For each of the features of malaria listed on the left select the most appropriate association from the list on the right. 67 a. Blackwater fever. b. Malignant tertian fever. c. Tropical splenomegaly syndrome. A. Acute intravascular haemolysis. B. Overwhelming parasitaemia with shock. C. Pericapillary ring haemorrhages. D. Regresses with long-term antimalarial therapy. E. Release of merozoites from burst RBC. The answer is A, E, D. Acute haemolysis occurs in non-immune patients folowing quinine treatment for falciparum malaria. Fever in malaria is either tertian (every 2 day) or quartan (every 3 days) and is due to release of merozoites from RBC’s. Malignant tertian fever is due to P. falciparum. Splenomegaly may occur in adults with falciparum malaria; its pathogenesis is uncertain. Overwhelming parasitaemia with vascular collapse (B) is seen in algid malaria shock syndrome. Pericapillary ring haemorhages are seen in cerebral malaria.
For each of the lesions on the left select the most appropriate association from the list on the right. a. Leishman-Donovan bodies in Kupffer cells. b. Meningo-encephalitis. c. Self-healing, crateriform ulcer. A. African trypanosomiasis. B. Cutaneous leishmaniasis. C. Muco-cutaneous leishmaniasis. D. South-American trypanosomiasis. E. Visceral leishmaniasis. The answer is E, A, B. In visceral leishmaniasis (‘Kala-azar’) the organisms infect macrophages. In African trypanosomiasis the flagellates stay in the circulation, enter the central nervous system and alter the sleep rhythm. In cutaneous leishmaniasis a papule develops at the site of the insect bite and ulcerates. In mucocutaneous leishmaniasis (C) non-healing secondary ulcers occur months or years after the primary lesion. South American trypanosomiasis (D) is characterised by infection of organs by the parasite (Chagas’ disease); the loss of bowel ganglion cells is a notable feature. 68
If the following events were placed in chronological order, which would come fourth? A. Hepatic abscess formation. B. Ingestion of contaminated water. C. Lysis of epithelial cells in caecum. D. Release of motile trophozoites. E. Trophozoites enter portal blood. The answer is E. Water is contaminated (B) by human faeces containing cysts; the cysts release 4 motile trophozoites in the intestine (D). If these are pathogenic they cause necrosis of intestinal cells (C), and invade the submucosa entering the portal blood stream (E) and resulting in a hepatic abscess (A).
If the following events were placed in chronological order, which would come fourth? A. Adult worms migrate to the perivesical veins. B. Cercaria released from snail. C. Human epidermis penetrated. D. Maturation in the portal veins. E. Miracidia hatch from eggs in fresh water. The answer is D. Eggs excreted in faeces or urine hatch out in fresh water (E) and release miracidia which invade snails; cercaria are released from the snail (B) and invade human skin (C) losing their tails. The larvae invades vessels, reaches the liver and enters the portal circulation (D) where it matures and the adults migrate to i.e., the perivesical veins (A). The adults lay eggs which are excreted by the host.
For each of the lesions on the left select the most appropriate parasite from the list on the right. a. Cyst in the right lobe of liver. b. Elephantiasis. c. Subcutaneous nodules, blindness. A. Echinococcus granulosus. B. Onchocerca volvulus. C. Opisthorchis sinensis. D. Taenia solium. E. Wuchereria bancrofti. The answer is A, E, B. Visceral cysts containing daughter cysts and scolices are the pathological features of hydatid disease. In lymphatic filariasis lymphatics are blocked by the adult worms, giving gross lymphoedema and reactive fibrosis of soft tissues. Ocular damage due to the presence of the microfilaria in the eye are the most serious effects (‘river blindness’). 69 The adult Opisthorchis attaches to the biliary epithelium, and may promote the development of cholangiocarcinoma (C). Man is the definitive host for T. solium (the pork tapeworm).
