Tropical and Parasitic Infections

Malaria - Mosquito's Kiss of Misery

• Agents: Plasmodium spp. (P.f - severe; P.v - common, relapses; P.o - relapses; P.m - quartan).
• Vector: Female Anopheles mosquito.
• Life Cycle: Sporozoites (infect) → Liver (exo-erythrocytic schizogony; hypnozoites in P.v/P.o cause relapse) → Merozoites → RBCs (erythrocytic schizogony, symptoms) → Gametocytes (transmit).
• Clinical: Periodic fever (cold-hot-sweat stages), chills, splenomegaly, anemia. Tertian (48h: P.f, P.v, P.o), Quartan (72h: P.m).
• Severe P. falciparum: Cerebral malaria, severe anemia (Hb < 5 g/dL), ARDS, hypoglycemia, renal failure (Blackwater fever), shock, acidosis, hyperparasitemia.
• Diagnosis:
  • Microscopy (Giemsa): Thick (detection), Thin (species, parasitemia). Ring forms; P.f gametocytes crescent-shaped.
  • RDTs: Detect HRP-2 (P.f) or pLDH (all species).
• Treatment (NVBDCP):
  • Uncomplicated P.v/P.o: Chloroquine + Primaquine (⚠️ check G6PD).
  • Uncomplicated P.f: ACT (e.g., Artemether-Lumefantrine).
  • Severe Malaria: IV Artesunate, then oral ACT.
• Prevention: Mosquito control (LLINs, IRS), repellents.

⭐ Blackwater fever (hemoglobinuria, renal failure) is a severe complication of P. falciparum malaria, often linked to quinine usage or G6PD deficiency with oxidant drugs during infection.

Other Protozoa - Tiny Terrors, Big Troubles

• Leishmaniasis (Kala-azar: L. donovani)
  • Vector: Sandfly (Phlebotomus).
  • Clinical: Fever, massive splenomegaly, pancytopenia, hypergammaglobulinemia.
  • Diagnosis: LD bodies (macrophages), rK39 antigen test.
  • Treatment: Amphotericin B (liposomal), Miltefosine.
• Trichomoniasis (T. vaginalis)
  • Transmission: Sexual (STD).
  • Female: Frothy yellow-green discharge, vulvovaginitis, "strawberry cervix" (colpitis macularis).
  • Male: Often asymptomatic; urethritis.
  • Diagnosis: Motile trophozoites on wet mount.
  • Treatment: Metronidazole (patient & partner). 📌 Treat partners!

Helminths - Crawling Critter Chaos

• Nematodes (Roundworms):
  • Ascaris lumbricoides (Giant roundworm): Intestinal/biliary obstruction, Loeffler's syndrome. Rx: Albendazole.
  • Ancylostoma/Necator (Hookworm): Ground itch, iron deficiency anemia. Rx: Albendazole.
  • Filariasis (Wuchereria bancrofti, B. malayi):
    • Lymphatic dysfunction → elephantiasis, hydrocele, chyluria.
    • Dx: Nocturnal microfilariae in blood. Rx: Diethylcarbamazine (DEC).
    • ⭐ > Wuchereria bancrofti microfilariae exhibit nocturnal periodicity, best detected in blood samples taken between 10 PM - 2 AM.
  • Strongyloides stercoralis: Larva currens, autoinfection; hyperinfection (immunocompromised). Rx: Ivermectin.
  • Enterobius vermicularis (Pinworm): Nocturnal perianal itching. Dx: Scotch tape test. Rx: Albendazole.
• Cestodes (Tapeworms):
  • Taenia solium (Pork Tapeworm):
    • Neurocysticercosis (NCC): Commonest cause of adult-onset seizures in endemic areas.
    • Dx: CT/MRI (calcified granulomas, vesicular cysts with scolex). Rx (NCC): Albendazole + Corticosteroids.
  • Echinococcus granulosus (Hydatid Disease):
    • Liver/lung cysts (eggshell calcification, hydatid sand). Rx: Albendazole, PAIR. ⚠️ Anaphylaxis on cyst rupture.
• Trematodes (Flukes):
  • Schistosoma haematobium: Hematuria, ↑ bladder Ca risk. S. mansoni/japonicum: portal hypertension. Rx: Praziquantel.
  • 📌 Mnemonic for Praziquantel: "Prazi for Flukes & Tapes!" (Schistosoma, Taenia).

High‑Yield Points - ⚡ Biggest Takeaways

• P. falciparum causes severe malaria; ACT is first-line. Primaquine for P. vivax/ovale radical cure (check G6PD).
• Dengue (Aedes): Tourniquet test, warning signs crucial. Supportive care.
• Kala-azar (sandfly): Fever, splenomegaly, pancytopenia. Liposomal Amphotericin B is DOC.
• Lymphatic Filariasis: Lymphedema, hydrocele. DEC is treatment.
• Amoebic liver abscess: Commonest extra-intestinal amoebiasis. Metronidazole is DOC.
• Neurocysticercosis (T. solium): Adult-onset seizures. Albendazole + steroids.
• Hookworm: Causes iron deficiency anemia. Treat with Albendazole.