Malaria
Conditions
Keywords
falciparum, gametocyte, elimination, anopheles, transmission, diagnostic
Brief summary
In the current study, three experimental approaches aiming at reducing malaria transmission will be tested. The study will cover two transmission season (2019 and 2020) and the interventions will vary by season. More specifically, in the 2019 transmission season (June-December) (Year 1), community case management of malaria (CCM) will be implemented in all eight villages as improved standard of care; in the 2020 transmission season (Year 2), the eight study villages will be divided into 4 study arms. CCM will continue in all villages; two villages will continue with CCM only (Arm 1, control); the three other pairs of villages will receive active fever screening and treatment (Arm 2); monthly mass screening and treatment (MSAT) (Arm 3); and mass drug administration (MDA) during the last 3 months of the dry season (April-June) (Arm 4). For MDA, the whole population (except for those not fulfilling the entry criteria) will be treated with a full course of dihydroartemisinin-piperaquine (DP) (320/40mg and 160/20mg piperaquine/ dihydroartemisinin per tablet) per manufacturer's guidelines (once daily for 3 days and according to body weight). The MDA treatment will be repeated 3 times at monthly intervals.
Detailed description
In the current study, the investigators will first improve access to care in all villages by implementing community-based clinical case management (CCM) (year 1). In this year, the investigators will quantify gametocyte carriage and transmission from clinical cases passively recruited by CCM, and gametocyte carriage and transmission from asymptomatic infections detected in community surveys. These data will support the interpretation of the main study outcomes in year 2 when the investigators will directly compare the effect of CCM on the human reservoir of infection as compared to three different approaches, namely i) active fever screening and treatment that should detect symptomatic infections for early treatment; ii) Mass Screening and Treatment (MSAT) that will systematically screen, using point-of-care diagnostics, the whole population, with infected individuals immediately treated; and iii) mass drug administration (MDA) that will treat the whole population with a full course of an antimalarial treatment.
Interventions
Community Case Management (CCM), consisting of community health workers able to diagnose malaria by standard RDTs and treating positive individuals with artemether-lumefantrine (AL), according to national guidelines.
OTHERWeekly fever screening and treatment
Consists of weekly visits by trained VHW who will screen for fever by taking the axillary temperature. If the body temperature is ≥37.5°C, a standard RDT will be performed and, if positive, the individual will be treated with AL, according to national guidelines.
OTHERMonthly malaria screening
CCM plus monthly screening of the whole population with high sensitive RDT (HS-RDT); positive individuals will be treated with AL regardless of symptoms (MSAT).
OTHERMDA
CCM plus 3 monthly rounds of MDA with dihydroartemisinin-piperaquine (DP) starting during the dry season, before the malaria transmission season starts.
Sponsors
Medical Research Council Unit, The Gambia
National Malaria Control Programme, The Gambia
Radboud University Medical Center
University of California, San Francisco
Institute for Disease Modeling
London School of Hygiene and Tropical Medicine
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
DIAGNOSTIC
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
6 Months to No maximum
Healthy volunteers
Yes
Inclusion criteria
1. Resident in the village. 2. Willingness to participate in repeated assessments of health and infection status and to donate a maximum of 30 mL (milliliter) of blood (children \<5 years of age), 37 mL (milliliter) of blood (children \<10 years of age) or 52 mL (milliliter) of blood (older individuals) during an 18-month period.
Exclusion criteria
1. Any chronic illness that would affect study participation. 2. Pre-existing severe chronic health conditions 3. History of intolerance to artemether-lumefantrine. 4. Participants \< 6months old and pregnant women in the first trimester (only for Arm with MDA-DP treatment). 5. Hypersensitivity to DP (only for Arm with MDA-DP treatment). 6. Taking drugs that influence cardiac function or prolong QTcorrected interval (only for Arm with MDA-DP treatment).
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Parasite prevalence by molecular detection at the end of study (cross-sectional survey). | 16 weeks | The primary outcome measure is parasite prevalence in the cross-sectional survey conducted at the end of the transmission season of year 2. |
| Parasite density by molecular detection at the end of study (cross-sectional survey). | 16 weeks | The primary outcome measure is parasite density (parasite/µL) in the cross-sectional survey conducted at the end of the transmission season of year 2. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Infectivity of P. falciparum infections to mosquitoes | Throughout study, an average of 18 months | For a selection of infections, infectiousness to mosquitoes is assessed by membrane feeding assays. |
| Gametocyte prevalence by molecular methods at the end of study (cross-sectional survey). | 16 weeks | Gametocyte prevalence in quantitative polymerase chain reaction (qPCR) detected infections is assessed by molecular methods and compared between arms. |
| Gametocyte density by molecular methods at the end of study (cross-sectional survey). | 16 weeks | Gametocyte density (gametocytes/µL) in qPCR detected infections is assessed by molecular methods and compared between arms. |
| Gametocyte prevalence of male and female gametocytes by molecular methods among P. falciparum infections at all study visits. | Throughout study, an average of 18 months | Gametocyte prevalence of male and female gametocytes will be assessed by molecular methods and compared between study arms. |
| Gametocyte density of male and female gametocytes by molecular methods among P. falciparum infections at all study visits. | Throughout study, an average of 18 months | Gametocyte density of male and female gametocytes will be assessed by molecular methods and compared between study arms. |
| Incidence of malaria infections | Throughout study, an average of 18 months | Regular visits by weekly active case detection and monthly screening will result in the identification of malaria infections that are not detected during CCM. Number of infections detected in each arm will be quantified and compared between arms. |
Other
| Measure | Time frame | Description |
|---|---|---|
| The detectability of infections by rapid diagnostic tests related to parasite density by molecular diagnostics. | Throughout study, an average of 18 months | For a selection of samples, the detectability of infections is assessed by conventional rapid diagnostic test and related to parasite density by molecular diagnostics. |
| The relationship between the proportion of infected mosquitoes (Direct Membrane Feeding Assay) and gametocyte density. | Throughout study, an average of 18 months | Gametocyte density will be assessed by molecular methods and associated with infectivity mosquitoes. |
| Gametocyte sex-ratio on the transmissibility of infections to mosquitoes. | Throughout study, an average of 18 months | To determine the impact of gametocyte sex-ratio on the transmissibility of infections to mosquitoes |
| The impact of human haemoglobinopathies on the transmissibility of infections to mosquitoes. | Throughout study, an average of 18 months | To determine the impact of red blood cell haemoglobinopathies and haemoglobin concentration on the transmissibility of infections to mosquitoes. |
| Mean fluorescence intensity (MFI) to inflammatory markers and naturally acquired antibody responses to gametocyte antigens on the transmissibility of infections to mosquitoes. | Throughout study, an average of 18 months | To determine the impact of inflammatory markers and naturally acquired antibody responses to gametocyte antigens and other host characteristics on the transmissibility of infections to mosquitoes. |
| Relationship between total parasite density (parasite/µL) and gametocyte density (gametocytes/µL) | Throughout study, an average of 18 months | To assess the relationship between asexual parasite density and gametocyte density in P. falciparum infections |
| Malaria transmission potential based on measured gametocyte densities (gametocytes/µL). | Throughout study, an average of 18 months | To determine malaria transmission potential of infections based on the gametocyte density |
| Number of acquired parasite clones based on genotyping. | Throughout study, an average of 18 months | Under this outcome, we aim to examine the complexity of P. falciparum infection by measuring the number of clones present in infections |
| Number of days that P. falciparum infections last in the dry season. | Up to 6 months | To evaluate the duration of P. falciparum carriage during the dry season, routine follow-up will be performed. |
| Mosquito exposure monitored by monthly CDC-light traps (CDC-LT) and Human landing catches (HLC) mosquito collections | Throughout study, an average of 18 months | For the quantification of the mosquito exposure, indoor and outdoor mosquito collections will be performed monthly during transmission and dry season. |
| Mean fluorescence intensity (MFI) antibody responses to mosquito saliva proteins during high and low transmission season. | Throughout study, an average of 18 months | To determine the exposure to Anopheles bites with serological markers of malaria infection. |
| Number of infections in community surveys that can be linked to a symptomatic or asymptomatic parent infection. | Throughout study, an average of 18 months | This outcome allow bridging mosquito feeding studies with actual transmission events in communities and at the same time quantify the relevance of infections associated with movement. |
| Number of human host from mosquito blood meal source. | Up to 12 months | To quantify the transmission potential of individuals by identification of human blood source by molecular typing. |
| The relationship between the proportion of infected mosquitoes (Direct Membrane Feeding Assay) and gametocyte sex-ratio. | Throughout study, an average of 18 months | Sex-ratio gametocytemia of P. falciparum will be assessed by molecular methods and associated with infectivity in mosquitoes. |
| The effect of infection characteristics (clonal parasite infection) on the transmissibility of infections to mosquitoes. | Throughout study, an average of 18 months | To determine the impact of duration and complexity of malaria infections on the transmissibility of infections to mosquitoes |
| The detectability of infections by highly-sensitive rapid diagnostic tests related to histidine rich protein-2 (HRP2) concentrations. | Throughout study, an average of 18 months | For a selection of samples, the detectability of infections is assessed by highly sensitive rapid diagnostic tests related to histidine rich protein-2 (HRP2) concentrations. |
| The detectability of infections by highly-sensitive rapid diagnostic tests related to duration of infection. | Throughout study, an average of 18 months | For a selection of samples, the detectability of infections is assessed by highly sensitive rapid diagnostic test and related to duration of infection. |
| The detectability of infections by rapid diagnostic tests related to duration of infection. | Throughout study, an average of 18 months | For a selection of samples, the detectability of infections is assessed by conventional rapid diagnostic tests and related to duration of infection. |
| The detectability of infections by highly-sensitive rapid diagnostic tests related to parasite density by molecular diagnostics. | Throughout study, an average of 18 months | The detectability of infections is assessed by highly sensitive rapid diagnostic test and related to parasite density by molecular diagnostics. |
Countries
The Gambia
Contacts
Primary ContactChris Drakeley, PhD
Backup ContactUmberto D'Alessandro, PhD, MD
Outcome results
None listed