The temporal dynamics of Plasmodium species infection after artemisinin-based combination therapy (ACT) among asymptomatic children in the Hohoe municipality, Ghana

Abstract

Background The routine surveillance of asymptomatic malaria using nucleic acid-based amplifcation tests is essen‑ tial obtaining reliable data that would inform malaria policy formulation and the implementation of appropriate control measures. Methods In this study, the prevalence rate and the dynamics of Plasmodium species among asymptomatic children (n=1697) under 5 years from 30 communities within the Hohoe municipality in Ghana were determined. Results and discussion The observed prevalence of Plasmodium parasite infection by polymerase chain reac‑ tion (PCR) was 33.6% (571/1697), which was signifcantly higher compared to that obtained by microscopy [26.6% (451/1697)] (P<0.0001). Based on species-specifc analysis by nested PCR, Plasmodium falciparum infection [33.6% (570/1697)] was dominant, with Plasmodium malariae, Plasmodium ovale and Plasmodium vivax infections account‑ ing for 0.1% (1/1697), 0.0% (0/1697), and 0.0% (0/1697), respectively. The prevalence of P. falciparum infection among the 30 communities ranged from 0.0 to 82.5%. Following artesunate-amodiaquine (AS+AQ, 25 mg/kg) treatment of a sub-population of the participants (n=184), there was a substantial reduction in Plasmodium parasite prevalence by 100% and 79.2% on day 7 based on microscopy and nested PCR analysis, respectively. However, there was an increase in parasite prevalence from day 14 to day 42, with a subsequent decline on day 70 by both micros‑ copy and nested PCR. For parasite clearance rate analysis, we found a signifcant proportion of the participants harbouring residual Plasmodium parasites or parasite genomic DNA on day 1 [65.0% (13/20)], day 2 [65.0% (13/20)] and day 3 [60.0% (12/20)] after initiating treatment. Of note, gametocyte carriage among participants was low before and after treatment. Conclusion Taken together, the results indicate that a signifcant number of individuals could harbour residual Plasmodium parasites or parasite genomic DNA after treatment. The study demonstrates the importance of routine surveillance of asymptomatic malaria using sensitive nucleic acid-based amplifcation techniques