Chapter 28: Infections – Leishmaniasis, Malaria, Toxoplasmosis, Trypanosomiasis

🦟 Vector-borne & parasitic infections · Visceral & cutaneous leishmaniasis · Plasmodium falciparum/vivax · Congenital toxoplasmosis · Chagas disease · Sleeping sickness
Forfar & Arneil's Textbook of Pediatrics – Clinical recognition, diagnosis, treatment, and prevention of major parasitic diseases.

📖 Key parasitic infections: Leishmaniasis, Malaria, Toxoplasmosis, Trypanosomiasis

🦟 Leishmaniasis
Visceral (kala-azar): fever, hepatosplenomegaly, pancytopenia, hypergammaglobulinemia. Cutaneous: ulcers/scars. Diagnosis: splenic/bone marrow aspirate (amastigotes), serology. Treatment: liposomal amphotericin B (visceral), miltefosine, antimonials.
🦟 Malaria
P. falciparum (severe: cerebral malaria, anemia, acidosis, hypoglycemia), P. vivax/ovale (relapse), P. malariae. Diagnosis: thick/thin smear, RDT. Treatment: artemisinin-based combination therapy (ACT) for uncomplicated; IV artesunate for severe.
🐱 Toxoplasmosis (Toxoplasma gondii)
Congenital: chorioretinitis, intracranial calcifications, hydrocephalus. Acquired: lymphadenopathy, mononucleosis-like. Immunocompromised: encephalitis. Diagnosis: serology (IgM, IgG, avidity), PCR (amniotic fluid, CSF). Treatment: pyrimethamine + sulfadiazine + leucovorin.
🪰 Trypanosomiasis
African (T. brucei gambiense/rhodesiense): sleeping sickness – neurological late stage. American (T. cruzi – Chagas disease): cardiomyopathy, megacolon, megaesophagus. Diagnosis: blood smear, PCR, serology. Treatment: nifurtimox, benznidazole (Chagas); pentamidine, suramin, eflornithine (African).
⚠️ Critical alerts: Severe malaria (cerebral, hyperparasitemia) – IV artesunate. Congenital toxoplasmosis – treat even if asymptomatic. Visceral leishmaniasis – suspect with fever + splenomegaly in endemic area. Chagas disease – can present with acute myocarditis or later megaviscera.

🩺 Stepwise management of major parasitic infections

1
Severe malaria (P. falciparum) – IV artesunate (2.4 mg/kg at 0,12,24h then daily). Monitor for hypoglycemia, seizures, anemia, respiratory distress. Exchange transfusion if hyperparasitemia >20%.
2
Visceral leishmaniasis (kala-azar) – Liposomal amphotericin B (total dose 18-21 mg/kg) or miltefosine (for >2y). Monitor for hemorrhage, intercurrent infection.
3
Congenital toxoplasmosis – Pyrimethamine + sulfadiazine + leucovorin for 12 months. Monitor for neutropenia. Ocular lesions require steroids if macula-threatening.
4
Chagas disease (acute) – Benznidazole (5-7 mg/kg/d for 60d) or nifurtimox. Chronic indeterminate stage: treat to prevent progression.
5
African trypanosomiasis (late stage) – Eflornithine + nifurtimox combination (or melarsoprol). Lumbar puncture to stage disease.

🧠 Reflex prompts – high-yield clinical pearls

🦟 Child with cyclic fever, anemia, splenomegaly after travel to sub-Saharan Africa. Thick smear positive. First-line treatment (uncomplicated)?
Artemisinin combination therapy (ACT).
🦟 Severe malaria: drug of choice and route?
IV artesunate (preferred over quinine).
🐱 Infant with chorioretinitis, intracranial calcifications, hydrocephalus. Most likely congenital infection?
Toxoplasmosis (Toxoplasma gondii).
🦟 Visceral leishmaniasis: classic triad?
Fever, massive splenomegaly, pancytopenia.
🪰 Chronic Chagas disease causes which organ complications?
Cardiomyopathy (dilated), megaesophagus, megacolon.
🐱 Diagnosis of congenital toxoplasmosis in neonate?
PCR of blood/CSF, + serology (IgM), and maternal IgG.
🦟 Which malaria parasite causes relapse from hypnozoites?
Plasmodium vivax and P. ovale (primaquine needed).
🦟 Drug of choice for cutaneous leishmaniasis (localized, New World)?
Pentavalent antimonials (meglumine antimonate) or miltefosine.
🪰 African trypanosomiasis: route of transmission?
Tsetse fly bite.
🐱 Toxoplasmosis treatment during pregnancy to prevent congenital infection?
Spiramycin (first trimester), then pyrimethamine+sulfadiazine+leucovorin after 18 weeks.