Impact of asymptomatic Plasmodium falciparum infection on the risk of subsequent symptomatic malaria in a longitudinal cohort in Kenya
Kelsey M Sumner,
Judith N Mangeni,
Andrew A Obala,
Elizabeth Freedman,
Lucy Abel,
Steven R Meshnick,
Jessie K Edwards,
Brian W Pence,
Wendy Prudhomme-O'Meara,
Steve M Taylor
Affiliations
Kelsey M Sumner
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, United States; Division of Infectious Diseases, School of Medicine, Duke University, Durham, United States
Judith N Mangeni
School of Public Health, College of Health Sciences, Moi University, Eldoret, Kenya
Andrew A Obala
School of Medicine, College of Health Sciences, Moi University, Eldoret, Kenya
Elizabeth Freedman
Division of Infectious Diseases, School of Medicine, Duke University, Durham, United States
Lucy Abel
Academic Model Providing Access to Healthcare, Moi Teaching and Referral Hospital, Eldoret, Kenya
Steven R Meshnick
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, United States
Jessie K Edwards
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, United States
Brian W Pence
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, United States
Wendy Prudhomme-O'Meara
Division of Infectious Diseases, School of Medicine, Duke University, Durham, United States; School of Public Health, College of Health Sciences, Moi University, Eldoret, Kenya; Duke Global Health Institute, Duke University, Durham, United States
Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, United States; Division of Infectious Diseases, School of Medicine, Duke University, Durham, United States; Duke Global Health Institute, Duke University, Durham, United States
Background: Asymptomatic Plasmodium falciparum infections are common in sub-Saharan Africa, but their effect on subsequent symptomaticity is incompletely understood. Methods: In a 29-month cohort of 268 people in Western Kenya, we investigated the association between asymptomatic P. falciparum and subsequent symptomatic malaria with frailty Cox models. Results: Compared to being uninfected, asymptomatic infections were associated with an increased 1 month likelihood of symptomatic malaria (adjusted hazard ratio [aHR]: 2.61, 95% CI: 2.05 to 3.33), and this association was modified by sex, with females (aHR: 3.71, 95% CI: 2.62 to 5.24) at higher risk for symptomaticity than males (aHR: 1.76, 95% CI: 1.24 to 2.50). This increased symptomatic malaria risk was observed for asymptomatic infections of all densities and in people of all ages. Long-term risk was attenuated but still present in children under age 5 (29-month aHR: 1.38, 95% CI: 1.05 to 1.81). Conclusions: In this high-transmission setting, asymptomatic P. falciparum can be quickly followed by symptoms and may be targeted to reduce the incidence of symptomatic illness. Funding: This work was supported by the National Institute of Allergy and Infectious Diseases (R21AI126024 to WPO, R01AI146849 to WPO and SMT).
