Protozoology - Amoebae, Ciliates & Flagellates MCQs

Option C - Metacyclic trypomastigotes are infective forms of parasite which after entry through bug bite, enters R-E cells and convert into amastigote forms. Some of them, after converting through epimastigote form, convert to trypomastigote forms inside blood. Reduviid bug is a vector which when feeds on human blood, acquires infection. Option A - Tsetse fly is a vector which transmits T.brucei Option B - Armadillo, cat ,dog and pigs are major reservoir Option D - complications of chronic diseases are common in adults, while in children acute disease is common. Reference : Paniker’s textbook of Parasitology - 8th Edition, Pg. No. -48

Option D – the only confirmatory way to diagnose E.histolytica infection (amoebic dysentery) is presence of trophozoites with ingested RBCs. Macrophage can be present in amoebic as well as bacillary dysentery. Though characteristically present in clumps, RBC’s can be present discrete and it is very difficult to identify type of dysentery based on arrangement of RBCs as its not very specific. Charcot-Leyden crystals are present in amoebic dysentery but it is also present in other parasitic infection and allergic conditions. Reference : Paniker’s textbook of Parasitology - 8th Edition, Pg. No. -20

Option C – Uninucleate cyst is spherical about 10-20 µ in size. It has a single nucleus, large glycogen mass and 1-4 chromatoid bodies. With successive nuclear division, glycogen mass is reduced in size and the chromatoid body disappears and the cyst is surrounded by refractile cyst wall. Reference : Paniker’s textbook of Parasitology - 8th Edition, Pg. No. -16

Option A – Protozoa reproduce by asexual and sexual methods. Asexual method like binary fission, multiple fission and endodyogeny. E.histolytica, Leishmania and Trypanosomes multiplies asexually by binary fission. Plasmodia multiplies by multiple fission (Schizogony). Some protozoa like Toxoplasma multiply by internal budding (Endodyogeny). Reference : Paniker’s textbook of Parasitology - 8th Edition, Pg. No. -16

Option B -Acanthamoeba causes primary amoebic granulomatous meningo-encephalitis. E.histolytica cause brain abscess secondary to infection in intestine. Naegleria causes acute suppurative inflammation. D.fragilis though classified as amoeboflagellate like Naegleria, causes gastro-intestinal symptoms like diarrhea, flatulence, abdominal pain, anorexia and fatigue. Reference : Paniker’s textbook of Parasitology - 8th Edition, Pg. No. -29

E.histolytica exists in three forms a)Trophozoite b)Precyst c)Cyst Mature quadrinucleate cyst is the infective form. It is passed in the feces of convalescents and carriers. The cysts remain viable under moist conditions for about 10 days. Reference: Ananthnarayan and Paniker's textbook of Microbiology 12 th edition pg no.503

E.dispar, E.bangladeshi are amoeba which are morphologically similar to E.histolytica.They are differentiated by a)Absence of Lectin antigen b)No RBC's inside trophozoites c)PCR Reference : Ananthnarayan and Paniker's textbook of Microbiology 12 th edition pg no.504-505

Ans. is 'b' i.e., Balantidium coli [Ref Paniker p. 111] Largest protozoa Balantidum coli Smallest intestinal amoeba Dientamoeba fragilis Smallest tapeworm found in H. nana human intestine Largest helminth (largest T. saginata (beef tapeworm) worm) Largest liver fluke F. hepatica Largest trematode infecting man→ Fasciolopsis buski Largest Nematode Ascaris Smallest Nematode - Trichinella Only protozoan parasite found in Giardia lamblia small intestine of man Only ciliate protozoan parasite of Balantidum coli man - Parthenogenic worm (female is Strongyloides stercoralis. able to produce fertile eggs or larvae without fertilization)