An Early Phase 1 interventional study of Sporozoite Challenge Model for Plasmodium vivax in Humans in Malaria, Vivax, sponsored by Malaria Vaccine and Drug Development Center. Completed at 1 site in Colombia. Open to participants aged 18 Years to 50 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2010-03-09.
Sponsored by Malaria Vaccine and Drug Development Center · Early Phase 1 and Interventional
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.
Study design:
The study was a randomized open label clinical trial to establish a sporozoite challenge model for Plasmodium vivax in humans. The development and standardization of such a model will make it possible to evaluate the efficacy of candidate P. vivax vaccines in Phase 2a trials. The study is divided into two successive steps:
Step A Parasite Blood Donation: Volunteers were recruited passively from a group of patients who presented with active P. vivax infection and accepted to donate infected blood. Samples of P. vivax infected blood was collected and was screened for infectious diseases, according to standard blood bank procedures. Colonized Anopheles albimanus mosquitoes were fed with this blood using a Membrane Feeding Assay (MFA). Sixteen (16) days after, selected positive mosquito batches were used for step B.
Step B Challenge: After informed consent signature, a total of 18 healthy volunteers were randomly allocated to Groups 1, 2 and 3, of 6 volunteers each and were challenged with the bite of 3±1, 6±1 or 9±1 P. vivax infected mosquitoes. Volunteers were closely monitored post infection, and were treated as soon as blood infection becomes patent as ascertained by microscopic examination of thick blood smears (TBS). Comparison of three bite patterns was used to select the optimal number of P. vivax-infected mosquito bites needed to provide reliable and reproducible blood infection.
Infection was expected to occur in the first 30 days. After that time, if infection was not documented, antimalarial treatment was planned. Nevertheless all exposed volunteers presented malarial infection. Despite infection was expected before day 30, a 18 month follow-up was performed with to be sure no delay malaria infection presented without detection. So, the total duration of the study was 18 months.
Infection was determined by the detection of P. vivax parasites on TBS from volunteers included.
Eligibility criteria for Blood donors Step A were:
Exclusion criteria
Eligibility and exclusion criteria for Challenge is described below in this format.
Close monitoring of adverse events was performed, both by medical examination as by telephone contact.
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This study's enrollment of 18 is below the median of 220 across 1,027 interventional studies indexed under Malaria.
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Exclusion Criteria:
Volunteers were exposed to mosquito biting for 10 min
Biological: Sporozoite Challenge Model for Plasmodium vivax in Humans
Volunteers were exposed to mosquito biting for 10 min
Biological: Sporozoite Challenge Model for Plasmodium vivax in Humans
Volunteers were exposed to mosquito biting for 15 min
Biological: Sporozoite Challenge Model for Plasmodium vivax in Humans
Eighteen naïve volunteers were exposed to the bite of carrying P. vivax sporozoites. Volunteers were randomly allocated to 1 of 6 groups and exposed to different numbers of mosquito biting, for 10 min. After feeding, dissection of all mosquitoes exposed in the cage was performed, to confirm the presence of a blood meal in their midguts and sporozoites in their salivary glands. If a volunteer did not get the number of infective bites assigned for his/her group, he/she was allowed to be bitten for a new group of mosquitoes until a total of 3±1, 6±1, or 9±1 mosquito bites were achieved.
Also known as: Controlled malaria vivax infection challenge
Percentage of infected naïve human volunteers after different number of infected mosquito biting
Time frame: 30 days
Minimal number of infected mosquitoes required to infect all volunteers with a reproducible prepatent period
Time frame: 30 days
This study is completed, as verified in Dec 2006. You cannot join it, but the record below documents what was studied.
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Malaria Vaccine and Drug Development Center