51. A micro-epidemiological analysis of febrile malaria in Coastal Kenya showing hotspots within hotspots
- Author
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Teun Bousema, Kevin Marsh, Evasius Bauni, Simon I. Hay, Thomas N. Williams, Judy Peshu, Peter W. Gething, Steffen Borrmann, Mark Otiende, Christopher Nyundo, David Benz, David L. Smith, Bryan Greenhouse, Mahfudh Bashraheil, and Philip Bejon
- Subjects
malaria control ,falciparum ,Risk Factors ,Epidemiology ,Malaria, Falciparum ,Biology (General) ,Child ,Pediatric ,Microbiology and Infectious Disease ,Ecology ,General Neuroscience ,Spatial epidemiology ,food and beverages ,General Medicine ,3. Good health ,Geography ,Infectious Diseases ,spatial epidemiology ,Medicine ,hotspot ,Infection ,Malaria falciparum ,Research Article ,Falciparum ,medicine.medical_specialty ,congenital, hereditary, and neonatal diseases and abnormalities ,Fever ,QH301-705.5 ,Science ,information science ,General Biochemistry, Genetics and Molecular Biology ,Rare Diseases ,Malaria transmission ,Hotspot (geology) ,parasitic diseases ,medicine ,Humans ,human ,Inverse correlation ,General Immunology and Microbiology ,Mean age ,biochemical phenomena, metabolism, and nutrition ,medicine.disease ,Kenya ,Malaria ,Vector-Borne Diseases ,Epidemiology and Global Health ,Good Health and Well Being ,lnfectious Diseases and Global Health Radboud Institute for Health Sciences [Radboudumc 4] ,Biochemistry and Cell Biology ,Demography - Abstract
Malaria transmission is spatially heterogeneous. This reduces the efficacy of control strategies, but focusing control strategies on clusters or ‘hotspots’ of transmission may be highly effective. Among 1500 homesteads in coastal Kenya we calculated (a) the fraction of febrile children with positive malaria smears per homestead, and (b) the mean age of children with malaria per homestead. These two measures were inversely correlated, indicating that children in homesteads at higher transmission acquire immunity more rapidly. This inverse correlation increased gradually with increasing spatial scale of analysis, and hotspots of febrile malaria were identified at every scale. We found hotspots within hotspots, down to the level of an individual homestead. Febrile malaria hotspots were temporally unstable, but 4 km radius hotspots could be targeted for 1 month following 1 month periods of surveillance. DOI: http://dx.doi.org/10.7554/eLife.02130.001, eLife digest Malaria remains a formidable threat to public health in tropical regions. The parasite that causes the disease is transmitted to humans by bites from infected mosquitoes, and the complicated lifecycle of the parasite makes developing vaccines difficult. However, preventive strategies are effective at reducing the spread of malaria. The two most widely used and effective strategies are the use of pesticide-treated bed nets to create a barrier between sleeping families and biting mosquitoes, and indoor residual spraying to reduce the numbers of mosquitoes biting sleeping families in homesteads. Other potential preventive strategies include killing mosquito larvae in breeding sites and mass anti-malarial drug treatment for infected humans. Targeting preventive efforts to malaria hotspots—the areas where the risk of malaria transmission is greatest—may help to eliminate malaria more efficiently. Unfortunately, identifying hotspots is complicated as there are many different factors that affect how malaria spreads. These factors range from ecological conditions such as rainfall and soil type, to human effects like population density and migration. Bejon et al. have examined the patterns of malaria transmission in Kenya over 9 years. Over this period, 54% of children who went to health clinics with a fever tested positive for the parasite that causes malaria. Infected children from areas with the highest rate of malaria infection were, on average, younger than those from less infected regions. This makes sense as in highly affected areas children have a greater chance of encountering the parasite at an early age. They are therefore more likely to get malaria when younger and, as exposure to the parasite can provide some immunity to a child, they are also less likely to get infected again when older. In addition, mapping the spread of malaria reveals hotspots at different geographical scales. Bejon et al. could see hotspots within hotspots, and in some cases could go as far as identifying the individual homesteads most at risk of malaria. Public health workers could potentially use these analyses to identify areas that are likely to be hotspots and then target preventive measures there for the next month. However, the constantly changing locations of the hotspots means workers would have to reanalyse the data and retarget their interventions at the end of each month. DOI: http://dx.doi.org/10.7554/eLife.02130.002
- Published
- 2014