Targeted Chemo-elimination (TCE) of Malaria
Palabras clave
Abstracto
Descripción
The spread of artemisinin resistance in Plasmodium falciparum, which compromises the therapeutic efficacy of artemisinin combination treatments (ACTs), is the greatest threat to current global initiatives to control and eliminate malaria and is considered the highest priority of the WHO Global Malaria Programme. If not eliminated, resistant parasites could spread across Asia to Africa, as happened with resistance to other antimalarials in the past.
Conventional descriptions of the epidemiology of malaria in low transmission settings suggest that malaria prevalences are low (<10%) and heterogeneous. Most or all infections are thought to be symptomatic so the focus of malaria control activities is on the identification and treatment of symptomatic individuals. We and others have shown recently that artemisinin resistant P. falciparum is prevalent in Western Cambodia, and that it is now also found along the Thailand-Myanmar border and Vietnam. We have recently developed highly sensitive quantitative PCR (uPCR) methods for parasite detection using >1mL of blood which are 5,000 times more sensitive than conventional microscopy, and 100 times more sensitive than currently used PCR.
We have studied villages along the Thai-Myanmar border which are typical for the region and are classified by conventional epidemiological techniques as low-transmission (5-20% malaria prevalence). Our studies suggest that the majority of the population is infected. In Pailin, Western Cambodia, in areas where the National Malaria Control Programme and WHO believe that malaria has been all but eliminated, we have also found very high rates (>80%) of sub-microscopic parasitaemia in patients with fever or history of fever who are RDT negative. Thus, there is a lot more asymptomatic malaria in low transmission settings than previously thought, suggesting that control and elimination activities need to be rethought.
Highly sensitive quantitative PCR (uPCR) requires a venous blood sample, a laboratory which can perform vacuum DNA extraction, and on average four weeks for processing. A rapid highly sensitive diagnostic test which can be performed at the point of care would be a technological breakthrough. Screening with highly sensitive RDTs and treating of asymptomatic carriers will have a range of public health applications. Such tests are becoming available in 2017 and will be evaluated side by side with uPCR.
This study is designed to conduct and evaluate the efficacy of pilot implementation of targeted chemo-elimination in selected areas with the goal of eliminating malaria in these regions. This differs from mass drug administration (MDA); it is a strategy used to identify specific areas where mass treatment is necessary, in this case to eliminate all malaria parasites. Elimination will be targeted at communities with significant levels of subclinical infection and transmission which will be identifiable in the future by comparing rates of positivity by RDT or microscopy from new population samples against our qPCR data, which shows the true falciparum prevalence.
The study will assess the feasibility, safety and acceptability of this strategy and its impact on the transmission of malaria and the progression of artemisinin resistance. In addition it will evaluate the contribution of low parasitaemia carriage to transmission of artemisinin resistant malaria. These pilot studies are a necessary prelude to future scale up and policy implementation.
Dihydroartemisinin-piperaquine (DP) is a highly efficacious and inexpensive ACT which is well tolerated by all age groups when used to treat uncomplicated multi-drug resistant falciparum malaria in South East Asia. Monthly DP treatments have proved highly effective and well tolerated. When used as part of a MDA strategy, the addition of a gametocytocidal drug contributes towards the goal of malaria elimination by adding a strong transmission blocking activity to the regimen. Primaquine (PQ), the only currently licensed 8-aminoquinoline, is relatively safe and very effective when used at a dose of 0.25 mg base/kg, and does not require G6PD screening. Thus, we propose to evaluate the potential of this strategy to eliminatie malaria focally in areas where artemisinin resistance in P. falciparum is prevalent using DP plus PQ.
fechas
| Verificado por última vez: | 07/31/2017 |
| Primero enviado: | 06/03/2013 |
| Inscripción estimada enviada: | 06/03/2013 |
| Publicado por primera vez: | 06/06/2013 |
| Última actualización enviada: | 08/25/2020 |
| Última actualización publicada: | 08/27/2020 |
| Fecha de inicio real del estudio: | 03/31/2013 |
| Fecha estimada de finalización primaria: | 06/30/2017 |
| Fecha estimada de finalización del estudio: | 06/30/2017 |
Condición o enfermedad
Intervención / tratamiento
Drug: malaria elimination using DP and low-dose primaquine
Fase
Grupos de brazos
| Brazo | Intervención / tratamiento |
|---|---|
| Experimental: malaria elimination using DP and low-dose primaquine Two villages randomly allocated to intervention (chemo-elimination) at each of the 4 sites (population approximately 500 people in each village). In these villages the entire population will be invited to receive three, monthly rounds of treatment with dihydroartemisinin-piperaquine and primaqunine to kill malaria parasites. The micro-epidemiology of malaria will be studied and prevalence and patterns of transmission used for comparison. NB, in Cambodia there will be no intervention villages and all four villages will be used to study the micro-epidemiology of malaria transmission in the absence of malaria elimination. | Drug: malaria elimination using DP and low-dose primaquine Treatment of all persons resident in the intervention villages including those who do not have malaria parasites as detected by rapid diagnostic test. This is to interrupt p.f malaria transmission by removing the reservoir of all potentially infectious people from the area. |
| No Intervention: Control villages Two villages randomly allocated to control (no chemo-elimination) at each of the 4 sites (population approximately 500 people in each village). In these villages only the micro-epidemiology of malaria will be studied and prevalence and patterns of transmission used for comparison. NB, in Cambodia there will be no intervention villages and all four villages will be used to study the micro-epidemiology of malaria transmission in the absence of malaria elimination.
From June 2013 to June 2014 Cambodia site conducted surveys with no medical intervention (treatment arm). In July 2015 Cambodia implemented the TCE protocol with two intervention and two control villages. Primaquine is not used in the TCE treatment regimen in Cambodia. Both studies were approved under OxTREC reference no. 1017-13 and 1015-13. |
Criterio de elegibilidad
| Edades elegibles para estudiar | 6 Months A 6 Months |
| Sexos elegibles para estudiar | All |
| Acepta voluntarios saludables | si |
| Criterios | OxTREC reference: 1017-13 Inclusion Criteria: - Age ≥6 months, male or female, - Written informed consent (by parent/guardian in case of children) Exclusion Criteria: - Pregnant women will not receive primaquine (urine pregnancy tests will be performed on women of appropriate age groups before drug administration at each TCE round) - History of allergy or known contraindication to artemisinins, piperaquine or PQ - Those who are, in the opinion of the study clinician, ill at the time of drug administration OxTREC reference: 1015-13 Inclusion Criteria - Age ≥6 months, male or female, - Written informed consent (by legally acceptable representative in case of children) - Healthy at the time of the survey or drug administration - Not pregnant Exclusion Criteria - Significant non-compliance with study requirements - Loss to follow up - Suspected severe adverse events - Severe illness OxTREC reference: 23-15 Part 1. qPCR survey for identification of potential TMT villages; Inclusion criteria: - Males and females 18 and above - Written informed consent Exclusion criteria: - Pregnant women in their first trimester - Presence of any acute severe illness at the time of survey Part 2. TMT villages will be given directly observed therapy (DOT) with DP for 3 days and PQ (0.25 mg/kg) will be given on day 1 Inclusion criteria for TMT - Age ≥one year, male and female, - Willing to provide consent for those 18 years and above. For children 10-18 years old, parents/guardians must provide consent, and the children must provide assent. For children below 10 years old, the parents/guardians must provide consent. Exclusion criteria for TMT - History of allergy or known contraindication to artemisinins, piperaquine or PQ. - Refusal of treatment. - Pregnant women in their 1st trimester. |
Salir
Medidas de resultado primarias
1. prevalence of falciparum malaria measured by qPCR (quantitative real time polymerase chain reaction), 12 months after the first administration of treatment with dihydroartemisinin-piperaquine and primaquine. (1017-13 and 23-15) [12 months]
2. prevalence of falciparum malaria measured by qPCR (quantitative real time polymerase chain reaction), 12 months after the first administration of targeted malaria elimination (1015-13) [12 months]
3. prevalence of falciparum malaria measured by qPCR (quantitative real time polymerase chain reaction), 4 months after the first administration of target malaria-elimination (23-15) [4 months]
Medidas de resultado secundarias
1. Safety and acceptability of targeted malaria elimination (1017-13 and 1015-13) [12 months]
Otras medidas de resultado
1. Effect on gametocyte carriage by targeted malaria elimination (1017-13 and 1015-13) [12 months]
2. Characterize parasite carriage using highly sensitive techniques in four geographically separate sites where resistance to artemisinin has been documented (1017-13 and 1015-13) [12 months]
3. Acceptability of targeted Chemo-elimination of malaria measured by number of peaople participate (1017-13) [12 months]
4. Cost estimates of targeted Chemo-elimination of malaria by sampling strategy (1017-13) [12 months]
5. incidence of clinical malaria in the villages over the first 12 months (1015-13) [12 months]
6. The proportion of Artemisinin resistance - P.falciparum infections (23-15) [12 months]
7. Sensitivity of novel RDTs (HS RDT) [12 months]
8. Specificity of novel RDTs (HS RDT) [12 months]
