Helminthology - Nematodes MCQs

Option B - in S.stercoralis infection, if patient has defective cellular response - AIDS patient, lepromatous leprosy, corticosteroid therapy or severe malnutrition, rhabditiform larva which are released in intestinal lumen instead of passing into feces develop into filariform larva in intestine which penetrate intestinal mucosa and lodge into lungs and various tissue and organs - condition called as intestinal re-infection or Hyper infection syndrome. Option A & D - intestinal re-infection usually does not occur in these parasites. Option C - auto-infection and retro-infection is a feature of E. vermicularis in which eggs deposited in perianal skin, autoinfects person due to itching and unhygienic habits or larva hatched in perianal skin moves retrograde through anus causing retrograde autoinfection. Reference: Paniker's textbook of Parasitology - 8th Edition, Pg. No. -184

Option C - Visceral larva migrans (VLM) or toxocariasis is a zoonotic infection usually caused by dog or cat ascarids of the Toxocara genus. The eggs are ingested and then hatch into larvae, which penetrate the intestine and start migrating. These nematodes can infect but not mature in humans so larva is not developed into adults. It is also seen in human nematodes like S.stercoralis and A.lumbricoides, when larvae of these parasites are not able to complete their normal development and enter ectopic sites. Reference : Paniker’s textbook of Parasitology - 8th Edition, Pg. No. -167

Ans. a. Trichuris trichura 706. In malaria, sexual cycle is - a) Sporozoite to gametocytes b) Gametocytes to Sporozoite c) Occurs in human d) Responsible for relapse Correct Answer - B Ans. is 'b' i.e., Gametocytes to sporozoite LIFE CYCLE OF PLASMODIUM Plasmodium passes its life cycle in two different hosts ?

Ans. is `b' i.e., Strongyloides [Ref Panikar 6th/e p. 171] Rhabditiform larva is the first stage feeding larva found in some nematodes. It is non-infective. Filiform larva is the non feeding infective larva in some nematodes. Rhabditiform larva and filiform larva are found in following important nematodes

Gingivostomatitis and pharyngitis are the most common clinical manifestations of first-episode HSV-1 infection, while recurrent herpes labialis is the most common clinical manifestation of reactivation HSV-1 infection. Reference: Harrison's Principles of Internal Medicine, 21 st ed, Ch: 192, Pg: 1473

Among the given options the most likely diagnosis is IMN, considering the age and the travel history. Familial Mediterranean fever should have recurrent history of fever. Tuberculosis is a chronic infection with a more prolonged course. There is nothing to suggest a sarcoidosis like mediatinal adenopathy and the duration is short. Infectious Mononucleosis occurs most commonly in adolescents and young adults. Clinical features occur after a 2-5 week incubation period and include fever, malaise, pharyngitis, and lymphadenopathy. Reference: Harrison's Principles of Internal Medicine, 21 st ed, Ch: 194, Pg: 1484