Tesfaye Rufael’s research while affiliated with The Pirbright Institute and other places

Pseudomonas species (including P. aeruginosa, P. putida, and P. fluorescens) are zoonotic bacterial pathogens that frequently cause disease and significant mortality among both cultured and wild fish worldwide. In Ethiopia, Pseudomonas species have been identified in Sebeta fish ponds and Rift Valley lakes. However, information on the molecular and phenotypic characteristics of Pseudomonas species in Ethiopian aquaculture ponds is limited. To address this gap, a cross-sectional study was conducted from November 2022 to May 2023 in selected aquaculture ponds in Ethiopia. A total of 637 samples were aseptically collected from the muscle, liver, spleen, and kidney of fish in these ponds using purposive sampling methods. The samples were cultured on Pseudomonas base agar with the selective supplement cetriNix (FD029) media and glycerol and subjected to morphological and biochemical tests to isolate and identify Pseudomonas species. The pathogen was isolated from 81 samples, accounting for 12.7% of the total. Among these isolates, 85.6% exhibited virulence traits, such as β-hemolysis on blood agar with 5% sheep blood. Additionally, 75 strains (92.59%) were confirmed using conventional PCR with Pseudomonas-specific primers and an optimized protocol. Among the PCR-positive samples, 8 (10.66%) were identified as P. aeruginosa, 28 (37.63%) as P. putida, and 39 (52%) as P. fluorescens from Nile Tilapia (O. niloticus). Antibiotic susceptibility testing on ten representative isolates showed that all Pseudomonas isolates were susceptible to Ciprofloxacin, Gentamicin, and Ceftriaxone, but resistant to Amoxicillin and Penicillin. The study concludes that Pseudomonas species (including P. aeruginosa, P. putida, and P. fluorescens) strains carrying the virulence gene Psul, which are β-hemolytic and resistant to commonly used antibiotics in human and veterinary medicine, are present in Ethiopian aquaculture. The detection of this pathogen in 75 fish samples is concerning due to the potential for outbreaks and zoonotic transmission. Therefore, further research into the molecular epidemiology of the disease is needed to understand potential inter-host transmission and antibiotic resistance traits. Additionally, public awareness about the risks of consuming undercooked or raw fish meat should be raised.

Nile tilapia ( Oreochromis niloticus ) one of the commercially important fast-growing and well-adapted freshwater fish is cultivated extensively worldwide (FAO 2018). The present study was conducted on 36 apparently healthy Nile Tilapia (130 ± 10 g. body weight and average 19.5 cm length) collected from the National Fisheries and Aquatic Life Research Center (NFARC), Sebeta. Fish were adapted for one week in the experimental greenhouse of NFARC before starting the experiment Fish were divided into two groups (18 fish per each), inoculated intraperitoneally using 0.2 ml of saline, and the pathogen, Pseudomonas fluorescens at a concentration of 3 x 106 CFU/ml. The inoculated fish were observed for 21 days for pathogenicity. The clinical signs observed on the second day post injection were loss of balance, excessive mucus secretions on skin and gills, ascites with slightly protruded reddish vent, hemorrhages all over the body surface, frayed fins, and an empty intestine. This study showed that Pseudomona s infection caused 55.4% (10) mortality, with severe alterations in RBC and WBC counts with severe histopathological changes in muscle, gills, liver, kidney, spleen, and intestine. The histopathological changes observed include hemorrhages, tubular cell necrosis, congestion, mononuclear cell aggregation and infiltration in the kidney; hepatocyte vacuolization in liver; lamellar fusion in gills; sloughed and mucosal necrosis in intestine; mononuclear cell aggregation and infiltration in muscle and hemosiderin accumulation in spleen.

Background Coxiella burnetii is causing infections in both humans and animals, resulting in Q fever and Coxiellosis, respectively. Information on the occurrence of C. burnetii infection is scarce in Ethiopia. This study estimated the sero-prevalence of C. burnetii infection and associated risk factors in four common livestock species from Addis Ababa, Adama, and Modjo abattoirs and pastoral areas of Oromia, Ethiopia. Results/principal findings Sera samples were analyzed for the presence of anti-C. burnetii antibodies using an indirect Enzyme Linked Immunosorbent Assay kit. Out of the 4140 serum samples tested, 777 (18.77%; 95% CI: 17.59, 19.99) were found positive for C. burnetii. The sero-prevalence estimate was 27.17% at Addis Ababa abattoir, 19.41% at Adama abattoir, 19.13% at Modjo abattoir and 12.1% in animals tested from pastoral areas. Sera analysis at the animal species level showed that cattle exhibited the lowest sero-prevalence estimate (11.83%; 95% CI, 10.27–13.53%), while the highest was observed in camels (28.39%; 95% CI, 25.16–31.80%). The sero-prevalence estimate was 21.34% (95% CI, 18.86–23.99%) in goats and 20.17% (95% CI, 17.49–23.07%) in sheep. The results of multivariable logistic regression analysis showed that species, age, sex of animals and tick infestation were important risk factors for C. burnetii infection. The odds of infection were 3.22 times higher in camels and almost twice as high in goats and sheep compared to cattle. Adult animals were infected more likely (OR = 3.23) than young ones. Interestingly, a significant difference was observed in the sero-prevalence of infection between animals that were infested with ticks (OR = 16.32) and those which were tick-free. Conclusion This study provides valuable insights into the sero-epidemiology of C. burnetii infection in four common livestock species at major abattoirs and pastoral areas of Ethiopia. The findings highlight the need for further studies and implementing surveillance and biosecurity measures to prevent the spread of the disease in both humans and livestock to safeguard the economical and public health aspects.

Background Q fever is a worldwide occurring neglected zoonotic disease with great economic importance. The etiological agent, Coxiella burnetii, is a bacterium usually associated with subclinical infections in livestock, but may also cause reproductive pathology and spontaneous abortions in artiodactyl species including goats, sheep and cattle which are deemed to be the primary reservoirs of this disease. Aims The present cross-sectional and questionnaire survey was undertaken in three districts of the South Omo zone with the aims to comprehend the community perception of livestock keepers and professionals about the disease, estimate the seroprevalence of Coxiella burnetii (C. burnetii) in cattle and small ruminants and to determine the species of potential tick vectors of C. burnetii infesting cattle, sheep and goats. Methods A standard questionnaire was used to assess the community perception of livestock keepers and animal health professionals in the area about Q fever. Sera samples were collected from 1350 ruminants comprising 450 cattle, 450 goats and 450 sheep to detect C. burnetii antibodies using the ELISA technique. Furthermore, a total of 279 cattle, 197 goats and 73 sheep were examined for the presence of ticks, and overall, 2720 ticks were collected (1299 from cattle, 1020 from goats and 401 from sheep) and identified to the species level using morphologically identification keys. Results Findings of the study indicated that 43% of animal owners were aware of the main symptoms of the disease while the remaining 57% did not notice these symptoms in their animals. Additionally, majority of animal health professionals 76.2% in the area reported they were familiar with the causative agent of Q fever, while 23.8% expressed uncertainty regarding the cause of coxiellosis. An overall seroprevalence of C. burnetii of 37.6% in cattle (37.4% in female and 37.8% in male cattle) and 28.7% in small ruminants was recorded (which is significantly higher in goats than in sheep). The study indicated statistically significantly higher seroprevalence of C. burnetii (49.8%) in cattle infested with ticks than in those cattle free of ticks (24.2%), with three times higher seropositivity (OR = 2.97, p = 0.000) as compared to those cattle free of ticks (24.2%). Similarly, statistically significantly higher seroprevalence of C. burnetii was recorded in both sheep and goats infested with ticks (43.6%) as compared to those animals without ticks (22.9%), with the former being twice as likely to test seropositive (OR = 2.15, p = 0.000). A total of nine different tick species were identified, namely Amblyomma variegatum (Am. variegatum) with 26.3% (342; 217 males, 101 females and 24 nymphs), Amblyomma cohaerens (Am. cohaerens) with 47.96% (370 males, 253 females), Amblyomma gemma (Am. gemma) with 4.00% (52; 29 males, 23 female), Rhipicephalus pulchellus (Rh. pulchellus) with 10.6% (138; 87 males, 51 females), Rhipicephalus pravus (Rh. pravus) with 0.2% (3; 2 males, 1 females), Rhipicephalus evertsi (Rh. evertsi) with 4.7% (61; 39 males, 22 females), Rhipicephalus praetextatus (Rh. praetextatus) with 0.8% (10; 7 males, 3 females), Rhipicephalus decoloratus (Rh decoloratus) with 2.9% (38; 4 males, 34 females) and Hyalomma truncatum (Hy. truncatum) with 2.5% (32 females). Conclusion The present study highlighted the significance of Q fever in ruminants and compiled information about the community perception of livestock keepers and veterinary professionals of the study areas. The role of ruminants and their ticks in the epidemiology of C. burnetii requires further research using molecular tools to better understand appropriate method of intervention that will help to reduce negative impacts on the productivities of livestock and the health of humans in Ethiopia.

Infectious bursal disease virus (IBDV) causes infectious bursal disease in poultry and poses a major challenge to the poultry industry globally. This study aimed to measure seroprevalences and so detect exposure to IBDV in backyard poultry in the selected zone of Horro Guduru Wollega. A cross-sectional study was conducted from January 2021 to November 2022. Blood samples were collected for serum extraction from 384 backyard chickens in the Horro and Horro Bulluq districts. IBDV antibody detection was conducted using an indirect ELISA serological diagnostic test. Questionnaires assessed poultry owners? knowledge and health/hygiene management practices regarding the disease. The over all seroprevalence of IBDV was 14.84%. Significant variations in seroprevalence were seen based on district, bird age, bird sex, and flock size. Limited owner experience (just 1-3 years), disposing of carcasses in pits, and poor hygiene on the backyard premises were associated with higher IBDV seroprevalence. In conclusion, IBDV seroprevalence was linked to chicken management practices. Recommendations include improving poultry management among owners to control IBDV. The study indicates backyard poultry in the region have considerable IBDV exposure, and control should focus on improving management practices identified as high-risk, such as pit disposal of carcasses and poor hygiene.