Parasitology Questions and Answers

Answer: D

River blindness is caused by Onchocerca volvulus.

This filarial nematode is transmitted by blackflies (Simulium), which breed in fast-flowing rivers, hence the disease's name. The microfilariae migrate through the skin and into the eye, where their death causes inflammation that can end in blindness.

Loa loa, the African eye worm, migrates across the eye but rarely causes blindness. Mansonella perstans and Mansonella streptocerca are filarial worms that cause mostly mild or skin infections.

Answer: B

Hookworm infection leads to iron deficiency.

Hookworms (Ancylostoma duodenale and Necator americanus) attach to the wall of the small intestine and feed on blood. Chronic blood loss, up to about 0.2 ml per worm per day for Ancylostoma, drains the body's iron and causes microcytic, hypochromic iron-deficiency anaemia.

Vitamin B12 deficiency is the classic effect of the fish tapeworm Diphyllobothrium latum. Vitamin B6 and folic acid deficiency are not characteristic of hookworm.

Answer: A

The parasite not transmitted by mosquitoes is Leishmania donovani (printed 'donovi').

Leishmania donovani, the cause of kala-azar (visceral leishmaniasis), is transmitted by the bite of sandflies of the genus Phlebotomus, not by mosquitoes.

The others are all mosquito-borne. Wuchereria bancrofti, which causes lymphatic filariasis, is spread mainly by Culex mosquitoes, and Plasmodium vivax and P. falciparum, which cause malaria, by female Anopheles mosquitoes.