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Background Brucellosis is an economically devastating animal disease and has public health concern. Serological methods such as Rose Bengal Plate Test (RBPT), Complement Fixation Test (CFT), and Indirect-Enzyme-Linked Immunosorbent Assay (I-ELISA) have been used to detect brucellosis. However, there is limited comparative evaluation studies and lack of molecular confirmation of the causative agents in the study areas. The study was aimed to compare RBPT, I-ELISA, CFT, and confirmation using Polymerase Chain Reaction (PCR). A total of 2317 sera samples were collected from brucellosis-affected areas of Ethiopia with no vaccination history. All sera were subjected to comparative serological assays. Post-cross tabulation, sensitivity, and specificity were determined using Receiver Operating Characteristics (ROC) curve analysis software. PCR was performed on 54 seropositive samples using genus- and species-specific primers. Results Among the 2317 sera tested for comparative serological assays, 189 (8.16%) were positive for RBPT, 191 (8.24%) for I-ELISA, and 48 (2.07%) for CFT. Sensitivity to RBPT was 100% (95%) in shoats and 74% (95%) in cattle. Specificity on RBPT was 98.69% (95%), 99.28% (95%), 100% (95%) in sheep, goats, and cattle, respectively. CFT sensitivity was 4 (95%) in sheep, 9.65 (95%) goats, and 72 (95%) cattle. Specificity on CFT was 100% (95%) for sheep, goats, and cattle. A 223bp Brucella genus-specific and 156bp B. abortus species-specific detected. However, B. melitensis not detected. Conclusion In this study, I-ELISA was the most sensitive and specific test. RBPT detected all Brucellosis-infected sheep and goats; nevertheless, it showed false positive in sheep and goats and false negative in cattle. The presence of B. abortus in small and large ruminants was confirmed by PCR. This is the first report of B. abortus detection in small ruminant in Ethiopia. B.abortus detected in non-preferred hosts. The findings suggest further study on molecular epidemiology of Brucella species.

Background Mannheimia haemolytica has been recognized as the principal cause of pneumonic pasteurellosis in sheep and goats. It is one of the important diseases of small ruminants in Ethiopia. While annual vaccination using a monovalent vaccine (inactivated Pasteurella multocida biotype A) is common, respiratory diseases are still reported in various parts of Ethiopia. This suggests the need for further investigation into the species and strains responsible for the disease, which is vital information for development of a multivalent vaccine. The objective of the current study was to isolate M. heamolytica associated with pneumonic cases of sheep in selected areas of Central Ethiopia, determine its role and the strains/genotypes of the bacterium circulating in the study area. Results Bacteriological analysis of nasal swab samples collected from a total of 76 pneumonic cases of sheep showed that M. haemolytica was isolated from 26 of them while B.trehalosi from two cases . Further molecular analyses of the isolates using M. haemolytica species-specific and M.haemolytica serotype-1 antigen specific PCR assays revealed, 26 of the isolates were identified as M. haemolytica of which 21 of them were M. haemolytica serotype-1. Both M. haemolytica and B.trehalosi isolates were not detected in a PCR assay targeting capsular biosynthesis gene ( capA ) of P.multocida despite the non-specific products observed in M. haemolytica isolates. Phylogenetic analysis of M. haemolytica isolates included in this study in comparison with the reference strains with respect to PHSSA and Rpt2 genes revealed that the Ethiopian M. haemolytica isolates constituted three distinct genotypes consistent with site of origin. Conclusion The study indicated that M.haemolytica is commonly associated with cases of pneumonia in sheep in the study areas of central Ethiopia although the remaining other pathogens responsible for majority of the cases are yet to be determined. Molecular characterization revealed the existence of three genotypes of M. haemolytica circulating in the study areas consistent to the site of isolation. The findings suggest further extensive work to determine all pathogens associated with sheep pneumonia and the strain distribution of M. heamolytica to understand its molecular epidemiology at national level and design cost effective prevention and control methods.

Background Avibacterium paragallinarum is a causative agent of infectious coryza (IC), a disease that affects the upper respiratory tracts and paranasal sinuses of chickens, resulting significant economic losses in the poultry industry. The objective of this study was to isolate and identify Av. paragallinarum using bacteriological and molecular methods between February 2022 and April 2024. A total of 74 swab samples were collected from chickens showing ocular and nasal discharges and swelling of the infraorbital sinuses. Method Clinical samples were collected from chickens showing symptoms of IC from six locations of Ethiopia for the isolation and identification of the causative agent. Swab samples from the nasal cavity and cheesy material from the infraorbital sinus were screened using conventional PCR and inoculated onto chocolate agar enriched with 5% sheep blood. Colonies suspected of being Av. paragallinarum were transferred to brain heart agar supplemented with horse serum. Gram staining was used to examine the morphology of bacteria in pure colonies grown on chocolate and brain heart infusion agar. Results The isolation of Av. paragallinarum on chocolate and brain heart infusion agar resulted in the observation of small, translucent, dewdrop-shaped colonies after 24 h of incubation at 37 °C in a 5% CO 2 incubator. A smear prepared from a single colony of revealed Gram-negative, short rod-shaped or coccobacilli Av. paragallinarum bacteria. Biochemical tests conducted on this isolate yielded negative results for catalase, oxidase, urease, indole, methyl red, and Voges-Proskauer tests. However, the bacterium exhibited positive fermentative activity with glucose, sucrose, and maltose. Biochemical assay revealed the presence of Av. Paragallinarum . The bacterial colonies confirmed a 511 bp PCR product. The partial HPG-2 gene nucleotide sequences of eleven isolates were sequenced and deposited in GenBank with the accession number PQ565862-72. A phylogenetic tree was constructed to determine the genetic relatedness of Ethiopian isolates with isolates from other African countries and elsewhere. Conclusion The current investigation confirmed that the outbreaks were caused by Avibacterium paragallinarum and provided scientific evidence on the presence of different strains of Av. paragallinarum in Ethiopia. This is the first study in Ethiopia to detect and identify Av. paragallinarum from diseased chickens using molecular approaches. Further molecular characterization of locally circulating Av. paragallinarum isolates is recommended to be used as a vaccine strain for the prevention and control of infectious coryza.

Background Avian infectious bronchitis (IB) is a highly contagious respiratory disease that affects the poultry industry globally. The disease is caused by avian infectious bronchitis virus (IBV), member of the genus Gammacoronavirus . In Ethiopia, IBV has been reported in both commercial and backyard chickens based on clinical observation. The objectives of this study were to isolate the virus, conduct molecular based identification, and phylogenetic analysis of the circulating IBV isolates. Methods and materials A cross-sectional study was conducted between November 2023 and May 2024 in Mekele and Bishoftu, Ethiopia. A total of 49 clinical samples were collected, comprising 12 tissue samples and 39 pooled swab samples. Of these, 6 samples—specifically, 5 swab samples and 1 tissue sample—tested positive for infectious bronchitis virus (IBV) through virus-specific conventional RT-PCR and real-time PCR. Nested PCR was performed using serotype-specific primers. The purified PCR products, which targeted the spike glycoprotein S1 subunit gene and the 3′ UTR of the IBV, were sequenced, followed by phylogenetic tree analysis. Results The six positive samples propagated into specific pathogen free embryonated eggs and exhibited characteristic IBV lesions and mortality observed over five consecutive passages. IBV isolates from Bishoftu ( n  = 4) and Mekele ( n  = 2) were amplified using one-step RT-PCR to target 466 bp of the S1 subunit gene and 433 bp of the 3ʹUTR. A BLAST search on the S1 partial gene and 3ʹUTR sequences, nested PCR, and phylogenetic analysis revealed that the present IBV isolates are genetically similar to the Massachusetts serotype. The S1 gene sequences of the five IBV isolates were deposited in GenBank with accession numbers PQ389500 to PQ389504. Conclusions This is the first detailed study on IB virus isolation, molecular detection, sequencing, and phylogenetic analysis in Ethiopia. The findings revealed that the outbreaks were caused by the IB virus, which created a serious health risk and economic losses in the chicken industry. To the author’s knowledge, this is the first comprehensive study on the isolation and genetic analysis of IBV in Ethiopia. Further research on the economic impact of IBV in chicken production, farm biosecurity, serotyping of circulating IB virus, and vaccine development based on the local serotypes is recommended.

Newcastle disease (ND) is caused by virulent strains of avian paramyxovirus type 1, also known as Newcastle disease virus (NDV). Despite vaccination, the frequency of reported outbreaks in Ethiopia has increased. From January to June 2022, an active outbreak investigation was conducted in six commercial chicken farms across areas of central Ethiopia to identify the circulating NDV strains. Thirty pooled tissue specimens were collected from chickens suspected of being infected with NDV. A questionnaire survey of farm owners and veterinarians was also carried out to collect information on the farms and the outbreak status. NDV was isolated using specific-pathogen-free (SPF)-embryonated chicken eggs and detected using haemagglutination and the reverse transcriptase–polymerase chain reaction (RT–PCR). The genotype and virulence of field NDV isolates were determined using phylogenetic analysis of fusion (F) protein gene sequences and the mean death time (MDT) test in SPF-embryonated chicken eggs. The questionnaire results revealed that ND caused morbidity (23.1%), mortality (16.3%), case fatality (70.8%), and significant economic losses. Eleven of thirty tissue specimens tested positive for NDV using haemagglutination and RT–PCR. The MDT testing and sequence analysis revealed the presence of virulent NDV classified as genotype VII of class II velogenic pathotype and distinct from locally used vaccine strains (genotype II). The amino acid sequences of the current virulent NDV fusion protein cleavage site motif revealed 112RRQKR↓F117, unlike the locally used avirulent vaccine strains (112GRQGR↓L117). The epidemiological data, MDT results, cleavage site sequence, and phylogenetic analysis all indicated that the present NDV isolates were virulent. The four NDV sequences were deposited in GenBank with accession numbers F gene (PP726912-15) and M gene (PP726916-19). The genetic difference between avirulent vaccine strains and circulating virulent NDV could explain the low level of protection provided by locally used vaccines. Further studies are needed to better understand the circulating NDV genotypes in different production systems.

Infectious bursal disease is a highly contagious disease of young chickens caused by the infectious bursal disease virus. This disease poses an important threat to the commercial poultry industry globally. This study was designed to develop an In-House Indirect Enzyme-Linked Immune Sorbent Assay Kit for the serological detection of antibodies against infectious bursal disease viruses. An infectious bursal disease virus antigen dilution (1:2), sample serum (1:500), and mouse anti-chicken immunoglobulin G (IgG) labeled with horseradish peroxidase (HRP) (1:2,000) were used in this assay. The calculated cutoff value was 0.24. This in-house indirect ELISA method was compared with a commercial ELISA kit for the detection of antibodies against infectious bursal disease virus in chickens. The performance of the newly developed and commercial ELISA kit was evaluated as described by Samad et al. (1994). The sensitivity and specificity of the current ELISA method were 98% (95% CI: 92.96–99.76) and 97% (95% CI: 91.48–99.38), respectively. The average intra-assay % CV of the triplet of 2 samples was 7.6, and interassay comparisons indicated a CV of 5.45%. As indicated by the results, we described a valuable and cost-effective, sensitive and specific in-house indirect ELISA kit for the serological diagnosis of infectious bursal disease in Ethiopia.

Pasteurella multocida can infect a multitude of wild and domesticated animals, with infections in cattle resulting in hemorrhagic septicemia (HS) or contributing to bovine respiratory disease (BRD) complex. Current cattle vaccines against P . multocida consist of inactivated bacteria, which only offer limited and serogroup specific protection. Here, we describe a newly identified surface lipoprotein, PmSLP, that is present in nearly all annotated P . multocida strains isolated from cattle. Bovine associated variants span three of the four identified phylogenetic clusters, with PmSLP-1 and PmSLP-2 being restricted to BRD associated isolates and PmSLP-3 being restricted to isolates associated with HS. Recombinantly expressed, soluble PmSLP-1 (BRD-PmSLP) and PmSLP-3 (HS-PmSLP) vaccines were both able to provide full protection in a mouse sepsis model against the matched P . multocida strain, however no cross-protection and minimal serum IgG cross-reactivity was identified. Full protection against both challenge strains was achieved with a bivalent vaccine containing both BRD-PmSLP and HS-PmSLP, with serum IgG from immunized mice being highly reactive to both variants. Year-long stability studies with lyophilized antigen stored under various temperatures show no appreciable difference in biophysical properties or loss of efficacy in the mouse challenge model. PmSLP-1 and PmSLP-3 vaccines were each evaluated for immunogenicity in two independent cattle trials involving animals of different age ranges and breeds. In all four trials, vaccination with PmSLP resulted in an increase in antigen specific serum IgG over baseline. In a blinded cattle challenge study with a recently isolated HS strain, the matched HS-PmSLP vaccine showed strong efficacy (75–87.5% survival compared to 0% in the control group). Together, these data suggest that cattle vaccines composed of PmSLP antigens can be a practical and effective solution for preventing HS and BRD related P . multocida infections.

Prevention of mother-to-child transmission of HIV (PMTCT) is a frequently used word for programs and intervention methods to decrease the risk of mother-to-child transmission of HIV. The aim of this study was to identify determinants of the reduction of CD4 count through time and the maternal transmission of HIV to their child on the PMTCT program at health centers in North Shewa Zone, Ethiopia. The cohort study design was conducted by using secondary data collected from the cohort register of PMTCT starting from September 1, 2014 to November 30, 2017. In this study, a longitudinal study was conducted for two types of result; these were longitudinal response measurements of HIV infected women CD4 count and the time to maternal transmission of HIV taken from 203 patients. The prevalence rate of HIV infection among exposed infants was 5.58%. Baseline CD4 count, visiting times, weight, and interaction between visiting time and baseline CD4 count had a statistically significant effect on the longitudinal biomarker. From the Weibull AFT model, ART start, partner test, clinical stage, educational status, place of delivery, and MUAC were statistically significant. Hence, as a measurement unit decreased in square root CD4 cell count by 1.18 elevates the risk of maternal transmission of HIV. In this study, the determinant of mother-to-child transmission of HIV including loss of weight, ART start (ANC), place of delivery at home, illiterate and mother with severe malnutrition, had a significant effect. The longitudinal biomarker also had a strong association with baseline CD4 and the risk of maternal transmission of HIV. Health education should be given about balanced diet, weight control, and take medication for HIV positive patients by the responsible bodies.