Serological, cultural and molecular evidence of Brucella melitensis infection in goats in Al Jabal Al Akhdar, Sultanate of Oman

Seroprevalence and Risk Factors of Brucellosis in Ruminants in Dhofar Province in Southern Oman

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.

Sero-prevalence of brucellosis, Q-fever and Rift Valley fever in humans and livestock in Somali Region, Ethiopia

Information on zoonotic diseases in humans and livestock are limited in pastoral/agro-pastoral communities in Ethiopia. A multi-stage cross sectional cluster design study was implemented with the aim to establish the seroprevalence of zoonotic diseases including brucellosis, Q-fever and Rift Valley fever (RVF) in humans and livestock in Adadle Woreda of the Somali Region, Ethiopia. Blood samples were collected from humans and livestock and tested by relevant serological tests. For brucellosis, Rose Bengal test (RBT) and indirect ELISA was used for screening and confirmatory diagnosis respectively. Indirect and competitive ELISA were also used for Q-fever and RVF respectively. The individual seropositivity of Q-fever in livestock was 9.6% (95% CI 5.9-15.1) in cattle, 55.7% (95% CI 46.0-65.0) in camels, 48.8% (95% CI 42.5-55.0) in goats, and 28.9% (95% CI 25.0-33.2) in sheep. In humans, seropositivity of Q-fever was 27.0% (95% CI 20.4-34.0), with prevalence in males of 28.9% vs 24.2% in females (OR = 1.3; 95% CI 0.6-2.5). Camel seropositivity of Q-fever was significantly associated with age (OR = 8.1; 95% CI 2.8-23.7). The individual apparent seroprevalence of RVF was 13.2% (95% CI 8.7-18.8) in humans, 17.9% (95% CI 11.0-27.8) in cattle, 42.6% (95% CI 34.8-50.7) in camels, 6.3% (95% CI 3.3-11.6) in goats and 7.4% (95% CI 4.7-11.5) in sheep. Camels had the highest seropositivity of both Q-fever and RVF. Only a weak correlation was observed between human and livestock seropositivity for both Q-fever and RVF. Only cattle and camels were seropositive for brucellosis by iELISA. The individual seroprevalence of brucellosis was 2.8(0.9-6.4) in humans, 1.5% (95% CI 0.2-5.2) in cattle and 0.6% (95% CI 0.0-3.2) in camels. This study showed the importance of zoonoses in Somali Region and is the first published study to describe RVF exposure in humans and livestock in the country. Even though human exposure to RVF virus was reported, public health sector of Somali Region has not given attention to such zoonoses. Collaboration between public and animal health sectors for further investigation on these zoonoses using the One Health concept is indispensable.

Seroprevalence of brucellosis in sheep and goats in the Arabian Gulf region

BACKGROUND AND AIM

Brucellosis is a zoonosis that occurs worldwide. There were more efforts to control brucellosis in all countries. This study was performed to determine the seroprevalence of brucellosis in sheep and goats in some areas in the Arabian Gulf.

MATERIALS AND METHODS

The study analyzed 8500 sera from non-vaccinated sheep and goats. Animals included 6441 sheep (3420 from farms and 3021 from quarantine) and 2059 goats (1580 from farms and 479 from quarantine). Sera were tested using the Rose Bengal Plate Test (RBPT) and confirmed with an indirect enzyme-linked immunosorbent assay (i-ELISA) test. Final confirmation analyzed blood samples from confirmed infected animals (n=30, 23 sheep and seven goats) using polymerase chain reaction (PCR) and culture.

RESULTS

The serological examination showed that 62/8500 of animals (0.729%, confidence interval [CI] 95% 0.57-0.94) were seropositive for brucellosis. Thirteen of 5000 (0.26%, CI 95% 0.15-0.45) and 49/3500 (1.4%, CI 95% 1.1-1.8) of animals from farms and quarantine were seropositive, respectively. Out of the 6441, 46 (0.71%) sheep and 16/2059 (0.78%) goats were seropositive. i-ELISA confirmed 41/62 RBPT-positive animals - 41/8500 (0.482%, CI 95% 0.36-0.65). Eight of 5000 of these animals (0.16%, CI 95% 0.08-0.32) and 33/3500 (0.94%, CI 95% 0.67-1.3) were confirmed positive in farms and quarantine, respectively. Thirty of 6441 (0.466%) and 11/2059 (0.534%) cases were positive in sheep and goats, respectively. PCR confirmed 18 of 41 positive animals (0.212% of all sera, CI 95% 0.13-0.34) identified by both RBPT and i-ELISA. Three of 5000 (0.06%, CI 95% 0.019-0.19) and 15/3500 (0.429%, CI 95% 0.26-0.71) from farms and quarantine were confirmed positive. Tissue samples (uterine, supra-mammary, testicular, and accessory glands lymph node) were collected from positive animals, as detected by RBPT and i-ELISA, at culling or slaughtering. Using in vitro culture, 14/30 were confirmed positive - 3/7 from farms (two sheep and one goat) and 11/23 from quarantine (nine sheep and two goats). Biovar 1 was dominant. PCR confirmed 23/30 tissue samples, 4/7 from farms (three sheep and one goat), and 19/23 from quarantine (15 sheep and four goats).

CONCLUSION

The overall brucellosis rate in sheep and goats is 0.48%, with fewer animals from farms testing positive (0.16%) in this area of the Arabian Gulf. The infection appears to be well controlled, and continuous effort is still needed to maintain control and completely eradicate brucellosis. Additional support is needed for testing and slaughterhouse monitoring. In quarantine (imported animals), brucellosis infection in the slaughterhouse (0.94%) could pose a risk for transmission and spread of infection. The effort is needed to monitor this threat, and PCR is a sensitive and time-saving test for brucellosis diagnosis. All 14 confirmed positive samples were Biovar 1 dominant.

Epidemiological features of human brucellosis in Tongliao City, Inner Mongolia province, China: a cross-sectional study over an 11-year period (2007-2017)

OBJECTIVES

To describe the epidemiology of human brucellosis in the past decade and provide evidence of disease control in Tongliao city, which is one of the highest-risk areas of human brucellosis in Inner Mongolia province, China.

DESIGN

Cross-sectional study.

PARTICIPANTS

Clinically and bacteriologically confirmed human brucellosis cases.

PRIMARY AND SECONDARY OUTCOME MEASURES

An analysis of the reported cases of human brucellosis during 2007-2017 was carried out to describe the age, sex and occupational distributions of the cases. The time series analysis model and the geographical information system were explored to describe the seasonality and spatiotemporal distribution, respectively, at the county level.

RESULTS

A total of 13 938 cases of human brucellosis was collected in Tongliao from 2007 to 2017; the majority was aged 25 years to 59 years (85.4%) and the male-to-female ratio was 2.64:1; most of them were agriculturalists (81.9%) and pastoralists (12.4%). The incidence rates increased dramatically from 9.22/100 000 in 2007 to 69.16/100 000 in 2011 with an annual increase of 14.99%. They decreased during 2012-2016 (annual decrease of 8.37%) and rose again in 2017 (44.32/100 000). The disease peaked during March-July, with a clear periodicity and trend of monthly anterior displacement since 2012. Jarud Banner, the region located in the north-west of Tongliao, had the highest accumulated incidence rate (130.1/100 000) compared with other counties. The high-risk regions were spread from the north-west to the south and east of Tongliao during the past decade.

CONCLUSIONS

The prevalence of human brucellosis in Tongliao was aggravated during the past decade and peaked during March-July. High-risk areas were mainly concentrated in the counties with extensive prairies and livestock.

Zoonotic Diseases in Oman: Successes, Challenges, and Future Directions

Objective: This article describes the situation analysis of endemic and emerging zoonoses, and includes prevention and control of zoonoses in Oman. It also suggests possible recommendations toward elimination and risk reduction of emerging zoonoses. Methods: Epidemiologic information has been drawn from official to assess the situation. There has been significant progress in reducing the risk of brucellosis, Middle East Respiratory Syndrome Coronavirus, Crimean-Congo hemorrhagic fever, and cutaneous leishmaniasis. Rabies, West Nile fever, Q fever, and cystic hydatid disease have been confined to wildlife or livestock. Results: There is an increasing threat of emerging and re-emerging zoonoses in Oman due to globalization of travel and trade, development activities, and impact of climate change and vector bionomics. Prevention, control, and subsequent elimination of zoonoses on a sustainable basis shall not be possible without intersectoral collaboration between the human and animal health sectors. There are challenges for establishing such strong collaboration and coordination mechanisms in Oman. Institutional and cultural barriers, data and resource sharing, and national capability for rapid and effective investigation of zoonotic infections and emerging zoonoses in humans and animal reservoirs are among others. Conclusions: In the light of achievements made on the prevention and control of zoonoses in Oman during the past decades, priority zoonoses should be identified for elimination, and continuous efforts should be made to further strengthen a holistic multidisciplinary and multisectorial approach for controlling zoonoses at source. Pivotal interventions would include urgent adoption of "One Health" strategic approach as well as establishment of a robust, integrated surveillance system with a strong laboratory investigation capacity to eliminate priority zoonoses and minimize the risk of entry, establishment, and spread of emerging zoonoses in Oman.

Substantial Virulence Genes among Brucella melitensis Field Strains Isolated from Cattle in Egypt

BACKGROUND AND OBJECTIVE

The economic losses due to brucellosis as well as its potential public health in human worldwide encourage more researches to find novel pathways for effective control methods of the disease. The objective of this study was to investigate the most prevalent Brucella strains obtained from cattle and their virulence genes.

MATERIALS AND METHODS

Three hundred small-holders cows in Menoufia governorate, Egypt, were screened for brucellosis using rose bengal test (RBT) and confirmed by complement fixation test (CFT). Milk samples and supra-mammary lymph nodes of serologically positive cows were collected for bacteriological isolation and identification. The obtained isolates were genotyped using PCR and their virulence genes (omp25, omp31, manA, manB, virB and znuA) were screened.

RESULTS

The prevalence rate of bovine brucellosis was 15 (5%), 11 (3.6%) and 7 (2.33%) by RBT, CFT and bacteriological examination, respectively. The seven isolates were identified and genotyped as Brucella melitensis biotype3. Furthermore, the molecular detection of substantial virulence genes revealed that manA, manB, omp25 and omp31 genes were detected in all tested B. melitensis strains. Meanwhile, the virB genes were detected in 4 strains and the znuA genes were detected in 3 strains among the isolated B. melitensis strains.

CONCLUSION

It was concluded that B. melitensis biotype3 was the pre-dominant Brucella spp. as well as omp25, omp31, manA and manB were the most common related-virulence genes which assumed to play a worthy function in the pathogenesis of brucellosis.