Serological and Community Awareness Study of Lumpy Skin Disease in Different Agro-Ecological Zones of Sidama Regional State, Southern Ethiopia.

The lumpy skin disease (LSD) vaccination status and epidemiological distribution remain unknown in some parts of Ethiopia, including the Sidama regional state. In this study, a serological survey of LSD was performed using a specific virus neutralization assay in selected districts of the Sidama regional state representing three agroecological zones from September 2021 to June 2022. Moreover, an assessment of community awareness and LSD vaccine-related problems was conducted using a questionnaire. Our results showed an overall animal and herd level seroprevalence of 40.8% (95%CI = 35.8, 45.8) and 81% (95%CI = 77, 85), respectively. High and low seroprevalence were observed in lowland (48%) and highland (28%) areas, although they were not statistically significant. However, risk factors such as management systems and breeds showed substantial differences in their LSD prevalence. The results obtained through the questionnaire showed that a small portion of respondents (29.2%) know about LSD and vaccinate their cattle (23.3%) against this disease. Only 20.8% of the respondents stated that there was LSD occurrence in their vaccinated cattle. In conclusion, both qualitative and quantitative study results showed the need for intervention in terms of community-based awareness creation about LSD clinical signs and vaccination advantages together with the frequently updated information on LSD prevalence.

Community Wastewater-Based Surveillance Can Be a Cost-Effective Approach to Track COVID-19 Outbreak in Low-Resource Settings: Feasibility Assessment for Ethiopia Context.

Wastewater surveillance systems have become an important component of COVID-19 outbreak monitoring in high-income settings. However, its use in most low-income settings has not been well-studied. This study assessed the feasibility and utility of wastewater surveillance system to monitor SARS-CoV-2 RNA in Addis Ababa, Ethiopia. The study was conducted at nine Membrane Bio-reactor (MBR) wastewater processing plants. The samples were collected in two separate time series. Wastewater samples and known leftover RT-PCR tested nasopharyngeal swabs were processed using two extraction protocols with different sample conditions. SARS-CoV-2 wastewater RT-PCR testing was conducted using RIDA GENE SARS-CoV-2 RUO protocol for wastewater SARS-CoV-2 RNA testing. Wastewater SARS-CoV-2 RNA RT-PCR protocol adaptation, optimization, and detection were conducted in an Addis Ababa, Ethiopia context. Samples collected during the first time series, when the national COVID-19 case load was low, were all negative. Conversely, samples collected during the second time series were all positive, coinciding with the highest daily reported new cases of COVID-19 in Ethiopia. The wastewater-based SARS-CoV-2 surveillance approach is feasible for Addis Ababa. The COVID-19 wastewater based epidemiological approach can potentially fill the evidence gap in distribution and dynamics of COVID-19 in Ethiopia and other low-income settings.

Evaluation of Postmortem Inspection Procedures to Diagnose Bovine Tuberculosis at Debre Birhan Municipal Abattoir.

Routine meat inspection in the abattoir was used to examine carcass for subsequent approval for consumption. However, the chance of missing lesions results in approval of carcass and/or the offal with lesions of tuberculosis. A cross-sectional study was conducted at Debre Birhan Municipal abattoir from October 2016 to May 2017. Lesion prevalence estimation and two meat inspection procedures' efficacy evaluation was attempted. The breeds of the animals inspected were zebu breeds. Routine abattoir meat inspection involves visual inspection, palpation and incision of intact organs such as the liver and kidneys, as well as inspection, palpation and incision of tracheobronchial, mediastinal and prescapular lymph nodes. The detailed meat inspection involves inspection of each of the carcass. In this case, the seven lobes of the two lungs, lymph nodes and organs were also thoroughly examined. The cut surfaces were examined under bright light sources for the presence of an abscess, cheesy mass, and tubercles in detail. The study involved and compared both routine and detailed meat inspections at the abattoir. Chi-square test of independence and odds ratio were used to see the association of lesion and different risk factors. Based on detailed meat inspection, the overall lesion prevalence of bovine tuberculosis in the carcass of cattle slaughtered at Debre Birhan municipality abattoir was found to be 4.7% but only 0.5% of the carcass examined had detectable bovine tuberculosis lesions when routine abattoir meat inspection alone was used. The majority of the lesions were distributed to the lungs and associated lymph nodes. There was a significant association (p < 0.05) in TB infection rate and body condition score. In conclusion, this study has clearly indicated the prevalence of bovine tuberculosis lesions in the abattoir that are missed by routine abattoir meat inspection. In addition, it showed low sensitivity of the routine meat inspection procedure used. Hence, our study warrants immediate attention to strengthen the current meat inspection practices at Debre Birhan public abattoir.

The variable prevalence of bovine tuberculosis among dairy herds in Central Ethiopia provides opportunities for targeted intervention.

Bovine tuberculosis (bTB) is an important disease for dairy productivity, as well as having the potential for zoonotic transmission. Previous prevalence studies of bTB in the dairy sector in central Ethiopia have suggested high prevalence, however, they have been limited to relatively small scale surveys, raising concerns about their representativeness. Here we carried out a cross sectional one-stage cluster sampling survey taking the dairy herd as a cluster to estimate the prevalence of bTB in dairy farms in six areas of central Ethiopia. The survey, which to date is by far the largest in the area in terms of the number of dairy farms, study areas and risk factors explored, took place from March 2016 to May 2017. This study combined tuberculin skin testing and the collection of additional herd and animal level data by questionnaire to identify potential risk factors contributing to bTB transmission. We applied the single intradermal cervical comparative tuberculin (SICCT) test using >4mm cut-off for considering an individual animal as positive for bTB; at least one reactor animal was required for a herd to be considered bTB positive. Two hundred ninety-nine dairy herds in the six study areas were randomly selected, from which 5,675 cattle were tested. The overall prevalence of bTB after standardisation for herd-size in the population was 54.4% (95% CI 48.7-60%) at the herd level, and it was 24.5% (95% CI 23.3-25.8) at the individual animal level. A Generalized Linear Mixed Model (GLMM) with herd and area as random effect was used to explore risk factors association with bTB status. We found that herd size, age, bTB history at farm, and breed were significant risk factors for animals to be SICCT positive. Animals from large herds had 8.3 times the odds of being tuberculin reactor (OR: 8.3, p-value:0.008) as compared to animals from small herds. The effect of age was strongest for animals 8-10 years of age (the oldest category) having 8.9 times the odds of being tuberculin reactors (OR: 8.9, p-value:<0.001) compared to the youngest category. The other identified significant risk factors were bTB history at farm (OR: 5.2, p-value:0.003) and cattle breed (OR: 2.5, p-value: 0.032). Our study demonstrates a high prevalence of bTB in central Ethiopia but with a large variation in within-herd prevalence between herds, findings that lays an important foundation for the future development of control strategies.

Molecular characterization of foot-and-mouth disease viruses circulating in Ethiopia between 2008 and 2019.

One of the constraints to controlling foot-and-mouth disease (FMD) in East Africa is the incomplete knowledge of the specific FMD virus (FMDV) strains circulating and the way in which these viruses move across countries in the region. This retrospective study focuses on Ethiopia, which has one of the largest FMD-susceptible livestock populations in Africa. Analyses of FMDV positive samples collected between 2008 and 2019 demonstrate that serotypes O (n = 175), A (n = 51) and SAT 2 (n = 33) were present in the country. Phylogenetic analysis of the VP1 sequences for these viruses showed that there were at least seven different FMD viral clades circulating during this period: O/EA-3, O/EA-4, A/AFRICA/G-I, A/AFRICA/G-IV, A/AFRICA/G-VII, SAT2/VII and SAT2/XIII. Although these results only represent a snapshot and might not reflect all FMDV lineages that were present, they highlight the importance of serotype O, as well as the complexity and co-existence of FMDV serotypes in Ethiopia and surrounding countries. These sequence data also support the idea that there are two FMDV ecosystems existing in East Africa. Data from retrospective studies, such as these presented here, will be beneficial for vaccine selection and vaccination campaigns to control FMDV within Ethiopia.

Sequence-based comparison of field and vaccine strains of infectious bursal disease virus in Ethiopia reveals an amino acid mismatch in the immunodominant VP2 protein.

Sequencing of the VP2 region was carried out to identify amino acid mismatches between vaccine strains and field isolates of infectious bursal disease virus (IBDV). Viruses were isolated in chicken embryo fibroblast (DF-1) cells using pooled samples of bursa collected from nine outbreaks, which affected 30,250 chickens in five localities, with an overall mortality of 47.87%. Virus strains were identified by comparing the deduced amino acid sequence between positions 232 and 446 of the immunodominant VP2 epitope. All of the pooled samples were positive for IBDV. RT-PCR yielded a 645-bp DNA fragment of the VP2 gene. Phylogenetic analysis of this fragment revealed clustering of these isolates with very virulent IBDV strains. The amino acid sequences of these isolates were identical to those of the European very virulent strains UK 661 and DV 86, except at position 222, but differed from the vaccine strains used in Ethiopia, suggesting the possible introduction of virulent virus strains to Ethiopia from Europe. Our study demonstrates the widespread presence of very virulent strains of IBDV on poultry farms in Ethiopia and demonstrates the need to evaluate the protective level of existing vaccines against circulating field viruses.

Seroprevalence and risk factors of lumpy skin disease in Ethiopia.

Lumpy skin disease (LSD) is an acute or inapparent viral disease of cattle which is endemic in many African and Middle East countries. LSD is one of the major transboundary livestock diseases in Ethiopia. A cross-sectional study using multistage cluster sampling was undertaken in central and north-western parts of Ethiopia with the objectives to estimate seroprevalence and to identify and quantify risk factors contributing to the occurrence of the disease. A total of 2386 cattle sera were sampled from 605 herds and 30 clusters (kebeles) located in 10 districts and tested for presence of LSD virus antibodies using virus neutralization test. All the serum samples were collected from cattle having no history of LSD vaccination. The overall animal level and herd level apparent seroprevalences were 25.4% (95% CI: 23.7-27.2) and 48.9% (95% CI: 44.9-52.9), respectively and varied significantly between districts. The true animal level and herd level prevalences were estimated as 26.5% (95% CI: 24.7-28.3) and 52.6% (95% CI: 48.3-56.9), respectively. At animal level, adult age (OR = 2.44 (95% CI: 1.67-3.55) compared to calf), contact with other animals (OR = 0.41 (95% CI: 0.23-0.74), compared to no contact) and presence of water bodies (OR = 1.61 (95% CI: 1.03-2.52), compared to no such bodies) were identified as the most important risk factors in relation to testing LSD positive. The putative risk factors altitude, breed, sex, and presence of animal trade route showed no significant association with LSD sero-status. Generally, cattle population with many adult animals and that live in wet areas are at highest risk, whereas cattle in frequent contact with other animals and animal species have lower risk, potentially due to a dilution effect of vectors.

Isolation, molecular characterization and sero-prevalence study of foot-and-mouth disease virus circulating in central Ethiopia.

BACKGROUND: Ethiopian livestock production and productivity is still very low due to widespread of diseases. Among the diseases, foot-and-mouth disease (FMD) is an extremely contagious and acute viral disease that causes significant economic problems in the country. A cross sectional study design was conducted from September 2015 to May 2016 to isolate and characterize FMD virus from outbreak cases; determine the sero-prevalence of antibodies against FMD virus (FMDV), and assess potential risk factors associated with sero-prevalence of the disease in selected areas of central Ethiopia. A multistage sampling technique was employed to select the study animals. Isolated viruses were characterized by antigen ELISA (IZLER, Brescia, Italy) and by genetic analysis of the sequence of the viral protein 1 (VP1). Sero-prevalence was determined using an ELISA for antibodies against non-structural proteins of FMDV based on the 3ABC proteins (ID Screen® FMD NSP Competition, ID-VET, Grabels, France). Risk factors for sero-prevalence of antibodies against FMD virus was investigated using logistic regression analysis. RESULT: From outbreak investigation, 28.8% (n = 378) cattle showed signs and lesions suggestive of FMD and 34 samples were subjected to virus isolation. Twenty eight of these cultures exhibited cytopathic effect (CPE) and were serotyped as O, A and SAT 2 FMD viruses. One A and two SAT 2 isolates named A-ETH-19-2015, SAT 2-ETH-18-2015 and SAT 2-ETH-20-2015 were further characterized by phylogenetic analysis. The overall sero-prevalence of antibodies against non-structural proteins of FMDV was 24.2% (n = 574). Cattle herds with crossbreed cattle, with older cattle (> 2 years), and kept together with small ruminants had higher sero-prevalences of antibodies against FMDV (p < 0.05). CONCLUSION: This study showed that FMD was present in the study areas. Among the associated risk factors, breed, age and herd composition were significantly associated with presence of antibodies against FMD virus. Three different serotypes (A, O and SAT 2) were responsible for the outbreaks of the disease. Genetic analysis indicated that the isolated viruses clustered differently from previous outbreaks. Thus, further molecular analyses coupled with protection potential of the existing vaccines against the isolates should be performed.