Browsing by Author "Lukambagire, AbdulHamid"

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Brucellosis testing patterns at health facilities in Arusha region, northern Tanzania
(Plos one, 2022-03-23) Yapi, Richard; Lukambagire, AbdulHamid; Shirima, Gabriel; Shayo, Damas; Mathew, Coletha; Kasanga, Christopher; Mmbaga, Blandina; Kazwala, Rudovick; Halliday, Jo
Background Brucellosis is listed as one of six priority zoonoses in Tanzania’s One Health strategic plan which highlights gaps in data needed for the surveillance and estimation of human brucellosis burdens. This study collected data on current testing practices and test results for human brucellosis in Arusha region, northern Tanzania. Methods Retrospective data were extracted from records at 24 health facilities in Arusha region for the period January 2012 to May 2018. Data were captured on: the test reagents used for brucellosis, procurement and testing protocols, the monthly number of patients tested for brucellosis and the monthly number testing positive. Generalised linear mixed models were used to evaluate relationships between health facility characteristics and the probability that brucellosis testing was conducted in a given month, and the proportion of individuals testing positive. Results Four febrile Brucella agglutination tests were used widely. The probability of testing for brucellosis in a given month was significantly associated with an interaction between year of testing and facility ownership. Test probability increased over time with more pronounced increases in privately owned as compared to government facilities. The proportion of individuals testing positive for brucellosis was significantly associated with facility type and district, with individuals tested in hospitals in Meru, Monduli and Ngorongoro districts more likely to test positive. Conclusions Febrile Brucella agglutination tests, known for their poor performance, were the mainstay of brucellosis testing at health facilities in northern Tanzania. The study indicates that historical data on human brucellosis in Arusha and other regions are likely to provide an inaccurate measure of true disease burden due to poor performance of the tests used and variation in testing practices. Measures to address these identified shortcomings could greatly improve quality of testing and surveillance data on brucellosis and ultimately inform prevention and control of this priority disease.
Complete genome sequence of Brucella abortus isolated from a human blood culture sample in Tanzania
(American society for microbiology, 2024-01-30) Mbwambo, Gershom; Zwetselaar, Marco; Sonda, Tolbert; Lukambagire, AbdulHamid; Njau, Judith; Wadugu, Boaz; Ignass, Ignass; Amani, Nelson; Hugho, Ephrasia; Rubach, Matthew; Sakasaka, Philoteus; Oisso, Rose; Mkenda, Nestory; Shirima, Gabriel; Ashford, Roland; Haydon, Daniel; Maro, Venance; Kazwala, Rudovick; Kumburu, Happiness; Mmbaga, Blandina; Halliday, Jo E.
Brucella abortus causes infections in humans and livestock. Bacterial isolates are challenging to obtain, and very little is known about the genomic epidemiology of this species in Africa. Here, we report the complete genome sequence of a Brucella abortus isolate cultured from a febrile human in northern Tanzania
Draft genome sequences of six Brucella melitensis isolates collected from humans and livestock in Tanzania
(American Society for Microbiology, 2025-06) Middlebrook, Earl; Hugho, Ephrasia; Lyimo, Beatus; Mathew, Coletha; Mayenga, Charles; Li, Lingling; Amani, Nelson; Lukambagire, AbdulHamid; Kumburu, Happiness; Munuo, Lidia; Lyimo, Samson; Shirima, Gabriel; Kazwala, Rudovick; Byukusenge, Maurice; Mmbaga, Blandina; Makondo, Zachariah; Kapur, Vivek; Buza, Joram; Fair, Jeanne; Katani, Robab
We present genome assemblies of six Brucella melitensis strains isolated from goats and humans in Tanzania’s Kagera region. These sequences provide insight into circulating Brucella strains in Tanzania and East Africa. These data will support future comparative genomics, epidemiological investigations, and regional brucellosis control strategies.
Livestock production losses attributable to brucellosis in northern and central Tanzania: Application of an epidemiological-economic modelling framework
(Public Library of Science, 2025-02-14) Mendes, Ângelo; Haydon, Daniel; Glanville, William; Bodenham, Rebecca; Lukambagire, AbdulHamid; Johnson, Paul; Shirima, Gabriel; Cleaveland, Sarah; McIntosh, Emma; Hanley, Nick; Halliday, Jo
Malignant catarrhal fever (MCF), caused by alcelaphine herpesvirus-1 (AIHV-1) transmitted from wildebeest, is a lethal cattle disease with significant impacts on East African pastoralists. Development of a live attenuated MCF vaccine has prompted research into its use in communities at risk. This study reports results from the first utilisation of the MCF vaccine in locally-owned cattle under field conditions. The study involved a primary two-dose course vaccination of 1634 cattle, followed a year later, by boost vaccination of 385 of these cattle. It aimed to: (a) evaluate the antibody response to a two-dose AlHV-1 primary vaccination course, including initial response, antibody levels after one year, and clinical events post-vaccination; (b) assess how factors like age, reproductive status, body condition, and breed influence the initial response; and (c) compare antibody responses to single- and two-dose booster protocols one year after primary vaccination. Analyses were carried out using linear mixed-effects models and paired t-tests. Clinical incidents were reported in 11/1634 cattle vaccinated during the primary course and in 0/385 cattle during the boost regimens. The primary vaccination resulted in a 9-fold increase in comparison to pre-vaccination antibody levels and the response was consistent across animals of different ages, reproductive statuses and body conditions. While antibody levels declined 11 months after primary vaccination, they remained high, and a single-dose booster vaccination was sufficient to elicit a strong immune response, with only marginal increases after a second booster. The study provides evidence of high immunogenicity and low incidences of clinical events of the vaccine in cattle across individual host factors and immunologically vulnerable groups, under prevailing environmental conditions. It also indicates the utility of a single-dose booster regimen. These findings will support progress towards commercial production and larger-scale adoption which could generate important benefits for the livelihoods, and sustainability of pastoral livestock systems.
Molecular epidemiology of Brucella species in mixed livestock-human ecosystems in Kenya
(Springer Nature Limited, 2021-04-23) Akoko, James; Pelle, Roger; Lukambagire, AbdulHamid; Machuka, Eunice; Nthiwa, Daniel; Mathew, Coletha; Fèvre, Eric; Bett, Bernard; Cook, Elizabeth; Othero, Doreen; Bonfoh, Bassirou; Kazwala, Rudovick; Shirima, Gabriel; Schelling, Esther; Halliday, Jo; Ouma, Collins
Brucellosis, caused by several species of the genus Brucella, is a zoonotic disease that affects humans and animal species worldwide. Information on the Brucella species circulating in different hosts in Kenya is largely unknown, thus limiting the adoption of targeted control strategies. This study was conducted in multi-host livestock populations in Kenya to detect the circulating Brucella species and assess evidence of host–pathogen associations. Serum samples were collected from 228 cattle, 162 goats, 158 sheep, 49 camels, and 257 humans from Narok and Marsabit counties in Kenya. Information on age, location and history of abortion or retained placenta were obtained for sampled livestock. Data on age, gender and location of residence were also collected for human participants. All samples were tested using genus level real-time PCR assays with primers specific for IS711 and bcsp31 targets for the detection of Brucella. All genus positive samples (positive for both targets) were further tested with a speciation assay for AlkB and BMEI1162 targets, specific for B. abortus and B. melitensis, respectively. Samples with adequate quantities aggregating to 577 were also tested with the Rose Bengal Test (RBT). A total of 199 (33.3%) livestock and 99 (38.5%) human samples tested positive for genus Brucella. Animal Brucella PCR positive status was positively predicted by RBT positive results (OR = 8.3, 95% CI 4.0–17.1). Humans aged 21–40 years had higher odds (OR = 2.8, 95% CI 1.2–6.6) of being Brucella PCR positive compared to the other age categories. The data on detection of different Brucella species indicates that B. abortus was detected more often in cattle (OR = 2.3, 95% CI 1.1–4.6) and camels (OR = 2.9, 95% CI 1.3–6.3), while B. melitensis was detected more in sheep (OR = 3.6, 95% CI 2.0–6.7) and goats (OR = 1.7, 95% CI 1.0–3.1). Both B. abortus and B. melitensis DNA were detected in humans and in multiple livestock host species, suggesting cross-transmission of these species among the different hosts. The detection of these two zoonotic Brucella species in humans further underpins the importance of One Health prevention strategies that target multiple host species, especially in the multi-host livestock populations.
Performance characteristics and costs of serological tests for brucellosis in a pastoralist community of northern Tanzania
(Springer Nature Limited, 2021-03-09) Lukambagire, AbdulHamid; Mendes, Ângelo; Bodenham, Rebecca; McGiven, John; Mkenda, Nestory; Mathew, Coletha; Rubach, Matthew; Sakasaka, Philoteus; Shayo, Davis; Maro, Venance; Shirima, Gabriel; Kasanga, Christopher; Kazwala, Rudovick; Halliday, Jo; Mmbaga, Blandina
The control of brucellosis across sub-Saharan Africa is hampered by the lack of standardized testing and the use of tests with poor performance. This study evaluated the performance and costs of serological assays for human brucellosis in a pastoralist community in northern Tanzania. Serum collected from 218 febrile hospital patients was used to evaluate the performance of seven index tests, selected based on international recommendation or current use. We evaluated the Rose Bengal test (RBT) using two protocols, four commercial agglutination tests and a competitive enzyme-linked immunosorbent assay (cELISA). The sensitivity, specificity, positive predictive value, negative predictive value, Youden’s index, diagnostic accuracy, and per-sample cost of each index test were estimated. The diagnostic accuracy estimates ranged from 95.9 to 97.7% for the RBT, 55.0 to 72.0% for the commercial plate tests, and 89.4% for the cELISA. The per-sample cost range was $0.69–$0.79 for the RBT, $1.03–$1.14 for the commercial plate tests, and $2.51 for the cELISA. The widely used commercial plate tests performed poorly and cost more than the RBT. These findings provide evidence for the public health value of discontinuing the use of commercial agglutination tests for human brucellosis in Tanzania.
Prevalence and risk factors for Q fever, spotted fever group rickettsioses, and typhus group rickettsioses in a pastoralist community of northern Tanzania, 2016–2017
(John Wiley & Sons Ltd., 2024-01-12) Moorthy, Ganga; Rubach, Matthew; Maze, Michael; .Refuerzo, Regina; Shirima, Gabriel; Lukambagire, AbdulHamid; Bodenham, Rebecca; Goldwasser, Shama; Thomas, Kate; Sakasaka, Philoteus; Mkenda, Nestory; Bowhay, Thomas; Perniciaro, Jamie; Nicholson, William; Kersh, Gilbert; Kazwala, Rudovick; Mmbaga, Blandina; . Buza, Joram; Maro, Venance; Haydon, Daniel; Crump, John; Halliday, Jo
Background: In northern Tanzania, Q fever, spotted fever group (SFG) rickettsioses, and typhus group (TG) rickettsioses are common causes of febrile illness. We sought to describe the prevalence and risk factors for these zoonoses in a pastoralist community. Methods: Febrile patients ≥2 years old presenting to Endulen Hospital in the Ngorongoro Conservation Area were enrolled from August 2016 through October 2017. Acute andconvalescent blood samples were collected, and a questionnaire was administered. Sera were tested by immunofluorescent antibody (IFA) IgG assays using Coxiella burnetii (Phase II), Rickettsia africae, and Rickettsia typhi antigens. Serologic evidence of exposure was defined by an IFA titre ≥1:64; probable cases by an acute IFA titre ≥1:128; and confirmed cases by a ≥4-fold rise in titre between samples. Risk factors for exposure and acute case status were evaluated. Results: Of 228 participants, 99 (43.4%) were male and the median (interquartile range) age was 27 (16–41) years. Among these, 117 (51.3%) had C. burnetii exposure, 74 (32.5%) had probable Q fever, 176 (77.2%) had SFG Rickettsia exposure, 134 (58.8%) had probable SFG rickettsioses, 11 (4.8%) had TG Rickettsia exposure, and 4 (1.8%) had probable TG rickettsioses. Of 146 participants with paired sera, 1 (0.5%) had confirmed Q fever, 8 (5.5%) had confirmed SFG rickettsioses, and none had confirmed TG rickettsioses. Livestock slaughter was associated with acute Q fever (adjusted odds ratio [OR] 2.54, 95% confidence interval [CI] 1.38–4.76) and sheep slaughter with SFG rickettsioses case (OR 4.63, 95% CI 1.08–23.50). Discussion: Acute Q fever and SFG rickettsioses were detected in participants with febrile illness. Exposures to C. burnetii and to SFG Rickettsia were highly prevalent, and interactions with livestock were associated with increased odds of illness with both path- ogens. Further characterisation of the burden and risks for these diseases is warranted.