropositivity of 5.9% (1.1-27.0%). Furthermore, CFT seropositivity in goats was 21.9% (CI: 11.3-38.9), cattle and sheep sera were negative and camel was 5.9% (1.1-27.0%). In phase 2, the seropositivity in goats was 1.9% (1.4-2.6%), sheep 4.5% (3.5-5.8%), cattle 1.1%, (0.5-2.3%) and camels 18.2% (5.1-47.7%), Phase 3 sera were collected 6 months after the human brucellosis outbreak. With RBT, the seropositivity in goats was 3% (1.0-8.5%), sheep 2% (0.6-7.1%) cattle 1% (0.2-5.5%). With I-ELISA, goats & camels were negative, sheep were 3% (1.0-8.5%) and cattle 1% (0.2-5.5%). Moreover, B. melitensis was isolated from a bronchial lymph node of the RBT and I-ELISA seropositive cow and confirmed by Multiplex PCR and biochemical tests. CONCLUSION: Using a retrospective study analysis of animal sera and following up after a human brucellosis outbreak, the present study showed a slight decrease in seropositivity of infected animals after the MAF implemented test and slaughter policy. The most interesting finding in this study was the isolation, identification and molecular characterization of Brucella melitensis in a cow (spillover), which is not a preferential host for Brucella melitensis.
