Introduction To Parasitology

Question 1

Parasite

Answer 1

A living organism which receives nourishment and shelter from another organism where it lives

Question 2

Host

Answer 2

An organism which harbours the parasite

Question 3

Host

Answer 3

An organism which harbours the parasite

Question 4

Types of parasite

Answer 4

1. Ectoparasite- living outside on the surface of the body of the host
2. Endoparasite - lives inside the body of host
3. Temporary parasite - visits host for a short period
4. Permanent parasite - leads a parasitic life throughout its life time
5. Facultative parasite- lives a parasitic life when opportunity arises
6. Obligate parasite - cannot exist without parasitic life
7. Occasional or accidental parasite - attacks on unusual host
8. Wandering or aberrant - happens to reach a place where it cannot live
9. Free living - non parasitic stage

Question 5

Types of host

Answer 5

1. Definitive host
2. Intermediate host
3. Paratenic host
4. Reservoir

Question 6

Definitive host

Answer 6

Definitive hosts either harbour the adult stage of the parasite
OR
Where the parasite utilizes the external method of reproduction
In the majority of human parasitic infection, man is the definitive host

Question 7

Intermediate host

Answer 7

It harbours the larval stage of the parasite
In some cases the larval development is completed in two different intermediate hosts, these are referred as first and second intermediate host
In malaria and hydatid disease man acts as an intermediate host

Question 8

Paratenic host

Answer 8

A host where the parasite remains viable without further development

Question 9

Reservoir hosts

Answer 9

It is a host which harbour parasite and serve as a source of infection to other susceptible host. Epidemiologically, reservoir hosts are important in the control of parasitic infection

Question 10

Vector

Answer 10

A vector is an agent, usually an insect that transmits an infection from one human host to another

Question 11

Mechanical vector

Answer 11

It is a vector which assists in transfer of parasitic form between hosts but is not essential in the life cycle of parasites.
Eg. A housefly that transfers amoebic cyst from faeces to food that is eaten by human

Question 12

Sources of infection

Answer 12

1. Contaminated soil and water
2. Fresh water fishes
3. Crabs and crayfish. - paragonimus wertermani
4. Raw or uncooked pork - t solium, trichinella spiralis
5. Raw or uncooked beef - t.saginata, toxoplasma gondii
6. watercress - fasciola hepatica
7. Blood sucking insect
8. Housefly - mechanical carrier of e histolytica
9. Dog - echinococcus granulosus and toxocara canis
10. Cat - t gondii
11. Man - E histolytica, h nana