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. 2008 Aug;79(2):185-91.

Relationship between exposure, clinical malaria, and age in an area of changing transmission intensity

Wendy P O'Meara  1 , Tabitha W Mwangi, Thomas N Williams, F Ellis McKenzie, Robert W Snow, Kevin Marsh
Affiliations

Relationship between exposure, clinical malaria, and age in an area of changing transmission intensity

Wendy P O'Meara et al. Am J Trop Med Hyg. 2008 Aug.

Abstract

The relationship between malaria transmission intensity and clinical disease is important for predicting the outcome of control measures that reduce transmission. Comparisons of hospital data between areas of differing transmission intensity suggest that the mean age of hospitalized clinical malaria is higher under relatively lower transmission, but the total number of episodes is similar until transmission drops below a threshold, where the risks of hospitalized malaria decline. These observations have rarely been examined longitudinally in a single community where transmission declines over time. We reconstructed 16 years (1991-2006) of pediatric hospital surveillance data and infection prevalence surveys from a circumscribed geographic area on the Kenyan coast. The incidence of clinical malaria remained high, despite sustained reductions in exposure to infection. However, the age group experiencing the clinical attacks of malaria increased steadily as exposure declined and may precede changes in the number of episodes in an area with declining transmission.

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Figures

Figure 1
Figure 1
Annual incidence of clinical malaria (fever plus parasites) per person year at risk (PYAR) with 95% confidence intervals in a longitudinal cohort of children between birth and 8 years old.
Figure 2
Figure 2
A, Incidence by year of all pediatric hospital admissions (light bars) and slide-positive pediatric admissions (dark bars) per 1,000 children 0–12 years old and residents of Ngerenya. B, Fraction of all admissions that were slide positive by year.
Figure 3
Figure 3
Mean age and 95% confidence intervals (dotted lines) of slide-positive pediatric admissions (left) and slide-negative pediatric admissions (right) by year from Ngerenya.
Figure 4
Figure 4
Mean age and incidence of slide-positive hospital admissions plotted versus infant parasite prevalence. Mean age is fit with a linear model and incidence with a power model to facilitate identification of trends.
See this image and copyright information in PMC

References

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