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NCT04666350

Clinical Investigation Study to Evaluate the Consistency and Reproducibility of Two Consecutive Mosquito Feeding Assays

Completed Results posted Last updated 29 April 2024
What this trial tests

trial testing Direct Skin Feeding Assay (DSFA) in Malaria in 42 participants. Completed in 20 December 2021.

Timeline
9 March 2021
Primary endpoint
20 December 2021
20 December 2021

Quick facts

Lead sponsorPATH
StatusCompleted
Study typeOBSERVATIONAL
Enrollment42
Start date9 March 2021
Primary completion20 December 2021
Estimated completion20 December 2021
Sites1 location across Kenya

Drugs / interventions tested

Conditions studied

Sponsor

PATH — full company profile →

Who can join

Adults 18 to 55, any sex, with Malaria. Patients with the condition only — healthy volunteers not accepted.

Results — posted to ClinicalTrials.gov

Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.

Oocyst Prevalence Primary · Feeding assays were performed on Day 1 and Day 2; Oocyst prevalence in surviving mosquitoes was assessed 9 days after feeding (Days 9 and 10).

Participants underwent feeding assays on two days, 24 hours apart (day 1 and Day 2). After feeding, mosquitoes were maintained in locked environmental chambers for 9 days to allow oocyst development. An oocyst is a structure that develops on the outer wall of the infected mosquito's stomach that contains developing sporozoites. Nine days after feeding mosquito midguts were dissected, stained with 1% mercurochrome and examined by optical microscopy. The number of oocysts in each midgut were recorded. Oocyst prevalence is defined as the percentage of mosquitoes in a cup with at least one oocy

Day 1 Feeding Assay
GroupValue95% CI
Direct Skin Feeding Assay5.2± 7.8
Direct Membrane Feeding Assay6.3± 16.2
Day 2 Feeding Assay
GroupValue95% CI
Direct Skin Feeding Assay2.3± 4.9
Direct Membrane Feeding Assay2.2± 4.4
Oocyst Density Secondary · Feeding assays were performed on Day 1 and Day 2; Oocyst density in surviving mosquitos was assessed 9 days after feeding (Days 9 and 10).

Participants underwent feeding assays on two days, 24 hours apart (Day 1 and Day 2). After feeding, mosquitoes were maintained in locked environmental chambers for 9 days to allow oocyst development. An oocyst is a structure that develops on the outer wall of the infected mosquito's stomach that contains developing sporozoites. Nine days after feeding mosquito midguts were dissected, stained with 1% mercurochrome and examined by optical microscopy. The number of oocysts in each midgut were recorded. Oocyst density is defined as the mean number of oocysts detected in infected mosquitoes that

Day 1 Feeding Assay
GroupValue95% CI
Direct Skin Feeding Assay1.1± 1.8
Direct Membrane Feeding Assay1.6± 4.1
Day 2 Feeding Assay
GroupValue95% CI
Direct Skin Feeding Assay0.4± 0.8
Direct Membrane Feeding Assay0.4± 0.8
Sporozoite Prevalence Secondary · Feeding assays were performed on Day 1 and Day 2; Sporozoite prevalence in surviving mosquitoes was assessed 14 days after feeding (Days 14 and 15).

Participants underwent feeding assays on two days, 24 hours apart (day 1 and Day 2). After feeding, mosquitoes were maintained in locked environmental chambers for 14 days to allow sporozoite development. Sporozoites are the forms of the plasmodium that are liberated from the oocysts in the mosquito, accumulate in the salivary glands of the mosquito, and are transferred to humans when the mosquito feeds. Fourteen days after feeding, salivary glands were dissected from live mosquitoes submerged in phosphate-buffered saline (PBS) in order to visualize motile sporozoites by microscopy. Sporozoi

Day 1 Feeding Assay
GroupValue95% CI
Direct Skin Feeding Assay5.1± 8.4
Direct Membrane Feeding Assay4.5± 8.0
Day 2 Feeding Assay
GroupValue95% CI
Direct Skin Feeding Assay1.8± 4.8
Direct Membrane Feeding Assay2.0± 5.7

Adverse events — posted to ClinicalTrials.gov

Time frame: 2 days. Reporting threshold: 0%. Adverse-event reports describe events observed during the trial — not all are caused by the drug.

Study Volunteers
Serious: 0/42 (0%)
Deaths: 0/42
Other adverse events (5 terms — click to expand)

ReactionSystemStudy Volunteers
PruritusSkin and subcutaneous tissue disorders
UrticariaSkin and subcutaneous tissue disorders
Abdominal pain upperGastrointestinal disorders
TonsillitisInfections and infestations
Arthropod biteInjury, poisoning and procedural complications

Data from ClinicalTrials.gov NCT04666350 adverse events section.

Sponsor's own description

The proposed trial design has been developed to assess the consistency and reproducibility of two consecutive direct skin feeding assays (DSFA) at 24-hour interval.

Publications & conference data

1 peer-reviewed publication reference this trial (live from Europe PMC):

  1. Consistency and reproducibility of independent feedings using blood from two consecutive days at varying Plasmodium falciparum gametocyte densities based on both direct membrane feeding assay and direct skin feeding assay.
    Akala HM, Aponte JJ, Achola MA, Juma DW, et al · · 2025 · PMID 40380146 · DOI 10.1186/s12936-025-05360-3

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Other recruiting trials for Malaria

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Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing