Intro to Parasitology (Day 1 Lecture)

Question 1

the science that deals with organisms living in the human body (the host) and the medical significance of this host-parasite relationship.

Answer 1

Medical Parasitology

Question 2

living organism, which takes its nourishment and other needs from a host; the host is an organism which supports the parasite.

Answer 2

Parasite

Question 3

vary depending on whether they harbor the various stages in parasitic development.

Answer 3

Hosts

Question 4

Different kinds of parasites:

Answer 4

1. Ectoparasite
2. Endoparasite
3. Obligate parasite
4. Facultative parasite
5. Accidental parasite
6. Erratic parasite
7. Non-pathogenic parasites
8. Pathogenic parasite

Question 5

a parasitic organism that lives on the outer surface of its host

Answer 5

Ectoparasite

Question 6

Examples of ectoparasite

Answer 6

lice, ticks, mites, etc

Question 7

parasites that live inside the body of their host

Answer 7

Endoparasite

Question 8

Example of Endoparasite:

Answer 8

Entamoeba histolytica

Question 9

This parasite is completely dependent on the host during a segment or all of its life cycle

Answer 9

Obligate parasite

Question 10

Example of ObligateParasite:

Answer 10

Plasmodium spp.

Question 11

an organism that exhibits both parasitic and non parasitic modes of living and hence does not absolutely depend on the parasitic way of life, but is capable of adapting to it if placed on a host.

Answer 11

Facultative Parasite

Question 12

Example of Facultative Parasite

Answer 12

Naegleria fowleri

Question 13

when a parasite attacks an unnatural host and survives

Answer 13

Accidental Parasite

Question 14

Example of Accidental Parasite:

Answer 14

Hymenolepis diminuta (rat tapeworm)

Question 15

is one that wanders in to an organ in which it is not usually found.

Answer 15

Erratic Parasite

Question 16

Example of Erratic Parasite

Answer 16

Entamoeba histtolytica in the liver or lung of humans

Question 17

parasite that do not cause disease

Answer 17

Non-Pathogenic Parasites

Question 18

disease-causing parasites

Answer 18

Pathogenic parasites

Question 19

Different Kinds of Hosts:

Answer 19

1. Definitive host
2. Intermediate host
3. Paratenic host
4. Reservoir host
5. Natural host
6. Accidental host

Question 20

a host that harbors a parasite in the adult stage or where the parasite undergoes a sexual method of reproduction.

Answer 20

Definitive host

Question 21

harbors the larval stages of the parasite or an asexual cycle of development takes place. In some cases, larval development is completed in two different intermediate hosts, referred to as first and second intermediate hosts.

Answer 21

Intermediate host

Question 22

a host that serves as a temporary refuge and vehicle for reaching an obligatory host, usually the definitive host, i.e. it is not necessary for the completion of the parasites life cycle. NO detectable morphological change of parasite. Also known as the Transport host.

Answer 22

Paratenic host

Question 23

a host that makes the parasite available for the transmission to another host and is usually not affected by the infection.

Answer 23

Reservoir host

Question 24

a host that is naturally infected with certain species of parasite.

Answer 24

Natural host

Question 25

a host that is under normal circumstances not infected with the parasite.

Answer 25

Accidental host

Question 26

Three common symbiotic relationships between two organisms:

Answer 26

1. Mutualism 2. Commensalism 3. Parasitism

Question 27

Effects of parasites on the host:

Answer 27

1. Direct Defects 2. Indirect Effects

Question 28

Under Direct Defects:

Answer 28

1. Mechanical injury 2. Deleterious effect of toxic substances 3. Deprivation of nutrients, fluids and metabolites

Question 29

may be inflicted by a parasite by means of pressure as it grows larger

Answer 29

Mechanical injury

Question 30

Example of mechanical injury:

Answer 30

Hydatid cyst causes blockage of ducts such as blood vessels producing infraction

Question 31

Ex: It is where a Plasmodium falciparum production of toxic substances may cause rigors and other symptoms.

Answer 31

Deleterious effect of toxic substances-

Question 32

this is where a parasite may produce disease by competing with the host for nutrients.

Answer 32

Deprivation of nutrients, fluids and metabolites

Question 33

Under Indirect Effects:

Answer 33

1. Immunological reaction 2. Excessive proliferation of certain tissue

Question 34

includes size, shape, color and position of different organelles in different parasites at various stages of their development.

Answer 34

Morphology

Question 35

This is especially important in laboratory diagnosis which helps to identify the different stages of development.

Answer 35

Morphology

Question 36

Distribution of parasites depends upon:

Answer 36

1. Host specificity 2. Food habits

Question 37

the route followed by a parasite from the time of entry to the host to exit, including the extracorporeal (outside the host) life. It can either be simple, when only one host is involved, or complex, involving one or more intermediate hosts.

Answer 37

Life cycle of parasites

Question 38

infection is the result of entry and development within the body of any injurious organism regardless of its size

Answer 38

Host parasite relationship

Question 39

Once the infecting organism is introduced into the body of the host, it reacts in different ways and this could result in:

Answer 39

1. Carrier state 2. Disease state 3. Parasite destruction

Question 40

a perfect host parasite relationship where tissue destruction by a parasite is balanced with the host’s tissue repair. At this point the parasite and the host live harmoniously, i.e. they are at equilibrium.

Answer 40

Carrier state

Question 41

this is due to an imperfect host parasite relationship where the parasite dominates the upper hand. It can result either from lower resistance of the host or a higher pathogenicity of the parasite.

Answer 41

Disease state

Question 42

occurs when the host takes the upper hand.

Answer 42

Parasite destruction

Question 43

depending on the nature of the parasitic infections, the following specimens are selected for laboratory diagnosis:

Answer 43

a. Blood b. Stool c. Urine d. Sputum e. Biopsy material f. Urethral, vaginal discharge, penile discharge

Question 44

Laboratory diagnosis: in those parasitic infections where the parasite itself in any stage of its development circulates in the blood stream

Answer 44

Blood

Question 45

important part in the diagnosis of intestinal parasitic infections and also for those helminthic parasites that localize in the biliary tract and discharge their eggs into the intestine.

Answer 45

Stool

Question 46

when the parasite localizes in the urinary tract, examination of this will be of help in establishing the parasitological diagnosis

Answer 46

Urine

Question 47

Examination of this is useful in the following: - In cases where the habitat of the parasite is in the respiratory tract, as in Paragonimiasis, the eggs of Paragonimus westermani are found. - In amoebic abscess of lung or in the case of amoebic liver abscess bursting into the lungs, the trophozoites of E. histolytica are detected in the sputum.

Answer 47

Sputum

Question 48

Examples of Biopsy material:

Answer 48

Spleen punctures in kala-aznar and muscle biopsy of Cysticercosis

Question 49

Example for diagnosis of Urethral, vaginal discharge, and penile discharge

Answer 49

Trichomonas vaginalis

Question 50

changes indicative of intestinal parasitic infections

Answer 50

Indirect evidences

Question 51

changes indicative of intestinal parasitic infections

Answer 51

Indirect evidences

Question 52

are carried out only in laboratories where special antigens are available.

Answer 52

Serological tests

Question 53

Indirect evidences where eosinophilia often gives an indication of tissue invasion by helminths, a reduction in white blood cell count is an indication of kala-azar, and anemia is a feature of hookworm infestation and malaria.

Answer 53

Cytological changes in the blood