Relapse of Plasmodium Vivax Malaria and Use of Primaquine in Pediatric Population at Tertiary Care Hospital

Objective: To determine the relapse rate of Plasmodium vivax malaria in pediatric patients treated with primaquine. Methodology: A prospective comparative interventional study was conducted in the Department of Pediatrics at Combined Military Hospital Malir, Karachi, from August 2024 to April 2025. Patients aged 1–12 years who presented with either a first episode or relapse of P. vivax malaria, were clinically stable, and of either gender were included. Children were categorized into a treatment group receiving standard antimalarial therapy with primaquine and a control group receiving standard therapy alone. Relapse was defined as the reappearance of Plasmodium vivax parasites on peripheral blood smear following initially documented successful treatment. Data were analyzed using SPSS version 26. Results: A total of 132 pediatric patients were included, with a mean age of 7.73 ± 3.58 years and an almost equal gender ratio. At one month post-treatment, relapse occurred in 9.1% of patients in the control group compared with 2.3% in the study group (p = 0.076). At the second month, relapse was significantly higher in the control group (29.5%) than in the study group (5.7%). At the third-month follow-up, the difference was even more pronounced (38.6% vs. 6.8%) (p = 0.0001). Additionally, the 14-day primaquine regimen showed the lowest relapse rates at both 2 months (4.5%) and 3 months (4.5%) compared with the 7-day regimen (6.8% and 9.1%, respectively) and the control group, indicating that prolonged primaquine therapy is most effective in preventing relapse. Furthermore, relapse rates did not differ significantly according to age within the pediatric population (p > 0.05). Conclusion: The use of primaquine significantly reduced the relapse rate of Plasmodium vivax malaria in pediatric patients compared with standard treatment alone, with the most sustained protection observed with the 14-day regimen.