Background:
Malaria is a disease caused by parasites transmitted to people by mosquitoes. Around the world, there were 241 million cases and 627,000 deaths from malaria in 2020. Researchers are working to develop vaccines and treatments for this disease.
Objective:
To learn how malaria develops in people; how the body's immune system reacts to malaria; and how malaria spreads from people to mosquitoes.
Eligibility:
Healthy people in the Washington DC area, aged 18 to 54 years. They cannot live alone during parts of the study.
Design:
Participants will be infected with a parasite that causes malaria. The parasite will be in donated blood; it will be given through an IV.
Participants will likely develop symptoms within a week after the injection. Researchers will call daily to check on their health. After about 6 days, participants will come to the NIH clinic each day for blood tests.
Participants will check in to the NIH clinic around 10 days after the injection. They will stay in the clinic 3 to 6 days. They will have multiple blood tests every day.
Participants will be bitten by mosquitoes up to 4 times. Cups containing mosquitoes will be held against their skin for 15 minutes.
Participants will begin taking chloroquine close to the end of their clinic stay. Chloroquine is a pill taken by mouth once or twice a day for 3 days. It is FDA-approved to treat malaria.
Participants will have follow-up visits 1 and 3 weeks after discharge.
Age >=18 and <=54 years.
RBCs positive for Duffy antigen/chemokine receptor.
Malaria comprehension exam passed prior to study activities.
Suitable accommodation and reliable access to the NIHCC for the duration of the study in the opinion of the investigator.
Planned travel to a P. vivax-endemic area during the study period (see https://www.cdc.gov/malaria/travelers/country_table/a.html).
History of travel to or residence in a P. vivax malaria-endemic region for more than 2 weeks during the past 2 years.
Prior confirmed P. vivax malaria diagnosis or clinical history consistent with likely P. vivax infection. At the investigator's discretion, participants may be enrolled if the exposure was remote, e.g., > 5 years ago.
Poor peripheral venous access, at the discretion of the investigator.
Single group
P. vivax challenge agent derived from PvHMB-CCE001
Biological/VaccineP. vivax challenge agent derived from PvHMB-CCE001 consists of infected and uninfected erythrocytes stabilized in glycerolyte. Challenge agent derived from this bank consists of thawed, washed, infected and uninfected erythrocytes suspended in injectable-grade normal saline.
To assess the safety of the P. vivax IBSM model following inoculation of healthy participants.
Incidence and severity of local and systemic AEs or SAEs.
To establish a dataset that may be used as a historical control in future interventional IBSM studies.
Demonstration of transmission in mosquito feeding assays among a requisite number of participants.
To evaluate transmission of P. vivax to vector mosquitoes in the IBSM model by mosquito feeding assays.
Transmission of P. vivax to Anopheles spp. using mosquito feeding assays including direct feeding assays and/or membrane feeding assays as determined by the detection of oocysts following midgut dissection. Additional optional measures may include salivary gland dissection or detection by molecular methods.
To establish an appropriate challenge agent dose for use in P. vivax IBSM studies.
A suitable dose of challenge agent which generates parasitemia in a reliable and timely manner as determined by the investigator.
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