Time filter

Source Type

Fernandes S.,London School of Hygiene and Tropical Medicine | Sicuri E.,University of Barcelona | Kayentao K.,University of science | Webster J.,London School of Hygiene and Tropical Medicine | And 5 more authors.
The Lancet Global Health | Year: 2015

Background: In 2012, WHO changed its recommendation for intermittent preventive treatment of malaria during pregnancy (IPTp) from two doses to monthly doses of sulfadoxine-pyrimethamine during the second and third trimesters, but noted the importance of a cost-ffectiveness analysis to lend support to the decision of policy makers. We therefore estimated the incremental cost-ffectiveness of IPTp with three or more (IPTp-SP3+) versus two doses of sulfadoxine-pyrimethamine (IPTp-SP2). Methods: For this analysis, we used data from a 2013 meta-analysis of seven studies in sub-Saharan Africa. We developed a decision tree model with a lifetime horizon. We analysed the base case from a societal perspective. We did deterministic and probabilistic sensitivity analyses with appropriate parameter ranges and distributions for settings with low, moderate, and high background risk of low birthweight, and did a separate analysis for HIV-negative women. Parameters in the model were obtained for all countries included in the original meta-analysis. We did simulations in hypothetical cohorts of 1000 pregnant women receiving either IPTp-SP3+ or IPTp-SP2. We calculated disability-adjusted life-years (DALYs) for low birthweight, severe to moderate anaemia, and clinical malaria. We calculated cost estimates from data obtained in observational studies, exit surveys, and from public procurement databases. We give financial and economic costs in constant 2012 US$. The main outcome measure was the incremental cost per DALY averted. Findings: The delivery of IPTp-SP3+ to 1000 pregnant women averted 113·4 DALYs at an incremental cost of $825·67 producing an incremental cost-ffectiveness ratio (ICER) of $7·28 per DALY averted. The results remained robust in the deterministic sensitivity analysis. In the probabilistic sensitivity analyses, the ICER was $7·7 per DALY averted for moderate risk of low birthweight, $19·4 per DALY averted for low risk, and $4·0 per DALY averted for high risk. The ICER for HIV-negative women was $6·2 per DALY averted. Interpretation: Our findings lend strong support to the WHO guidelines that recommend a monthly dose of IPTp-SP from the second trimester onwards. Funding: Malaria in Pregnancy Consortium and the Bill & Melinda Gates Foundation. © 2015 Fernandes et al. Open Access article distributed under the terms of CC BY-NC-SA.


Knox T.B.,Vestergaard Frandsen Ltd. East Africa | Knox T.B.,Vestergaard Frandsen SA | Juma E.O.,Vestergaard Frandsen Ltd. East Africa | Ochomo E.O.,KEMRI CDC Research and Public Health Collaboration | And 11 more authors.
Parasites and Vectors | Year: 2014

Background: Malaria control programmes across Africa and beyond are facing increasing insecticide resistance in the major anopheline vectors. In order to preserve or prolong the effectiveness of the main malaria vector interventions, up-to-date and easily accessible insecticide resistance data that are interpretable at operationally-relevant scales are critical. Herein we introduce and demonstrate the usefulness of an online mapping tool, IR Mapper. Methods. A systematic search of published, peer-reviewed literature was performed and Anopheles insecticide susceptibility and resistance mechanisms data were extracted and added to a database after a two-level verification process. IR Mapper () was developed using the ArcGIS for JavaScript Application Programming Interface and ArcGIS Online platform for exploration and projection of these data. Results: Literature searches yielded a total of 4,084 susceptibility data points for 1,505 populations, and 2,097 resistance mechanisms data points for 1,000 populations of Anopheles spp. tested via recommended WHO methods from 54 countries between 1954 and 2012. For the Afrotropical region, data were most abundant for populations of An. gambiae, and pyrethroids and DDT were more often used in susceptibility assays (51.1 and 26.8% of all reports, respectively) than carbamates and organophosphates. Between 2001 and 2012, there was a clear increase in prevalence and distribution of confirmed resistance of An. gambiae s.l. to pyrethroids (from 41 to 87% of the mosquito populations tested) and DDT (from 64 to 91%) throughout the Afrotropical region. Metabolic resistance mechanisms were detected in western and eastern African populations and the two kdr mutations (L1014S and L1014F) were widespread. For An. funestus s.l., relatively few populations were tested, although in 2010-2012 resistance was reported in 50% of 10 populations tested. Maps are provided to illustrate the use of IR Mapper and the distribution of insecticide resistance in malaria vectors in Africa. Conclusions: The increasing pyrethroid and DDT resistance in Anopheles in the Afrotropical region is alarming. Urgent attention should be afforded to testing An. funestus populations especially for metabolic resistance mechanisms. IR Mapper is a useful tool for investigating temporal and spatial trends in Anopheles resistance to support the pragmatic use of insecticidal interventions. © 2014 Knox et al.; licensee BioMed Central Ltd.


Desai M.,KEMRI CDC Research and Public Health Collaboration | Desai M.,Centers for Disease Control and Prevention | Odhiambo F.O.,KEMRI CDC Research and Public Health Collaboration | Katana A.,KEMRI CDC Research and Public Health Collaboration | And 8 more authors.
PLoS ONE | Year: 2013

Background:Pregnancy-related (PR) deaths are often a result of direct obstetric complications occurring at childbirth.Methods and Findings:To estimate the burden of and characterize risk factors for PR mortality, we evaluated deaths that occurred between 2003 and 2008 among women of childbearing age (15 to 49 years) using Health and Demographic Surveillance System data in rural western Kenya. WHO ICD definition of PR mortality was used: "the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the cause of death". In addition, symptoms and events at the time of death were examined using the WHO verbal autopsy methodology. Deaths were categorized as either (i) directly PR: main cause of death was ascribed as obstetric, or (ii) indirectly PR: main cause of death was non-obstetric. Of 3,223 deaths in women 15 to 49 years, 249 (7.7%) were PR. One-third (34%) of these were due to direct obstetric causes, predominantly postpartum hemorrhage, abortion complications and puerperal sepsis. Two-thirds were indirect; three-quarters were attributable to human immunodeficiency virus (HIV/AIDS), malaria and tuberculosis. Significantly more women who died in lower socio-economic groups sought care from traditional birth attendants (p = 0.034), while less impoverished women were more likely to seek hospital care (p = 0.001). The PR mortality ratio over the six years was 740 (95% CI 651-838) per 100,000 live births, with no evidence of reduction over time (χ2 linear trend = 1.07; p = 0.3).Conclusions:These data supplement current scanty information on the relationship between infectious diseases and poor maternal outcomes in Africa. They indicate low uptake of maternal health interventions in women dying during pregnancy and postpartum, suggesting improved access to and increased uptake of skilled obstetric care, as well as preventive measures against HIV/AIDS, malaria and tuberculosis among all women of childbearing age may help to reduce pregnancy-related mortality. © 2013.


Ochomo E.,Maseno University | Ochomo E.,KEMRI CDC Research and Public Health Collaboration | Bayoh N.M.,KEMRI CDC Research and Public Health Collaboration | Kamau L.,Center for Biotechnology and Research Development | And 11 more authors.
Parasites and Vectors | Year: 2014

Background: Increasing pyrethroid resistance in malaria vectors has been reported in western Kenya where long lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the mainstays of vector control. To ensure the sustainability of insecticide-based malaria vector control, monitoring programs need to be implemented. This study was designed to investigate the extent and distribution of pyrethroid resistance in 4 Districts of western Kenya (Nyando, Rachuonyo, Bondo and Teso). All four Districts have received LLINs while Nyando and Rachuonyo Districts have had IRS campaigns for 3-5 years using pyrethroids. This study is part of a programme aimed at determining the impact of insecticide resistance on malaria epidemiology. Methods. Three day old adult mosquitoes from larval samples collected in the field, were used for bioassays using the WHO tube bioassay, and mortality recorded 24 hours post exposure. Resistance level was assigned based on the 2013 WHO guidelines where populations with <90% mortality were considered resistant. Once exposed, samples were identified to species using PCR. Results: An. arabiensis comprised at least 94% of all An. gambiae s.l. in Bondo, Rachuonyo and Nyando. Teso was a marked contrast case with 77% of all samples being An. gambiae s.s. Mortality to insecticides varied widely between clusters even in one District with mortality to deltamethrin ranging from 45-100%, while to permethrin the range was 30-100%. Mortality to deltamethrin in Teso District was < 90% in 4 of 6 clusters tested in An arabiensis and <90% in An. gambiae s.s in 5 of 6 clusters tested. To permethrin, mortality ranged between 5.9-95%, with <90% mortality in 9 of 13 and 8 of 13 in An. arabiensis and An. gambiae s.s. respectively. Cluster specific mortality of An. arabiensis between permethin and deltamethrin were not correlated (Z = 2.9505, P = 0.2483). Conclusion: High levels of pyrethroid resistance were observed in western Kenya. This resistance does not seem to be associated with either species or location. Insecticide resistance can vary within small geographical areas and such heterogeneity may make it possible to evaluate the impact of resistance on malaria and mosquito parameters within similar eco-epidemiological zones. © 2014 Ochomo et al.; licensee BioMed Central Ltd.


PubMed | University of Liverpool, University of Barcelona, KEMRI CDC Research and Public Health Collaboration, Navrongo Health Research Center and 2 more.
Type: Comparative Study | Journal: The Lancet. Global health | Year: 2015

In 2012, WHO changed its recommendation for intermittent preventive treatment of malaria during pregnancy (IPTp) from two doses to monthly doses of sulfadoxine-pyrimethamine during the second and third trimesters, but noted the importance of a cost-effectiveness analysis to lend support to the decision of policy makers. We therefore estimated the incremental cost-effectiveness of IPTp with three or more (IPTp-SP3+) versus two doses of sulfadoxine-pyrimethamine (IPTp-SP2).For this analysis, we used data from a 2013 meta-analysis of seven studies in sub-Saharan Africa. We developed a decision tree model with a lifetime horizon. We analysed the base case from a societal perspective. We did deterministic and probabilistic sensitivity analyses with appropriate parameter ranges and distributions for settings with low, moderate, and high background risk of low birthweight, and did a separate analysis for HIV-negative women. Parameters in the model were obtained for all countries included in the original meta-analysis. We did simulations in hypothetical cohorts of 1000 pregnant women receiving either IPTp-SP3+ or IPTp-SP2. We calculated disability-adjusted life-years (DALYs) for low birthweight, severe to moderate anaemia, and clinical malaria. We calculated cost estimates from data obtained in observational studies, exit surveys, and from public procurement databases. We give financial and economic costs in constant 2012 US$. The main outcome measure was the incremental cost per DALY averted.The delivery of IPTp-SP3+ to 1000 pregnant women averted 1134 DALYs at an incremental cost of $82567 producing an incremental cost-effectiveness ratio (ICER) of $728 per DALY averted. The results remained robust in the deterministic sensitivity analysis. In the probabilistic sensitivity analyses, the ICER was $77 per DALY averted for moderate risk of low birthweight, $194 per DALY averted for low risk, and $40 per DALY averted for high risk. The ICER for HIV-negative women was $62 per DALY averted.Our findings lend strong support to the WHO guidelines that recommend a monthly dose of IPTp-SP from the second trimester onwards.Malaria in Pregnancy Consortium and the Bill & Melinda Gates Foundation.


Izurieta H.S.,U.S. Food and Drug Administration | Zuber P.,World Health Organization | Bonhoeffer J.,Brighton Collaboration Foundation | Bonhoeffer J.,University of Basel | And 8 more authors.
Vaccine | Year: 2013

With the advent of new vaccines targeted to highly endemic diseases in low- and middle-income countries (LMIC) and with the expansion of vaccine manufacturing globally, there is an urgent need to establish an infrastructure to evaluate the benefit-risk profiles of vaccines in LMIC. Fortunately the usual decade(s)-long time gap between introduction of new vaccines in high and low income countries is being significantly reduced or eliminated due to initiatives such as the Global Alliance for Vaccines and Immunizations (GAVI) and the Decade of Vaccines for the implementation of the Global Vaccine Action Plan. While hoping for more rapid disease control, this time shift may potentially add risk, unless appropriate capacity for reliable and timely evaluation of vaccine benefit-risk profiles in some LMIC's are developed with external assistance from regional or global level. An ideal vaccine safety and effectiveness monitoring system should be flexible and sustainable, able to quickly detect possible vaccine-associated events, distinguish them from programmatic errors, reliably and quickly evaluate the suspected event and its association with vaccination and, if associated, determine the benefit-risk of vaccines to inform appropriate action. Based upon the demonstrated feasibility of active surveillance in LMIC as shown by the Burkina Faso assessment of meningococcal A conjugate vaccine or that of rotavirus vaccine in Mexico and Brazil, and upon the proof of concept international GBS study, we suggest a sustainable, flexible, affordable and timely international collaborative vaccine safety monitoring approach for vaccines being newly introduced. While this paper discusses only the vaccine component, the same system could also be eventually used for monitoring drug effectiveness (including the use of substandard drugs) and drug safety. © 2013.


Kwambai T.K.,KEMRI CDC Research and Public Health Collaboration | Kwambai T.K.,Ministry of Public Health and Sanitation | Dellicour S.,KEMRI CDC Research and Public Health Collaboration | Desai M.,KEMRI CDC Research and Public Health Collaboration | And 7 more authors.
BMC Pregnancy and Childbirth | Year: 2013

Background: Poor utilisation of facility-based antenatal and delivery care services in Kenya hampers reduction of maternal mortality. Studies suggest that the participation of men in antenatal and delivery care is associated with better health care seeking behaviour, yet many reproductive health programs do not facilitate their involvement. This qualitative study conducted in rural Western Kenya, explored men's perceptions of antenatal and delivery care services and identified factors that facilitated or constrained their involvement.Methods: Eight focus group discussions were conducted with 68 married men between 20-65 years of age in May 2011. Participants were of the Luo ethnic group residing in Asembo, western Kenya. The area has a high HIV-prevalence and polygamy is common. A topic guide was used to guide the discussions and a thematic framework approach for data analysis.Results: Overall, men were positive in their views of antenatal and delivery care, as decision makers they often encouraged, some even 'forced', their wives to attend for antenatal or delivery care. Many reasons why it was beneficial to accompany their wives were provided, yet few did this in practice unless there was a clinical complication. The three main barriers relating to cultural norms identified were: 1) pregnancy support was considered a female role; and the male role that of provider; 2) negative health care worker attitudes towards men's participation, and 3) couple unfriendly antenatal and delivery unit infrastructure.Conclusion: Although men reported to facilitate their wives' utilisation of antenatal and delivery care services, this does not translate to practice as adherence to antenatal-care schedules and facility based delivery is generally poor. Equally, reasons proffered why they should accompany their wives are not carried through into practice, with barriers outweighing facilitators. Recommendations to improve men involvement and potentially increase services utilisation include awareness campaigns targeting men, exploring promotion of joint HIV testing and counselling, staff training, and design of couple friendly antenatal and delivery units. © 2013 Kwambai et al.; licensee BioMed Central Ltd.


Lievens M.,Glaxosmithkline | Aponte J.J.,University of Barcelona | Williamson J.,KEMRI CDC Research and Public Health Collaboration | Mmbando B.,National Institute for Medical Research | And 3 more authors.
Malaria Journal | Year: 2011

Background: There has been much debate about the appropriate statistical methodology for the evaluation of malaria field studies and the challenges in interpreting data arising from these trials. Methods. The present paper describes, for a pivotal phase III efficacy of the RTS, S/AS01 malaria vaccine, the methods of the statistical analysis and the rationale for their selection. The methods used to estimate efficacy of the primary course of vaccination, and of a booster dose, in preventing clinical episodes of uncomplicated and severe malaria, and to determine the duration of protection, are described. The interpretation of various measures of efficacy in terms of the potential public health impact of the vaccine is discussed. Conclusions: The methodology selected to analyse the clinical trial must be scientifically sound, acceptable to regulatory authorities and meaningful to those responsible for malaria control and public health policy. Trial registration. © 2011 Lievens et al; licensee BioMed Central Ltd.


PubMed | University of Witwatersrand, World Health Organization, University of KwaZulu - Natal, KEMRI CDC Research and Public Health Collaboration and 4 more.
Type: Journal Article | Journal: Journal of global health | Year: 2015

Coverage of civil registration and vital statistics varies globally, with most deaths in Africa and Asia remaining either unregistered or registered without cause of death. One important constraint has been a lack of fit-for-purpose tools for registering deaths and assigning causes in situations where no doctor is involved. Verbal autopsy (interviewing care-givers and witnesses to deaths and interpreting their information into causes of death) is the only available solution. Automated interpretation of verbal autopsy data into cause of death information is essential for rapid, consistent and affordable processing.Verbal autopsy archives covering 54182 deaths from five African and Asian countries were sourced on the basis of their geographical, epidemiological and methodological diversity, with existing physician-coded causes of death attributed. These data were unified into the WHO 2012 verbal autopsy standard format, and processed using the InterVA-4 model. Cause-specific mortality fractions from InterVA-4 and physician codes were calculated for each of 60 WHO 2012 cause categories, by age group, sex and source. Results from the two approaches were assessed for concordance and ratios of fractions by cause category. As an alternative metric, the Wilcoxon matched-pairs signed ranks test with two one-sided tests for stochastic equivalence was used.The overall concordance correlation coefficient between InterVA-4 and physician codes was 0.83 (95% CI 0.75 to 0.91) and this increased to 0.97 (95% CI 0.96 to 0.99) when HIV/AIDS and pulmonary TB deaths were combined into a single category. Over half (53%) of the cause category ratios between InterVA-4 and physician codes by source were not significantly different from unity at the 99% level, increasing to 62% by age group. Wilcoxon tests for stochastic equivalence also demonstrated equivalence.These findings show strong concordance between InterVA-4 and physician-coded findings over this large and diverse data set. Although these analyses cannot prove that either approach constitutes absolute truth, there was high public health equivalence between the findings. Given the urgent need for adequate cause of death data from settings where deaths currently pass unregistered, and since the WHO 2012 verbal autopsy standard and InterVA-4 tools represent relatively simple, cheap and available methods for determining cause of death on a large scale, they should be used as current tools of choice to fill gaps in cause of death data.


Lunde T.M.,University of Bergen | Lunde T.M.,University Research | Bayoh M.N.,KEMRI CDC Research and Public Health Collaboration | Lindtjorn B.,University of Bergen
Parasites and Vectors | Year: 2013

Background: It is well known that temperature has a major influence on the transmission of malaria parasites to their hosts. However, mathematical models do not always agree about the way in which temperature affects malaria transmission. Methods. In this study, we compared six temperature dependent mortality models for the malaria vector Anopheles gambiae sensu stricto. The evaluation is based on a comparison between the models, and observations from semi-field and laboratory settings. Results: Our results show how different mortality calculations can influence the predicted dynamics of malaria transmission. Conclusions: With global warming a reality, the projected changes in malaria transmission will depend on which mortality model is used to make such predictions. © 2013 Lunde et al; licensee BioMed Central Ltd.

Loading KEMRI CDC Research and Public Health Collaboration collaborators
Loading KEMRI CDC Research and Public Health Collaboration collaborators