Risk associated with asymptomatic parasitaemia occurring post-antimalarial treatment

Piero Olliaro*, Loretxu Pinoges, Francesco Checchi, Michel Vaillant, Jean Paul Guthmann

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

18 Citations (Scopus)

Abstract

Objective: Parasites may recur asymptomatically after initial clearance by antimalarial treatment. Current guidelines recommend treatment only when patients develop symptoms or at the end of follow-up. We wanted to assess prospectively the probability of becoming symptomatic and the risks of this practice. Methods: We analysed data collected in 13 trials of uncomplicated paediatric malaria conducted in eight sub-Saharan African countries. These studies followed all cases of post-treatment asymptomatic parasitaemia until they developed symptoms or to the end of the 28-day follow-up period, at which time parasite genotypes were compared to pre-treatment isolates to distinguish between recrudescences and new infections. Results: There were 425 asymptomatic recurrences after 2576 treatments with either chloroquine, sulfadoxine/ pyrimethamine or amodiaquine, of which 225 occurred by day 14 and 200 between day 15 and day 28. By day 28, 42% developed fever (median time to fever = 5 days) and 30% remained parasitaemic but afebrile, while 23% cleared their parasites (outcome unknown in 4%). Young age, parasitaemia ≥500 parasites/μl; onset of parasitaemia after day 14, and treatment with amodiaquine were the main variables associated with higher risk of developing fever. Conclusion: In areas of moderate to intense transmission, asymptomatic recurrences of malaria after treatment carry a substantial risk of becoming ill within a few days and should be treated as discovered. Young children are at higher risk. The higher risk carried by cases occurring in the second half of follow-up may be explained by falling residual drug levels.

Original languageEnglish
Pages (from-to)83-90
Number of pages8
JournalTropical Medicine and International Health
Volume13
Issue number1
DOIs
Publication statusPublished - Jan 2008

Keywords

  • Asymptomatic parasitaemia
  • Malaria
  • Malaria treatment

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