Asymptomatic Plasmodium infection among primary schoolchildren and Anopheles-mediated malaria transmission: A cross-sectional study in Ouidah; south-western Benin

• Published in: Parasite epidemiology and control Vol. 21; p. e00285
• Main Authors: Medjigbodo, Adandé A., Djossou, Laurette, Adoha, Constantin J., Djihinto, Oswald Y., Ogouyemi-Hounto, Aurore, Donnelly, Martin J., Weetman, David, Djogbénou, Luc S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.05.2023; Elsevier
• Subjects: An. gambiae; Asymptomatic; Gametocyte; Original Research article; Plasmodium falciparum; Transmission; L1014F; Transmission; NMCP; Asymptomatic; Gametocyte; IRS; MDA; IPT; DMFAs; An; Plasmodium falciparum; DDT; MSaT; G119S; WHO; OP; USA; PYR; s.l; ITNs; spp; WBCs; CX; An. gambiae; s.s; IPT, Intermittent Preventive Therapy; ITNs, Insecticide-treated bed nets; spp., species; WHO, Word Health Organization; s.l., sensu lato; DDT, Dichlorodiphenyltrichloroethane; s.s., sensu stricto; USA, United States of America; CX, Carbamates; G119S, Glycine substitution by Serine at codon 119; WBCs, White blood cells; NMCP, National Malaria Control Programme; IRS, Indoor residual spraying; PYR, Pyrethroids; L1014F, Leucine substitution by Phenylalanine at codon 1014; OP, Organophosphates; MDA, Mass Drug Administration; An., Anopheles; MSaT, Mass Screening and Treatment; DMFAs, Direct membrane feeding assays
• ISSN: 2405-6731; 2405-6731
• DOI: 10.1016/j.parepi.2023.e00285

Understanding the contribution of asymptomatic Plasmodium carriers in malaria transmission might be helpful to design and implement new control measures. The present study explored the prevalence of asymptomatic and symptomatic Plasmodium infections (asexual and sexual stages) and the contribution of asymptomatic P. falciparum carriers to Anopheles-mediated malaria transmission in Ouidah (Benin). Thick and thin blood smears were examined from finger-prick blood specimens using light microscopy, and the density of both asexual and sexual stages of Plasmodium species was calculated. Infectivity of gametocyte-infected blood samples to Anopheles gambiae was assessed through direct membrane feeding assays. The prevalence of asymptomatic Plasmodium infections was 28.73% (289/1006). All the asymptomatic gametocyte-carriers (19/19), with gametocytaemia ranging from 10 ̶ 1200 gametocytes/μL of blood, were infectious to An. gambiae mosquitoes. The mean oocyst prevalences varied significantly (χ2 = 16.42, df = 7, p = 0.02) among laboratory mosquito strains (6.9 ̶ 39.4%) and near-field mosquitoes (4.9 ̶ 27.2%). Likewise, significant variation (χ2 = 56.85, df = 7, p = 6.39 × 10−10) was observed in oocyst intensity. Our findings indicate that asymptomatic Plasmodium carriers could significantly contribute to malaria transmission. Overall, this study highlights the importance of diagnosing and treating asymptomatic and symptomatic infection carriers during malaria control programmes.