Browsing by Author "Ochwo, Sylvester"

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    Comparative detection of foot-and-mouth disease virus by reverse transcription loop-mediated isothermal amplification assay and real time polymerase chain reaction in Uganda
    (Int J Biotechnol Food Sci, 2016) Mukasa, Hussein Kafeero; Mwiine, Frank Norbert; Atuhaire, David Kalenzi; Ochwo, Sylvester; Nanteza, Ann
    Foot-and-mouth disease (FMD) is a viral disease. FMD diagnosis in the field is based on clinical signs that are shared by other vesicular diseases, hence to confirm FMD a laboratory is needed. Laboratory diagnostic techniques including serology may fail to distinguish between vaccinated and new infection, virus isolation may take up to 4 days to yield results, while molecular techniques including PCR, which are accurate, sensitive, specific and rapid, are costly and require special training of the laboratory staff. These challenges limit laboratory diagnosis yet in Uganda FMD outbreaks are common since the disease is endemic. This work reports the comparative detection of Foot-and-mouth disease virus (FMDV) by reverse transcription-loop mediated isothermal amplification (RT-LAMP) and Real-Time polymerase chain reaction (rRT-PCR) in Uganda based on the 3D polymerase (3Dpol) gene. The rRT-PCR assay is considered as the gold standard. A total of 89 cattle samples that included epithelial tissues (16.9%) and oral swabs (83.1%) were collected from outbreak cases in Eastern Districts of Mbale and Budaka. These were applied to molecular assays of rRT-PCR and RT- LAMP using primers and probes targeting the 3Dpol gene. The diagnostic sensitivity and specificity of RT-LAMP as a screening test and rRT-PCR as the reference test was 94.44% (95% CI = 94.11 to 94.78%) and 98.59% (95% CI = 98.50 to 98.68%), respectively. The kappa value for diagnostic agreement between rRT-PCR and RT-LAMP was 93.0% (95% CI = 83.50 to 100%), showing a perfect agreement. In conclusion, the RT-LAMP assay had a very high sensitivity and specificity when compared to the reference test of rRT-PCR. It was also very rapid since it gave results in 45 to 60 min. Due to its simplicity, sensitivity and specificity, LAMP assay has the potential for use in routine surveillance of FMD in Uganda.
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    Epidemiological Overview of African Swine Fever in Uganda (2001–2012)
    (Journal of Veterinary Medicine, 2013) Atuhaire, David Kalenzi; Ochwo, Sylvester; Afayoa, Mathias; Mwiine, Frank Norbert; Arinaitwe, Eugene; Ademun-Okurut, Rose Anna; Okuni, Julius Boniface; Nanteza, Ann; Ayebazibwe, Christosom; Okedi, Loyce; Olaho-Mukani, William; Ojok, Lonzy
    African swine fever (ASF) is a contagious viral disease, which can cause up to 100% mortality among domestic pigs. In Uganda there is paucity of information on the epidemiology of the disease, hence a study was carried out to elucidate the patterns of ASF outbreaks. Spatial and temporal analyses were performed with data collected monthly by the district veterinary officers (DVOs) and sent to the central administration at MAAIF from 2001 to 2012. Additionally, risk factors and the associated characteristics related to the disease were assessed based on semistructured questionnaires sent to the DVOs. A total of 388 ASF outbreaks were reported in 59 districts. Of these outbreaks, 201 (51.8%) were reported in districts adjacent to the national parks while 80 (20.6%) were adjacent to international borders. The number of reported ASF outbreaks changed over time and by geographical regions; however, no outbreak was reported in the North-Eastern region. ASF was ranked as second most important disease of pigs, and it occurred mostly during the dry season (𝑃 = 0.01). Pig movements due to trade (OR 15.5, CI 4.9–49.1) and restocking (OR 6.6, CI 2.5–17.3) were the major risk factors. ASF control strategies should focus on limiting pig movements in Uganda
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    Identification of Peste des Petits Ruminants Transmission Hotspots in the Karamoja Subregion of Uganda for Targeting of Eradication Interventions
    (Frontiers in veterinary science, 2019) Nkamwesiga, Joseph; Coffin-Schmitt, Jeanne; Ochwo, Sylvester; Mwiine, Frank Norbert; Palopoli, Annabella; Ndekezi, Christian; Isingoma, Emmanuel; Nantima, Noelina; Nsamba, Peninah; Adiba, Rogers; Hendrickx, Saskia; Mariner, Jeffrey C.
    This paper describes an assessment of the patterns of peste des petits ruminants virus circulation in the Karamoja subregion of Uganda conducted to identify the communities that maintain the virus and inform the development of a targeted vaccination strategy. Participatory epidemiological methods were used to develop an operational hypothesis for the patterns of PPR in Karamoja that was subsequently validated through outbreak investigation and genomics. The participatory epidemiological assessment included risk mapping with livestock owners, community animal health workers and veterinarians and indicated there were two critical foci of virus transmission on the Uganda-Kenya border. One was located in two adjacent subcounties of Kotido and Kaabong Districts in northern Karamoja and the other in Loroo subcounty of Amudat District in southern Karamoja. Participants reported that these were locations where outbreaks were usually first observed in Karamoja and subsequently spread to other areas. Following the participatory assessment, surveillance activities were implemented across the Karamoja subregion in 2018. Three outbreak were detected, investigated and sampled. Two outbreaks were located in the northern and one on the southern focus of transmission. No Outbreaks were diagnosed in Karamoja outside of these foci during 2018. Genomics indicated different clusters of viruses were associated with the northern and southern foci that were more closely related to other East African isolates than to each other. This indicates these are two separate systems of virus circulation which should be explicitly addressed in eradication as separate cross-border systems that require integrated cross-border interventions.
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    Invasive Cattle Ticks in East Africa: Morphological and Molecular Confirmation of The Presence of Rhipicephalus Microplus in South‑Eastern Uganda
    (Parasites & Vectors, 2020) Muhanguzi, Dennis; Byaruhanga, Joseph; Amanyire, Wilson; Ndekezi, Christian; Ochwo, Sylvester; Nkamwesiga, Joseph; Mwiine, Frank Norbert; Tweyongyere, Robert; Fourie, Josephus; Madder, Maxime; Schetters, Theo; Horak, Ivan; Juleff, Nick; Jongejan, Frans
    Rhipicephalus microplus, an invasive tick species of Asian origin and the main vector of Babesia species, is considered one of the most widespread ectoparasites of livestock. The tick has spread from its native habitats on translocated livestock to large parts of the tropical world, where it has replaced some of the local populations of Rhipicephalus decoloratus ticks. Although the tick was reported in Uganda 70 years ago, it has not been found in any subsequent surveys. This study was carried out to update the national tick species distribution on livestock in Uganda as a basis for tick and tick-borne disease control, with particular reference to R. microplus.The study was carried out in Kadungulu, Serere district, south-eastern Uganda, which is dominated by small scale livestock producers. All the ticks collected from 240 cattle from six villages were identified microscopically. Five R. microplus specimens were further processed for phylogenetic analysis and species confirmation.The predominant tick species found on cattle was Rhipicephalus appendiculatus (86.9 %; n = 16,509). Other species found were Amblyomma variegatum (7.2 %; n = 1377), Rhipicephalus evertsi (2.3 %; n = 434) and R. microplus (3.6 %; n = 687). Phylogenetic analysis of the 12S rRNA, 16S rRNA and ITS2 gene sequences of R. microplus confirmed the morphological identification.It is concluded that R. microplus has replaced R. decoloratus in the sampled villages in Kadungulu sub-county, since the latter was not any longer found in this area. There is currently no livestock movement policy in force in Uganda, which could possibly limit the further spread of R. microplus ticks. Future surveys, but also retrospective surveys of museum specimens, will reveal the extent of distribution of R. microplus in Uganda and also for how long this tick has been present on livestock without being noticed.
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    Molecular characterization and phylogenetic study of African swine fever virus isolates from recent outbreaks in Uganda (2010–2013)
    (Virology journal, 2013) Kalenzi Atuhaire, David; Afayoa, Mathias; Ochwo, Sylvester; Mwesigwa, Savannah; Okuni, Julius Boniface; Olaho-Mukani, William; Ojok, Lonzy
    African swine fever (ASF) is a highly lethal and economically significant disease of domestic pigs in Eastern Africa particularly in Uganda where outbreaks regularly occur. Sequence analysis of variable genome regions have been extensively used for molecular epidemiological studies of African swine fever virus (ASFV) isolates. By combining p72, P54 and pB602L (CVR), a high level resolution approach is achieved for viral discrimination. The major aim of this study therefore, was to investigate the genetic relatedness of ASF outbreaks that occurred between 2010 and 2013 in Uganda to contribute to the clarification of the epidemiological situation over a four year period. Methods: Tissue samples from infected domestic pigs associated with an ASF outbreak from 15 districts in Uganda were confirmed as being infected with ASFV using a p72 gene-based polymerase chain reaction amplification (PCR) assay recommended by OIE. The analysis was conducted by genotyping based on sequence data from three single copy ASFV genes. The E183L gene encoding the structural protein P54 and part of the gene encoding the p72 protein was used to delineate genotypes. Intra-genotypic resolution of viral relationships was achieved by analysis of tetramer amino acid repeats within the hypervariable CVR of the B602L gene. Results: Twenty one (21) ASF outbreaks were confirmed by the p72 ASF diagnostic PCR, however; only 17 isolates were successfully aligned after sequencing. Our entire isolates cluster with previous ASF viruses in genotype IX isolated in Uganda and Kenya using p72 and P54 genes. Analysis of the CVR gene generated three sub-groups one with 23 tetrameric amino acid repeats (TRS) with an additional CAST sequence, the second with 22 TRS while one isolate Ug13. Kampala1 had 13 TRS. Conclusion: We identified two new CVR subgroups different from previous studies. This study constitutes the first detailed assessment of the molecular epidemiology of ASFV in domestic pigs in the different regions of Uganda.
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    Molecular characterization of African swine fever virus in apparently healthy domestic pigs in Uganda
    (African Journal of Biotechnology,, 2014) Kalenzi Atuhaire, David; Ochwo, Sylvester; Afayoa, Mathias; Mwesigwa, Savannah; Mwiine, Frank Norbert; Okuni, Julius Boniface; Olaho-Mukani, William; Ojok, Lonzy
    African swine fever (ASF) is a highly lethal and economically significant disease of domestic pigs in Uganda where outbreaks regularly occur. There is neither a vaccine nor treatment available for ASF control. Twenty two African swine fever virus (ASFV) genotypes (I - XXII) have been identified based on partial sequencing of the C-terminus of the major capsid protein p72 encoded by the B646L gene. The majority of previously characterized Ugandan ASFV strains belong to genotype IX. The major aim of the current study was to determine the ASFV genotypes among asymptomatic slaughter pigs at Wambizi slaughterhouse and in some parts of the country where surveillance was done. Three discrete regions of the ASFV were analysed in the genomes of viruses detected in asymptomatic domestic pigs. The analysis was conducted by genotyping based on sequence data from three single copy ASFV genes. The E183L gene encoding the structural protein P54 and part of the gene encoding the p72 protein were used to delineate genotypes, before intra-genotypic resolution of viral relationships by analysis of tetramer amino acid repeats within the hypervariable central variable region (CVR) of the B602L gene. All the ASF viruses obtained from this study clustered with previous viruses in genotype IX based on analysis of the p72 and P54 genes. Analysis of the CVR gene grouped the viruses in three different subgroups; 13, 23 and 25. Only one genotype is circulating in Uganda among asymptomatic domestic pigs and it is the same virus causing outbreaks in the country and parts of neighbouring Kenya.
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    Molecular Detection and Phylogenetic Analysis of Lumpy Skin Disease Virus from Outbreaks in Uganda 2017–2018
    (BMC veterinary research, 2020) Ochwo, Sylvester; VanderWaal, Kimberly; Ndekezi, Christian; Nkamwesiga, Joseph; Munsey, Anna; Witto, Sarah Gift; Nantima, Noelina; Mayanja, Franklin; Okurut, Anna Rose Ademun; Atuhaire, David Kalenzi
    Lumpy skin disease (LSD) is an infectious viral disease of cattle caused by a Capripoxvirus. LSD has substantial economic implications, with infection resulting in permanent damage to the skin of affected animals which lowers their commercial value. In Uganda, LSD is endemic and cases of the disease are frequently reported to government authorities. This study was undertaken to molecularly characterize lumpy skin disease virus (LSDV) strains that have been circulating in Uganda between 2017 and 2018. Secondly, the study aimed to determine the phylogenetic relatedness of Ugandan LSDV sequences with published sequences, available in GenBank.A total of 7 blood samples and 16 skin nodule biopsies were screened for LSDV using PCR to confirm presence of LSDV nucleic acids. PCR positive samples were then characterised by amplifying the GPCR gene. These amplified genes were sequenced and phylogenetic trees were constructed. Out of the 23 samples analysed, 15 were positive for LSDV by PCR (65.2%). The LSDV GPCR sequences analysed contained the unique signatures of LSDV (A11, T12, T34, S99, and P199) which further confirmed their identity. Sequence comparison with vaccine strains revealed a 12 bp deletion unique to Ugandan outbreak strains. Phylogenetic analysis indicated that the LSDV sequences from this study clustered closely with sequences from neighboring East African countries and with LSDV strains from recent outbreaks in Europe. It was noted that the sequence diversity amongst LSDV strains from Africa was higher than diversity from Eurasia.The LSDV strains circulating in Uganda were closely related with sequences from neighboring African countries and from Eurasia. Comparison of the GPCR gene showed that outbreak strains differed from vaccine strains. This information is necessary to understand LSDV molecular epidemiology and to contribute knowledge towards the development of control strategies by the Government of Uganda.
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    Occurrence of Cryptosporidium hominis in cattle bordering the Lake Mburo National Park in Kiruhura district, Western Uganda
    (bioRxiv, 2019) Witto, Sarah Gift; Kankya, Clovice; Kazibwe, Anne; Akurut, Gloria; Ochwo, Sylvester
    Cryptosporidium is an emerging opportunistic zoonotic pathogen that causes diarrhea illness in a wide range of hosts including livestock and humans. Globally there is exponential increase in livestock production to meet the worlds’ demand for animal protein as well as for financial reasons. However, there is raised concern of the public health threat due to contamination of the environment by livestock waste carrying zoonotic pathogens such as Cryptosporidium. This study set out to establish the prevalence of Cryptosporidium as well as the circulating genotypes in order to elucidate the potential role of cattle in the spread of human cryptosporidiosis. We collected rectal coprological samples from 363 cattle in 11 households in Kiruhura district, Southwestern Uganda. The samples were screened for presence of Cryptosporidium oocysts using the phenol auramine staining method followed by fluorescent microscopy. DNA was then extracted from the microscopy positive samples and the COWP gene amplified using PCR. Amplified gene products were sequenced and subjected to phylogenetic analysis.
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    The prevalence and genetic characterisation of Cryptosporidium isolates from cattle in Kiruhura district, South Western Uganda
    (Journal of Parasitic Diseases, 2021) Witto, Sarah Gift; Kankya, Clovice; Akurut, Gloria; Mugasa, Claire Mack; Kazibwe, Anne; Ochwo, Sylvester
    Cryptosporidium is an emerging opportunistic zoonotic pathogen that causes diarrheal illness in a wide range of hosts including livestock and humans. This study set out to establish the prevalence of Cryptosporidium as well as the circulating genotypes in order to elucidate the potential role of cattle in the spread of human cryptosporidiosis. Rectal coprological samples from 363 cattle in 11 households in Kiruhura district, Southwestern Uganda were collected and screened for the presence of Cryptosporidium oocysts using the phenol auramine staining method followed by fluorescent microscopy. DNA was extracted from the microscopy positive samples and the COWP gene amplified using PCR. PCR products were sequenced and subjected to phylogenetic analysis. Additionally a multiplex realtime PCR was used to identify the Cryptosporidium spp. Multivariable mixed effect logistic regression models were used to identify potential risk factors for Cryptosporidium infection. The overall
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    Prevalence of African swine fever virus in apparently healthy domestic pigs in Uganda
    (BMC veterinary research, 2013) Atuhaire, David Kalenzi; Afayoa, Mathias; Ochwo, Sylvester; Mwesigwa, Savannah; Mwiine, Frank Norbert; Okuni, Julius Boniface; Mukani, William Olaho; Ojok, Lonzy
    African swine fever (ASF) is a contagious viral disease which can cause up to 100% mortality among domestic pigs leading to serious socio-economic impact on people’s livelihoods. ASF is endemic in Uganda and there is paucity of information on the epidemiology of the disease. The major aim of this study was to determine the seroprevalence and prevalence of African swine fever virus (ASFV) in apparently healthy slaughter pigs at Wambizi slaughterhouse in Kampala city, Uganda. We also estimated the presence of ASFV antibodies and circulating viral antigens in pigs from selected districts of Uganda during targeted surveillance. We analysed 540 and 181 blood samples collected from slaughter pigs and pigs from targeted surveillance districts respectively.The prevalence of ASFV in slaughter pigs was 52.96% (95% CI, 48.75-57.14) and 11.5% (95% CI, 9.06-14.45) by ELISA and PCR respectively. In surveillance districts, the proportion of ASFV positive pigs was 53.59% (95% CI, 46.33-60.71) and 0.55% (95% CI, 0.1-3.06) by ELISA and PCR respectively.The study has found out a high seroprevalence of ASFV antibodies in apparently healthy slaughter pigs and also a high proportion of ASFV antibody seropositive pigs in surveyed districts in Uganda indicating exposure to ASFV. However, there was a lower prevalence of ASFV infection implying that there could be low virulent strains of ASFV circulating in domestic pigs in Uganda which requires further investigation.
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    Spatial distribution and risk factors for foot and mouth disease virus in Uganda: Opportunities for strategic surveillance
    (Preventive veterinary medicine, 2019) Munsey, Anna; Mwiine, Frank Norbert; Ochwo, Sylvester; Salinas, Lauro Velazquez; Ahmed, Zaheer; Maree, Francois; Rodriguez, Luis L.; Rieder, Elizabeth; Perez, Andres; VanderWaal, Kimberly
    Foot-and-mouth disease virus (FMDV) has a substantial impact on cattle populations in Uganda, causing short- and long-term production losses and hampering local and international trade. Although FMDV has persisted in Uganda for at least 60 years, its epidemiology there and in other endemic settings remains poorly understood. Here, we utilized a large-scale cross-sectional study of cattle to elucidate the dynamics of FMDV spread in Uganda. Sera samples (n = 14,439) from 211 herds were analyzed for non-structural protein reactivity, an indication of past FMDV exposure. Serological results were used to determine spatial patterns, and a Bayesian multivariable logistic regression mixed model was used to identify risk factors for FMDV infection. Spatial clustering of the disease was evident, with higher risk demonstrated near international borders. Additionally, high cattle density, low annual rainfall, and pastoralism were associated with increased likelihood of FMD seropositivity. These results provide insights into the complex epidemiology of FMDV in Uganda and will help inform refined control strategies in Uganda and other FMDV-endemic settings.