Browsing by Author "Atuhaire, David Kalenzi"

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    Comparative detection of African swine fever virus by loop-mediated isothermal amplification assay and polymerase chain reaction in domestic pigs in Uganda
    (African Journal of Microbiology Research, 2014) Atuhaire, David Kalenzi; Afayoa, Mathias; Katiti, Dianah; Mwiine, Frank Norbert; Nanteza, Ann; Mugasa, Claire Mack; Matovu, Enock; Olaho-Mukani, William; Ojok, Lonzy
    African swine fever (ASF) is a contagious viral disease, which can cause up to 100% mortality among domestic pigs. Pig production is growing rapidly in Uganda among East African countries and is not only a source of food but also an important income for many people living in the rural areas. Field diagnosis of ASF depends only on clinical signs and has to be confirmed in the laboratory since the clinical signs are not pathognomonic. Diagnostic techniques for ASF are focused on serological tests for detection of antigen and antibody, genomic DNA detection by polymerase chain reaction (PCR), and on virus isolation and localization in clinical samples. There have been many recent reports of ASF outbreaks in Uganda yet laboratory diagnosis is limited due to the high cost and expertise required. This work reports the evaluation and application of a loop-mediated isothermal amplification (LAMP) test for detecting African swine fever virus (ASFV) DNA based on the topoisomerase II gene. Thirty (30) tissue samples obtained from suspected ASF outbreaks were collected from different regions of Uganda. The tissue samples were found to have lesions consistent with ASF. One hundred and eighty eight (188) additional blood samples were obtained from the abattoir and field surveillance. Six primers targeting the topoisomerase II gene were used. The sensitivity and specificity of LAMP and OIE recommended diagnostic PCR were compared. The LAMP assay is rapid with results obtained within 1 h (45-60 min). The sensitivity of LAMP for the detection of ASFV was 100% (95% CI: 91.78-100) while the specificity was 44% (95% CI: 36.52-51.69). The Kappa statistic for level of agreement between PCR and LAMP test in the detection of ASFV was 23.7% (95% CI: 16.42-30.91). This Kappa value indicated a fair agreement between the two assays. No cross reaction was observed with Porcine circovirus type 2virus and E. coli isolated from pigs in Uganda. This is the first study evaluating and applying the LAMP assay in the detection of ASF in domestic pigs in Uganda. The LAMP assay was found to be more sensitive than PCR. Due to its simplicity, sensitivity and specificity, the LAMP assay has the potential for use in the diagnosis and routine surveillance of ASF in Uganda.
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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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    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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    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.