M.D. MSc.
Chau Van Khanh
Department of Tropical Diseases Clinical Treatment and Research, Institute of Malariology, Parasitology, and Entomology Quy Nhon, Gia Lai Province
Title: Current Antimalarial Treatments in Vietnam: High Efficacy but Delayed Parasite Clearance and First Clinical Evidence on Plasmodium malariae
Name(s): Chau Van Khanh, MD, MTM; Huynh Hong Quang, MD, PhD
Department of Tropical Diseases Clinical Treatment and Research
Institute of Malariology, Parasitology, and Entomology Quy Nhon, Gia Lai Province, Vietnam
Background: Malaria remains the “king of infectious diseases” due to its unique biological and epidemiological complexities. Although Vietnam is approaching malaria elimination, antimalarial drug resistance continues to threaten treatment efficacy. In addition to Plasmodium falciparum and P. vivax, recent reports indicate an unprecedented increase of P. malariae in Vietnam, yet therapeutic efficacy data for this species are almost entirely lacking. Robust Therapeutic Efficacy Studies (TES) are therefore essential to guide evidence-based national treatment policies.
Objectives: To evaluate the clinical treatment efficacy of current antimalarial regimens for P. falciparum, P. vivax, and P. malariae in Vietnam.
Methods: A TES, the gold standard for antimalarial resistance monitoring, was conducted from 2023 to 2025 in Khanh Hoa Province. Patients with P. falciparum were prospectively followed for 42 days, while those with P. vivax and P. malariae were followed for 28 days. Standard regimens included artesunate-pyronaridine plus primaquine for P. falciparum and chloroquine plus primaquine for non-falciparum species.
Results:
A total of 389 malaria patients were recruited, including 133 P. falciparum, 61 P. vivax, and 195 P. malariae mono-infections. Median (IQR) parasite densities at Day 0 were 9,045 (2,385–19,210) parasites/µL for P. falciparum, 5,464 (1,742–8,107) for P. vivax, and 1,800 (487–5,257) for P. malariae. Gametocyte carriage was notably high in P. vivax (96.7%) and P. malariae (91.8%).
Adequate Clinical and Parasitological Response (ACPR) remained high: 96.6% (95%CI: 91.4–98.9) for P. falciparum, 100% (95%CI: 94.0–100) for P. vivax, and 98.9% (95%CI: 96.0–99.9) for P. malariae. Treatment failures included four late clinical failures in P. falciparum and two early treatment failures in P. malariae. Delayed parasite clearance was observed, with Day 3 positivity rates of 28.7% (P. falciparum), 0% (P. vivax), and 19.9% (P. malariae). Mean parasite clearance half-life was 6.48, 4.93, and 6.20 hours for P. falciparum, P. vivax, and P. malariae, respectively.
Conclusions:
Current antimalarial regimens remain highly effective, with ACPR >90% across all species. However, delayed parasite clearance in P. falciparum and P. malariae indicates emerging resistance that may compromise future treatment efficacy. This study provides one of the largest TES datasets in Vietnam and the first substantial clinical evidence on P. malariae. Continuous drug efficacy and molecular surveillance are essential to sustain malaria elimination efforts.
Biography of the presenting author
Dr. Chau Van Khanh is a medical doctor and clinical researcher at the Department of Tropical Diseases – Clinical Treatment and Research, Institute of Malariology, Parasitology and Entomology Quy Nhon (IMPE-QN), Vietnam. He obtained his Degree of Doctor of Medicine from Hue University of Medicine and Pharmacy in 2019 and completed a Master of Tropical Medicine (Distinction) and a Diploma in Tropical Medicine and Hygiene (DTMH) at Nagasaki University, Japan in 2023.
His research focuses on malaria epidemiology, antimalarial drug resistance, and therapeutic efficacy studies, particularly in the Greater Mekong Subregion. He has served as principal investigator and co-investigator in multiple national and international malaria research projects, including therapeutic efficacy surveillance and molecular resistance monitoring.
He has authored and co-authored numerous publications in peer-reviewed journals, including Journal of Antimicrobial Chemotherapy, Emerging Microbes & Infections, Malaria Journal, and BMC Infectious Diseases. His recent work has contributed to understanding the emerging epidemiology of Plasmodium malariae in Vietnam.
Dr. Khanh is actively involved in national malaria elimination programs and has presented at several national and international scientific conferences.
Presenting author details
Full name: Chau Van Khanh
Contact number: (+84) 868551799
Email: cvkhanh01@gmail.com
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ORCID: 0009-0006-9787-2316
Website: https://cvkhanh01.blogspot.com
Session name/ number:
Category: Oral presentation