Malaria remains a major global health challenge, necessitating the development of highly sensitive and reliable diagnostic technologies capable of detecting subtle variations in blood properties. In this work, a novel photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor incorporating rectangular and circular air-slot features is proposed for broad-range refractive index (RI) sensing and malaria detection in human body. A 30 nm gold layer is employed as the plasmonic medium, and the sensing characteristics are numerically investigated using the finite element method over an analyte RI range of 1.26 to 1.40. The proposed sensor achieves a maximum wavelength sensitivity of 15,000 nm/RIU, amplitude sensitivity of 2197.4 RIU-1, a sensor resolution of 6× 10-6 RIU, and a figure of merit of 357 RIU-1. To assess the potential of the proposed sensor for malaria detection, RI variations corresponding to different stages of infection are analyzed. A maximum wavelength sensitivity of 11,578 nm/RIU for the Trophozoite phase, 10000 nm/RIU for the Schizont phase, and 5714 nm/RIU for the Ring phase was achieved. Validation through comparison with previously reported experimental and simulation – based SPR structures demonstrates close agreement in resonance characteristics, supporting the reliability of the proposed model. Fabrication tolerance analysis also confirms the robustness of the sensor under practical structural variations. Compared with malaria sensors reported in the literature, the proposed sensor achieves a maximum sensitivity while maintaining a broad operating wavelength range of 530 to 1050 nm. These results demonstrate the capability of the proposed sensor to resolve RI variations associated with malaria-infected blood and highlight its potential for future biomedical and refractive index sensing applications.