Abstract:
Background: Malaria remains a major public health problem in Kenya
accounting for the highest morbidity and mortality especially among children.
Previous reports indicate that infectious agents display heterogeneity in both
space and time and malaria is no exception. Heterogeneity has been shown to
reduce the effectiveness of interventions. Previous studies have implicated
genetic (both human and parasite) and environmental factors as mainly
responsible for variation in malaria risk. Human behaviour and its potential
risk for contributing to variation in malaria risk has not been extensively
explored.
Objective: To determine if there were behavioural differences between the
people living in hotspots (high malaria burden) and cold spots (low malaria
burden) within a geographically homogeneous and high malaria transmission
region.
Design: A prospective closed cohort study.
Setting: The study was conducted in the Health and Demographic Surveillance
Site in Bungoma East sub-County.
Subjects: A total of 400 people in randomly selected households in both the
fever hotspots and cold spots were tested for malaria at quarterly intervals
using malaria rapid diagnostic tests (RDTs).
Results: Significant heterogeneity in malaria incidence and prevalence was
observed between villages. Incidence of malaria was significantly higher in
the hotspots (high malaria burden areas) compared to the cold spots (low
malaria burden) (49 episodes per 1000 person months compared to 26/1000,
ttest p < 0.001). The incidence also varied significantly among the individual
villages by season (P: 0.0071). Knowledge on malaria therapy was significantly associated with whether one was in the cold spot or hotspot (P: 0.033).
Behavioural practices relating to ITN use were significantly associated with
region during particular seasons (P: 0.0001 and P: 0.0001 respectively).
Conclusion: There is marked and significant variation in the incidence of
malaria among the villages creating actual hotspots of malaria within the
larger hotspot. There is a significant difference in malaria infections between
the hotspots and cold spots. Knowledge on malaria therapy and behavioural
factors such as ITN use may contribute to the observed differences during
some seasons.