Yarden Yavne1, Eyal Leshem1,2, Yael Paran1,3, Eyal Nadir4, Miriam Weinberger1,5, Michal Stein6, Neta Petersiel7, Dafna Yahav8, Tamar Grossman9, Eli Schwartz1,2. 1. Sackler Faculty of Medicine, Tel-Aviv University. 2. Center for Geographic Medicine and Department of Medicine C, Chaim Sheba Medical Center, Tel Hashomer. 3. Infectious Diseases Unit, Sourasky Medical Center, Tel Aviv. 4. Infectious Diseases Unit, Kaplan Medical Center, Rehovot, affiliated to the School of Medicine, Hebrew University and Hadassah, Jerusalem. 5. Infectious Diseases Unit, Assaf Harofeh Medical Center. 6. Infectious Diseases Unit, Hillel Yaffe Medical Center, Hadera. 7. Unit of Infectious Diseases and Internal Medicine B, Rambam Medical Center and Bruce Rappaport Faculty of Medicine, Technion, Haifa. 8. Unit of Infectious Diseases, Rabin Medical Center, Beilinson Hospital, Petah-Tikva. 9. Reference Parasitology Laboratory, Central Laboratories, Public Health Services, Ministry of Health, Jerusalem, Israel.
Abstract
BACKGROUND: Little is known about Plasmodium malariae, a relatively rare cause of malaria in returned travelers. Recently, polymerase chain reaction (PCR) use for malaria diagnosis has enhanced specificity of P. malariae detection. The study objective was to describe the unique aspects of P. malariae diagnosis and clinical course in travelers. METHODS: Malaria is a reportable disease in Israel. All PCR-proven P. malariae monoinfections in Israeli travelers between January 2008 and January 2017 were retrieved from the Ministry of Health Reference Parasitology Laboratory. Data regarding method and timing of diagnosis, clinical characteristics, and laboratory testing were collected from patient charts. RESULTS: Eighteen patients with P. malariae were included. All cases were acquired in Africa. During the study period, the relative proportion of P. malariae increased (2%-10% of all malaria cases). Malaria was identified by blood smear in 10 of 18 patients (56%) on admission, and by rapid antigen test in 5 of 18 (29%) patients only, while P. malariae speciation was correctly identified by smear in 2 of 18 (11%) patients. Though all patients reported fever, only 4 of 18 (22%) described a quartan fever course. In 7 of 18 (39%) patients, malaria was contracted despite prophylactic treatment. Five patients had prolonged prepatent periods (median, 55 days), all of whom received prior prophylaxis. CONCLUSIONS: The relative proportion of P. malariae is on the rise. Diagnosis in routine clinical settings is inadequate due to the low sensitivity and specificity of blood smears. PCR should be considered when clinical suspicion is high. Prophylaxis failure, which caused delayed clinical presentation, was documented.
BACKGROUND: Little is known about Plasmodium malariae, a relatively rare cause of malaria in returned travelers. Recently, polymerase chain reaction (PCR) use for malaria diagnosis has enhanced specificity of P. malariae detection. The study objective was to describe the unique aspects of P. malariae diagnosis and clinical course in travelers. METHODS: Malaria is a reportable disease in Israel. All PCR-proven P. malariae monoinfections in Israeli travelers between January 2008 and January 2017 were retrieved from the Ministry of Health Reference Parasitology Laboratory. Data regarding method and timing of diagnosis, clinical characteristics, and laboratory testing were collected from patient charts. RESULTS: Eighteen patients with P. malariae were included. All cases were acquired in Africa. During the study period, the relative proportion of P. malariae increased (2%-10% of all malaria cases). Malaria was identified by blood smear in 10 of 18 patients (56%) on admission, and by rapid antigen test in 5 of 18 (29%) patients only, while P. malariae speciation was correctly identified by smear in 2 of 18 (11%) patients. Though all patients reported fever, only 4 of 18 (22%) described a quartan fever course. In 7 of 18 (39%) patients, malaria was contracted despite prophylactic treatment. Five patients had prolonged prepatent periods (median, 55 days), all of whom received prior prophylaxis. CONCLUSIONS: The relative proportion of P. malariae is on the rise. Diagnosis in routine clinical settings is inadequate due to the low sensitivity and specificity of blood smears. PCR should be considered when clinical suspicion is high. Prophylaxis failure, which caused delayed clinical presentation, was documented.