26th April 2024

A 37-year-old man presents with a 7-day history of cyclical fever, severe headaches, and profuse sweating.

A 37-year-old man presents with a 7-day history of cyclical fever, severe headaches, and profuse sweating. He recently returned from a two-week trekking expedition in Southeast Asia. 

He reports that he intermittently took malaria prophylaxis during the trip. On examination, his temperature is 38.8°C, pulse rate 96 bpm regular, and BP 110/70 mmHg. He appears lethargic and complains of general body aches. There is no rash or lymphadenopathy. Laboratory investigations show mild anaemia and thrombocytopenia.

Which of the following is the most likely causative organism?