MISDIAGNOSIS RATES AND TREATMENT OUTCOMES of PLASMODIUM FALCIPARUM AND PLASMODIUM VIVAX MIXED INFECTIONS AT A HEALTH FACILITY IN ARBA MINCH, ETHIOPIA

Abstract

Accurate malaria diagnosis and treatment are crucial for malaria control. Diagnosing mixed Plasmodium infections using microscopy can be challenging, and the documentation of treatment outcomes is lacking. This study evaluated diagnostic accuracy and treatment outcomes for mixed infections at a health facility in Arba Minch, Ethiopia. A prospective single-arm study was conducted from March to August 2023, involving 90 uncomplicated mixed P. falciparum and P. vivax infections aged 15 years and older. Eighty were included for primary endpoint analyses. The accuracy of the microscopy diagnosis at health facility was evaluated by senior microscopists and nested polymerase chain reactions (nPCR) assay. Participants received a standard dose of Artemether-Lumefantrine (AL) following treatment guidelines and a low-dose primaquine (PQ) regimen for 14 days. They were then monitored for clinical and parasitological outcomes over a 28-day follow-up period. Results showed an alarming 85% (68/80) misdiagnosis rate, with only 15% (12/80) of infections confirmed as mixed infections through nPCR. Among the nPCR-confirmed infections, 58.8% (47/80) were identified as P. vivax, while 26.35 (21/80) were P. falciparum mono-infections. The overall cure rate for AL combined with PQ in all malaria infections was 95% (95% CI: 87.7-98.6). Microscopically, 98% of the patients (n = 79) cleared asexual parasites by day three, and all were afebrile. Gametocytes were detected in 57.5% of all malaria infections, and complete clearance was achieved on day 21. During the 28-day follow-up period, PCR-based analysis identified 17.5% (14/80) recurrent infections, while only 5% (4/80) were detected using microscopy. Among the PCR-based recurrent infections, 65% (9/14) were infections caused by P. vivax, 21% (3/14) were due to P. falciparum, and 14% (2/14) were mixed infections. All recurrent infections were identified on days 21 and 28 after treatment. Genotypic analysis showed that all P. falciparum recurrent cases were reinfections. The combination treatment of AL and PQ was found to be effective against P. vivax, P. falciparum, and mixed infections. However, relying solely on microscopy may not be sufficient for malaria diagnosis. Therefore, it is recommended to utilize more sensitive diagnostic tools in therapeutic efficacy studies to accurately assess drug effectiveness.