Mixed Plasmodium Infections: Report of Four Cases from the Military Hospital of Tunis

<ns3:p> Background Malaria is a life-threatening vector-borne disease caused by five species of the genus <ns3:italic>Plasmodium (P.)</ns3:italic> It can present as mixed infections that remain underreported and pose diagnostic, therapeutic and prognostic challenges. The objective of the present study was to describe the epidemiological, clinical, and biological features of four cases of mixed <ns3:italic>Plasmodium</ns3:italic> infection. Methods This retrospective descriptive study included cases of mixed <ns3:italic>Plasmodium</ns3:italic> infections diagnosed at the Parasitology Laboratory of the Military Hospital of Tunis between 2022 and 2025. Diagnosis was established using May–Grünwald–Giemsa–stained thin blood smears, Giemsa–stained thick smears, and rapid diagnostic tests. <ns3:italic>Plasmodium</ns3:italic> species were identified according to standard microscopic morphological criteria. Results We report four cases of mixed <ns3:italic>Plasmodium</ns3:italic> infection diagnosed in military personnel returning from deployment in Central Africa. The patients were aged 31–52 years (mean age 38.8 years) with sex ratio 3. They presented within 10–30 days post-return with fever (38–42 °C) associated with headache, myalgia, abdominal pain, and/or vomiting. All had adhered to malaria chemoprophylaxis, and three reported no prior malaria episodes, while one patient had a history of six previous attacks. Rapid diagnostic tests were positive for pan-Plasmodium pLDH in all cases; two patients were also positive for HRP2. Peripheral blood smears confirmed mixed infections. Parasitemia was generally low (<1% in three cases, 1% in one case). Treatment consisted of artemether–lumefantrine (Coartem <ns3:sup>®</ns3:sup> ) for all patients, combined with primaquine for those with <ns3:italic>P. ovale</ns3:italic> infection. Clinical evolution was favorable in all cases, and follow-up blood smears on days 3, 7, and 28 confirmed parasitological clearance, with only rare degenerated trophozoites observed in one patient on day 3. Conclusion Mixed <ns3:italic>Plasmodium</ns3:italic> infections can influence disease severity, treatment outcomes, and drug resistance. Accurate diagnosis and radical therapy are keys to preventing relapses. </ns3:p>