Parasitology VIVA Question and Answer

Parasitology VIVA Question and Answer
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1) What is a parasite?

  • The organism that depends on the host (other organisms) for all of its lifecycle or for some parts of its lifecycle is known as a parasite.

2) What is the host?

  • The host is any organism or animal that harbors the parasite.
  • There it provides nourishment and shelter.

3) What is the difference between definitive, intermediate, and reservoir host?

  •  Definitive host:  Sexual reproduction of parasites takes place. In its most highly developed form of a parasite occurs.  Examples: Mosquito is the definitive host of the malarial parasite. Humans are the definitive host for Taenia saginata. 
  •  Intermediate host: Asexual form of parasite takes place. It is essential for the completion of the lifecycle of the parasite. Examples: Cattle are the intermediate host for Taenia saginata. Tsetse fly for Trypanosome.
  • Reservoir host:  Host which harbors the parasites and serves as an important source of infection to other susceptible hosts. The infected person or animal may act as a reservoir ( source of parasitic infection ) for transmission. Examples: Dog is the reservoir host for cystic echinococcosis. Antelope is the reservoir host of African Trypanosomiasis.

4) What is the difference between ectoparasite and endoparasite?

  • Ectoparasite: Lives on the outer surface or in the superficial tissue of the host. Example: Lice.
  • Endoparasite: Lives within (inside) the host. Example: Roundworm.

5) Define

  • Temporary parasite: visits host for a short period of time.
  • Permanent parasite: leads a parasitic life throughout the whole period of its life.
  • Facultative parasite : lives a parasitic life when opportunity arises.
  • Obligatory parasite: which cannot exist without a parasitic life.
  • Occasional or Accidental parasite: attacks on the unusual host.
  • Wandering or Aberrant parasite: happens to reach a place where it cannot live.

6) How does reproduction occur in protozoa ?

  • Asexual multiplication: a) By binary fission      b) By multiple fission or schizogony
  • Sexual multiplication:   a) By conjugation         b) By syngamy or sporogony

7) Classify the pathogenic protozoa on the basis of the organ of locomotion.

  • Rhizopoda: move with the help of pseudopodia.
  • Mastigophora: have elongated, thread-like filaments, flagella (Trypanosoma ).
  • Sporozoa: exhibit no movement. Example: the malarial parasite.
  • Ciliata: move with the help of cilia. Example: Balantidium coli.

8) What do you mean by pseudopodia?

  • In order to engulf food material, protozoa have false feet like structure which is called pseudopodia.
  • It looks like feet and helps in movement.

9) What is the difference between flagella and cilia?

  • Flagella are hair-like long filaments whereas cilia are short processes.

10) Define

  • Trophozoite: It is the invasive form of parasite and motile stage.
  • Cyst: it is the infective stage of the parasite and resistant stage.
  • Encystment: The process in which trophozoite of protozoa encloses itself in a resistant wall to form a cyst.
  • Excystation: The process of coming out from a cyst.

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12) Common names and Scientific names

  • Roundworm: Ascaris lumbricoides
  • Pinworm: Enterobius vermicularis
  • Whipworm: Trichuris trichiura
  • Hookworm: Ancyclostoma duodenale
  • Beef Tapeworm: Taenia saginata
  • Pork Tapeworm: Taenia solium 

13) Give examples of important parasites in humans, that complete the lifecycle in a single  (1)  host i.e. Simple life cycle.

  • Entamoeba histolytica
  • Giardia lamblia
  • Ascaris lumbricoides
  • Enterobius vermicularis
  • Trichuris trichiura
  • Strongyloides stercoralis
  • Ancylostoma duodenale

Mnemonics: STRONG CAR and TRI CYcLENTER GIAnt HISTOry in 1 (single) time.

14) Give the examples of parasites that complete the lifecycle in 2 hosts ( 1 definitive and 1 intermediate) i.e. complex lifecycle.

  • Plasmodium species
  • Leishmania donovani
  • Wuchereria bancrofti
  • Taenia solium
  • Taenia saginata

Mnemonics: LEISHaa WitCH BANned TaSa SO gave PLASMA (2 times).

15) Name the species of Leishmania which causes disease in the human being?

  • Leishmania donovani causes Kala-azar
  • Leishmania tropica causes oriental sore
  • Leishmania braziliensis causes mucocutaneous leishmaniasis.

16) What are the two differences between Taenia solium and Taenia saginata?

  • Taenia solium: Intermediate host is Pig, and the larva is Cysticercus cellulosae.
  • Taenia saginata: Intermediate host is Cattle, and the larva is Cysticercus bovis.

17) What is the larval form of Echinococcus granulosus called?

  • Hydatid cyst

18 )What is the terminology used for an embryo having 3 pairs of hooklets?

  • Hexacanth embryo

19) How will you recognize the eggs of Hookworm?

  • Its egg is surrounded by a thin transparent hyaline shell membrane and contains 7-8 blastomeres.

20) In the lab, how will you identify Whipworm ( Trichuris trichiura ). Any unique property?

  • Its egg is barrel-shaped with a colorless protruding mucus plug at each end.

21) What is karyosome? What is its use?

  • The minute mass in the center of the nucleus is called the karyosome. It is useful in distinguishing between genera and species.

22) Which protozoa thrive on bacterial flora?

  • Intestinal protozoa.

23 ) What is the major route of infection of Entamoeba histolytica?

  • Ingestion of mature quadrinucleated cysts (4 nuclei ) containing food and water.

24) How many species of Entamoeba are present?

  • Six
  • Entamoeba histolytica is pathogenic to humans.

25) How can you differentiate Entamoeba histolytica from E. coli?

  • By the position of karyosome in the nucleus.
  • E. histolytica has a central karyosome.
  • E. coli has an eccentric karyosome.

26) How can you differentiate E. histolytica from E. dispar?

  • By ingested RBC.
  • The tropozoite of E. histolytica contains ingested RBCs whereas E. dispar doesnot contain it.
  • The cysts of E. dispar and E. histolytica cannot be differentiated under a microscope.

References and Sources

  1. Chatterjee KD (2009), Parasitology, 13th edition, CBS publishers, and distributors Pvt. Ltd.
  2. Panjarathinam R (2007), Textbook of Medical Parasitology, 2nd edition, Orient Longman Private Limited.
  3. Mandal PK (2016), A Textbook of Microbiology for Nursing, 2nd edition, Vidyarthi Pustak Bhandar.
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About Author

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Sushmita Baniya

Sushmita Baniya completed her Masterโ€™s degree in Medical Microbiology from the National College of Science and Technology (NIST), Kathmandu, Nepal. She did her Bachelorโ€™s degree in Microbiology from Birendra Multiple Campus, Chitwan, Nepal. She is interested in Genetics and Molecular Biology.

16 thoughts on “Parasitology VIVA Question and Answer”

  1. Me also I need all briefly explanation about parasitology and and also many questions needed like multiple choice questions

  2. this is scientific questions thanks for you and we need if possible other types of questions as fill in blanks and matching ———–


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