Veterinary Microbiology
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Item ―bovine mastitis in dair y farms in and around akaki kality sub city and sululta town: emphasis on isolation and identifica tion of pathogenic staphylococcus and antimicrobial susceptibility test of staphylococcus aureus(Addis Abeba University, 2019) Getahun Tesfaye; HikaWaktoleA cross sectional study was conducted from November 2017 to May 2018 in and around Akaki Kality Sub-city of Addis Ababa and Sululta Town with major emphasis of isolation and identification of pathogenic Staphylococcus species and determination of antimicrobial susceptibility pattern of Staphylococcus aureus isolates. Besides the prevalence of clinical and sub-clinical mastitis and associated risk factors were investigated. A total of 768 lactating cows were examined by physical examinations of udder and by California mastitis test. Milk from clinical and sub clinical cases were cultured to isolate pathogenic Staphylococcus species. Antimicrobial susceptibility pattern of Staphylococcus aureus isolates was done by Kirby-Bauer disk diffusion method using eight antimicrobials.The overall prevalence of mastitis was 58.5%, out of which 10.8% was clinical and 47.7% subclinical mastitis.When the prevalence of study sites were considered separately it was 64.6% in Akaki Kality Sub-city, and 52.3% in Sululta Town of which clinical and sub-clinical mastitis were respectively 13.3% and 8.3% in Akaki Kality Sub-city and 51.3% and 44.0% in Sululta Town. In both study sites, univariable logistic regression analysis indicated bovine mastitis was more likely to occur with increasing age of cow, presence of teat lesion, poor housing hygiene and udder/teats hygiene. Based on primary and secondary biochemical characterizations and pathogenicity tests, pathogenic staphylococci were isolated in 25.4% at Akaki Kality Sub-city of which 18.5% was S. aureus, 4.03% S. intermidious and 2.8% S. hyicus. at Sululta, the proportions of pathogenic staphylococci were 20.9% of which S. aureus was 16.9%, S. intermedious was 2.5% and S. hyicus was 1.5%. A total of 68 Staphylococcus aureus isolates (34 of each study area) were assessed for antimicrobial susceptibility. Staphylococcus aureus from both study sites were resistant to ampicillin and penicillin. However, susceptibility to gentamicin was (91.2% and 85.3%), oxacillin (85.3 and 82.35%), cefoxitin (67.6% and 85.3%), erythromycin (70.6% and 94.11%), and vancomycin (82.35% and 91.2%) in Akaki Kality and Sululta Town, respectively. It could be concluded that prevalence of bovine mastitis in general, and isolation of pathogenic Staphylococcus species in particular was high in the study sites. The Staphylococcus aureus that were found to be totally resistant to ampicillin, and penicillin might be due to repeatedly use of these drugs.Item Infectious Bursal Disease Viru : Outbreaks Investigation, Molecular Characterization and Development of Live Attenuated Vaccine Using Local Isolates(Addis ababa Universty, 2012-04-15) Senait Belete; Tesfaye SisayThis study was conducted on sample collected from different regions of the country, where infectious bursal disease (IDB) outbreaks were reported. Samples were processed both at National Veterinary Institute and University of Liverpool, United Kingdom, with the aims of molecular characterization of local isolates, analyzing genetic relatedness of IDB virus circulating in the country with currently produced vaccine and development of vaccine from local isolates. The nucleotide and deduced amino acid sequence for VP2 hypervariable region (HVR) of ten IBDV isolates collected from 2009 until 2011 was also determined by RT-PCR and sequencing, and compared with well characterised IBDV isolates worldwide. A total of 136 bursa sample were pulled into 44 samples. Bursa samples were processed and cultured onto both confluent primary CEF cell cultures as well as fully confluent established cell line (Vero). Viruses were isolated from 41 (93 .2%) samples out of the 44 pulled samples. All the (Vero). Viruses were isolated from 41 (93 .2%) samples out of the 44 pulled samples. All the isolates were grown and able to demonstrate CPEs on CEF cell cultures on the first passage Phylogenetically, Ethiopian IBDV isolates were from one of two genetic lineages: very virulent lBDV and variants of the classical attenuated vaccine strain (078). Nucleotide identity between Ethiopian vvIBDVs range between 0% to 2.6% over VP2 HVR. isolate was superior to the current commercially available vaccine. The adapted trial vaccine isolate was superior to the current commercially available vaccine. The adapted trial vaccineEthiopian vvIBDVs clustered phylogenetically with the African IBDV genetic lineage, independent of the Asian/European genetic. This indicates the circulating of vvIBDV among Ethiopian chickens. Classical variant strain (IBDV 06/10) was selected for adaptation trial using Vero cells. The 9th Vero passage local isolate was evaluated with the current NVI vaccine for immunogenicity and pathogenesity on chicken. The result showed that the adapted local isolate was superior to the current commercially available vaccine. The adapted trial vaccine induced significantly (P<0.05) higher mean antibody titre (3281.35± 101.43) compared to the cun'ently used vaccine strain (2784.12±92.34). The mean bursa weight from the unvaccinated control groups was 20.8±1.2 g while it was 3.6±O.l6g and 2.8±0.07g, respectively, for commercial vaccine and 9th passaged local isolate. Although the difference in the mean bursa weight between the vaccinated groups was not statistically significant (P>0.05), the difference in the mean bursal weight between control and vaccinated groups was statistically significant (P<0.05).Item Isolation and Identification of Corynebacterium Pseudotuberculosis from Superficial Lymphlinodes of Sheep and Goat at Organic Export Abbatoir, Modjo Ethiopia(Addis Ababa University, 2012-06) Daniel Abebe; Tesfaye SisayCorynebacterium pseudotuberculosis is the causative agent of caseous lymphadenitis (CL.J\), a disease characterized by the formation of suppurative abscesses, particularly in superficial and internal lymph nodes, and in internal organs in small ruminants. The present study was conducted from November to April 201 1/ 2012 only on the superficial lymph nodes and carcass of small ruminants. Out of 768 small ruminants slaughtered at Organic slaughterhouse during the study period, 82 (68 in goats and 14 in sheep) were found to have gross evidence of abscess or caseous lymphadenitis. The typical gross lesion is a discrete abscess distended by thick and often dry, greenish yellow or white, purulent exudates. The most frequent sites of abscesses in goats occurred in the periscapular, pretemporal and popliteal lymph node and carcass 34(5.5'10/0). 24(3.91 %),2(0.33%) and 8(1.30%) respectively. In sheep 7(4.54%) in the periscapular, 5(3.25%) in pretemporal and 0% in popliteal lymph node and 2(1.23%) abscess on carcass were found. The study indicated that in both species young animals are more in number than adult, however, caseous lymphadenitis was found to be higher in ad ult than young animals in both species. There was statistically significant difference in the occurrence of CLA between age groups (P<0.05 J. Out of 68 bacterial cutes from goats 18 and 50, pure and mixed colonies, respectively. livre obtained; while out of 14 bacterial cultures boom sheep 4 and 10, pure and mixed colonies, respectively, were obtained. Corynebacterium pseudotuberculosis isolates were obtained from S9 out of 82 collected abscessed lymph nodes and carcass. Bacterial colonies were identified on the basis of morphological characteristics, primary and secondary biochemical tests, i.e cablese, urease, trehalas, xylose, maltose, and glucose fermentation tests and reverse CAMP test (antagonistic hemolysis between C. pseudotuberculosis and Staphylococcus aureus). Isolates positive for catalase, urease, maltose, and glucose, but with inhibiting hemolysin of Soured' by phospholipase D of C. pseudotuberculosis and negative for trehalas, and xylose "ere considered as C. pseudotuberculosis. The susceptibility pattern of C. pseudotuberculosis to antimicrobial agents varied among isolates. Out of 59 isolates of C. pseudotuberculosis isolated from lesions of caseous lymphadenitis in goats and sheep were susceptible to the antibi optics norfloxacin, tetracycline, doxycycline HCl and kanamycin. Keywords: Antimicrobial agents; Caseous lymphadenitis; Corynebacterium pseudotuberculosis; Goat; Lymph nodes; Mixed colonies; Pure colonies; Sheep.Item Virological Investigation of Emerging Camel Disease in Ethiopia(Addis Ababa University, 2010-06) Dejene Milkessa; Fufa Dawo; Tesfaye Sisay; Gelagay AyeletThe dromedary of East Africa particularly, Ethiopia has been suffering from different diseases for the past so many years. Of the many diseases of camels that are rampant in the region, the recently emerged camel disease with still unknown causes is the single most important disease. This camel disease is the leading problem inflicting high morbidity and mortality among the camel population. To this effect, isolation and characterization of the causative agent has of paramount importance. This study was undertaken in the National Veterinary Institute laboratory, Debre Zeit, Ethiopia from October 2009 - June 2010 to isolate and characterize the viral agent from camel postmortem tissues collected during the outbreak of 2007 in Ethiopia. The study was conducted on the basis of cell culture, degenerate oligonucleotide primed polymerase chain reaction (PCR) and laboratory animal assay. Virus isolation was attempted for virus in Vero and Dubca cells; four specimens yielded cytopathic virus when inoculated onto the Vero cell culture. The cytopathic effect (CPE) consisted of round floating cells, giant cells, rounded refractive cells, ballooning of cells, sloughing, and some syncytia formation were observed from day two to day seven post inoculation. The appearance of the CPE was looking uniform among different purified tissue samples used for cell infection. The growth of virus was confirmed by degenerate oligonucleotide primed PCR in which amplification was recorded particularly, where extracted RNA was amplified, both from tissue and cell culture. The growth of the virus after storage in -20 DC for days was lost while it can grow from +4 DC and -85 DC in Vero cells. The cell culture suspension was injected to laboratory guinea pigs in which the animals were observed to develop abnormal clinical signs that resulted in death. Although many scientists suspected different known viruses for the cause of outbreak, the isolated virus was confirmed to be out of adenovirus, morbillivirus, parainfluenza 1-3 and respiratory syncytial virus groups. However, although the above known viruses were excluded, a variant of the above viruses that can skip detection using previously known primers and other emerging viruses might not be excluded. Key words: Came l, Cell culture, Emerging disease, Molecular diagnosis, Viral etiologies, Virus isolation.Item Sero-Prevalence and Participatory Study of Contagious Caprine Plueropneumonia in Gulina Wereda, Afar National Regional State, Ethiopia(Addis Ababa University, 2012-04-10) Amare Getu; Tesfaye SisayA cross sectional study of Contagious Caprine Pleuro pneumoma (CCPP) in goats was conducted from October 2007 to April 2008 to determine sero prevalence in Gulina district of Afar National Regional State. A total of 446 sera were collected from goats. Complement Fixation Test (CFT) was carried out at National Veterinary Institute. The Participatory approaches are holistic in nature where by all aspects of the phenomenon questions are studied by the use of multiple methods in a process referred to as triangulation. Camels had the highest proportion (44.6%) followed by 30.6% of goats to the relative importance of livestock species to pastoralists. The possible source of CCPP is watering followed by grazing (31.9%) due to goats gathered from different sites for the search of feed and water. The main control tactic for CCPP is Isolation of the affected goat(s). Among the cases in the area 34.7% were pasteurellosis followed by CCPP. Significant numbers of goat were lost due to CCPP (32.6%) next to PPR (38.7%). Drought (65%) is a major challenge to their livestock. The overall sero prevalence was 42.8% (n = 191). The age group sero prevalences were 42.4, 36.8 and 49% in age group less than 1, 1-3 years and >3 years older respectively. Sex specific sero prevalence observed was 40.9% in males and 43.7% in females. Because of few male goats compared to females in each flock, the contribution of males to the total sero positivity was only 32.9%. High significance association was found between Flock size 51-150 and greater than 150 (OR=25.6, P=O.OOO) to CFT test. Goats ofless than 1 year were found to be safer (OR=0.974, P=0.324).Item Isolation and Characterization of Mycobacterial Species Causing Tuberculosis Lesions in Slaughtered Camels in Eastern Ethiopia(Addis Ababa University, 2011-06) Kaleab Zerom; Tesfaye Sisay; Gobena Ameni; Gezahaegne MamoA cross sectional study was conducted on 293 apparently healthy camels slaughtered at Jigjiga. Harar, Aweday and Dire Dawa abattoirs between December 2010 and April 20 11, The objective of the study was to isolate and characterize Mycobacterial species causing tuberculous lesions III slaughtered camels through postmortem examination. mycobacteria logical culturing. and multiplex polymerase chain reaction (PCR). A prevalence or 12.3% (36 /293) was recorded on the basis of postmortem examination and the di afference was statistically significant in females (X'=7.474. 1'=0.006) and in poor body condition (X'~ 7.323, 1'=0.025) camels when compared to their counter parts. About 79.5% of tuberculous lesions were found in lungs and associated lymph nodes in thoracic cavity and 15.9% in the lymph nodes of the head indicating inhalation as principal route of infection .Of the 36 camels with gross suspicious TB lesion organs and tissues cultured mica bacterial growth was observed in 66.7% (24 /3 6). Genotyping of the 17 isolates using multiplex polymerase chain reaction identified 88.2% (15/ 17) of them as member of mycobacteria other than Mycobacterium liber calliopsis complex and only once as member of M)lcobaCleriul1l ,tuberculosis complex. The relatively higher isolate ion of nontuberculous mycobacteria from most of camel 1'B lesions in this study could indicate their pathogenic or opportunistic role in the pathology or camel 1'13 signifying the need to further examine these species as cause of came l 'I'll so as to c1kctively elucidate its pathology. and enhance the effort in the control 01' the disease. Key words: Camels, Genotyping, Mycobacterium tuberculosis complex. Nontuberculous mycobacteria, Prevalence, TuberculosisItem Isolation and Molecular Characterization of Mycobacteria From Infected Cattle in and Around Bako, Western Oromia, Ethiopia(Addis Ababa University, 2010-06) Temesgen Ayana; Tesfaye Sisay; Gobena AmeniA cross-sectional study was conducted on 858 heads of cattle (371 recruited from Bako Agricultural Research Center, BARC and 487 from Bako municipal abattoir) from October 2009 to April 2010 to estimate the prevalence of bovine tuberculosis (BTB) and characterize its causative agents. To this effect, comparative intradermal tuberculin (ClOT) test, post mortem examination, bacteriological culturing, genus typing using multiplex polymerase chain reaction (PCR) were applied. At the cut-off point of ~4mm (recommendation of the Office des International Epizooties, OlE), animal prevalence of BTB was 1.3%. Re-analysis of the same data using the newly defined cut-off point of >2mm gave a prevalence of 4.6%. There was a highly significant difference (P=O.OOO) in prevalence estimated using the two cut-off points in zebu cattle. The prevalence was significantly associated with age (P=0.012) and origin (P=0.04) of the animal. On the other hand, the prevalence was 9.3% (46/492) in cattle slaughtered at Bako abattoir. Lesions were more frequent and severe in the mesenteric (60.9%), retropharyngeal (17.4%), and bronchial (17.4%) lymph nodes of slaughtered cattle. Culture positivity in suspicious tissues was 32.6% (29/89) although only 69% (20/29) were confirmed to be acid-last bacilli (AFB) by Ziehl Neelsen staining. Of the 20 AFB positive isolates, 17 were characterized by multiplex PCR and almost all (94%) of the isolates showed signal for the Genus Mycobacterium. Nevertheless, none of these isolates showed signal for the Mycobacterium Tuberculosis complex as revealed by multiplexer. Therefore, further identification and characterization of these isolates should be done. Furthermore, the pathogenicity of these mycobacteria in livestock requires further investigation. Key words: Bovine tuberculosis, Prevalence, Pathology, Culturing, Molecular typing, Mycobacteria, Balm, Ethiopia.Item Investigation of Respiratory Viruses in Camels Slaughtered at Addis Ababa Akaki Abattoir(Addis Ababa University, 2011-06) Wossene Negash; Tesfaye Sissay; GeJagay AyeJetThis study was conducted from September 20 10- June 20 11 at Debre Zeit National Veterinary Institute (NVI) with an attempt to isolate and characterize respiratory viruses from pneumonic lungs of camels slaughtered at Addis Ababa Akaki abattoir. Accordingly, pneumonic camel lung tissues were collected and transported in ice box to NVI virology laboratory and temporarily stored at -85°C and then processed and inoculated on confluent vero cells mono layers, incubated at 37°C and followed for the development of CPE for 4-15 days. All CPEs observed developed between 4-14 days. Thirty five (35) pneumonic camel lungs were cultured among which 27 of them were CPE positive characterized majorly by initial rounding of vero cells, elongation, syncytia formation, swelling and rounding, floating and sloughing of cells. Some of the supernatant suspensions of those samples exhibiting CPEs were taken and extracted both for DNA and RNA viral genomes. cDNAs were synthesized from RNA extracted samples. The DNAs and cDNAs were used to test both DNA and RNA viruses, respectively using universal (DOP- PCR) and conventional PCR techniques. Respiratory syncytial virus, Adenovirus, Pest des polities ruminants virus, Parainfluenza I virus, Parainfluenza 2 virus and Parainfluenza 3 virus were tested. All six samples tested were negative for PPRV and Parainfluenza virusesl-3. But nine of ten samples tested were positive for Respiratory syncytial virus and two of six samples tested were positive for Adenovirus. Finally, further investigative, epidemiological and molecular characterization studies were forwarded . Key words: Abattoir, Camel, Polymerase chain reaction, Respiratory viruses, Virus isolationItem Study on Foot and Mouth Disease Virus Vaccine Strain Selection of Ethiopian Isolates(Addis Ababa University, 2012-04-30) Mekonnen sorsa; Tesfaye SisayThis study was conducted at National Veterinary Institute (NVI) on foot and mouth disease viruses of known serotypes and topotypes identified and characterized ./i•om samples collected from cattle and swine, at different times from different parts of Ethiopia. The study was designed with the aim of selecting appropriate vaccine strains that can provide a broad spectrum cross protection against the circulating serotypes or strains by assessing the serological or antigenic match between the candidate vaccine strains and field isolates of 0, A, and SAT2. The study was done by two-dimensional virus neutralization assay to determine the serological or antigenic relationship 'rl' value between the candidate vaccine strains and field isolates. A total of 21 serotype 0 , 7 serotype A, and 8 serotype SAT2 FMD viruses were used for the study including candidate vaccine strains. The study findings revealed that out of 19 serotype 0 field isolates tested for vaccine match with antisera raised against candidate vaccine strains, 0-ETH/58/2005 and 0-ETHl38/2005, all (J 00%) were found to be antigenically similar with vaccine viruses with 'rl' values above the cut-off point (0.3)(with mean 'rl' value of 0.83 and 0.84, respectively), indicating that both these vaccine strain candidates can confer protection for serotype 0 field viruses circulating in the country. Of the 5 serotype A field strains tested, 4 (80%) match serologically with antisera raised against candidate vaccine strains, A-ETHl6/2000 and AETHl7/2008 with 'rl ' value greater than the cut-off point (mean 'r1 ' value of 0.58 and 0.70, respectively). But 1 serotype A field virus, A-ETHI13/1981 showed significant antigenic variation with vaccine strains with 'r 1' value below the cut-off point (r 1 value: 0.14 and 0.25 for AETHl6/2000 and A-ETHl7/2008, respectively). Furthermore, the 'r1' value obtained by serological matching between 6 SAT2 serotype field isolates and two vaccine strain candidates, SAT2-ETHl64/2009 and SAT2-ETHI76/2009, revealed that the vaccine strains can protect field viruses circulating in the country (Mean 'r1' value: 0.70 and 0.76, respectively). In general, the overall assessment of antigenic relations between the candidate vaccine strains and circulating field isolates tested showed better matching. The protection level of the selected vaccine strains against the challenge by field viruses should be supported by potency testing or animal challenge.Item Assessment of antimicrobial use practices and antimicrobial susceptibility of Listeria monocytogenes along the beef value chain in Adama and Modjo, Ethiopia: One Health perspectives.(Addis Abeba University, 2026) Meskerem Mulisa; Takele BeyeneListeriosis, caused by Listeria monocytogenes, is a significant foodborne zoonotic disease with serious public health implications. This study assessed antimicrobial use (AMU) practices and antimicrobial susceptibility patterns of L. monocytogenes along the beef value chain in Adama and Modjo, Ethiopia, using a One Health approach. A cross-sectional study was conducted from November 2025 to May 2026. Data were collected through questionnaires (n = 60) and laboratory analysis of 460 samples, including carcass swabs, fecal samples, hand swabs, and environmental samples. Isolation and identification of L. monocytogenes were performed using standard culture methods, biochemical tests, and MALDI-TOF mass spectrometry. Antimicrobial susceptibility testing (AST) was carried out using the disk diffusion method, and detection of the virulence gene (hlyA) was conducted using PCR. The results showed that 74.8% of respondents had poor knowledge of AMU and antimicrobial resistance (AMR), while 88.7% demonstrated a favorable attitude toward the use of antibiotics for growth promotion. Out of 460 samples, 106 (23%) showed presumptive Listeria growth, of which 59 isolates were confirmed by biochemical tests. Of the 29 isolates further analyzed using MALDI-TOF, 6 were confirmed as L. monocytogenes, predominantly from carcass samples (n = 5) and one from a water sample. All confirmed isolates carried the hlyA virulence gene. Antimicrobial susceptibility testing showed that all isolates were fully susceptible to ampicillin, entamicin, ciprofloxacin, cotrimoxazole, streptomycin, and chloramphenicol. However, high levels of resistance were observed to penicillin (100%), vancomycin (66.7%), and tetracycline (50%). In conclusion, poor antimicrobial use practices and the presence of resistant and virulent L. monocytogenes strains indicate a potential public health risk. Strengthening antimicrobial stewardship and improving hygiene practices along the beef value chain are essential.Item Microplastics Pollution and its associated Determinants in Donkeys, Humans, and the Environment in Central Ethiopia(Addis Abeba University, 2026) Masresha Gebeyehu; Bersissa Kumssa; Dinka Ayana; Yitbarek GetachewMicroplastic (MPs) pollution has become a major global public health and environmental sustainability issue. In Ethiopia, the health implications of MP contamination remain understudied compared to global studies. This study aimed to detect MPs in donkey feces, human urine, and water samples collected from near and around some rivers in central Ethiopia; assess the determinants of plastic ingestion in working donkeys; to assess the awareness of community members and donkey owners about the effects of plastic pollution; and analyze the retrospective clinical records on colic cases in donkeys associated with plastic ingestion, within a One Health framework. This study employed a cross-sectional approach, sampling river water (27), human urine (36), and donkey feces (41). Additionally, 223 cases of retrospective veterinary records (2020-2026) of donkey colic cases were reviewed to examine the prevalence of plastic-related risks. Community member (110) and donkey owner (110) awareness surveys were conducted to assess the perceptions of plastic pollution. Descriptive statistics were applied to summarize contamination levels, and a one-way ANOVA was used to assess spatial differences. A multivariate logistic regression was applied to identify factors associated with donkey health outcomes. MPs were detected in all sample types, with water having the highest concentration (2.01 ± 0.91 particles/L). Donkey feces and human urine had concentrations of 1.36 ± 0.50 particles/g and 1.12 ± 0.89 particles/mL, respectively. ANOVA confirmed statistically significant variation among sample types (p<0.05). The dominant shape of MP particles was fiber across all sample types, with a size range of <500 μm. In the retrospective analysis, 95.7% of donkey colic cases were linked to plastic ingestion, with a mortality rate of 23.5% in Merkato and 56.1% in Bishoftu. A logistic regression indicated that no significant predictors of outcome were identified, including age, sex, or plastic risk. Community awareness of the health risks of plastic was moderate (40.9%), with higher levels in urban centers. MP contamination is widespread across environmental and biological samples in Ethiopia. This study underscores the urgent need for an interconnected waste management strategy, awareness campaign, strong policy, and One Health interventions to reduce plastic pollution.Item Detection and Evaluation of Aflatoxins Contamination in Feed and Milk, with the Assessment of Knowledge, Attitude and Practices of Dairy Cattle Owners Towards Aflatoxin in Addis Ababa, Ethiopia(Addis Abeba University, 2026) Chernet Balcha; Gezahagn MamoAflatoxins are toxic metabolites produced by Aspergillus flavus and Aspergillus parasiticus that contaminate foods and feeds. Aflatoxin B1 (AFB1) is a highly carcinogenic and genotoxic compound. Aflatoxin M1 (AFM1) is a hydroxylated metabolite of AFB1 formed in the liver. This study was designed to evaluate aflatoxin contamination in raw milk and feeds intended for dairy cattle, as well as to assess dairy cattle owners’ knowledge, attitude and practices regarding aflatoxin and related health risks in Addis Ababa. A cross-sectional study was employed from December 2024 to May 2026, and a total of 60 pooled dairy feed and 40 raw milk samples were collected and analyzed for AFB1 and AFM1 using ELISA and Ultra-HPLC methods, respectively. The results showed that 88.3% of the feed samples were contaminated with AFB1 (276.05±239.74 µg/kg), and all of these exceeded the maximum limit set by the Codex (20 µg/kg). On the other hand, AFM1 was found in only 10% of milk samples, with a mean concentration of 0.019±0.01 μg/L, and all values were below the EU limit of 0.05 µg/L. A mean AFB1 concentration of 285.1±250.05 µg/kg was detected in 88.9% of pooled feeds containing commercial concentrate feed (p = 0.0251). In contrast, a higher AFB1 concentration of 317.7±290.1 µg/kg was detected in 90.9% of pooled feeds containing oil seed cake (p = 0.0724), indicating that it is an important source of AFB1. High level of AFB1 contamination was detected in 91.7% of feeds (652.2±300.19 µg/kg) stored under poor conditions than feeds (87.5%) from good storage conditions (177.54±54.87 µg/kg) (p = 0.0004). In addition, 90% of dairy cattle owners were unaware of aflatoxins in feed. Likewise, 91.8% of dairy cattle owners did not know about aflatoxin in milk. These results indicate a high level of AFB1 contamination in feed, highlighting the need for safe feed handling practices. The findings also stress the importance of increasing dairy cattle owners’ awareness of aflatoxins in feed, their transfer into milk, and the possible risks to dairy cattle and public healthItem A one Health Assessment of Antimicrobial Use and Associated Resistance in Escherichia Coli Along the Beef Value Chain in Akaki Kality Sub City, Addis Ababa, Ethiopia(Addis Abeba University, 2026) Chaltu Desalegn; Takele Beyenemproper use of antimicrobials (AMU) in food animals contributes the emergence of antibiotic resistant bacteria, which subsequently disseminate through the food chain between animals and humans, posing significant threats to public health and food security. This study aimed to assess AMU and antimicrobial resistance (AMR) profile of Escherichia coli (E. coli) and identify potential risk factors for resistance along the beef value chain in Akaki Kality sub city, Addis Ababa. A cross-sectional study design was employed from November 2025 to May 2026. Data collection included laboratory analysis, farmers‟ knowledge, attitudes, and practices (KAP) regarding AMU and AMR, and assessment of hygienic practice among meat handlers. Statistical analysis of Fisher‟s exact test was used to analyze KAP data, while Chi-square and logistic regression for laboratory findings. This study showed that, overall 50%, 46.2% and 42.3% respondents have poor knowledge, attitude, and practice toward AMU and AMR, respectively. Low educational level, small farm size, shorter experience in beef fattening, limited training and lack of access to AMU and AMR information were risk factor of poor KAP of farmers. Of 663 samples examined, 176 (26.5%) were positive for E. coli and 19(2.9%) for E. coli O157: H7. E. coli isolates were recovered from beef farms 31(18.7%), abattoir 88(34.2%), and butcher shops 57(23.8%), while E. coli O157:H7 isolates were detected in farms 7(4.2%), abattoir 9(3.5%), and butcher shops 3(1.3%). Antimicrobial susceptibility testing against 12 antibiotics revealed that E. coli isolates were most susceptible to chloramphenicol 16(69.6%), imipenem 13(56.5%), and ciprofloxacin 13(56.5%), whereas E. coli O157:H7 isolates were most susceptible to, imipenem 13(68.4%), chloramphenicol 12(63.2%) and amoxicillin clavulanate 11(57.9%). Multidrug resistance was observed in 17(73.9%) E. coli and 16 (84.2%) E. coli O157:H7 isolates. In general, the study revealed challenges in proper AMU, hygiene practices, and high prevalence of microbial contamination along the beef value chain. These findings collectively emphasize the need for integrated One Health interventions addressing antimicrobial stewardship, farm biosecurity, meat hygiene, and AMR surveillance.Item One Health Surveillance of Zoonotic Diseases at the Wildlife– Human–Livestock Interface in Borena Zone, Ethiopia: Detection and Characterization of Listeria Monocytogenes(Addis Abeba University, 2026) Guyo Gelma; Olana MereraThis study in investigated the prevalence of Listeria monocytogenes in raw camel milk and assessed community knowledge, perceptions, and practices related to zoonotic disease transmission at the livestock-human-wildlife interface in Borena Zone, southern Ethiopia. A cross-sectional study was undertaken from November 2025 to May 2026 in Yabello, Elwaye, and Gomole districts to investigate the zoonotic diseases occurrence and transmission at the livestock- uman-wildlife interface. Additionally, isolation and characterization of Listeria monocytogenes in raw camel milk and milking equipment was done. A total of 411 camel milk related samples were collected from lactating camels and milk handling equipment, while 207 pastoralists participated in a questionnaire survey. Microbiological isolation and identification of Listeria monocytogenes standard bacteriological procedures were employed, and antimicrobial susceptibility testing was performed using the disk diffusion method. The overall prevalence of Listeria in camel milk and related samples was 3.89% (95% CI: 2.0–5.7%), with slightly higher contamination at the animal level (4.47%) than in milk handling equipment (3.77%). None of the investigated animal-level factors, including age, herd size, and body condition, showed a statistically significant association with Listeria occurrence (p > 0.05). Antimicrobial susceptibility testing revealed high sensitivity of isolates to Gentamicin (100%) and high susceptibility to Chloramphenicol, Ciprofloxacin, Amoxicillin, Doxycycline, Azithromycin, and Meropenem (80%). However, Penicillin and Cefoxitin shows higher resistance against tested isolates 80% and 100%, respectively, with evidence of multidrug resistance among some isolates. The questionnaire survey discovered widespread livestock–wildlife interactions, frequent cross-border livestock movement, and high-risk practices including consumption of raw animal products and lack of quarantine measures. Although community awareness of disease risks was relatively high, risky management and unsafe food consumption behaviors remained common. The findings highlight the presence of Listeria monocytogenes in camel milk and emphasize the importance of improved milk hygiene, antimicrobial stewardship, and integrated One Health approaches to mitigate zoonotic disease risks in pastoral production systems.Item Heavy Metal Contamination and Antimicrobial Resistance of Escherichia coli in the Akaki Wastewater Treatment Plant and Akaki River Catchment: A One Health Framework(Addis Abeba University, 2026) Melaku Taye; Takele Beyene; Lishan Asef; Feleke ZewgeAntimicrobial resistance (AMR) and heavy metal pollution in Wastewater treatment plants (WWTPs) and river catchments present significant global public health risks, potentially driving resistance via co-selection. This study assessed heavy metal contamination and AMR in Escherichia coli within the Akaki WWTP and river catchment, using a One Health framework, focusing on an extended spectrum beta-lactamase (ESBL) and carbapenemase production. A cross - sectional comparative study was conducted utilizing 232 samples from wastewater, river water, human stool, cattle feces, and milk. Six heavy metals (Cd, Pb, Cr, Cu, Mn, and Zn) were quantified by ICP-OES. E. coli was isolated using standard biochemical methods and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF). Phenotypic resistance; ESBL and carbapenemase production were confirmed by disk diffusion, double-disk synergy tests (DDST) and modified carbapenem inactivation method (mCIM), respectively. Data were analyzed using logistic regression, chi-square, and one-way ANOVA (p < 0.05). Manganese (Mn) was the dominant contaminant, exceeding permissible across seasons. While, Zink (Zn) peaked during the rainy season. E. coli was isolated from 31 (13.4%) of samples, predominantly from water sources. High resistance was observed against Ampicillin (93.5%), Tetracycline (74.2%) , Sulphamethoxazole (64.5%), and Cefotaxime (58.0%). Multidrug resistance (MDR) rea ched 27 (87.1 %) and 14 (45.2%) were ESBL producers; no carbapenemase production was detected. Higher MDR and ESBL rates correlated with elevated Mn concentrations, indicating potential heavy metal–AMR co-selection. The Akaki WWTP and river catchment are critical reservoirs for MDR and ESBLproducing E. coli. Evidence of Mn driven co-selection underscores the urgent need for integrated One Health surveillance, improved wastewater efficiency and strict antimicrob ial stewardshipItem “Evaluating the Alternative Use of Phytogenics as Feed Additives: Effects on Growth Performance and Immune Response in Newcastle Disease-Vaccinated Broiler Chickens(Addis Abeba University, 2025) Robel Girma; Takele BeyeneBackground: Phytogenic feed additives (PFAs) a group of medicinal plants and their essential oils—are increasingly used in poultry sector due to their biologically active compounds that promote animal health, enhance immune function, stimulate growth, boost productivity and reduce mortality. This study aimed to evaluate the effects of dietary PFAs on the growth performance and immunological response of broiler chickens to Newcastle disease (ND). Methods: Experimental study was conducted on a total of 200 Cobb 500 chicks. The chicks were randomly assigned to six groups, with each group comprising three replicates of 10 chicks. To establish baseline immunological data, 20 chicks were bled before the experiment. One treatment group (G4) received only basal diet, while the remaining groups (G1, G2, G3, G5, and G6) were supplemented with 2% of specific phytogenics: thyme (Thymus vulgaris, G1 and G6), lemongrass (Cymbopogon schoenanthus, G2), and rosemary (Rosmarinus officinalis, G3). Additionally, G5 received a commercially available vitamin supplement commonly used by medium-scale poultry farms. Throughout the 42-day study period, mortality, feed conversion ratio (FCR), body weight gain (BWG), and feed intake were recorded. Serological tests were conducted on three representative chickens per replication to assess antibody responses by ELISA test. Results: The findings of this study demonstrated that the inclusion of PFAs to the diet had no significant effect on overall feed intake. Body weight (BW), BWG, and average daily weight gain (ADWG) did not differ significantly among groups during the starter and grower stages. However, by day 42, G2 and G5 exhibited significantly greater final BW, overall BWG, and ADWG (p < 0.01) compared to the other groups. Over the study duration, G5 chickens achieved the best FCR, followed by G2 and G4. Serological results showed that on day 42 of the trial, the G3 and G5 chickens had a higher antibody titer against the ND vaccination. These findings suggested that adding 2% of this PFA leaf powder to broiler diets had no detrimental effects on feed consumption, while emongrass inclusion enhances growth performance (BW and ADWG) and FCR similarly to commercially available vitamins. However, the inclusion of these dietary PFAs did not significantly influence immune organs development. Rosemary inclusion into the diet and supplementing vitamins improved the immune status of broiler chickens against ND. Conclusion: The selected herbs, particularly lemongrass and rosemary, may be used as effective natural alternatives to synthetic supplements by improving growth performance and immune response in broiler chickens. Further research is needed to fully elucidate their potential as substitutes for antibiotic growth promoters in commercial poultry productionItem Study on Cryptosporidium in Calves, Children, and Drinking Water Sources in Akaki Kality, Addis Ababa(Addis Abeba University, 2025) Abdurahman Meribo; Dinka AyanaCryptosporidiosis, caused by protozoan parasites of the genus Cryptosporidium, poses a significant public health and veterinary challenge globally, particularly in low-resource settings with inadequate water, sanitation, and hygiene (WASH) conditions. This cross-sectional study (November 2024–June 2025) estimated the prevalence, burden, and associated risk factors of Cryptosporidium infection in calves, children under five, and drinking water sources (Akaki, Gefersa, and Legedadi rivers) using a One Health approach. A total of 232 calf fecal samples, 124 stool samples from children, and 60 water samples were examined using the modified ZiehlNeelsen acid-fast staining technique. The overall prevalence was 13.4% in calves, 7.3% in children, and 60% in water samples. Significant differences in calf prevalence were observed among production systems (*p* = 0.005), body condition (*p* = 0.007), and presence of calving pens (*p* = 0.043). Calves in extensive systems had the highest infection rate (50%), and those in poor condition were most susceptible. In children, infection was significantly associated with parental illiteracy (*p* = 0.008) and animal contact (*p* = 0.049), while age and sex were nonsignificant. All Akaki River samples were contaminated (100%), followed by Gefersa (80%); Legedadi showed no contamination. Microscopy-based burden assessment revealed the highest oocyst loads in calves under three months and children below one year, with no high-burden cases in children. The study underscores the critical role of animal management, environmental sanitation, and public health behaviors in transmission. Integrated One Health strategies addressing human-animal-environment interactions are essential to reduce the zoonotic and waterborne burden in urban Ethiopia.Item Assessment of Staphylococcus aureus and Methicillin-Resistant S. aureus (MRSA) in Dairy Farms of Sheger City, Oromia, Ethiopia: A one Health approach(Addis Abeba University, 2025) Makida Elias; Fufa AbunnaAntimicrobial resistance (AMR), particularly involving S. aureus and methicillin-resistant S. aureus (MRSA), presents a growing public health concern in low- and middle-income countries such as Ethiopia. A cross-sectional study was carried out to investigate the occurrence, antimicrobial resistance profiles and environmental risk factors of S. aureus and MRSA in dairy farms in Sheger City, Oromia Region, using a One Health approach. A total of 312 sample comprising 212 udder milk, 40 hand swabs, and 60 environmental swab were collected from December 2024 to May 2025. Bacterial isolation was performed usingconventional culture methods and confirmed by MALDI-TOF MS and antimicrobial susceptibility was tested using the disk diffusion method according to CLSI, (2022) guidelines. Out of the 312 samples, 65 (20.83%) were found to be positive for S. aureus, and 31 (9.9%) were identified as MRSA. The prevalence of S. aureus was 23.11% in udder milk, 27.5% in hand swabs, and 8.3% in environmental swabs. MRSA was detected only in udder milk samples, with a prevalence of 14.62%. All isolates exhibited multidrug resistance (MDR), with 100% resistance to amoxicillin, penicillin, tetracycline, clindamycin, and cloxacillin. High susceptibility was observed for ciprofloxacin, gentamicin, and norfloxacin according to Interpretive categories and zone diameter breakpoint (CLSI, 2022). Significant associations were found between S. aureus prevalence and poor hygiene practices, including inadequate handwashing, udder cleaning, and substandard drainage systems.The detection of S. aureus and MRSA particularly the exclusive occurrence of MRSA in milk samples raises serious concerns regarding milk safety and the potential for zoonotic transmission. The widespread multidrug resistance among isolates further emphasizes the need for targeted interventions. These findings call for urgent improvements in farm hygiene, promotion of prudent antimicrobial use and implementation of integrated AMR surveillance systems to mitigate the risks to animal and public health.Item Prevalence of Escherichia Coli O157:H7 and Antimicrobial Resistance Profile in Dairy Farms and in Contact Humans in Bishoftu and Modjo Towns(Addis Abeba University, 2025) Taye Dinku; Teshale SoriE. coli O157:H7 poses a serious challenge to public health worldwide with ongoing acquisition of resistant to different antimicrobials. The cross-sectional study with stratified and simple random sampling was conducted to isolate and assess antimicrobial resistance profile of E. coli O157:H7 from dairy cattle, milk, in contact humans, soil and different water sources used in dairy farms as well as assess the associated risk factors of E. coli O157:H7 infection in dairy farms and in contact humans in Bishoftu and Modjo towns. Three hundred eighty two (382) containing cows’ feces, milk, stool and environmental samples were collected and processed using bacteriological isolation, biochemical identification and confirmed by serological assay. Descriptive analyses were used to compute the prevalence of E. coli O157:H7 and the association between the outcomes and independent variables was analyzed using chi-square test at p value <0.05 and 95% confidence interval. Overall prevalence of E. coli O157:H7 was found to be 3.9%. The occurrence in soil and floor swab, fecal, stool 6.7%, 5.7%, 4.6%, respectively while it was 3.3% in milk, water and udder swab samples. There was no occurrence of E. coli O157:H7 detected on equipment and hand swabs. The occurrence of E. coli O157:H7 in fecal sample was significantly associated with floor type, cleaning frequency of the pen, pen cleanness and manure management sites. The prevalence in milk samples showed a statistically significant association (p<0.05) with factors like floor type, ways of udder cleaning, hand washing practice and manure management sites. Occurrence in soil samples was significantly associated (p<0.05) with floor type and manure disposal site while only manure management sites had statistically significant association (p<0.05) with occurrence in water samples. Risk factors such as age, drinking of raw milk, history of diarrhea and hand washing practice were found to be statistically significantly associated with E. coli O157:H7 occurrence in human. antimicrobial sensitivity test to selected drugs revealed that all of the isolates (100%) were susceptible to nalidixic acid while all of the isolates (100%) were resistance to ceftazidime with multidrug resistance observed in 86.7% of the isolates. Therefore, there should be strict dairy farm hygienic practices such as manure management and rational uses of drug were recommended.Item Assessing Food Safety Management System: One Health Approach to improve Water Quality and Meat Hygiene in Abattoir in and around Addis Ababa Ethiopia(Addis Abeba University, 2025) Seble Aweke; Bekele MegersaFood borne diseases pose a major global public health challenge, particularly in low-income countries like Ethiopia, where food safety in abattoirs is a serious concern. This study aimed to assess food safety management systems in six Central Ethiopian abattoirs using a cross-sectional design from October 2024 to April 2025. A total of 108 individuals were surveyed, and 120 samples were collected for microbial analysis focusing on water quality and meat hygiene within the One Health framework. Data were gathered through questionnaires, observations, and microbial testing. Microbial loads (Aerobic plate count, S. aureus, and E. coli) were quantified and identified using bioMérieux TEMPO®, and OmniLog ID System, respectively. Questionnaire observational survey findings revealed significant weaknesses in the implementation of Food Safety Management Systems (FSMS) while respondents generally reported adherence to hygienic protocols and the use of personal protective clothing. However, direct observation indicated a lack of consistent and proper application. Only about a one-third of facilities conducted internal hygiene audits. For water hygiene, while many facilities performed regular testing, less than half maintained proper records, indicating significant gaps in documentation and monitoring. Furthermore, observations highlighted inadequate infrastructure including poor ventilation, insufficient designated processing areas, and ineffective waste management systems. Additional study with sample analysis from these facilities showed an overall highest mean APC, S. aureus and E.coli in sampled water, equipment and in both equipment and hands, respectively. Further microbial analysis revealed significant differences in microbial loads across abattoirs and sample types (p<0.05), likely due to varying hygiene practices. The identification of pathogens such as E. coli O157:H7, Salmonella and S. aureus in this study across different abattoirs and samples including water implies a serious public health concern that needs rigorous interventions. In addition to poor microbial quality, the water used for cleaning in the abattoirs showed high concentration of some of the harmful toxic metals (Cd, Pb, and Mn) and salinity which can further compromise food safety thereby requiring urgent attention. The study highlights critical gaps in food safety management and hygiene practices, evidenced by high microbial loads and heavy metal concentrations, which calls for interventions measures through implementation of proper hygienic protocols and comprehensive personnel training to safeguard the public health