Spatial Clustering and Risk Factors for Malaria Infections and Marker of Recent Exposure to Plasmodium falciparum from a Household Survey in Artibonite, Haiti

Abstract

Targeting malaria interventions in elimination settings where transmission is heterogeneous is essential to ensure the efficient use of resources. Identifying the most important risk factors among persons experiencing a range of exposure can facilitate such targeting. A cross-sectional household survey was conducted in Artibonite, Haiti, to identify and characterize spatial clustering of malaria infections. Household members (N = 21,813) from 6,962 households were surveyed and tested for malaria. An infection was defined as testing positive for Plasmodium falciparum by either a conventional or novel highly sensitive rapid diagnostic test. Seropositivity to the early transcribed membrane protein 5 antigen 1 represented recent exposure to P. falciparum. Clusters were identified using SaTScan. Associations among individual, household, and environmental risk factors for malaria, recent exposure, and living in spatial clusters of these outcomes were evaluated. Malaria infection was detected in 161 individuals (median age: 15 years). Weighted malaria prevalence was low (0.56%; 95% CI: 0.45-0.70%). Serological evidence of recent exposure was detected in 1,134 individuals. Bed net use, household wealth, and elevation were protective, whereas being febrile, over age 5 years, and living in either households with rudimentary wall material or farther from the road increased the odds of malaria. Two predominant overlapping spatial clusters of infection and recent exposure were identified. Individual, household, and environmental risk factors are associated with the odds of individual risk and recent exposure in Artibonite; spatial clusters are primarily associated with household-level risk factors. Findings from serology testing can further strengthen the targeting of interventions.

Figure 1.

Study area boundaries in Verrettes and La Chapelle, Artibonite, Haiti.

Figure 2.

Spatial clusters of RDT positives, La Chapelle and Verrettes, Artibonite, Haiti. cRDT = conventional rapid diagnostic test; HS-RDT = highly sensitive rapid diagnostic test.

Figure 3.

Spatial clusters of seropositives for IgG indicating recent exposure to Plasmodium falciparum, La Chapelle and Verrettes, Artibonite, Haiti.

Figure 4.

Unweighted prevalence of malaria, by operational unit (OU) 1x1km grid, Artibonite, Haiti.