Malaria Transmission Studies in Mali

Malaria, Falciparum Clinical Trial

Official title: Epidemiologic Studies of Plasmodium Falciparum Gametocytemia and Transmission-blocking Immunity in Kenieroba, Mali

Status Completed

Clinical Trial Summary

Background:

• Malaria is an illness caused by a parasite spread by mosquitoes. When a mosquito bites a person who is infected with a kind of parasite called a gametocyte, it is able to spread the infection to another person. Not everyone infected with parasites have gametocytes in their blood. As a result, not everyone can spread malaria to others. Researchers are interested in learning more about why some healthy people have gametocytes in their blood and others do not. Identifying the people who have gametocytes in their blood can help target treatment and reduce the spread of malaria. This study will focus on the people of the village of Kenieroba in Mali, where malaria is common.

Objectives:

• To study the relationship between gametocytes and malaria transmission in Mali.

Eligibility:

• Individuals between 6 months and 65 years of age who live in Kenieroba, Mali, and will stay in the area for 1 year.

Design:

• For 1 year, participants will have study visits once every 2 weeks (twice a month, for a total of 24 visits). The visits will last 30 minutes each.

• At each visit, participants will provide a small blood sample. They will report any symptoms of malaria such as fever, headache, and body aches. Participants will be encouraged to seek medical treatment if they experience malaria symptoms between visits.

• Participants who have malaria symptoms will have a blood test for malaria parasites. Those who have parasites in the blood will receive antimalarial treatment.

• Three times over 1 year, a larger blood sample will be collected. These blood samples will be taken once in the dry season, once in the wet season, and once in the next dry season.

• Women between 14 and 45 years of age will also provide urine samples to test for pregnancy. Pregnant women will not be asked to give blood samples.

Clinical Trial Description

Plasmodium falciparum malaria continues to evade control efforts in part through the complexity of its life cycle, which involves both humans and mosquitoes. While it is known that the gametocyte form of the parasite transmits disease, it is unclear which individuals constitute the primary gametocyte reservoir in a given human population. It is also unclear how an individual s asexual parasite density, acquired immune responses, and red blood cell (RBC) polymorphisms affect the presence and transmission of gametocytes. Investigating these effects has been limited in part because gametocytes are often present in peripheral blood at densities below the limit of microscopic detection. Recent technical advances in the molecular detection of gametocytes have set the stage for a better understanding of gametocyte epidemiology and biology in humans. In a setting of highly seasonal transmission, we are conducting an epidemiological study to estimate gametocyte prevalence over 1 year in the village of Kenieroba, Mali. In a cohort of 500 individuals that represents the age-distribution of the entire village population, we will explore how age, asexual parasite prevalence, season, and RBC polymorphisms affect variation in gametocyte prevalence (detected by a sensitive molecular method). From these same individuals, we will purify plasma IgG and compare its transmission-blocking activity by age group and season. These assessments will provide a foundation for future studies of gametocytemia dynamics within individuals as well as the impact of host immunity on gametocyte infectivity in our study population. Such information will enable us to identify those individuals that are primarily responsible for malaria transmission in Kenieroba. Incorporation of such findings into new or existing computer-based models of parasite infection and transmission may improve our evaluation of existing malaria control strategies. ;

Related Conditions & MeSH terms

• Malaria
• Malaria, Falciparum

• NCT number: NCT01829737
• Study type: Observational
• Source: National Institutes of Health Clinical Center (CC)
• Status: Completed
• Start date: March 20, 2013
• Completion date: January 20, 2015