Impact of transmission intensity and age on plasmodium falciparum density and associated fever: Implications for malaria vaccine trial design

Christine Beadle, Peter D. Mc Elroy, Charles N. Oster, John C. Beier, Aggrey J. Oloo, Fred K. Onyango, David K. Chumo, Aggrey J. Oloo, James D. Bales, James A. Sherwood, Stephen L. Hoffman

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

To facilitate design of vaccine trials, malaria was studied in 6-month- to 6-year-old Kenyans during high (HI) and low intensity transmission seasons. During 84 days after cure, exposure to infected mosquitoes was 9-fold greater in the HI group, yet incidence of P. falciparum infection was increased only 2-fold, with no age effect. The density of recurrent P. falciparum was 14- fold greater in the HI group, and there was a striking association between age and parasitemia ≥5000/μL. Fever was the only clinical manifestation attributable to parasitemia and only when the parasite density was ≥5000/μL. Sixty-four percent of children with ≥20,000 parasites/μL versus 10% with 1-4999/μL were febrile when parasitemic. Recurrent P. falciparum infection as a vaccine trial end point can be studied year-round among children ≥6 years in western Kenya. However, high-grade parasitemia (≥5000 or 20,000/μL) with or without elevated temperature will be optimally studied in the high transmission season among children <2 years.

Original languageEnglish (US)
Pages (from-to)1047-1054
Number of pages8
JournalJournal of Infectious Diseases
Volume172
Issue number4
DOIs
StatePublished - Oct 1995
Externally publishedYes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Infectious Diseases

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