A 32-year-old male labourer from rural Jharkhand presents to the PHC with fever, chills, and sweating for 3 days. He reports that fever occurs every alternate day, preceded by rigors and followed by profuse diaphoresis. His wife and two children are asymptomatic. On examination, temperature is 39.5°C, spleen is palpable 2 cm below the costal margin, and liver edge is felt 1 cm below the costal margin. Blood smear shows ring forms and trophozoites within RBCs. Which Plasmodium species is most likely responsible, and what is the epidemiological significance of his clinical presentation?