A cross-sectional seroepidemiological study of camel (Camelus dromedarius) brucellosis and associated risk factors in the Sultanate of Oman

An Epidemiological Study of Brucellosis in Different Animal Species from the Al-Qassim Region, Saudi Arabia

Brucellosis is a zoonotic bacterial illness that affects humans and a variety of domestic animals, especially ruminants. It is mostly transmitted through the consumption of contaminated drinks, foods, undercooked meat, or unpasteurized milk or contact with infected animals. Therefore, the present study aimed to investigate the seroprevalence of brucellosis in camels, sheep, and goat herds in the Qassim region, Saudi Arabia, using commonly used diagnostic serological procedures such as the Rose Bengal test (RBT), complement fixation test (CFT), and enzyme-linked immunosorbent assay (ELISA). The seroprevalence of brucellosis in camels, sheep, and goats was determined in the selected areas using a cross-sectional study design and a total of 690 farm animals of both sexes of different ages from the three animal species (274 camels, 227 sheep, and 189 goats). According to RBT results, 65 sera were positive for brucellosis, including 15 (5.47%) for camels, 32 (14.09%) for sheep, and 18 (9.50%) for goats. CFT and c-ELISA were performed as confirmatory tests on positive samples resulting from RBT. With c-ELISA, 60 serum samples were confirmed positive, in 14 (5.10%), 30 (13.21%), and 16 (8.46%) camels, sheep, and goats, respectively. There were 59 serum samples confirmed as positive for CFT, including 14 (5.11%), 29 (12.77%), and 16 (8.46%) for camels, sheep, and goats, respectively. Overall, the highest seroprevalence of brucellosis was found in sheep while the least was found in camels from the three tests (RBT, c-ELISA, and CFT). The highest seroprevalence of brucellosis was found in sheep while the least seroprevalence was found in camels. There was also a higher seroprevalence of brucellosis among female animals than males as well as among old animals than young animals. The study, thus, demonstrates brucellosis seroprevalence among farm animals (camels, sheep, and goats) and the significance of intervention measures against brucellosis incidence in both humans and animals through the creation of public awareness and other relevant policy measures such as livestock vaccination, effective hygiene management, and adequate quarantine or serological analysis for newly introduced animals.

Characterization of an H7N9 Influenza Virus Isolated from Camels in Inner Mongolia, China

The H7N9 subtype of influenza virus can infect birds and humans, causing great losses in the poultry industry and threatening public health worldwide. However, H7N9 infection in other mammals has not been reported yet. In the present study, one H7N9 subtype influenza virus, A/camel/Inner Mongolia/XL/2020 (XL), was isolated from the nasal swabs of camels in Inner Mongolia, China, in 2020. Sequence analyses revealed that the hemagglutinin cleavage site of the XL virus was ELPKGR/GLF, which is a low-pathogenicity molecular characteristic. The XL virus had similar mammalian adaptations to human-originated H7N9 viruses, such as the polymerase basic protein 2 (PB2) Glu-to-Lys mutation at position 627 (E627K) mutation, but differed from avian-originated H7N9 viruses. The XL virus showed a higher SA-α2,6-Gal receptor-binding affinity and better mammalian cell replication than the avian H7N9 virus. Moreover, the XL virus had weak pathogenicity in chickens, with an intravenous pathogenicity index of 0.01, and intermediate virulence in mice, with a median lethal dose of 4.8. The XL virus replicated well and caused clear infiltration of inflammatory cells and increased inflammatory cytokines in the lungs of mice. Our data constitute the first evidence that the low-pathogenicity H7N9 influenza virus can infect camels and therefore poses a high risk to public health. IMPORTANCE H5 subtype avian influenza viruses can cause serious diseases in poultry and wild birds. On rare occasions, viruses can cause cross-species transmission to mammalian species, including humans, pigs, horses, canines, seals, and minks. The H7N9 subtype of the influenza virus can also infect both birds and humans. However, viral infection in other mammalian species has not been reported yet. In this study, we found that the H7N9 virus could infect camels. Notably, the H7N9 virus from camels had mammalian adaption molecular markers, including altered receptor-binding activity on the hemagglutinin protein and an E627K mutation on the polymerase basic protein 2 protein. Our findings indicated that the potential risk of camel-origin H7N9 virus to public health is of great concern.

Seroprevalence of camel brucellosis in Qatar

Brucellosis is a significant zoonotic disease and one of the most common neglected diseases worldwide. It can infect a wide range of domestic and wild animal species. Infected animals are usually culled, causing substantial economic losses to animal owners and the country's economy in general. The disease is endemic among cattle, sheep, and goats in many countries around the Middle East and prevalent in most Gulf Cooperation Council countries, comprising a significant public health risk in the region. This study investigated the seroprevalence of brucellosis among camels in Qatar. Two hundred and forty-eight samples were collected from dromedary camels from 28 farms across the entire country. Each sample was tested for Brucella antibodies with both Rose Bengal and competitive enzyme-linked immunosorbent assay. Only samples that tested positive by both tests were considered seropositive for brucellosis. The overall prevalence was (20.6%, 95% CI, 15.7-26.1). The association between sex and seropositivity was slightly significant (Χ² = 4.32, P = 0.04), with higher seroprevalence in females. Camels below breeding age (i.e., < 4 years old) showed decreased seropositivity (3.4%, 95% CI, 0.1-17.8), compared to (22.8%, 95% CI, 17.4-29.0) seropositivity in camels ≥ 4 years of age, with a significant association between age groups and seropositivity (P = 0.02). Our results indicate that the seroprevalence of brucellosis in Qatar's camels is alarming, mandating more efforts to control the disease. The findings of this study will aid in selecting better effective measures to control camel brucellosis in Qatar. Further studies need to be conducted on Brucella infection among camels to determine the predisposing risk factors and the steps that should be followed to control brucellosis.

Seroprevalence and Risk Factors Associated with Brucella Infection in Camels in the Puntland State of Somalia

Brucellosis is an important zoonotic disease caused by members of the genus Brucella. Camel brucellosis has been reported in almost all camel-rearing countries in Africa and Asia. A cross-sectional study was conducted between February 2020 and February 2021 in Galkayo, Garowe, and Bosaso districts in the Puntland State of Somalia to investigate the seroprevalence and risk factors of brucellosis in camels. A competitive enzyme-linked immunosorbent assay (c-ELISA) was used to detect anti-Brucella antibodies, while a structured questionnaire was used to collect epidemiological data. A total of 441 camel sera were screened against Brucella antibodies. Thirty-one (7%; 95% CI: 4.8–9.8%) samples were positive, and thirteen (54.2%; 95% CI: 32.8–74.4%) out of the twenty-four farms sampled had at least one seropositive animal. Galkayo district had the highest number of Brucella-seropositive camels (10.3%), followed by Bosaso district (8.6%), while Garowe district had the lowest number of seropositive camels (1.4%). The binary logistic regression model revealed that camels in Galkayo district (p = 0.015; OR: 9.428; 95% CI: 1.539–57.755), camels from large herd sizes of >50 animals (p = 0.019; OR: 5.822; 95% CI: 1.336–25.371), and those in contact with small ruminants (p = 0.011; OR: 10.941; 95% CI: 1.728–69.285) were significantly associated with seropositive cases of camel brucellosis in the Puntland State of Somalia. The present study shows that Brucella infections in camels are prevalent in the three districts covered by the study. This poses a public health risk, because milk from these camels is used for human consumption. Studies focusing on the isolation of Brucella strains in camels and investigating brucellosis in ruminants and humans are recommended in the study area. Validation of serological tests—including c-ELISA—for Brucella antibody detection in camels is also needed.