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Malaria Studies in Cambodia

17. august 2018 opdateret af: National Institute of Allergy and Infectious Diseases (NIAID)

Studies of P. Vivax and P. Falciparum Malaria in Cambodia

This study, conducted by the National Center for Parasitology, Entomology and Malaria Control of Cambodia s Ministry of Health and the National Institute of Allergy and Infectious Diseases, will explore whether the following factors confer protection against malaria and associated anemia: certain blood groups, the hemoglobin E variant, G6PD-deficiency and alpha-thalassemia. Malaria is caused by parasites (P. falciparum and P. vivax) that are transmitted to humans through mosquito bites. This protocol includes two studies, a cohort study and a P. vivax collection study.

Individuals are eligible for enrollment in the studies as follows:

Cohort study:

Residents of all ages of Kandal, Ekapheap and Sangkumthmey villages (Thmar Da commune) who plan to remain in Thmar Da commune for the next 5 years.

P. vivax collection study:

2 years of age and older

Participating in NIAID protocol 05-I- N210 ( Severe Malaria and Anti-malarial Drug Resistance in Cambodia ) and diagnosed with P. vivax malaria

Participants undergo the following procedures:

Cohort study:

Baseline evaluation, including the following:

  • Collection of demographic information
  • Malaria history, temperature measurement and review of current symptoms, if any
  • Blood draw of 300 microliters
  • Additional blood draw of 10 milliliters in selected adults 18 years of age and older

Treatment with artesunate-piperaquine at a commune health post for subjects who develop malaria

Contact once a year for 5 years to determine continued residency in Thmar Da commune

P. vivax collection study:

  • Medical history and physical examination
  • Hemoglobin level measurement
  • Blood draw
  • Treatment with chloroquine
  • Blood draw 3 to 5 weeks after treatment in some patients 18 years of age or older

Studieoversigt

Status

Afsluttet

Betingelser

Detaljeret beskrivelse

Cohort study. Hemoglobin (Hb) and red blood cell (RBC) polymorphisms that give rise to HbE, alpha-thalassemia, G6PD-deficiency, and ABO blood groups occur at high frequency along the Thailand-Cambodia border, where Plasmodium vivax and P. falciparum have been and continue to be transmitted. To determine whether these Hb/RBC polymorphisms have been naturally selected because they confer protection against malaria and malaria-associated anemia, we will conduct a cohort study of ethnic Khmer in Cambodia. Approximately 1000 individuals of all ages will be genotyped for the four polymorphisms listed above and then followed for 5 years to determine the mean incidence rates for both P. vivax and P. falciparum malaria, stratified by genotype. Incidence rate ratios (IRRs) will be calculated for each polymorphism relative to the wildtype genotype. Differences between Hb levels during acute episodes of malaria and Hb levels at baseline will also be calculated to determine if Hb/RBC polymorphisms influence the degree of malaria-associated anemia.

P. vivax collection study. Unlike P. falciparum, P. vivax cannot be efficiently cultivated in vitro. Improved cultivation methods are needed to make progress on nearly all aspects of P. vivax malariology, including pathogenesis, naturally-acquired immunity, vaccination, and antimalarial drug resistance. We plan to improve both short- and long-term cultivation methods in order to test various hypotheses of P. vivax pathogenesis and protection. Using freshly obtained parasite isolates from individuals with P. vivax malaria, we will test whether Hb/RBC polymorphisms influence potentially pathogenic properties of P. vivax parasites, such as their ability to bind non-infected RBCs and other host cells. It is believed that P. vivax selectively invades reticutocytes. This tropism has frustrated attempts at long-term cultivation of this parasite, which requires a constant source of reticulocyte-rich blood not easily obtained even in developed countries. The host reticulocyte receptor that mediates the highly selective tropism of P. vivax has not been identified. Fresh P. vivax parasites will also be used in in vitro experiments to identify the putative receptor that defines reticulocyte tropism. Any P. vivax ligand that bound selectively to a reticulocyte receptor will then be discovered and worked up as a promising vaccine candidate.

Undersøgelsestype

Observationel

Tilmelding (Faktiske)

1978

Kontakter og lokationer

Dette afsnit indeholder kontaktoplysninger for dem, der udfører undersøgelsen, og oplysninger om, hvor denne undersøgelse udføres.

Studiesteder

  • Cambodja
      • Phnom Penh, Cambodja
        • National Center for Parasitology, Entomology, and Malaria Controk, Ministry of H
      • Preah Vihear Province, Cambodja
        • Preah Vihear Referral Hospital
      • Ratanakiri Province, Cambodja
        • Ratanakiri Referral Hospital

Deltagelseskriterier

Forskere leder efter personer, der passer til en bestemt beskrivelse, kaldet berettigelseskriterier. Nogle eksempler på disse kriterier er en persons generelle helbredstilstand eller tidligere behandlinger.

Berettigelseskriterier

Aldre berettiget til at studere

Ikke ældre end 100 år (Barn, Voksen, Ældre voksen)

Tager imod sunde frivillige

Ja

Køn, der er berettiget til at studere

Alle

Beskrivelse

  • INCLUSION CRITERIA: (Cohort Study)

Resident of Kandal, Ekapheap, and Sangkumthmey villages (Thmar Da commune), and no plans to leave the Thmar Da commune for the next 5 years.

Willingness to participate in the study as evidenced by informed consent of subjects or his/her parent or guardian, and willingness to come to commune health posts if he/she develops fever or other symptoms of malaria.

Individuals of all ages will be enrolled.

EXCLUSION CRITERIA: (Cohort Study)

Any condition that in the opinion of the investigator would render the subject unable to comply with the protocol (e.g., psychiatric disease).

Any health condition that in the opinion of the investigator would confound data analysis or pose unnecessary exposure risks to study personnel (e.g., individuals who are known to be HIV-infected or to have AIDS).

INCLUSION CRITERIA: (P. vivax Collection Study)

P. vivax malaria (mono-infection).

Willingness to participate in the study as evidenced by informed consent of subjects or his/her parent or guardian.

Age greater than or equal to 2.

Hematocrit greater than or equal to 25%.

EXCLUSION CRITERIA: (P. vivax Collection Study)

Any condition that in the opinion of the investigator would render the subject unable to comply with the protocol (e.g., psychiatric disease).

Any health condition that in the opinion of the investigator would confound data analysis or pose unnecessary exposure risks to study personnel (e.g., individuals who are known to be HIV-infected or to have AIDS).

Pregnancy.

Prior use of antimalarials during the past 2 months.

INCLUSION CRITERIA: (Cord and Peripheral Blood Collection Study)

Healthy male or female adults greater than or equal to 18 years old or healthy pregnant female adults greater than or equal to 18 years old.

Willingness to participate in the study as evidenced by informed consent.

EXCLUSION CRITERIA: (Cord and Peripheral Blood Collection Study)

Any condition that in the opinion of the investigator would render the subject unable to comply with the protocol (e.g., psychiatric disease).

Any health condition that in the opinion of the investigator would confound data analysis or pose unnecessary exposure risks to study personnel (e.g., individuals who are known to be HIV-infected or to have AIDS).

INCLUSION CRITERIA: (Collection of peripheral blood for identifying and isolating memory B cells)

Healthy male or non- pregnant female adults greater than or equal to 18 years old.

Previous enrollment on the P. vivax collection study.

Willingness to participate in the study as evidenced by written informed consent.

EXCLUSION CRITERIA: (Collection of peripheral blood for identifying and isolating memory B cells)

For the follow-up blood draw (250 mL), symptomatic parasitemia with any species of Plasmodium.

For the follow-up blood draw (250 mL), hemoglobin level <9 g/dL.

For the follow-up blood draw (250 mL), weight <45 kg.

Any condition that in the opinion of the investigator would render the subject unable to comply with the protocol (e.g., psychiatric illness).

Any health condition that in the opinion of the investigator would confound data analysis or pose unnecessary exposure risks to study personnel (e.g., individuals who are known to be HIV-infected or to have AIDS).

Studieplan

Dette afsnit indeholder detaljer om studieplanen, herunder hvordan undersøgelsen er designet, og hvad undersøgelsen måler.

Hvordan er undersøgelsen tilrettelagt?

Design detaljer

Samarbejdspartnere og efterforskere

Det er her, du vil finde personer og organisationer, der er involveret i denne undersøgelse.

Sponsor

National Institute of Allergy and Infectious Diseases (NIAID)

Publikationer og nyttige links

Den person, der er ansvarlig for at indtaste oplysninger om undersøgelsen, leverer frivilligt disse publikationer. Disse kan handle om alt relateret til undersøgelsen.

Generelle publikationer

Datoer for undersøgelser

Disse datoer sporer fremskridtene for indsendelser af undersøgelsesrekord og resumeresultater til ClinicalTrials.gov. Studieregistreringer og rapporterede resultater gennemgås af National Library of Medicine (NLM) for at sikre, at de opfylder specifikke kvalitetskontrolstandarder, før de offentliggøres på den offentlige hjemmeside.

Studer store datoer

Studiestart

24. marts 2008

Studieafslutning

5. december 2013

Datoer for studieregistrering

Først indsendt

19. april 2008

Først indsendt, der opfyldte QC-kriterier

19. april 2008

Først opslået (Skøn)

22. april 2008

Opdateringer af undersøgelsesjournaler

Sidste opdatering sendt (Faktiske)

20. august 2018

Sidste opdatering indsendt, der opfyldte kvalitetskontrolkriterier

17. august 2018

Sidst verificeret

5. december 2013

Mere information

Begreber relateret til denne undersøgelse

Nøgleord

Yderligere relevante MeSH-vilkår

Andre undersøgelses-id-numre

  • 999908094
  • 08-I-N094

Disse oplysninger blev hentet direkte fra webstedet clinicaltrials.gov uden ændringer. Hvis du har nogen anmodninger om at ændre, fjerne eller opdatere dine undersøgelsesoplysninger, bedes du kontakte register@clinicaltrials.gov. Så snart en ændring er implementeret på clinicaltrials.gov, vil denne også blive opdateret automatisk på vores hjemmeside .

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