Question : A 24- year- old man presents to the emergency department with fever, nausea, and muscle aches for 2 days. He returned ten days previously from a two- month backpacking trip to Cambodia. He initially took doxycycline for malaria prophylaxis but this was later discontinued because he developed a photosensitive rash. On examination, his temperature is 39.2 °C, heart rate 100 beats per minute, blood pressure 115/ 75 mmHg, peripheral oxygen saturation 99% on room air. Abdominal examination reveals a palpable splenic tip. Investigations: Haemoglobin 157 g/ L (130– 180), Platelets 65 × 109/ L (150– 400). Malaria thick blood film: plasmodium species parasites seen. Malaria thin blood film: trophozoites with large single chromatin dots and amoeboid cytoplasm are seen inside enlarged distorted red blood cells containing pale red dots. Which plasmodium species is most likely responsible for this infection?