Veterinary Microbiology

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Active Outbreak Investigation, Isolation, and Molecular Characterization of Infectious Bronchitis Virus from Poultry Farms in Mekele and Bishoftu, Ethiopia
(Addis Abeba University, 2024) Nigusu Berhanu; Dr. Eyob Hirpa; Dr. Esayas Gelaye
Avian Infectious Bronchitis (AIBV) is a highly contagious respiratory disease that affects the poultry industry globally. In Ethiopia, AIBV has been reported in both commercial and backyard chickens. The currently used vaccine effectiveness is limited due to a lack of cross-strain protection and outbreaks continue to make mitigating the disease in Ethiopia difficult. Therefore, the objectives of this study were to isolate, genomic, and phylogenetic analysis of circulating field AIBV. A cross-sectional study was conducted from November 2023 to May 2024 in Mekele (eighteen samples) and Bishoftu (thirty-one samples) cities. Twelve tissue and thirtyseven pooled swab samples were collected, and six out of forty-nine samples (five swab samples and one tissue sample) tested positive for AIBV using real-time PCR and conventional RT-PCR. The six samples propagated into embryonated eggs and exhibited characteristic AIBV lesions and mortality over five consecutive passages. All the six isolates originating from Bishoftu (n=4) and Mekele (n=2), were amplified targeting 466 bp of the S1 gene and 433 bp of the 3'UTR using one-step RT-PCR. The purified PCR product of the five isolates targeting the 3ˊUTR region was sequenced and analyzed using bioinformatics tools. The sequence alignment of Ethiopia’s five isolates revealed a similar sequence except for one isolate (Bishoftu/03/2024) showed a single nucleotide change (A: C) resulting in amino acid change Glutamine(Q) to Proline (P). The phylogenetic analysis demonstrated the genetic distance was lower among the newly reported isolates (0.001) compared to the broader set of GenBank isolates (0.01), indicating a closer evolutionary relationship between the current local isolates and the Mexican isolates. Therefore, the findings identify genetically related local viral lineages that differ from strains used in imported vaccines. It also indicates that outbreaks were caused by infection with the IB virus which is creating a serious health risk in the poultry industry. Further research on the economic impact of AIB in poultry production, serotyping of circulating AIB viruses, and vaccine development based on the local isolates are recommended.
Adaptation Newcastle Disease Virusvaccinal Strainin Vero Cell Line and Evaluation of Vaccine Safety Immunogenecity in Chicken under Laboratory Condition
(2018-06) Leta, Abera; Dr. Fufa Dawo, Dr. Tefere Degefa
Newcastle disease (ND) is a highly infectious disease causing considerable economic losses to poultry industry worldwide. Traditionally, substrates for production of ND vaccines have been embryonated eggs, a method which has the disadvantages of being labor-intensive, time consuming and requires large area for the incubation of eggs. The present study was conducted to develop Vero cell-adapted, NDV I-2 vaccine and evaluate its safety and immunogenicity in chicken under laboratory condition. For this study, healthy and confluent monolayer of vero cell were further sub-cultured to prepare semi confluent monolayers then infected with 0.25 ml of Newcastle disease virus I-2 vaccine strain. The passage 1(P1) virus was harvested and used for the next passage in this way virus was given 12 serial passages on Vero cell line, where characteristic cytopathic effects (CPEs) were observed starting from fourth passages. Typical syncytium (irregularly shaped cells), gaint cells, clustering of infected cells, death of cells (plaque) were noticed on passage 4 from 72hourspost-infection. The positive hemagglutination and hemagglutination inhibition test confirmed that all vero cell adapted NDVI-2 adapted virus was Newcastle disease virus.The infectivity titer of adapted virus increased from log10 3.2 to log107.2 tissue culture infected dose/ ml.From the vaccine strain NDVI-2, Vero cell adapted live vaccine was produced. The antibody titer of experimental vero cell adapted live vaccine was determined in chicken by comparing with conventional live commercial vaccine (NDV I-2). Before experimental vaccination of the chicks, the level of antibody titre was very low (1.8±0.6). Following experimental vaccination, antibodies production were gradually increase after day 7 of post vaccination and the mean antibodies of the two vaccines (groups) were increased across each week of the followed up. The peak antibody titer was observed in the both groups at day 21 of post vaccination. After vaccination the two group chickens had antibody titres of >4 log2 starting from day and remain within protective range at day 35 final sera collection.The vaccine stain of NDV was well adapted to Vero cell line after successive passages and appeared equally immunogenic.
Adaptation of Inactivated Mycoplasma Gallisepticum Vaccine in Ethiopia
(2020-06) ASHETU, NEGEWO; Dr. Fufa Dawo, Dr. Takele Abayneh
However Mycoplasmosis is economically very important disease in poultry farm, but still the disease is undermined in Ethiopia. There was no more study and adapted vaccine on this infectious disease. This experimental study was taken from December 2018 up to May 2020 at National Veterinary Institute, Bishoftu, Ethiopia. The objective of this study was to adapt inactivated Mycoplasma gallisepticum vaccine from National veterinary gene bank, to determine appropriate media which already used by national veterinary institute for production of mycoplasma vaccine of both contagious bovine pleuropnemonia and contagious caprine pleuropnemonia, for growth of Mycoplasma gallisepticum bacteria and to evaluate the adapted inactivated vaccine, safety by follow up of vaccinated chicken for seven days for any clinical sign and death. The media selection was by important three experiments which were optical density, power of hydrogen meter reading and titration. Identification of Mycoplasma gallisepticum vaccine strain was conducted by conventional polymerase chain reaction using species specific primers targeting Mgc2 gene of Mycoplasma gallisepticum at 185bp before using for vaccine production. Polymerase chain reaction confirmed strain was used for the production of oil based formaldehyde inactivated Mycoplasma gallisepticum vaccine. In this study each activity was done according to national veterinary institute standard operation procedure. A total of 60 chickens were used for this experimental study. Chickens were grouped into three groups. All purchased chickens were screened by indirect Enzyme link immune sorbent assay test against mycoplasma gallisepticum anti body. The identity test of mycoplasma gallisepticum vaccine strain was positive at 185bp. The experiment indicates that contagious caprine pleuropnemonia growth media was proper media for growth of Mycoplasma gallisepticum vaccine. All chickens were free from mycoplasma gallisepticum anti body. The vaccine was considered to safe against Mycoplasma gallisepticum vaccine if the number of surviving vaccinated chickens that show no clinical sign and death at the end of the experiment.
Antigen and Molecular Detection of Peste Des Petits Ruminants Virus From Disease Outbreak Cases in Sheep and Goats in Asossa Zone, Benishangul-Gumuz Region, Ethiopia
(2020-06) Tolessa, Ebissa; Dr. Fufa Dawo
Peste des Petits Ruminants (PPR) disease is a severe, highly contagious and fatal viral disease of small ruminants causing a lot of production loss and mortality in Ethiopia. Limited serological and molecular reports indicated that the disease was highly prevalent in the study area and recently the data from the regional livestock agency indicated there was an improvement in vaccination coverage. Despite this, there was continuous occurrence of disease outbreak in the region. Thus, the aim of this study was to isolate and genetically identify recently circulating PPR virus (PPRV) by molecular tools from outbreak cases in small ruminants in the Asossa zone, Benishangul-gumuz regional state. Cross sectional study design were applied from November 2019 to April 2020 for investigation of the disease in outbreak areas. A total of 27 swab samples (22 nasal and 5 rectal swab) were purposively collected from clinically suspected animals and examined for the presence of PPRV by Immune capture Enzyme Linked Immunosorbent Assay (Ic ELISA) and a one-step Reverse Transcription Polymerase Chain Reaction (conventional and real time RT-PCR) assay. Of the clinical samples examined, 45.4% and 36.4% of the samples were positive for PPRV using Reverse Transcription Polymerase Chain Reaction (RT-PCR) and Immune capture Enzyme Linked Immunosorbent Assay (Ic ELISA) respectively. Two out of twenty two PPRV XIII suspected sample was successfully isolated on Vero dog SLAM (VDS) cell line with the dog signaling lymphocyte activation molecule (SLAM) receptor expressed on the cell surface and confirmed with Ic ELISA and RT-PCR. As evidenced from clinical finding, virus isolation and molecular detection indicated PPRV was circulating in the area where all of the cases were associated with unvaccinated and newly introduced small ruminants from the neighboring region indicating the possibility of the virus spread to different districts in the region. Therefore, vaccination strategies and vaccine coverage should be improved and implemented especially in newly introduced sheep and goat. Further investigation should be done regarding the molecular epidemiology and genetic analysis of the virus circulating in the region.
ANTIMICROBIAL RESISTANCE TEST OF SALMONELLA ISOLATES FROM MILK AND FECAL SAMPLES OF APPARENTLY HEALTHY DAIRY CATTLE IN DEBREZEIT
(2014-06) Yemisrach, Mulugeta; Dr. Biruk Tesfaye, Dr. Getachew Tadesse
A cross sectional study to determine the antimicrobial profile of salmonella isolated from milk and fecal samples of apparently healthy cattle found in dairy farms of Debrezeit was undertaken from November 2013- April 2014. A total of 296 samples (148 fecal and milk each) were collected and processed in college of veterinary medicine and agriculture debrezeit. The overall prevalence of salmonella was found to be 12.8%. Prevalence of 2.0 and 10.8% was observed from milk and fecal samples respectively. The isolates were tested for the effect of 11 antimicrobial by disk diffusion technique they have indicated 89.5%, 100%, 42.1%, 63.3%, 15.8%, 10.5%, 31.6%,42.1%, 52.6% resistant to amoxacyline, tetracycline and gentamycin, kanamycin, trimetoprim, streptomycin, cotrimoxazol, chloramphenicol, nalidixic acid and cefoxitin respectively no resistance has been found for ciprofloxacin. However no statistical difference (P>0.05) was observed between milk and fecal samples. Totally 8 Multiple Drug Resistance (MDR) pattern were also observed. The highest MDR was for three antibiotics with the combination Amc, Te, Cn being more frequent. In general MDR to three, seven and eight antibiotics dominate the resistance patterns (31.6%, and 21.1% each). From this study we conclude that milk can be a potential source of drug resistant salmonella infection and multidrug resistance is developing due to unmonitored and inappropriate use of drugs in dairy farm which needs due consideration as it affects the dairy industry and the people at large.
Antimicrobial Susceptibility of Escherichia Coli Isolates from Feaces of Slaughtered Cattle, Beef carcass and Abattoir Environment at Karalo Abattoir and Surrounding Butcher Shops, Addis Ababa, Ethiopia
(2020-06) Gebremichael Tilahun; Dr. Gezahegn Mamo, Dr. Tadesse Eguale
The wide spread occurrence of food borne bacterial pathogens and antimicrobial resistance are currently becoming the growing concern for animal and public health authorities. A cross-sectional study was conducted at Karalo area in Addis Ababa from December 2019 to May 2020 to investigate the occurrence and antimicrobial susceptibility profile of E .coli isolates from faeces of cattle brought for slaughter, beef carcass, floor of slaughter hall and meat transporting vehicles at Karalo abattoir and the surrounding butcher shops. A total of 175 samples were systematically collected and examined to isolate and identify E.coli by using standard bacteriological technique. The overall occurrence of E.coli was 51/175 (29.1%; 95% CI: 22.8-36.37) and isolation of E.coli was the highest in faeces (13/35; 37.1%) followed by floor swab (12/35; 34.3%), vehicle swab (10/35; 28.6%), carcass swab in butcher shops (9/35; 25.7%) and carcass swab in abattoir (7/35; 20%). All E.coli isolates from different sample sources were 100% susceptible to Nalidixic acid , Ciprofloxacin and Cefitriaxone . On the other hand, 84.3% (43/51) of E.coli isolates showed resistance to two or more antimicrobial agents. The highest level of resistance was observed to Sulfisoxasole (76.5%) in all samples followed by Cephalotine (64.7%), Ampicillin (47.1%), Amoxicillin clavulanic acid (43.1%), Tetracycline (41.2%) and Streptomycin (33.3%). Over 69% of isolates from fecal samples and 90% of isolates obtained from vehicle swab were resistant to 3 or more antimicrobials of which multidrug resistance as high as seven antimicrobials was recorded in a single isolate from feacal sample. Considerable proportions of feaces, carcass and premises in the present study harbored drug resistant E.coli which has a significant risk to public health by passing through food of animal origin. Therefore, appropriate intervention program and awareness creation on best practice of hygiene and sanitary measures on abattoirs as well as best handing practice of carcass in butcher shops are essential to minimize the risk associated with consumption of contaminated meat. Education on the surveillance and rational use of antimicrobial agents in animals and animal products are crucial. Furthermore, investigation on sources of contamination of meat in abattoirs, their environment and associated butcher shops play an important role in decreasing microbial contamination to ensure consumer safety.
Assessing Farmers’ Acaricides Use and Efficacy Evaluation of Different Acaricides and Selected Herbal Extracts Against Cattle Ticks
(Addis Ababa University, 2023) Solomon Desta; Dr. Lishan Assefa
Tick-controlling activity has been carried out by using a variety of commercially available chemical acaricides. However, the extensive use of chemicals promotes resistance and resulted in toxicity to animals and the environment, and residues in food animal products. Therefore, this study was aimed at assessing farmers’ acaricides use and efficacy evaluation of different acaricides and selected herbal extracts against cattle ticks. The study was carried out using the questionnaire survey and in vitro experimental activity to evaluate the acaricidal activities of hydromethanolic leaf extracts of Calpurnia aurea, Datura stramonium, Nicotina tobaccum, and Ricinus communis against Amblyomma cohaerence by comparing with the efficacy of deltamethrin, diazinon, amitraz and five brands of ivermectin, and with DMSO (10%) as the negative control. Adult immersion test (AIT) following complete randomized design was used to test the efficacy. The result showed that farmers in the study area have poor knowledge (50%) and improper practices (91%) about acaricides use. Deltamethrin and the five brands of ivermectin were showed the highest level of efficacy (100±0.00 %) in tick mortality, while diazinon and amitraz were the least ranked (83.3±8.82% and 63.3±8.82%) within 72hrs of exposure time, respectively. There were statistical significance differences in efficacy between amitraz and other acaricides (p = 0.000). All extracts at the concentration of 100mg/ml were showed a significant difference in tick killing after 48hr post-exposure time, while below 50mg/ml showed insignificant effect (p > 0.05). At 72hr post-exposure time, N. tobaccum showed better efficacy (86.7±8.8%) followed by D. stramonium (76.7±6.7%) at 100mg/ml. Besides, R. communis showed slightly better efficacy (70±5.8%) than C. aurea with a statistical mean (63.3±8.8%). Finally, N. tobaccum and D. stramonium showed good acaricidal activity, followed by R. communis and C. aurea. While compared with commercial acaricides, all herbal extracts showed higher efficacy than amitraz 12.5%. Hence, the current study recommends, herbal extracts that showed high efficacy should be used as an alternative therapy and commercial acaricides with low efficacy should be reserved from using on animals to control tick infestation.
Assessment of stray dog counting and knowledge, attitudes, and practice to wards rabies in households in Addis Ababa city, Ethiopia
(Addis Abeba University, 2024) Tewodros Legesse; Dr. Olana Merera
Rabies is a fatal viral disease of animals and people. Dogs are the primary source of infection and the majority of human rabies cases result from dog bites. Information on both domestic and stray dog populations along Knowledge Attitude Practice (KAP) assessment regarding rabies is vitally important for rabies control. However the situation of rabies is poorly known in Ethiopia, mainly in urban areas. Therefore, this study aimed to assess the demography of stray dogs, the incidence of dog bites, and the knowledge, attitude, and practice (KAP) of society concerning rabies. Questionnaire survey was collected from November, 2023 to May, 2024 using Kobo Collect toolbox in selected sub city Gulele, Yeka and Arada in order to assess KAP of the respondents towards rabies in ouseholds. In the survey, out of 384 households (96.35%) of households owned at least one dog with a total number of 463 dogs (range: 1 to 5 dogs per household); the mean number of dogs per household was 1.25 (SE 0.58). From this 96.35% of dog owning households 51.2% of respondents, owned only one dog with dog: human ratio of 1:9. 70% of dog owning households have vaccinated their dogs against rabies. Nearly all (99%) of the respondents recognized the right response regarding the route of rabies transmission and had heard of rabies. However, 64.3% of research participants had a satisfactory level of suitable rabies prevention practices score, whereas 61.8% of individuals had a moderate level of knowledge and 59.8% had an intermediate level of attitude. In this study, even though the study participants have moderate knowledge, attitude and practice towards rabies, the dog bite management and dog vaccination practice is unsatisfactory on the last three years. Age, occupation, and the source of rabies information were all significantly correlated with knowledge score (P<0.05). The counting method was by using photo capturing method and by observation. In this study, male dogs were higher than female dogs. The total dog estimation of Gulele, Arada and Yeka sub cities had estimate 1050,783, 1282 respectively. There is huge population of stray dog in the studied sites which may serve as a risk for maintaining and transmission of rabies. Along the set of study objectives, the RabiCare android app was developed to create awareness on transmission, prevention and control of rabies in three most spoken languages.
ASSESSMENT OF THE EFFECTS OF ACTIVATED LACTOPEROXIDASE SYSTEM ON MICROBIOLOGICAL QUALITY OF RAW COW MILK ON DIFFFERENT CLIMATIC ZONE OF ETHIOPIA
(2018-06) HANI, SELEMON; Dr. Fanta Desissa, Dr. Gezahegn Mamo
The objective of this study was to assess the antimicrobial effect of the Lactoperoxidase system (LPS) in milk under different agro-climatic zones taking into account the variability of environmental temperatures toward improving milk quality and safety in Ethiopia. Experimental study design was employed to assess the antimicrobial effect of LPS on the keeping quality of raw cow milk. Milk samples were collected from Addis Ababa University Business enterprise Bishoftu fattening, dairy and poultry farm. A total of 12 liters of milk samples were collected and grouped into activated (treated with sodium thiocyante and Hydrogen peroxide) and nonactivated (control). The activated and non-activated milk samples were subjected to four treatment groups based on temperature. The treatments were designed to represent the average temperatures of the four agro-ecology of the country namely cool to cold humid zone (14oC), warm to cool, semi-humid zone (18°C), warm to hot, semi-arid zone (24oC) and hot, arid zone (37oC). The samples were incubated in adjustable incubator at each temperature. The effect of the system was evaluated using alcohol tests, total plate count and analysis of the composition of the milk every two hours. LPS activation has resulted in decrease of the number of microbial load significantly. Its effect tended to be more efficient as storage temperature decreases. There was significant reduction of microbial load in LPS activated milk samples as compared to the control group (P<0.05). The microbial load was decreased by 66.7%, 75%, 67.9% and 64.3% in activated milk samples kept at 370c, 240c, 180c and 140c, respectively. The activation of LPS can prolong the shelf life of milk ranging from 6 to 12 hours without deterioration. The study showed that LPS increased the shelf life of milk significantly at all temperatures. This study revealed that application of LPS had no significant impact on the nutritional composition of milk. In conclusion, activation of the LPS potentially decreases the microbial load and prolongs the shelf life of raw cow milk up to 6-12 hours based on the storage temperatures. Further studies should be done in different parts of the country under the specific temperatures especially in the high milk-shed areas of the country particularly by rural smallholder dairy farmers for practical usage of the system.
BACTERIOLOGICAL STUDIES ON THE RESPIRATORY TRACTS OF APPARENTLY HEALTHY AND PNEUMONIC CAMELS (CAMELUS DROMEDARIES) IN SELECTED DISTRICTS OF AFAR REGION, ETHIOPIA
(2012-06) MU’UZ, GEBRU; Dr. Tesfaye Sisay, Dr. Genene Tefera
A cross-sectional study was conducted to isolate and characterize the normal bacterial flora and bacterial agents implicated in pneumonia from the respiratory tract of the apparently healthy and pneumonic camels in the selected districts of Asayita and Dubti woredas of Afar Region. A total of 532 samples including 384 nasal swabs, 74 lung tissues and the same number of corresponding tracheal swabs were collected for bacteriological examination from September 2011 to May 2012. Generally, 903 bacterial isolates that constituted 14 different genera were identified from both the field and abattoir based study. The 384 nasal specimens collected yielded a total of 641 bacterial isolates. CNS, 28.6%, Bacillus, 13.5%, S. aureus, 13.3% and E. coli, 7.8% were the leading bacterial species isolated from the nasal tracts of apparently healthy camels. Nasal swabs collected from the pneumonic camels revealed S. aureus, CNS, Bacillus species and K. pneumoniae at a rate of 28.0%, 11.7%, 11.3% and 7.0%, respectively. E. coli, 12.7%, Proteus species, 10.9%, and K. pneumoniae, 9.1% were recognized at higher proportions among the 55 bacteria identified from the normal lungs. On the other side, S. aureus, S. equi subsp. equi and P. multocida were the frequently encountered species in the pneumonic lungs with the incidence of 16.3%, 13.0% and 10.9%, respectively. The majority of the isolates colonized all the anatomical sites investigated. However, a general decrease in the isolation rate was observed as one goes down the respiratory passageways. There was a statistically significant difference between the health status of the camels as well as along the anatomical sites studied with the isolation rates of the major camel respiratory pathogens (p<0.05). Streptococcus equi subsp. equi, S. equi subsp. zooepidemicus and S. pneumoniae were identified using the Omnilog®-Biolog identification system at the Institute of Biodiversity Conservation, Addis Ababa. The majority of the strains of the camel respiratory pathogens were found susceptible to norfloxacin, streptomycin and gentamicin but resistant to the action of ampicillin and tetracycline on the invitro test. Further studies on the demonstration of the role of other microorganisms, the pathogenicity of S. equi subsp. equi, identification of the serotypes involved and development of polyvalent vaccine are recommended to allow the progress of preventive methods.
BOVINE MASTITIS IN DAIRY FARMS IN AND AROUND AKAKI KALITY SUB CITY AND SULULTA TOWN: EMPHASIS ON ISOLATION AND IDENTIFICATION OF PATHOGENIC STAPHYLOCOCCUS AND ANTIMICROBIAL SUSCEPTIBILITY TEST OF STAPHYLOCOCCUS AUREUS
(2019-06) Getahun, Tesfaye; Mr. Hika waktole, Dr. Tilaye Demissie; Dr. Getachew Terefe
A 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 clin-ical and sub clinical cases were cultured to isolate pathogenic Staphylococcus species. Antimicro-bial 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.
CHARACTERIZATION OF S. GALLINARUM, S. PULLUROM AND S. ENTERITIDIS ISOLATED FROM CHICKEN IN CENTRAL ETHIOPIA AND EVALUATION OF PROTECTIVE AND CROSS PROTECTIVE EFFICACY OF SALMONELLA GALLINARUM 9R VACCINE AGAINST S. GALLINARUM, S. PULLUROM AND S. ENTERITIDIS
(2015-06) Kassaye, Adamu; Dr. Takele Abayneh, Hunderra Sori
Salmonellosis is one of the most important bacterial diseases of poultry with significant impact due to the loss of productivity in affected birds and its potential public health hazard. This study is performed with the aim of evaluating the immunizing and protective efficacy of the vaccine currently being used against salmonella strains precipitating disease outbreaks in poultry. Necropsy samples were collected from suspected cases showing typical pathological lesions for bacterial isolation. Isolation and identification of bacteria was carried out employing conventional bacteriological and biochemical methods followed by characterization using mPCR. Salmonella strains (12 Salmonella Gallinarum, 1 Salmonella Pullorum and 1 Salmonella Enteritidis) isolated from suspected cases were used for the challenge experiment in chicken vaccinated against salmonellosis at 42 days of age using 9R vaccine. Vaccinated chicken showing strong immune reaction as observed with slide agglutination test were challenged with field strains of virulent salmonella Gallinarum, salmonella Pullorum and salmonella Enteritidis strains (5 x 107 CFU/ml of each) 1ml orally at 14 days post vaccination. Post challenge follow-up for 2 weeks to determine the degree of protection of the vaccine showed that no mortality was observed in the vaccinated and salmonella Gallinarum challenged group despite that 3 (20%) chicken had pinpoint hemorrhages on the liver and enlarged spleen during post-mortem examination. However, in the non-vaccinated group, 8(53.3%) birds died, 5(33.3%) showed macroscopic lesions while the remaining 2(13.3%) had no any lesion. Observation of mortality and extent of lesion after challenge with the salmonella Pullorum virulent strain, showed no mortality in the immunized group while 2 (13.3%) birds died in the un-immunized group. One (6.7%) chick in the immunized group showed macroscopic lesion, while 13(86.7%) chicken showed post-mortem lesion in the un-immunized group. In salmonella Enteritides virulent strain challenge group, no mortality and macroscopic lesion were observed in vaccinated group, while postmortem lesion were observed with no mortality in 10(66.7%) chicken in the non vaccinated group. Assessment of the degree of protection showed that vaccination with live salmonella Gallinarum 9R strain significantly reduced the mortality and severity of infection due to salmonella Gallinarum and also provided remarkable cross-protection against salmonella Pullorum and salmonella Enteritidis challenge in tested birds.
Comparative Evaluation of Direct Rapid Immuno-Histochemical Test (DRIT) with Direct Fluorescent-Antibody Test (DFAT) for laboratory diagnosis of animal Rabies in Ethiopia
(Addis Ababa University, 2021) Sintayehu Abedla; Hika Waktole; Dr. Gezahegne Mamo; Dr. Abraham Ali
Direct fluorescent antibody test (DFAT) is used as a gold standard method for rabies virus detection. The present study aimed was to compare and evaluate DRIT with Direct Fluorescent Antibody Test (DFAT) to use equivalently as one of rabies virus diagnosing methods in areas where DFAT is not accessible. The method is based on the capture of rabies nucleoprotein (N) antigen in brain smears using a cocktail of biotinylated monoclonal antibodies specific for the N protein and color development by streptavidin peroxidase-amino ethyl carbazole and counterstaining with hematoxylin. The test was performed in parallel with the standard DFAT and mice inoculation test (MIT) using 100 brain specimens from various species of animals. The majority of them were dogs (n=88), ollowed by cats (n =8), cattle (n =3), and donkey (n =1), and also from those samples that were tested by DRIT and DFAT, we randomly selected and tested 12 brain samples by MIT. The results indicated that 63% of the tests were positive by DFAT and 64% were positive by DRIT. A slight difference was observed in such a way that one sample was negative by DFAT but positive by DRIT and MIT. The DRIT provides powerful, economical tool for rabies diagnosis to improve existing rabies surveillance, prevention and control programs in Ethiopia. Although further laboratory and field examinations are essential, our findings were providing and remark the potential value of the DRIT for countries with limited diagnostic resources.
COMPARATIVE STUDY OF THE STABILITY AND IMMUNOGENICITY OF INACTIVATED BACTERIN, ALUM PRECIPITATED AND OIL ADJUVANTED HEMORRHAGIC SEPTICEMIA VACCINE
(2018-06) Hassen, Belay; Dr. Nick Nwankpa; Dr. Bedaso Mammo, Dr. Fufa Daewoo
Haemorrhagic septicaemia (HS) is the most devastating disease of cattle and buffalo particularly to smallholder farmers where husbandry and preventive practices are poor. Due to the acute nature of the disease and the presence of carrier animals after recovery, vaccination is considered as the only efficient method of controlling the disease. Although alum precipitated vaccine is the most widely used; it has come across drawbacks including poor stability and weak immune response. Oil adjuvanted vaccine on the other hand has been emerging with better stability, longer periods of protection and stronger immune response. Therefore, this experimental study was conducted with the objectives of comparing the stability and immunogenicity of inactivated bacterin (IBV), alum precipitated (APV) and oil adjuvanted (OAV) HS vaccine candidates. To achieve this, Pasteurella multocida B:2 (Ethiopian isolate) was grown on tryptose soy broth (TSB) supplemented with 10% horse serum, inactivated with formalin (0.5%) and the turbidity was standardized to contain 1.5mg antigen/ml. APV was prepared by admixing aluminium potassium sulphate (1%) with the bacterin whereas OAV was prepared by mixing the bacterin with equal volume of Montanide ISA 61 VG. The inactivated culture was used as IBV. The three vaccine formulations were stored at 4ºC and tested for stability (potency and identity) once a month for 5 months. Potency test was conducted on mice while test for identity was conducted using polymerase chain reaction. On the other hand, nine calves were divided into three groups, each group vaccinated with each candidate and boosted on day 28 post primary vaccination. Sera were collected on days 0, 28, 42 and 56 to assess the immune response. The IBV and APV showed retention of stability when stored at 4°C for 30 days. The potency dropped to 0.2 log10 and 0.8 log10 for IBV and APV respectively when storage period was extended to 60 days whereas there was no difference between vaccinated and unvaccinated groups when both formulations were stored for 90 days. OAV retained stability when stored at 4°C for 90 days and potency dropped to 0.6 log10 and 0.2 log10 when storage was extended to 120 and 150 days respectively. Application of indirect hemmaglutination test on sera obtained from calves revealed that OAV induced stronger immune response with peak antibody titre of 3.4 log10 on day 56 while APV induced protective, but, relatively weaker immune response with peak antibody titre of 2.4 log10 on day 56. The IBV induced weak immunity (1.5 log10 on day 56) indicating the need for incorporation of a suitable adjuvant. There was a significant difference in the immune response between the vaccine groups (P<0.05, ANOVA). Therefore, this study revealed the weak stability as well as immunogenicity of the conventionally used alum precipitated vaccine and urges the need to produce oil adjuvanted vaccine for the control of the disease.
COMPARISON OF CLINICAL TRIALS OF BOVINE MASTITIS WITH THE USE OF ANTIBIOTICS AND HONEY
(2007-06) TAMRAT, TOMAS; Prof. A.R.S. Moorthy
A total of 423 representative randomly selected Holstein, Jersey and local zebu lactating cows located in Wolaita zone at Soddo Zuria Woreda of Southern Nation Nationalities and Peoples Regional State were examined. All the 46 lactating cows of Soddo dairy farm, 11 lactating cows from Soddo Veterinary Clinic, 103 lactating cows from urban dairy holders and the rest 263 were X randomly selected lactating dairy cows from 18 rural Kebeles were included and tested to determine the prevalence of mastitis by using mastitis detecting BOVI-VET (RUUSE, DENMARK), indicator paper and white side test. Milk samples were cultured from 329 cows infected with different grades of mastitis. Examination for mastitis infection in Soddo Zuria Woreda revealed that there were 99 (23.4 %) clinical and 230 (54.3 %) sub clinical cases. Out of 423 cows 99 clinical cases and 230 sub-clinical cases were recorded and grouped into grade I, II, III, IV level of infection and only clinical cases were subjected to antibiotics and honey intramammary infusion treatment. The prime objective of the study is to examine the safety and efficacy of honey compared to a known antibiotic infusion in lactating mastitic cows. Minimum Inhibitory Concentration (MIC) of honey was determined by using different dilutions and different species of bacteria available at the microbiology laboratory of FVM. And it was revealed that minimum concentration of honey that inhibited E. coli was 10 %; L. monocytogenes and K. pneumoniae inhibited at 20 %; Staphylococcus and Streptococcus spp, were inhibited at 30% concentration, where as Micrococcus spp. at 40 % concentration. Salmonella enteritidis was resistant (shown growth in all concentrations). Out of ninety-nine clinical cases, forty-eight cases were treated with antibiotic (Multiject IMM.) infusion and fifty cases were treated with Beza honey. Milk samples from the cows identified and recorded for treatment trial groups were re-cultured within one month post-treatment. Cases included in the analysis had at least one mastitis pathogen isolated from the initial milk samples. Overall bacteriological cure rate of treated cases was 54 % (53 of 98). The effectiveness of honey in clearing bacterial infection in the intramammary infusion for mastitis treatment revealed similar to antibiotic (54.2% (Multiject IMM.) treated cases. Antibiotic and non-antibiotic treatment responses were associated with grade of affection. Honey treatment was more effective 78.1% in grade III type of mastitis when compared to treatment of grade II type of mastitis (11.1%); where as multiject was more effective in grade II type of mastitis (41.9%) and slightly less curative rate (76.4%) for grade III type of mastitis when compared to honey. The present study indicated that honey treatment could be an alternative treatment to antibiotics so that indiscriminate use of antibiotics and emergence of antibiotic resistance strains of microorganisms could be avoided and at the same time financial benefits can be obtained. Treatment with honey is more economical i.e.7-8 times cheaper than the available mastitis treatment drugs in the country. As an alternative to antibiotic treatment for XI mastitis, 10 ml of 40% honey intramammary infusion for each quarter for 3 consecutive days can be tried.
Comparison of Diagnostic Efficacy of Blocking Elisa with Competitive Elisa for the Detection of Peste Des Petits Ruminants Virus Antibodies in Ruminants and Camels Sera in Ethiopia
(2020-06) Kumela, Lelisa; Dr. Fanta Desissa, Dr. Tesfaye Rufael
A Peste des petits ruminant (PPR) is one of the top hindrance to small ruminants production. To facilitate the global effort to eradicate PPR, sufficient, reliable, fast and cost effective screening tests are important. This study compares the diagnostic performance of two anti-PPRV antibodies detection methods namely: ID Screen® PPR Competition ELISA (ID Screen® PPR c-ELISA) and Haemagglutinin based PPR blocking ELISA (HPPR b-ELISA®) kits using 480 sera collected from goats, sheep, cattle and camels. The results of the two tests were validated against virus neutralization test (VNT). The agreements between the tests were determined using Cohen’s Kappa statistics and two-way contingency table. The diagnostic sensitivity and specificity of HPPR b-ELISA® test were 79.55 and 99.74%, respectively relative to the ID Screen® PPR c-ELISA with almost perfect agreement (=0.86) between the two tests. Conversely, the diagnostic sensitivity and specificity of ID Screen® PPR c-ELISA relative to HPPR b-ELISA® were 98.59 and 95.60%, respectively. There was almost perfect agreement between the two tests in goats (=0.82) and sheep (=0.98), while the agreement was substantial in cattle (=0.78). However, there was no agreement between HPPR b-ELISA® and ID Screen® PPR cxiii ELISA in detecting antibodies against PPRV in camels’ sera (=0.00). On the other hand, the results of the two tests were validated against VNT. The HPPR b-ELISA® test had a diagnostic sensitivity and specificity of 80 and 96.36%, respectively compared to VNT with substantial agreement. The agreements were almost perfect in goats (=0.83) and sheep (=0.89), moderate in cattle (=0.50) and none in camels (=0.00). The sensitivity and specificity of ID Screen® PPR c-ELISA relative to VNT were 92.00 and 76.36%, respectively. The ID Screen® PPR c-ELISA test had substantial agreement in goats (=0.69) and sheep (=0.78), fair agreement in cattle (=0.30) and no agreement in camels (=0.00) in detecting specific antibodies directed against PPRV relative to VNT. The HPPR b-ELISA® test was shown to be a good screening test to be used alone or in combination with ID Screen® PPR c-ELISA test for PPR serological surveys or monitoring in ruminants. Based on these results it can be concluded that the serology based on both tests represents a reliable and valid method for detection of anti-PPRV antibodies in ruminants, however, the use of ID Screen® PPR c-ELISA and HPPR b-ELISA® tests in detection of anti-PPRV antibodies in camels’ sera requires further investigation. Findings suggest that the newly developed HPPR b-ELISA® is suitable for screening of antibodies against PPRV in ruminants.
CROSS SECTIONAL STUDY OF MIDDLE EAST RESPIRATORY SYNDROME (MERS CoV INFECTION) IN CAMELS IN SELECTED SITES OF AMIBARA DISTRICT, AFAR REGION, ETHIOPIA
(2019-06) Demeke, Sibhatu; Dr. Gezahegn Mamo, Dr. Fassil Aklilu
A cross sectional study of MERS CoV in camel was conducted between February 2018 to April 2019 in three selected sites of Amibara district of Afar Region, Northeast Ethiopia. The study was aimed to observe the current sero-prevalence status of MERS, assess the presence of active cases through detection RNA viral particle using RT -PCR and investigate possible risk factors for the MERS-CoV in camels. A total of 589 sera were collected and tested with indirect Enzyme linked Immuno Sorbent Assay (iELISA).The overall seroprevalance of MERS-CoV with this test was 87.3% (n=514/589, 95% CI: 84.5-89.9). Out of the total sera samples, 198 sera were retested by pseudo particle neutralization test (ppNT)at Hong Kong University (HKU). A total of 857 nasal swab samples were collected for the detection of MERS CoV RNA particle using RTPCR. Association of different risk factors with seroprevalance revealed that origin (X2=13.39, P=0.001), sex (X2=4.5 P=0.034), age ((X2=185.7, P=0.001) season (X2=41.7, P=0.000) and reproduction status (X2=96.1, P=0.001) showed a statistical significant difference for MERS CoV antibody detection among the groups (P<0.05) while herd size did not show a statistically significant difference among groups (p>0.05). In multivariable logistic regression analysis, age (OR=7.39, 95% CI:3.43-15.91), season (OR=4.83, 95% CI:-2.14-10.90), and in adult female camel reproduction status (OR=7.39, 95% CI:3.43-15.91) showed statistically significant difference among the groups for MERS CoV antibody detection while risk factors of origin, animal sex and herd size difference were statistically insignificant. Out of the total 198 sera samples tested using ppNT, 197 (99.5%; 95%CI: 98.4-100) were positive where as in indirect ELISA of 198 sera sample only 182 (91.9%; 95% CI: 88-95.7) were seropositive indicating ppNT is more sensitive than iELISA for MERS CoV antibody detection. Despite the presence of high seropositivity for MERS CoV antibody, all 857 camel nasal swabs samples tested by Real- time reverse transcription polymerase chain reaction (RT-PCR) technique for detection MERS – CoV RNA viral particle were Negative after testing at NAHDIC and H.K.U. School Public Health laboratories .In conclusion, the present study revealed a high seroprevalance of MERS CoV in adult camels. However, in spite of high seroprevalance the lack of any RNA viral particle in the present study suggests the need for further in depth longitudinal study to detect the circulating virus focusing on juveniles and young camels whereby seroprevalance of antibody is low when compared with adult camel in order to get the active virus before the camel develop antibody. Moreover, the zoonotic significance and potential transmission routes of MERS CoV to pastoral communities should also be investigated and design strategy for the preparedness in control of the diseases in Ethiopia
CROSS SECTIONAL STUDY OF MIDDLE EAST RESPIRATORY SYNDROME CORONAVIRUS IN SELECTED KEBELES OF YABELLO DISTRICT OF BORENA ZONE, OROMIA REGION, ETHIOPIA
(2019-06) Ayelech, Muluneh; Dr. Gezahegn Mamo, Dr. Fassil Aklilu
Middle East respiratory syndrome is a respiratory and an enteric disease caused by a recently discovered virus called MERS-CoV. It is a zoonotic virus in which camels are implicated as the major source of infection in humans. A cross-sectional study was conducted from February, 2018 to April, 2019, with the objectives of detection and characterization of MERS-CoV and determining the seroprevalence and its association with risk factors. The study animals were camels found in Borena zone, in three kebeles, namely, Areri, Dikale and Harwoyu of Yabello district. A total of 1050 nasal swab and 525 sera samples were collected at a rate of 150 nasal swab and 75 sera at a time. The nasal swab were tested for the presence of specific viral RNA using qRT-PCR at Hong Kong University and NAHDIC.The sera samples were tested for the presence IgG antibody using indirect ELISA at NAHDIC, Ethiopia. Additionally 75 of 525 serums were retested by ppNT in Hong Kong University. Based on ELISA result, the overall seroprevalence of MERS-CoV in the study area was 74% (390/525, 95%CI 70 to78).Association of risk factors with seroprevalence was identified. The seroprevalence found were 87% in adult, 48% in young’s and 50% in juvenile camels, the variation was statistically significant, adjusted OR; 7.5 CI= 4.5 - 12.4.Also small size herd had 80% seroprevalence than medium 78.8% and large herd size 67.8%, the variation was statistically significant, adjusted OR; 3.44;CI=1.76 to 6.75.High seroprevalence was recorded in Dikale 76% than Harwoyu74% and Areri 72%. ,the variation was statistically significant,adjusted OR=2.3;CI=1.27to4.35.Gravid females had high seroprevalence 91% than lactating 83% and dry females 67%,the variation was statistically significant,adjusted OR= 1.5;CI=1.045 to 2.917.No statistical significance difference was observed among sexs and sampling seasons.In comparison of the two serology methodologies, 69% of the test result agreed, and showed higher seroprevalence of MERS-CoV antibody in all kebeles of Yabello district camels which reflects the evidence of prior MERS-CoV infection. All 1050 nasal swab samples showed negative result. Zero detection might suggest absence of active circulation of the virus at the time of sampling and the need of designing longitudinal based active surveillance by concidering the calving season of the camels and the short viral shedding window (2-5days). Early detection and imposing control intervention reduces risk of transmission of the virus to the pastoralist and consumers of camel products in the country.
Cysticercusbovis and Taenia Saginata: Prevalence, Public Health Significance and Community Perception about Meat Borne Zoonosis in Three Selected Districts of West Shoa Zone of Oromia Region, Ehiopia
(AAU, 2014-06) worku, Abate; Mamo, Bedaso(Dr
A cross-sectional study was conducted from November 2013 to March 2014 on bovine cysticercosis in cattle slaughtered at Holata, Addis Alem and Ginchi municipal abattoirs in west Shoa zone of Oromia Regional State with the objective of estimates the prevalence of Taenia saginala/cystiercosis, organ distribution, viability of the cysts, associated risk factors and community knowledge about meat-borne zoonosis. Routine meat inspection method and questionnaire survey on conveniently selected respondents in the study areas were used. Out of 600 carcasses examined during the study period in three municipality abattoirs 2.5 % (15/600) were infected with C. hovis. A prevalence of 2.5% (95% CI: 0.3%-4.7%) (5/200), 1.6% (95% CI: 0.2%-3.5%) (3/180), and 3.2% (95% Cl: 0.9%-5.5%) (7/220) in Holeta, Addis Alem and Ginchi were observed, respectively. Cysts wcre found in heart (46.6%), tongue (33.33%) and shoulder muscle (20%). Out of the cysts 46.6 % (7/15) were viable, while 53.3% (8/15) were non-viable. The questionnaire survey revealed that T. saginata/taeniosis is a wide spread problem in these three towns and surrounding rural areas. Out of 110 respondents 63.6% (70/110) had contracted T. saginata. Age, sexe, religion, occupation, education status, raw meat consumption, knowledge about the disease and presence or absence of the latrine was found as potential risk factors of taeniosis. The present study indicate that Taenia saginata/cysticercosis is highly distributed in the study areas warranting professional intervention and community based control programs should be introduced
Cysticercusbovis and Taenia Saginata: Prevalence, Public Health Significance and Community Perception about Meat Borne Zoonosis in Three Selected Districts of West Shoa Zone of Oromia Region, Ethiopia
(AAU, 2014-06) Worku, Abate; Hailu, Yacob(Dr.
A cross-sectional study was conducted from November 2013 to March 2014 on bovine cysticercosis in cattle slaughtered at Holata, Addis Alem and Ginchi municipal abattoirs in west Shoa zone of Oromia Regional State with the objective of estimates the prevalence of Taenia saginala/cystiercosis, organ distribution, viability of the cysts, associated risk factors and community knowledge about meat-borne zoonosis. Routine meat inspection method and questionnaire survey on conveniently selected respondents in the study areas were used. Out of 600 carcasses examined during the study period in three municipality abattoirs 2.5 % (15/600) were infected with C. hovis. A prevalence of 2.5% (95% CI: 0.3%-4.7%) (5/200), 1.6% (95% CI: 0.2%-3.5%) (3/180), and 3.2% (95% Cl: 0.9%-5.5%) (7/220) in Holeta, Addis Alem and Ginchi were observed, respectively. Cysts wcre found in heart (46.6%), tongue (33.33%) and shoulder muscle (20%). Out of the cysts 46.6 % (7/15) were viable, while 53.3% (8/15) were non-viable. The questionnaire survey revealed that T. saginata/taeniosis is a wide spread problem in these three towns and surrounding rural areas. Out of 110 respondents 63.6% (70/110) had contracted T. saginata. Age, sexe, religion, occupation, education status, raw meat consumption, knowledge about the disease and presence or absence of the latrine was found as potential risk factors of taeniosis. The present study indicate that Taenia saginata/cysticercosis is highly distributed in the study areas warranting professional intervention and community based control programs should be introduced.

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