Neglected Tropical Diseases and Helminthic Infections — WACS Viva & Clinical Scenarios (Infectious and Tropical Diseases)

Exam-style neglected tropical diseases and helminthic infections viva scenarios with examiner probes and model answers for Internal Medicine candidates.

Scenarios covered

• SCENARIO 1: A 48-year-old male with a history of systemic lupus erythematosus maintained on high-dose oral prednisolone presents with high-grade fever, diffuse abdominal cramping, watery diarrhoea, dry cough, shortness of breath, and altered sensorium. Blood cultures yield Escherichia coli and Klebsiella pneumoniae. Stool microscopy demonstrates numerous actively motile rhabditiform larvae. Discuss the pathophysiology of Strongyloides stercoralis hyperinfection syndrome, the mechanisms underlying secondary polymicrobial bacteremia, the diagnostic evaluation, and the definitive therapeutic regimen.
• SCENARIO 2: A 32-year-old farmer from an agricultural settlement along the Volta Basin presents with hematemesis, melena, and marked abdominal distension. Clinical examination reveals massive splenomegaly, firm non-tender hepatomegaly, and ascites, without peripheral stigmata of chronic liver disease such as spider naevi or gynaecomastia. Upper gastrointestinal endoscopy reveals high-grade bleeding oesophageal varices. Abdominal ultrasonography demonstrates dense periportal echogenicity conforming to Symmers pipe-stem fibrosis. Detail the immunopathogenesis of Schistosoma mansoni infection leading to non-
• SCENARIO 3: A 40-year-old female living in a forest-savannah transition zone in West Africa presents with severe pruritus, lichenified papular skin lesions (onchodermatitis), and visual impairment. Physical examination reveals painless subcutaneous nodules over the iliac crests and bilateral punctate keratitis on slit-lamp biomicroscopy. The attending team considers mass administration of ivermectin, but thick blood film examination reveals Loa loa microfilaraemia of 32000 microfilariae/mL. Explain the physiological risks of standard antiparasitic therapy in this co-infected individual, the mechanism of f
• SCENARIO 4: A 29-year-old male forest worker from an endemic rural district presents with intermittent fevers, posterior cervical lymphadenopathy (Winterbottom sign), daytime somnolence, nocturnal insomnia, and extrapyramidal tremors. Describe the systematic staging of Human African Trypanosomiasis (HAT) caused by Trypanosoma brucei gambiense, the cerebrospinal fluid criteria that differentiate stage 1 from stage 2 disease, and the comparative pharmacotherapy including oral fexinidazole and nifurtimox-eflornithine combination therapy (NECT).
• SCENARIO 5: A 35-year-old male presents with multiple hypopigmented, anaesthetic macules with raised erythematous borders over the extensor surfaces of both arms and trunk, along with bilateral enlargement and tenderness of the ulnar and common peroneal nerves. Three weeks after starting treatment, he develops acute neuralgic pain, worsening erythema and swelling of pre-existing skin plaques, and sudden drop in right wrist dorsiflexion. Classify this clinical scenario according to the Ridley-Jopling framework, identify the acute immunological complication, and detail the complete therapeutic protocol for