Last Updated on November 3, 2020 by Sagar Aryal
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.
- 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.
- 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.
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 CYcLe ENTER 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?
- 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
- Chatterjee KD (2009), Parasitology, 13th edition, CBS publishers, and distributors Pvt. Ltd.
- Panjarathinam R (2007), Textbook of Medical Parasitology, 2nd edition, Orient Longman Private Limited.
- Mandal PK (2016), A Textbook of Microbiology for Nursing, 2nd edition, Vidyarthi Pustak Bhandar.
- 3% – https://meromicrobiology.blogspot.com/2011/08/
- 2% – https://www.researchgate.net/publication/319443154_Basic_Veterinary_Parasitology_Introduction_and_Systemic_Platyhelminths_Third_Year_Stage_2017-2018
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- <1% – https://answers.yahoo.com/question/index?qid=20131103163110AAJtcHF