Browsing by Author "Bodenham, Rebecca"

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Latent class evaluation of the performance of serological tests for exposure to Brucella spp. in cattle, sheep, and goats in Tanzania
(PLOS Medicine, 2021-08-24) Bodenham, Rebecca; Mazeri, Stella; Cleaveland, Sarah; Crump, John; Fasina, Folorunso; Glanville, William; Haydon, Daniel; Kazwala, Rudovick; Kibona, Tito; Maro, Venance; Maze, Michael; Mmbaga, Blandina; Mtui-Malamsha, Niwael; Shirima, Gabriel; Swai, Emanuel; Thomas, Kate; deC Bronsvoort, Barend; Halliday, Jo
Brucellosis is a neglected zoonosis endemic in many countries, including regions of sub-Saharan Africa. Evaluated diagnostic tools for the detection of exposure to Brucella spp. are important for disease surveillance and guiding prevention and control activities. Methods and findings Bayesian latent class analysis was used to evaluate performance of the Rose Bengal plate test (RBT) and a competitive ELISA (cELISA) in detecting Brucella spp. exposure at the individual animal-level for cattle, sheep, and goats in Tanzania. Median posterior estimates of RBT sensitivity were: 0.779 (95% Bayesian credibility interval (BCI): 0.570–0.894), 0.893 (0.636–0.989), and 0.807 (0.575–0.966), and for cELISA were: 0.623 (0.443–0.790), 0.409 (0.241–0.644), and 0.561 (0.376–0.713), for cattle, sheep, and goats, respectively. Sensitivity BCIs were wide, with the widest for cELISA in sheep. RBT and cELISA median posterior estimates of specificity were high across species models: RBT ranged between 0.989 (0.980–0.998) and 0.995 (0.985–0.999), and cELISA between 0.984 (0.974–0.995) and 0.996 (0.988–1). Each species model generated seroprevalence estimates for two livestock subpopulations, pastoralist and non-pastoralist. Pastoralist seroprevalence estimates were: 0.063 (0.045–0.090), 0.033 (0.018–0.049), and 0.051 (0.034–0.076), for cattle, sheep, and goats, respectively. Non-pastoralist seroprevalence estimates were below 0.01 for all species models. Series and parallel diagnostic approaches were evaluated. Parallel outperformed a series approach. Median posterior estimates for parallel testing were ≥0.920 (0.760–0.986) for sensitivity and ≥0.973 (0.955–0.992) for specificity, for all species models. Conclusions Our findings indicate that Brucella spp. surveillance in Tanzania using RBT and cELISA in parallel at the animal-level would give high test performance. There is a need to evaluate strategies for implementing parallel testing at the herd- and flock-level. Our findings can assist in generating robust Brucella spp. exposure estimates for livestock in Tanzania and wider sub-Saharan Africa. The adoption of locally evaluated robust diagnostic tests in setting-specific surveillance is an important step towards brucellosis prevention and control.
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.
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 human leptospirosis at a hospital serving a pastoralist community, Endulen, Tanzania
(PLOS Neglected Tropical Diseases, 2023-12-20) MazeI, Michael; Shirima, Gabriel; Lukambagire, Abdul-Hamid; Bodenham, Rebecca; Rubach, Matthew; Cash-Goldwasser, Shama; Carugati, Manuela; Thomas, Kate; Sakasaka, Philoteus; Mkenda, Nestory; Allan, Kathryn; Kazwala, Rudovick; Mmbaga, Blandina; Buza, Joram; Maro, Venance; Galloway, Renee; Haydon, Daniel; T., John; Halliday, Jo
Background Leptospirosis is suspected to be a major cause of illness in rural Tanzania associated with close contact with livestock. We sought to determine leptospirosis prevalence, identify infecting Leptospira serogroups, and investigate risk factors for leptospirosis in a rural area of Tanzania where pastoralist animal husbandry practices and sustained livestock contact are common. Methods We enrolled participants at Endulen Hospital, Tanzania. Patients with a history of fever within 72 hours, or a tympanic temperature of ≥38.0°C were eligible. Serum samples were collected at presentation and 4–6 weeks later. Sera were tested using microscopic agglutination testing with 20 Leptospira serovars from 17 serogroups. Acute leptospirosis cases were defined by a ≥four-fold rise in antibody titre between acute and convalescent serum samples or a reciprocal titre ≥400 in either sample. Leptospira seropositivity was defined by a single reciprocal antibody titre ≥100 in either sample. We defined the predominant reactive serogroup as that with the highest titre. We explored risk factors for acute leptospirosis and Leptospira seropositivity using logistic regression modelling. Results Of 229 participants, 99 (43.2%) were male and the median (range) age was 27 (0, 78) years. Participation in at least one animal husbandry practice was reported by 160 (69.9%). We identified 18 (7.9%) cases of acute leptospirosis, with Djasiman 8 (44.4%) and Australis 7 (38.9%) the most common predominant reactive serogroups. Overall, 69 (30.1%) participants were Leptospira seropositive and the most common predominant reactive serogroups were Icterohaemorrhagiae (n = 20, 29.0%), Djasiman (n = 19, 27.5%), and Australis (n = 17, 24.6%). Milking cattle (OR 6.27, 95% CI 2.24–7.52) was a risk factor for acute leptospirosis, and milking goats (OR 2.35, 95% CI 1.07–5.16) was a risk factor for Leptospira seropositivity. Conclusions We identified leptospirosis in approximately one in twelve patients attending hospital with fever from this rural community. Interventions that reduce risks associated with milking livestock may reduce human infections.
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.
Prevalence and speciation of brucellosis in febrile patients from a pastoralist community of Tanzania.
(Springer Nature Limited, 2020-04-27) Bodenham, Rebecca; Lukambagire, Abdul; Ashford, Roland; Buza, Joram; Cash-Goldwasser, Shama; Crump, John; Kazwala, Rudovick; Maro, Venance; McGiven, John; Mkenda, Nestory; Mmbaga, Blandina; Rubach, Matthew; Sakasaka, Philoteus; Shirima, Gabriel; Swai, Emanuel; Thomas, Kate; Whatmore, Adrian; Haydon, Daniel; Halliday, Jo
Brucellosis is an endemic zoonosis in sub-Saharan Africa. Pastoralists are at high risk of infection but data on brucellosis from these communities are scarce. The study objectives were to: estimate the prevalence of human brucellosis, identify the Brucella spp. causing illness, describe non-Brucella bloodstream infections, and identify risk factors for brucellosis in febrile patients from a pastoralist community of Tanzania. Fourteen (6.1%) of 230 participants enrolled between August 2016 and October 2017 met study criteria for confirmed (febrile illness and culture positivity or ≥four-fold rise in SAT titre) or probable (febrile illness and single SAT titre ≥160) brucellosis. Brucella spp. was the most common bloodstream infection, with B. melitensis isolated from seven participants and B. abortus from one. Enterococcus spp., Escherichia coli, Salmonella enterica, Staphylococcus aureus and Streptococcus pneumoniae were also isolated. Risk factors identified for brucellosis included age and herding, with a greater probability of brucellosis in individuals with lower age and who herded cattle, sheep or goats in the previous 12 months. Disease prevention activities targeting young herders have potential to reduce the impacts of human brucellosis in Tanzania. Livestock vaccination strategies for the region should include both B. melitensis and B. abortus.