A 32-year-old male from rural Bihar presents with fever, chills, and jaundice for 5 days. He reports a history of mosquito bites 10 days ago. Physical examination reveals hepatosplenomegaly and mild anaemia. Peripheral blood smear shows ring forms and crescent-shaped gametocytes within RBCs. Haemoglobin is 9.2 g/dL. What is the most likely diagnosis?

Explanation

## Identification of Plasmodium falciparum **Key Point:** The crescent-shaped (banana-shaped) gametocytes are pathognomonic for *Plasmodium falciparum*. These are the only plasmodium species that produce distinctively curved gametocytes visible on blood smear. ### Morphological Features on Peripheral Smear | Feature | P. falciparum | P. vivax | P. malariae | P. ovale | |---------|---------------|---------|-------------|----------| | **Gametocyte shape** | Crescent/banana | Round | Round | Round | | **Ring forms** | Multiple per RBC, delicate | Single, thick | Single | Single | | **RBC size** | Normal or slightly enlarged | Enlarged | Normal | Enlarged, fimbriated | | **Maurer's dots** | Present | Absent | Absent | Absent | | **Stippling** | Maurer's clefts | Schüffner's dots | Maurer's dots | Schüffner's dots | **High-Yield:** *P. falciparum* is the most dangerous species, causing severe malaria with complications like cerebral malaria, acute kidney injury, and severe anaemia—all evident in this patient's presentation (jaundice, anaemia, hepatosplenomegaly). ### Clinical Correlation **Clinical Pearl:** The 10-day incubation period and acute presentation with fever, jaundice, and anaemia are consistent with *P. falciparum*, which has the shortest incubation period (8–11 days) among plasmodia and causes the most severe disease. **Mnemonic:** **CFAR** — *Crescent gametocytes = Falciparum Always Recognized* [cite:Park 26e Ch 8]