Browsing by Author "Mathew, Coletha"

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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.
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.
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.
Serological and molecular evidence of Brucella species in the rapidly growing pig sector in Kenya.
(BioMed Central Ltd, 2020-05-11) Akoko, James; Pelle, Roger; Kivali, Velma; Schelling, Esther; Machuka, Eunice; Mathew, Coletha; Fèvre, Eric; Kyallo, Victoria; Falzon, Laura; Lukambagire, Abdul; Halliday, Jo; Bonfoh, Bassirou; Kazwala, Rudovick; Ouma, Collins; Shirima, Gabriel
Background: Brucellosis is an emerging yet neglected zoonosis that has been reported in Kenya. Epidemiological data on brucellosis in ruminants is readily accessible; however, reports on brucellosis in pigs remain limited. This study sought to detect Brucella infection in pig serum by both serological and molecular techniques. Serum from 700 pigs randomly collected at a centralized abattoir in Nairobi region, Kenya were screened in parallel, using both Rose Bengal Test (RBT) and competitive Enzyme-Linked Immuno-sorbent Assay (cELISA) for antibodies against Brucella spp. All sera positive by RBT and 16 randomly selected negative samples were further tested using conventional PCR targeting bcsp31 gene and real-time PCR (RT-PCR) assays targeting IS711 and bcsp31 genes. Results: A prevalence of 0.57% (n = 4/700) was estimated using RBT; none of these samples was positive on cELISA. All RBT positive sera were also positive by both PCRs, while two sero-negative samples also tested positive on RTPCR (n = 6/20). Brucella abortus was detected in four out of the six PCR positive samples through a real-time multiplex PCR. Conclusion: The detection of antibodies against Brucella spp. and DNA in serum from slaughterhouse pigs confirm the presence of Brucella in pigs. Therefore, investigation of the epidemiology and role of pigs in the transmission of brucellosis in Kenya is needed. Further targeted studies would be useful to systematically quantify and identify the spp. of Brucella in pigs.
Seroprevalence and risk factors for brucellosis amongst livestock and humans in a multi-herd ranch system in Kagera, Tanzania
(Frontiers, 2024-11-01) Lyimo, Beatus; Hugho, Ephrasia; Mathew, Coletha; Mayenga, Charles; Lyimo, Samson; Munuo, Lidia; Byukusenge, Maurice; Withall, Jodie; Mmbaga, Blandina; Bartlow, Andrew; Fair, Jeanne; Shirima, Gabriel; Cattadori, Isabella; Buza, Joram; Katani, Robab
Background: Brucellosis remains a significant health and economic challenge for livestock and humans globally. Despite its public health implications, the factors driving the endemic persistence of Brucella at the human-livestock interface in Tanzania remain poorly elucidated. This study aimed to identify the seroprevalence of Brucella infection in livestock and humans within a ranching system and determine associated risk factors for disease endemicity. Methods: A cross-sectional sero-epidemiological study was conducted in 2023 in Tanzania’s Karagwe District, involving 725 livestock (cattle, goats, sheep) from 10 herds and 112 humans from associated camps. Seroprevalence was assessed using competitive ELISA while epidemiological data were collected via questionnaires. Generalized Linear Models and Contrast Analysis were used to identify risk factors for infection. Results: Overall seroprevalence was 34% in livestock and 41% in humans. Goats exhibited the highest prevalence (69.2%), while cattle had the lowest (22.6%). Mixed-species herds (Odds Ratio, OR = 2.96, CI [1.90–4.60]) and small ruminants-only herds (OR = 6.54, CI [3.65–11.72]) showed a significantly higher risk of seropositivity compared to cattle-only herds. Older cattle (OR = 5.23, CI [2.70–10.10]) and lactating females (OR = 2.87, CI [1.78–4.63]) represented significant risks for brucellosis in livestock. In humans, close contact with animals (OR = 7.20, CI [1.97–36.31]) and handling animals during parturition or aborted fetuses (OR = 2.37, CI [1.01–5.58]) were significant risk factors. Notably, no spatial association was found in seroprevalence between herds and nearby human communities. Conclusion: The lack of spatial correlation between livestock and human seroprevalence suggests complex transmission dynamics, potentially involving endemic circulation in livestock and human infections from multiple sources of exposure to livestock. This study highlights the need for comprehensive zoonotic risk education and targeted intervention strategies. Further research is crucial to elucidate transmission pathways and improve Brucella infection control. This includes developing robust methods for identifying infective species and implementing effective strategies to mitigate Brucella infection in endemic regions.