Browsing by Author "Jemberu Alemu"

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    Epidemiology of Rift Valley Fever Virus and West Nile Virus in Livestock Populations and Their Public Health Implications in the Afar Region, Northeastern Ethiopia
    (Addis Abeba University, 2025) Jemberu Alemu; Gezahegne Mamo
    Ethiopia faces heightened risk of Rift Valley fever (RVF) and West Nile virus (WNV) outbreaks due to proximity to endemic countries (Kenya, Somalia, Djibouti), climatesensitive conditions (heavy rainfall, flooding), climate change, unrestricted livestock movement, and widespread mosquito vectors. Regions like Afar, with tropical ecosystems, are particularly vulnerable, mirroring trends across the Horn of Africa. Despite significant public health and economic threats, the epidemiology of these arboviruses in Ethiopia remains understudied. Therefore, the general objective of the study was to investigate the epidemiological status of Rift Valley Fever and West Nile viruses, along with their associated risk factors, in livestock populations and to assess the public health importance of these diseases in the Afar pastoral region of northeastern Ethiopia. A total of 736 serum samples were collected from 224 cattle, 155 camels, 144 sheep, 121 goats, and 92 donkeys in the Amibara and Haruka districts. The detection of anti-RVF nucleoprotein antibodies of Rift Valley Fever virus and anti- West Nile virus antibodies were performed using the ID Screen® Rift Valley Fever and West Nile competition multispecies ELISA kits. A total of 150 human participants (60 livestock owners, 40 animal health workers and paraveterinarians, and 50 public health professionals) were involved in the KAP study. The overall eroprevalence of RVF was 22.0% (162/736; 95% CI: 19.41–24.79%). The seroprevalence was significantly higher in goats (42.2%, 95% CI: 39.61–44.99%) compared to that of cattle (14.3%, 95% CI: 11.74–17.09%), sheep (21.5%, 95% CI: 18.91– 24.29%), or camels (30.97%, 95% CI: 28.38–33.76%) (P < 0.001). The study showed that seropositivity for IgG antibody to RVF infection was associated with locality and species of animal. Goats were two times more likely to be seropositive for RVF infection than cattle (OR: 2.3, 95% CI: 1.462–3.574, P = 0.001). Livestock in the Kealatburi sub-district were five times more likely to be seropositive for RVF infection than those in the Halidegei sub-district (OR: 5.074, 95% CI: 3.066–8.396, P = 0.001). Among 736 tested livestock serum samples, 50.7% (373/736) showed anti-WNV IgG antibodies evaluated using the ID screen® WNV competition multispecies ELISA kits (95% CI: 47%–54.4%; P < 0.01). The seroprevalence was higher (p<0.01) in donkeys (76.1%), followed by camels (69.1%), cattle (52.2%), goats (34.7%) and sheep (25.7%), respectively. The study showed a statistically significant difference of WNV seropositivity between species of animals (OR:1.5, 95%CI =1.038-2.212). Donkeys were (OR: 6.447, 95% CI = 3.888-10.688) seven times more likely to be seropositive for WNV infection than sheep (p < 0.01). The study also revealed 9.1%, 95%CI= 8.86-9.29) seroprevalence of co-circulation of RVF and WNV. High 32/155 (20.7%) seroprevalence of co-circulation was seen in camels followed by goat 14/121(11.6%), cattle16/224(7.14%) and sheep 5/144(3.5%) respectively and higher 41/421(9.7%) seroprevalence of co-circulation was observed in Amibara district than Haruka district. Camels were seven times (OR: 7.016, 95% CI = 2.639-18.653) more likely to be seropositive for the co-circulation than sheep (p =0.000). Of the participants, 29.3% (44/150) believed zoonotic diseases spread through animal-based food or mosquito bites, while 63.3% (95/150) expressed insecurity about infections like Rift Valley fever, West Nile fever, or other zoonoses. This study found substantial knowledge gaps, a low level of risk concern, and high behavioral practices regarding zoonotic disease. Animal health workers had higher mean scores of knowledges of Rift Valley fever, West Nile fever and other zoonotic disease 27.3 ± 10.9 than public health professionals and livestock farmers/owners at p< 0.05. Mean score statistical difference was also observed among Illiterate, primary education, and secondary and above educational status groups. In conclusion, the present study showed that eropositivity of different species of livestock to RVF and WNV is an indication of its widespread occurrence of RVF and WNV in the study area, domestic livestock, especially in large herds, can serve as useful sentinels for the infections and warrants the need for further investigation on molecular epidemiology of RVF and WNV in livestock, their potential zoonotic significance to the pastoral communities and understanding of the vectors in transmission of the viruses in the study area in order to design a feasible control strategy.
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    Molecular Epidemiology of Bovine Tuberculosis in Cattle and its Public Health Implications in Gambella Town and Its Surroundings, Gambella Regional State, Ethiopia
    (Addis Ababauniversity, 2015-06) Jemberu Alemu; Mamo Bedaso
    A cross sectional study was conducted in Gambella town municipal abattoir and health centers in Gambella People Regional State of southwest Ethiopia, to investigate the prevalence of bovine tuberculosis, isolation and molecular characterization of its causative agents and to assess its public health implications from December 2013 to May 2014. Postmorm examination, bacteriological culturing, multiplex PCR, RD deletion typing and spoligotyping were used for investigation. A total of 500 Cattle and 50 AFB positive human TB patients were recruited under the study. The overall prevalence of bovine tuberculosis in cattle was 13.2% (66/500) (95%CI: 10.22-16.18) on the basis of detailed postmortem examination. Statistical significant difference was observed in the prevalence of BTB among different groups of body condition scoring (χ2 = 39.105, P=0.000, df =1), between sex (χ2 = 7.661, P=0.006, df =1) and breeds (χ2 = 24.996, P=0.000, df =1). Poor body conditioned animals were more likely to develop TB lesions (OR=12.16, 95%CI, 4.58-32.24) than good body conditioned animals. Out of 82 tissue samples cultured, 14(17.07%) were bacteriologically culture positive and all were acid fast positive. From a total of 50 sputum sample collected and cultured from human TB cases, 17 (34%) showed growth on LJ medium. Molecular characterization of 11 mycobacterial isolates from human patients using RD9 deletion typing showed that all were M. tuberculosis and further spoligotyping of the isolated revealed that SIT289, SIT134, SIT1634, SIT142 and one new strain not found in the spoligotype databases. Of these M. tuberculosis strains identified SIT 289 and SIT134 were found in cluster with 45.5% ( 5/11) cluster rate for SIT289 and 27.3(3/11) for SIT134 indicating the recent transmission of the stains in the community. Lineage of the human isolates indicated that 27.3% (3/11) Euro-American, 9.1% (1/11) Indo-oceanic and 63.6% (7/11) were unknown lineage family in TB-insight database. Interestingly, one isolate from animal taken from cranial mediastinal lymph node was confirmed to be M. tuberculosis using RD4 deletion typing and spoligotyping, in which the isolate was identified as SIT523 with indo-oceanic lineage family. This isolation of M. tuberculosis from cattle suggests that the presence of reverse zoonosis which needs further investigation. Awareness of cattle owners for BTB XIV was found to be insufficient (22%) and the result also revealed the presence of potential risk factor for zoonotic transmission. In conclusion, the present study revealed a moderately high prevalence of BTB in cattle of Gambella Region, the presence of clustering indicates the recent transmission of the stains in the community and moreover isolation of M. tuberculosis in cattle and occurrence of various strains of M. tuberculosis in the communities warrants further investigation on the transmission of the disease in Gambella Region. Key words: Bovine tuberculosis, Gambella, Molecular epidemiology, RD typing Spoligotyping, Public health, Zoonosis