Parasitology 01: General Parasitology

1. PARASITOLOGY
By:
MrArshit

2. GENERAL
PARASITOLOGY
A. Classification of parasites
B. Types of Parasite
C. Types of Host
D. Host-Parasite Relationship
E. Source of infection
F. Portal of Entry
G. Life Cycle of the parasite
H. Pathogenesis
I. Immunity in Parasitic infection
J. Laboratory Diagnosis

3. A)Classification of parasites
Protozoa
Helminths

4. B)Types of Parasite
1. Ectoparasite: A parasite which lives on the external surface of the host.
2. Endoparasite: A parasite which lives within the body of the host.
3. Obligate parasite: Organisms which cannot survive outside the body of the
host.
4. Facultative parasite: Organisms which under favourable condition may live
a parasitic life but free living existence may also occur.
5. Accidental parasite: Organisms which infect an unusual host.
6. Aberrant parasite: Organisms which infect a host where it cannot live or
develop further.

5. C)Types of Host
1. Definitive Host: The host in which the parasite undergoes sexual
reproduction.
2. Intermediate Host: The host in which larval or asexual stage of the
parasite are found.
3. Paratenic Host: The host in which larval stage of the parasite survives but
cannot develop further.
4. Reservoir Host: It is a host which harbor the parasite and act as an
important source of the infection to other susceptible hosts.

6. D)Host-Parasite Relationship
1. Symbiosis: Both parasite and host are depend on each other for survival
but none of them suffer any harm from the relationship.
2. Commensalism: Only parasite is driving the benefit without causing any
harm to the host.
3. Parasitism: Parasite is driving benefit from the host. Host got nothing in
return but suffers some injury.

7. E)Source of infection
1. Contaminated water and soil
2. Raw or undercooked meat
3. Cyclops
4. Blood-sucking insects
5. Edible aquatic plants
6. Fishes
7. Crab

8. F) Portal of Entry
1. Mouth
2. Skin
3. Sexual contact
4. Congenital

9. G)Life Cycle of the parasites
Parasite may complete their life cycle in a single host or more than one host.
Details are discuss in their respective slides.

10. H)Pathogenesis
1. Trauma
2. Lytic necrosis
3. Allergic manifestations
4. Inflammatory reactions
5. Neoplasia

11. I)Immunity in Parasitic infection
1. Cell mediated immunity:
a. Cytotoxic T-Cell, Natural killer cell, macrophages
2. Humoral immunity:
a. IgM, IgG, IgE
b. First antibody to appear is IgM.
c. IgG usually most abundant in parasitic infection.
d. IgE increases in ectoparasites and helminthic infection.
3. Concomitant immunity:
a. In most of the parasitic infection, immunity last till the infection remains active. This type
of infection is known as concomitant immunity.
b. It is also known as -
i. Premunition immunity
ii. Infection immunity

12. J)Laboratory diagnosis
1. Specimen collection
a. Stool
b. Blood
c. Urine
d. CSF
e. Sputum
f. Tissue and aspirates
g. Genital specimens
2. Direct demonstration of parasite
3. Serological tests
4. Skin tests
5. Molecular methods

13. THANKS