The epidemiology of brucellosis in the Sultanate of Oman

Brucellosis is a serious disease of cattle in many countries of the world, including Mediterranean and Middle Eastern countries. The study outlined in this thesis was conducted to investigate the epidemiology of brucellosis in the Sultanate of Oman. Thirty of 1267 holdings tested in the Sultanate contained seropositive animals for brucellosis (herd prevalence 2.4%, 95% CI 1.6, 3.4%). The southern governorate (Dhofar) had significantly more seropositive holdings (n = 20, 8.6%, 95% CI 5.3, 13) than did the northern governorates (n = 10, 0.97%, 95% CI 0.5, 1.8) (p < 0.001) highlighting the endemic nature of the disease in Dhofar. Although there were no significant differences between the herd seroprevalence for individual species, the highest herd level seroprevalence was reported in cattle (4.9%) followed by camels (2.3%), goats (1.4%) and sheep (0.6%). The overall individual animal seroprevalence of brucellosis in Oman was generally at a low level (0.4%; 95% CI 0.2, 0.5). The individual seroprevalence level in the different species was also low, being 0.4%, 0.4%, 0.4% and 0.1% in cattle, camels, goats and sheep, respectively. The practice of moving animals without testing between governorates is likely to have allowed the spread of infection throughout Oman. The active importation of live animals from other countries in the Horn of Africa, without prior monitoring of their brucellosis status, inter-species contact, sharing of common pasture, large herd size and the presence of poor biosecurity/unhygienic conditions in herds in the southern governorate may have facilitated the spread of brucellosis in the Dhofar region and from here infection may have been transmitted to other governorates. A logistic-regression analysis was undertaken to identify risk factors for disease. This analysis indicated associations of breed, age, herd size and production system with seropositivity. A higher seroprevalence was found in imported animals (OR 3.71, 95% CI 0.68, 20.43), and the seroprevalence increased with age. The latter finding is possibly because of a higher risk of contracting the disease after puberty through increased contacts with potentially infected animals. Only Brucella melitensis was cultured from different species of animals and biotype 1 was the only type identified in Oman by molecular means and phage typing. Sequencing of DNA revealed that all isolates had a very similar pattern. In the current study although there was no significant difference observed in the seroprevalence detected by different diagnostic assays (cELISA, iELISA and RBPT), the ELISAs were capable of detecting more positive samples than the RBPT and Rapid test. This may reflect the better sensitivity of the ELISAs and it is recommended that these tests be used in the control and eradication of brucellosis in Oman, where vaccination is undertaken. In Oman, human brucellosis was first reported in 1979 in the southern Dhofar governorate. A retrospective analysis of human brucellosis data sourced from the Ministry of Health, Oman from 1995 to 2012 was conducted. Information regarding location, age, gender, nationality of patients and year were included in the analysis. During this period, 2737 human cases of brucellosis were reported, with 96.7% of these in Dhofar. The incidence of disease was highest in young individuals (0-10 years of age), highlighting that these subjects were more at risk of acquiring brucellosis. The incidence of brucellosis was slightly higher in males (56%) than females (44%). Most of the positive patients were Omani nationals, most likely because of more opportunity for contact with infected animals on privately owned farms. The failure of disease control programmes in the southern region (2003 until 2012) could be due to a lack of information, inappropriate planning or administrative issues. With the information gathered from this study, it is considered there is a need to build a strategy to control the disease throughout Oman, rather than restricting control to the Dhofar governorate. However it is recommended that the control program adopted in the southern region (Dhofar), where the seroprevalence is high, be different to that implemented in the northern regions, where the disease prevalence is lower and more manageable. In the southern region, implementing a vaccination programme, along with individual animal identification and disease screening with a plan of intensive involvement and extension in the community, should be considered. In contrast in the northern region a test and slaughter program could be implemented

Sero-Survey of Equine Infectious Anemia in the Sultanate of Oman during 2007-2009

Equine infectious anemia (EIA) is a fatal and relapsing infectious disease of equines caused by the lentivirus of Retroviridae family which occurs world-wide. It tends to become an inapparent infection if death does not result from the acute clinical attack. The virus persists in infected animals for life and can be detected by serological tests like enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) tests. Keeping in view the importance of EIA, a sero-survey and passive surveillance was designed to establish the status of EIA in Oman. For the current study, ELISA was carried out on 331 random horse serum samples collected from all over Oman and 262 serum samples submitted from race horses. Four (0.67%) out of total 593 serum samples were found positive on ELISA. These samples were further tested by agar gel immunodiffusion (AGID) test for the confirmation and were found negative. Based on the analysis of the samples, it can be assumed that the horse population in the Sultanate was free of the disease during the study period (2007-2009)

Clinico-Histopathological Findings and PCR Based Diagnosis of Lumpy Skin Disease in the Sultanate of Oman

Current report describes the clinical, histopathological and molecular diagnosis of lumpy skin disease (LSD) outbreak in the Sultanate of Oman during 2009. Outbreak was suspected on the basis of clinical picture in 13 cattle (n=201) farms belonging to Al-Batinah (7 holdings), Al-Dakhiliyah (2 holdings) and Ash Sharqiyah (4 holdings) regions. All suspected cases were clinically examined and a tentative diagnosis of LSD was made upon observation of classical signs. Morbidity and mortality rates were recorded as 27.9 and 5.5%, respectively. Apparent case fatality rate observed was 19.6%. Histopathological examination of the suspected skin biopsy samples revealed presence of ballooning degeneration and intracytoplasmic inclusion bodies characteristic of LSD. PCR reaction was carried out to confirm the presence of disease. Amplification of 221bp (base pair) PCR product from samples belonging to all 3 affected regions confirmed the presence of LSD virus DNA

African Lineage Brucella melitensis Isolates from Omani Livestock

Brucellosis is a common livestock disease in the Middle East and North Africa, but remains poorly described in the region both genetically and epidemiologically. Traditionally found in goats and sheep, Brucella melitensis is increasingly recognized as infecting camels. Most studies of brucellosis in camels to date have focused on serological surveys, providing only limited understanding of the molecular epidemiology of circulating strains. We genotyped B. melitensis isolates from Omani camels using whole genome SNP assays and VNTRs to provide context for regional brucellosis cases. We identified a lineage of B. melitensis circulating in camels as well as in goats, sheep, and cattle in Oman. This lineage is genetically distinct from most genotypes from the Arabian Peninsula and from isolates from much of the rest of the Middle East. We then developed diagnostic assays that rapidly identify strains from this lineage. In analyses of genotypes from throughout the region, Omani isolates were genetically most closely related to strains from brucellosis cases in humans and livestock in North Africa. Our findings suggest an African origin for B. melitensis in Oman that has likely occurred through the trade of infected livestock. Moreover, African lineages of B. melitensis appear to be undersampled and consequently are underrepresented in genetic databases for Brucella. As we begin to more fully understand global genomic diversity of B. melitensis, finding and characterizing these unique but widespread lineages is essential. We predict that increased sampling of humans and livestock in Africa will reveal little known diversity in this important zoonotic pathogen