The relationship between facility-based malaria test positivity rate and community-based parasite prevalence

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

Introduction

Malaria surveillance is a key pillar in the control of malaria in Africa. The value of using routinely collected data from health facilities to define malaria risk at community levels remains poorly defined.

Methods

Four cross-sectional parasite prevalence surveys were undertaken among residents at 36 enumeration zones in Kilifi county on the Kenyan coast and temporally and spatially matched to fever surveillance at 6 health facilities serving the same communities over 12 months. The age-structured functional form of the relationship between test positivity rate (TPR) and community-based parasite prevalence (PR) was explored through the development of regression models fitted by alternating the linear, exponential and polynomial terms for PR. The predictive ranges of TPR were explored for PR endemicity risk groups of control programmatic value using cut-offs of low (PR <5%) and high (PR ≥ 30%) transmission intensity.

Results

Among 28,134 febrile patients encountered for malaria diagnostic testing in the health facilities, 12,143 (43.2%: 95% CI: 42.6%, 43.7%) were positive. The overall community PR was 9.9% (95% CI: 9.2%, 10.7%) among 6,479 participants tested for malaria. The polynomial model was the best fitting model for the data that described the algebraic relationship between TPR and PR. In this setting, a TPR of ≥ 49% in all age groups corresponded to an age-standardized PR of ≥ 30%, while a TPR of < 40% corresponded to an age-standardized PR of < 5%.

Conclusion

A non-linear relationship was observed between the relative change in TPR and changes in the PR, which is likely to have important implications for malaria surveillance programs, especially at the extremes of transmission. However, larger, more spatially diverse data series using routinely collected TPR data matched to community-based infection prevalence data are required to explore the more practical implications of using TPR as a replacement for community PR.

Related collections

Most cited references 51

Record: found
Abstract: found
Article: found

Is Open Access

Mapping the global prevalence, incidence, and mortality of Plasmodium falciparum , 2000–17: a spatial and temporal modelling study

Daniel Weiss, Tim C. D. Lucas, Michele Nguyen … (2019)

Summary Background Since 2000, the scale-up of malaria control interventions has substantially reduced morbidity and mortality caused by the disease globally, fuelling bold aims for disease elimination. In tandem with increased availability of geospatially resolved data, malaria control programmes increasingly use high-resolution maps to characterise spatially heterogeneous patterns of disease risk and thus efficiently target areas of high burden. Methods We updated and refined the Plasmodium falciparum parasite rate and clinical incidence models for sub-Saharan Africa, which rely on cross-sectional survey data for parasite rate and intervention coverage. For malaria endemic countries outside of sub-Saharan Africa, we produced estimates of parasite rate and incidence by applying an ecological downscaling approach to malaria incidence data acquired via routine surveillance. Mortality estimates were derived by linking incidence to systematically derived vital registration and verbal autopsy data. Informed by high-resolution covariate surfaces, we estimated P falciparum parasite rate, clinical incidence, and mortality at national, subnational, and 5 × 5 km pixel scales with corresponding uncertainty metrics. Findings We present the first global, high-resolution map of P falciparum malaria mortality and the first global prevalence and incidence maps since 2010. These results are combined with those for Plasmodium vivax (published separately) to form the malaria estimates for the Global Burden of Disease 2017 study. The P falciparum estimates span the period 2000–17, and illustrate the rapid decline in burden between 2005 and 2017, with incidence declining by 27·9% and mortality declining by 42·5%. Despite a growing population in endemic regions, P falciparum cases declined between 2005 and 2017, from 232·3 million (95% uncertainty interval 198·8–277·7) to 193·9 million (156·6–240·2) and deaths declined from 925 800 (596 900–1 341 100) to 618 700 (368 600–952 200). Despite the declines in burden, 90·1% of people within sub-Saharan Africa continue to reside in endemic areas, and this region accounted for 79·4% of cases and 87·6% of deaths in 2017. Interpretation High-resolution maps of P falciparum provide a contemporary resource for informing global policy and malaria control planning, programme implementation, and monitoring initiatives. Amid progress in reducing global malaria burden, areas where incidence trends have plateaued or increased in the past 5 years underscore the fragility of hard-won gains against malaria. Efforts towards elimination should be strengthened in such areas, and those where burden remained high throughout the study period. Funding Bill & Melinda Gates Foundation.

0 comments Cited 143 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: found

Is Open Access

An in vitro toolbox to accelerate anti-malarial drug discovery and development

Susan Charman, Alice Andreu, Helena Barker … (2020)

Background Modelling and simulation are being increasingly utilized to support the discovery and development of new anti-malarial drugs. These approaches require reliable in vitro data for physicochemical properties, permeability, binding, intrinsic clearance and cytochrome P450 inhibition. This work was conducted to generate an in vitro data toolbox using standardized methods for a set of 45 anti-malarial drugs and to assess changes in physicochemical properties in relation to changing target product and candidate profiles. Methods Ionization constants were determined by potentiometric titration and partition coefficients were measured using a shake-flask method. Solubility was assessed in biorelevant media and permeability coefficients and efflux ratios were determined using Caco-2 cell monolayers. Binding to plasma and media proteins was measured using either ultracentrifugation or rapid equilibrium dialysis. Metabolic stability and cytochrome P450 inhibition were assessed using human liver microsomes. Sample analysis was conducted by LC–MS/MS. Results Both solubility and fraction unbound decreased, and permeability and unbound intrinsic clearance increased, with increasing Log D7.4. In general, development compounds were somewhat more lipophilic than legacy drugs. For many compounds, permeability and protein binding were challenging to assess and both required the use of experimental conditions that minimized the impact of non-specific binding. Intrinsic clearance in human liver microsomes was varied across the data set and several compounds exhibited no measurable substrate loss under the conditions used. Inhibition of cytochrome P450 enzymes was minimal for most compounds. Conclusions This is the first data set to describe in vitro properties for 45 legacy and development anti-malarial drugs. The studies identified several practical methodological issues common to many of the more lipophilic compounds and highlighted areas which require more work to customize experimental conditions for compounds being designed to meet the new target product profiles. The dataset will be a valuable tool for malaria researchers aiming to develop PBPK models for the prediction of human PK properties and/or drug–drug interactions. Furthermore, generation of this comprehensive data set within a single laboratory allows direct comparison of properties across a large dataset and evaluation of changing property trends that have occurred over time with changing target product and candidate profiles.

0 comments Cited 113 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: found

Is Open Access

Profile: The Kilifi Health and Demographic Surveillance System (KHDSS)

J Anthony G Scott, Evasius Bauni, Jennifer Moïsi … (2012)

Summary The Kilifi Health and Demographic Surveillance System (KHDSS), located on the Indian Ocean coast of Kenya, was established in 2000 as a record of births, pregnancies, migration events and deaths and is maintained by 4-monthly household visits. The study area was selected to capture the majority of patients admitted to Kilifi District Hospital. The KHDSS has 260 000 residents and the hospital admits 4400 paediatric patients and 3400 adult patients per year. At the hospital, morbidity events are linked in real time by a computer search of the population register. Linked surveillance was extended to KHDSS vaccine clinics in 2008. KHDSS data have been used to define the incidence of hospital presentation with childhood infectious diseases (e.g. rotavirus diarrhoea, pneumococcal disease), to test the association between genetic risk factors (e.g. thalassaemia and sickle cell disease) and infectious diseases, to define the community prevalence of chronic diseases (e.g. epilepsy), to evaluate access to health care and to calculate the operational effectiveness of major public health interventions (e.g. conjugate Haemophilus influenzae type b vaccine). Rapport with residents is maintained through an active programme of community engagement. A system of collaborative engagement exists for sharing data on survival, morbidity, socio-economic status and vaccine coverage.

0 comments Cited 91 times – based on 0 reviews      Review now

Bookmark

All references

Author and article information

Contributors

Alice Kamau:

ORCID: http://orcid.org/0000-0001-9846-5372

Role: ConceptualizationRole: Formal analysisRole: Funding acquisitionRole: InvestigationRole: MethodologyRole: Project administrationRole: SoftwareRole: SupervisionRole: ValidationRole: VisualizationRole: Writing – original draftRole: Writing – review & editing

Grace Mtanje: Role: Project administrationRole: Supervision

Christine Mataza: Role: Project administrationRole: Supervision

Lucas Malla: Role: Formal analysisRole: MethodologyRole: Validation

Philip Bejon: Role: ConceptualizationRole: Funding acquisitionRole: SupervisionRole: ValidationRole: Writing – review & editing

Robert W. Snow:

ORCID: http://orcid.org/0000-0003-3725-6088

Role: ConceptualizationRole: Formal analysisRole: Funding acquisitionRole: MethodologyRole: SupervisionRole: ValidationRole: VisualizationRole: Writing – review & editing

Érika Martins Braga: Role: Editor

Journal

Journal ID (nlm-ta): PLoS One

Journal ID (iso-abbrev): PLoS One

Journal ID (publisher-id): plos

Journal ID (pmc): plosone

Title: PLoS ONE

Publisher: Public Library of Science (San Francisco, CA USA )

ISSN (Electronic): 1932-6203

Publication date (Electronic): 7 October 2020

Publication date Collection: 2020

Volume: 15

Issue: 10

Electronic Location Identifier: e0240058

Affiliations

[1 ] KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya

[2 ] Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom

[3 ] Ministry of Health, Kilifi County Government, Kilifi, Kenya

Universidade Federal de Minas Gerais, BRAZIL

Author notes

Competing Interests: The authors have declared that no competing interests exist.

* E-mail: akamau@ 123456kemri-wellcome.org

Author information

Alice Kamau http://orcid.org/0000-0001-9846-5372

Robert W. Snow http://orcid.org/0000-0003-3725-6088

Article

Publisher ID: PONE-D-20-13643

DOI: 10.1371/journal.pone.0240058

PMC ID: 7540858

PubMed ID: 33027313

SO-VID: ded751bf-33c9-4aad-8779-ebdcc6676162

License:

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

History

Date received : 8 May 2020

Date accepted : 17 September 2020

Page count

Figures: 3, Tables: 4, Pages: 17

Funding

Funded by: funder-id http://dx.doi.org/10.13039/100004440, Wellcome Trust;

Award ID: 103602

Award Recipient :

ORCID: http://orcid.org/0000-0003-3725-6088

Robert W Snow

Funded by: funder-id http://dx.doi.org/10.13039/100010269, Wellcome Trust;

Award ID: 212176

Award Recipient :

ORCID: http://orcid.org/0000-0003-3725-6088

Robert W Snow

Funded by: DELTAS Africa Initiative

Award ID: DEL-15-003

Award Recipient :

ORCID: http://orcid.org/0000-0001-9846-5372

Alice Kamau

This work was supported through support to RWS as part of his Wellcome Trust Principal Fellowship (103602 and 212176) and support to AK through the DELTAS Africa Initiative [DEL-15-003]. The DELTAS Africa Initiative is an independent funding scheme of the African Academy of Sciences (AAS)’s Alliance for Accelerating Excellence in Science in Africa and supported by the New Partnership for Africa’s Development Planning and Coordinating Agency with funding from the Wellcome Trust [107769] and the UK government. All authors are grateful to the support of the Wellcome Trust to the Kenya Major Overseas Programme (203077). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Custom metadata

Data Availability Data that support the findings of this study cannot be shared publicly because it includes homestead level coordinates as an essential component and these are personal identifiable data. These data are available through a formal requesting process to the KEMRI Institutional Data Access/Ethics Committee. The details of the guidelines can be found in the KEMRI Wellcome website ( https://kemri-wellcome.org/about-us/#ChildVerticalTab_15). Access to data is provided via the KEMRI Wellcome Data Governance Committee: dgc@ 123456kemri-wellcome.org .

The relationship between facility-based malaria test positivity rate and community-based parasite prevalence

Read this article at

Abstract

Introduction

Methods

Results

Conclusion

Related collections

PLOS Climate

Most cited references 51

Mapping the global prevalence, incidence, and mortality of Plasmodium falciparum , 2000–17: a spatial and temporal modelling study

An in vitro toolbox to accelerate anti-malarial drug discovery and development

Profile: The Kilifi Health and Demographic Surveillance System (KHDSS)

Author and article information

Contributors

Journal

Affiliations

Author notes

Author information

Article

History

Page count

Funding

Categories

Custom metadata

Comments

Comment on this article

Similar content 224

Cited by 8

Most referenced authors 1,934