Plasmodium malariae in Israeli Travelers: A Nationwide Study

Area of Science:

• Tropical medicine
• Infectious diseases
• Diagnostic parasitology

Background:

• Plasmodium malariae is a rare cause of malaria in travelers.
• Polymerase chain reaction (PCR) improves P. malariae detection specificity.
• Limited understanding of P. malariae diagnosis and clinical presentation in travelers.

Purpose of the Study:

• To describe unique aspects of P. malariae diagnosis in travelers.
• To analyze the clinical course of P. malariae infections in travelers.

Main Methods:

• Retrospective study of PCR-proven P. malariae monoinfections in Israeli travelers (2008-2017).
• Data collected on diagnosis methods, clinical characteristics, and laboratory findings.
• Analysis of malaria cases reported to the Ministry of Health Reference Parasitology Laboratory.

Main Results:

• Eighteen P. malariae cases were identified, all acquired in Africa.
• The proportion of P. malariae increased from 2% to 10% of malaria cases.
• Blood smears and rapid antigen tests showed low sensitivity and specificity for P. malariae diagnosis.
• Prophylaxis failure occurred in 39% of patients, leading to prolonged prepatent periods.

Conclusions:

• P. malariae proportion is rising among travelers.
• Routine diagnostic methods (blood smear, antigen test) are inadequate for P. malariae.
• PCR is recommended for high clinical suspicion.
• Prophylaxis failure can cause delayed diagnosis and presentation.