Active clinical trials for "Malaria, Vivax"

Primaquine (PQ) is the only widely available treatment to prevent P. vivax relapses. World Health Organization recommends increased PQ doses in East Asia and Oceania, frequently relapsing strains. In 2005, the Centers for Diseases Control and Prevention began also recommending higher dose PQ to treat infections from all parts of the world. In Latin America, PQ for a radical cure has been largely implemented as 3.5 mg/kg over 14 days (standard dose, long-course, PQsd14) or 3.5 mg/kg over 7 days (short-course, or PQsd7) in combination with chloroquine (CQ). A recent randomized controlled trial in Brazil showed that a 7 mg/kg double dose regimen over 14 days (PQdd14) was superior in preventing relapses compared to the standard of care regimen in Brazil of 3.5 mg/kg over 7 PQsd7 Direct Observed Therapy (DOT) and PQsd7 without DOT and with or 14 days PQsd14 with DOT (92% versus 66% were relapse-free in the 6-month follow-up in adjusted analyses). These data were presented at the 2019 PAHO Malaria Technical Advisory Group (TAG) meeting. To inform whether there should be a policy change by Panamerican Health Organization, the Malaria TAG recommended more evidence from the results of another trial to confirm the efficacy of high versus low-dose PQ. This project aims to generate the necessary evidence to inform a policy decision regarding high-dose PQ. Impact Malaria (IM) proposes to conduct another trial, per the PAHO Malaria TAG's recommendation, assessing the efficacy of high-dose PQ compared to low-dose PQ. The objective is to compare a standard regimen, which in Colombia is PQsd14 (3,5mg/kg divided in 14 days), to a double dose alternative PQ 7 mg/kg double dose regimen over 14 days (PQdd14).

The purpose of this study is to demonstrate that volunteers can be safely and reproducibly infected with Plasmodium vivax (P. vivax) by the bites of experimentally infected Anopheles dirus (An. dirus) mosquitoes carrying P. vivax sporozoites in their salivary glands.

This is a continuous cohort study consisting of 200 participants (one third 6 months old to 5 years, one third 6 to 15 years old, one third ≥ 15 years old) i.e. a new patient will be recruited (from the same age group) for any patient who develops a Pv infection so that the cohort will always have 200 patients for 3 years. Each patient will be actively followed-up every 8 weeks until Plasmodium vivax infection occurs but the duration of follow up and the number of follow up visits for each patient will vary depending on when or if a vivax infection occurs and when the patient is recruited. Therefore, the minimum follow up period for each patient will be 6 months or time to vivax infection and the maximum will be 3 years if a patient does not get vivax infection and is recruited at the beginning of the study.

This was a phase I double blind controlled vaccine trial, evaluating safety, tolerability and immunogenicity of mixtures of N, R and C LSP derived from the P. vivax CS protein formulated in two adjuvants Montanide ISA 720 and Montanide ISA 51. The primary objective was to assess in malaria-naïve adults, the safety and reactogenicity of these peptides formulated in the two adjuvants We recruited 40 healthy men and women volunteers from Cali, Colombia, a city non-endemic for malaria. Volunteers were 19--41 years of age and had no history of malaria. During a period of three months a total of 100 volunteers were assessed for eligibility criteria in order to select a total of 40 volunteers willing to participate in the clinical trial. By consecutive allocation, eight participants were allocated to each of the five experimental groups (A--E): four groups (A--D) were immunized with the vaccine formulations at two different dose concentrations and formulated in two different adjuvants. A control group (E) was injected with placebo (saline solution)

This will be a randomized, single-blind, placebo controlled, parallel group study. Approximately 260 subjects will be enrolled in five groups. This study is designed to compare the effects of tafenoquine, administered as single dose as well as administered over three consecutive days, on the changes in QT duration to those observed in subjects dosed with either moxifloxacin or placebo.

To determine whether two cheap antifolates (chlorproguanil-dapsone and sulfadoxine-pyrimethamine) which work against falciparum malaria in this region are sufficiently effective against vivax malaria to be deployed in areas where diagnosis is poor and the burden of malaria is high, a randomised controlled trial of the three drugs is being undertaken comparing their efficacy in treating malaria.

This is a sporozoite-challenge clinical study with the primary aim of assessing the safety and feasibility of controlled human P. vivax malaria infection in two healthy volunteers. The investigators will also assess the growth of and the immune response to P. vivax infection, and assess the induction of sexual gametocytaemia post-CHMI via the natural route of malaria infection (mosquito bite). A secondary objective is to develop a blood inoculum of P. vivax-infected blood for future testing of candidate vaccines.

A clinical trial aimed to standardize a vivax sporozoite infection model in human volunteers was conducted at the Malaria Vaccine and Drug Development Center (MVDC) in collaboration with the Immunology Institute at Valle State University and the Fundación Clínica Valle del Lili (FCVL) in Cali, Colombia. The primary objective was to determine if naïve human volunteers could be safely and reproducibly infected by the bite of An. albimanus mosquitoes carrying P. vivax sporozoites in their salivary glands and a secondary objective consisted in determining the minimal number of infected mosquitoes required to infect all volunteers, with a reproducible pre-patent period. The trial was divided into two steps: Step A directed to obtain human blood infected with P.vivax parasite used to infect anopheles mosquitoes and Step B to produce P. vivax sporozoites in Anopheles mosquitoes to determine the dose response of naive human volunteers exposed to 3 +/- 1, 6 +/- 1 y 9 +/- 1 mosquitoes bites. A total of 15 samples of P. vivax infected donors were used to infect different batches of mosquitoes.

Both artemether-lumefantrine and chloroquine are currently used and recommended by Malaysian Ministry of Health as blood stage treatments for non-severe P. vivax and P. knowlesi malaria. Microscopic misdiagnosis between Plasmodium species remains a large issue in Sabah, Malaysia and elsewhere. In order to facilitate potential policy change to a unified ACT guideline for all malaria species in Sabah artemether-lumefantrine needs to be evaluated for P. vivax malaria. Preliminary data in a recently completed RCT evaluating artesunate-mefloquine vs chloroquine for P. vivax showed up to 36% P. vivax recurrence with chloroquine monotherapy by day 28 post treatment without primaquine. Based on these data blood stage chloroquine treatment failure rates should also be evaluated in the context of standard concurrent (rather than delayed) liver stage primaquine dosing, due to both its potential blood stage synergistic effect in addition to known decreased recurrence rates. As artemether-lumefantrine is one of the current first line Ministry of Health ACTs used in Sabah with a lower adverse event profile compared to artesunate-mefloquine, this was recommended as the more appropriate ACT to evaluate against chloroquine.

In Thailand, the proportion of P.vivax infection has now been increasing and is equal to Plasmodium falciparum since 1998. The incidence of P.vivax has recently been reported as 20 per 1000 population per year. Unlike Plasmodium falciparum, P.vivax infection rarely develops into complicated malaria and death is unusual. However, P.vivax has a dormant stage (the hypnozoite) that persists in the human liver and may cause relapse weeks, months, or even years later. Therefore, P.vivax infection is considered to have greater impact on morbidity than mortality, resulting in significant social and economic burden. Moreover, it is very difficult to control P.vivax transmission, because gametocytes appear almost simultaneously with schizonts. Radical treatment of the infection, therefore, normally consists of a blood schizontocidal course of chloroquine and a course primaquine for the elimination of the hypnozoites as anti-relapse therapy. In Thailand, chloroquine and primaquine have remained the mainstay chemotherapeutics for the treatment of P.vivax for more than 60 years and resistance has not yet been reported . The relapse rates at day 28 are about 50% without primaquine therapy and about 20% with standard primaquine therapy. Relapse has not been observed among patients receiving high dose primaquine therapy (30 mg daily for 14 days). Since January 2007, the evidence of reduced susceptibility of Plasmodium falciparum to artemisinins in Western Cambodia at Thai-Cambodia border was first presented and confirmed in a subsequent detailed pharmacokinetic-pharmacodynamic study. Nevertheless, a trend of gradual decline of in vitro sensitivity to chloroquine has been documented in some areas of the country, particularly Thai-Myanmar border. There has been no clinical-parasitological evidence of chloroquine resistant P.vivax in Thai-Cambodia border, Thailand. The objectives of the present study are to assess in vivo efficacy of first line regimen of chloroquine given with primaquine, and in vitro susceptibility of P.vivax isolates in areas along Thai-Cambodia border, Thailand.