Longitudinal Analysis of Plasmodium Falciparum-Specific Immunity in Travelers and Immigrants From Malaria Endemic Areas to the United States

Plasmodium falciparum malaria is a major cause of morbidity and mortality in tropical and sub-tropical areas worldwide. Repeated P. falciparum infections in endemic areas induce protective immunity, thus providing optimism that an effective malaria vaccine can be developed. Key to the development of such a vaccine is an understanding of the immune mechanisms underlying protection and the longevity of these responses in the absence of continuous P. falciparum exposure. Anecdotal evidence suggests clinical immunity to malaria wanes within months to years after an immune individual leaves an endemic area. A detailed, systematic description of the quality and longevity of the P. falciparum-specific humoral and cellular immune responses in such individuals over time in the absence of ongoing exposure is lacking.

This protocol will attempt to fill this knowledge gap through comprehensive longitudinal immunological analyses of two populations of healthy adult volunteers: 1) naive travelers returning from malaria endemic areas recently treated (within 2 weeks) for acute P. falciparum malaria and referred from hospitals in the metropolitan Washington DC area; and 2) immigrants from malaria endemic areas living in the metropolitan Washington DC area with serologic evidence of past P. falciparum exposure. In both groups, venipuncture and possibly apheresis will be performed for the isolation of plasma, RNA and peripheral blood mononuclear cells (PBMCs) which will be analysed to understand the components of innate and adaptive immunity to malaria. Na(SqrRoot) ve travelers returning from malaria endemic areas recently treated for acute malaria will undergo venipuncture at enrollment, then once every 2 weeks for 2 months, then every 3 months for 1 year, and then every 6 months for up to 5 years. Immigrants will be seen every three months for one year and then every six months for up to 5 years. All subjects who return to the U.S. from a malaria endemic area will be evaluated within two weeks of return for repeat venipuncture and will restart the same sequence of blood draws as naive travelers. Optional apheresis will be performed on both na(SqrRoot) ve travelers and immigrants at enrollment, at 1, 6, and 12 months, then yearly therafter.

The primary objective is to estimate the quality and longevity of P. falciparum-specific humoral and cellular immune responses in the absence of ongoing P. falciparum exposure in both returned na(SqrRoot) ve travelers and immigrants. The secondary objective is to compare the P. falciparum-specific humoral and cellular immune response in na(SqrRoot) ve travelers and immigrants to individuals in malaria-endemic areas enrolled in ongoing LIG protocols in Mali.

...

Study Overview

• Status: Terminated
• Conditions: Malaria

Detailed Description

Plasmodium falciparum malaria is a major cause of morbidity and mortality in tropical and sub-tropical areas worldwide. Repeated P. falciparum infections in endemic areas induce protective immunity, thus providing optimism that an effective malaria vaccine can be developed. Key to the development of such a vaccine is an understanding of the immune mechanisms underlying protection and the longevity of these responses in the absence of continuous P. falciparum exposure. Anecdotal evidence suggests clinical immunity to malaria wanes within months to years after an immune individual leaves an endemic area. A detailed, systematic description of the quality and longevity of the P. falciparum-specific humoral and cellular immune responses in such individuals over time in the absence of ongoing exposure is lacking.

This protocol will attempt to fill this knowledge gap through comprehensive longitudinal immunological analyses of two populations of healthy adult volunteers: 1) naive travelers returning from malaria endemic areas recently treated (within 2 weeks) for acute P. falciparum malaria and referred from hospitals in the metropolitan Washington DC area; and 2) immigrants from malaria endemic areas living in the metropolitan Washington DC area with serologic evidence of past P. falciparum exposure. In both groups, venipuncture and possibly apheresis will be performed for the isolation of plasma, RNA and peripheral blood mononuclear cells (PBMCs) which will be analysed to understand the components of innate and adaptive immunity to malaria. Na(SqrRoot) ve travelers returning from malaria endemic areas recently treated for acute malaria will undergo venipuncture at enrollment, then once every 2 weeks for 2 months, then every 3 months for 1 year, and then every 6 months for up to 5 years. Immigrants will be seen every three months for one year and then every six months for up to 5 years. All subjects who return to the U.S. from a malaria endemic area will be evaluated within two weeks of return for repeat venipuncture and will restart the same sequence of blood draws as naive travelers. Optional apheresis will be performed on both na(SqrRoot) ve travelers and immigrants at enrollment, at 1, 6, and 12 months, then yearly therafter.

The primary objective is to estimate the quality and longevity of P. falciparum-specific humoral and cellular immune responses in the absence of ongoing P. falciparum exposure in both returned na(SqrRoot) ve travelers and immigrants. The secondary objective is to compare the P. falciparum-specific humoral and cellular immune response in na(SqrRoot) ve travelers and immigrants to individuals in malaria-endemic areas enrolled in ongoing LIG protocols in Mali.

• Study Type: Observational
• Enrollment (Actual): 3

Contacts and Locations

Study Locations

• United States
  • Maryland
    • Bethesda, Maryland, United States, 20892
      • National Institutes of Health Clinical Center, 9000 Rockville Pike

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 65 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

• INCLUSION CRITERIA:
• All Subjects: Age 18-65
• Agree to have blood specimens stored for future research and genetic studies

Malaria endemicity will be defined according to CDC Yellow Book criteria available at:

http://wwwnc.cdc.gov/travel/yellowbook/2014/chapter-3-infectious-diseases-related-totravel/malaria#3929

NaIve travelers returning from malaria endemic areas recently treated for malaria:

-Treated for acute P. falciparum malaria within 4 weeks of enrolling in this study as determined by clinical and microbiologic evidence (including blood smear) of infection as indicated by medical records

Immigrants from malaria endemic areas:

• Confirmation of having lived in a malaria endemic area through documentation or verifiable detailed immigration history.
• Evidence of past P. falciparum exposure with positive AMA -1 ELISA.

SUBJECT EXCLUSION CRITERIA:

• History of HIV and/or hepatitis C.
• Inadequate peripheral venous access
• Current use of the steroid equivalent of prednisone 20mg/day or more or other systemic immunosuppressants
• Underlying heart disease, lung disease, bleeding disorder, or other conditions that, in the judgment of the investigator, contraindicates study participation
• Temperature greater than or equal to 37.5 (Infinite)C or other clinical evidence of an acute infection
• Currently pregnant (positive urine beta-HCG) or breastfeeding

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Estimate the quality and longevity of P. falciparum-specific humoral and cellular immune responses in the absence of ongoing P. falciparum exposure.	Five years

Secondary Outcome Measures

Outcome Measure	Time Frame
Compare the P. falciparum-specific humoral and cellular immune response in na(SqrRoot) ve travelers and immigrants to age and sex matched individuals in malaria-endemic areas enrolled in ongoing LIG protocols in Mali.	5 years

Collaborators and Investigators

• Sponsor: National Institute of Allergy and Infectious Diseases (NIAID)
• Investigators: Principal Investigator: Eugene W Liu, M.D., National Institute of Allergy and Infectious Diseases (NIAID)

Publications and helpful links

General Publications

• Trape JF, Rogier C, Konate L, Diagne N, Bouganali H, Canque B, Legros F, Badji A, Ndiaye G, Ndiaye P, et al. The Dielmo project: a longitudinal study of natural malaria infection and the mechanisms of protective immunity in a community living in a holoendemic area of Senegal. Am J Trop Med Hyg. 1994 Aug;51(2):123-37. doi: 10.4269/ajtmh.1994.51.123.
• Perignon JL, Druilhe P. Immune mechanisms underlying the premunition against Plasmodium falciparum malaria. Mem Inst Oswaldo Cruz. 1994;89 Suppl 2:51-3. doi: 10.1590/s0074-02761994000600013.
• Deloron P, Chougnet C. Is immunity to malaria really short-lived? Parasitol Today. 1992 Nov;8(11):375-8. doi: 10.1016/0169-4758(92)90174-z.

Study record dates

Study Major Dates

• Study Start: May 15, 2014
• Primary Completion (Actual): March 15, 2016
• Study Completion (Actual): March 15, 2016

Study Registration Dates

• First Submitted: May 31, 2014
• First Submitted That Met QC Criteria: May 31, 2014
• First Posted (Estimate): June 3, 2014

Study Record Updates

• Last Update Posted (Actual): December 17, 2019
• Last Update Submitted That Met QC Criteria: December 14, 2019
• Last Verified: March 15, 2016

More Information

Terms related to this study

• Keywords: Malaria Immunity Longevity
• Additional Relevant MeSH Terms: Infections; Vector Borne Diseases; Parasitic Diseases; Protozoan Infections; Malaria
• Other Study ID Numbers: 140121; 14-I-0121