Title: Seasonality and malaria in a West African village: does high parasite density predict fever incidence?

POPLINE Document Number: 125328

Author(s):

Bouvier P
Rougemont A
Breslow N
Doumbo O
Delley V
Dicko A
Diakite M
Mauris A
Robert CF

Source citation:

AMERICAN JOURNAL OF EPIDEMIOLOGY, 1997 May 1;145(9):850-7.

Abstract:

In a cohort study, the effect of blood malaria parasite density on fever incidence in children was studied in an endemic area with 9 days' follow-up of children aged 1-12 years during two time periods: the end of the dry season (May 1993: n = 783) and the end of the rainy season (October 1993: n = 841) in Bougoula, West Africa (region of Sikasso, Mali). The number of registered children was 928 in the dry season and 998 in the rainy season. Complete follow-up and information were available for 835 children in the dry season and for 964 children in the rainy season. The 9-day cumulative fever incidence (body temperature above 38.0 degrees Celsius) increased from 2.0% in the dry season to 8.2% in the rainy season (p < 0.0001). In the rainy season, the risk of fever increased in children aged 1-3 years (relative risk [RR] = 2.5; 95% confidence interval [CI], 1.6-4.1); in those with an initial parasitemia greater than 15,000/mcl (RR = 2.7; 95% CI, 1.4-5.4); in those with an enlarged spleen (RR = 2.0; 95% CI, 1.2-3.3); or in those with anemia (hematocrit <30%: RR = 1.8; 95% CI, 1.1-2.9). In the dry season, anemia (hematocrit <30%) was the only predictor of fever incidence with a cumulative incidence of 10.0%. In nonanemic children, a parasite count of >2000/mcl was the next best predictor. In the rainy season, the best predictors of fever were age (<4 years), enlarged spleen, and high parasite density (>1/mcl). Even in the higher risk groups, the cumulative incidence was <20%. Most children with high parasite density do not develop fever subsequently. The association between parasite density and fever varies according to age and season. Since even high levels of parasite density do not reliably predict fever incidence, parasite density should be considered not so much a direct marker of an ongoing attack but as just one indicator of the likelihood of a current or imminent attack or even one just passed.

Keywords:

Mali
Cohort Analysis
Malaria
Child
Child Health
Seasonal Variation
Hemoglobin Level
Signs and Symptoms
Developing Countries
Africa, Western
Africa, Sub Saharan
Africa
Research Methodology
Parasitic Diseases
Diseases
Youth
Age Factors
Population Characteristics
Demographic Factors
Population
Health
Population Dynamics
Hemic System
Physiology
Biology