BSMT2-01 | Parasitology
Introduction to Parasitology
Amapola Puaso, RMT, MSMT
November 6, 2019
First Semester A.Y. 2019-2020
Preliminary Exam
1-1
OUTLINE
I.
WHAT IS PARASITOLOGY
A. Different Types of Host
B. Classification of Parasites
C. Types of Relationship Between Host and Parasite
D. Modes of Transmission
E. Classification of Microorganisms
F. Different Portals of Entry of Parasites
G. Diagnosis
II. EPIDEMIOLOGICAL TERMS
A. Epidemiology
B. Epidemic
C. Endemic
D. Pandemic
III. TEST QUESTIONS
REFERENCES
1. Amapola Puaso, RMT, MSMT’s ppt
2. Recording
3. Zeibig, E. (2012). Clinical Parasitology
5. Paratenic host – harbors the infective stage of a parasite
6. Incidental host – infected person is not necessary for the
parasite but they need them for survival and development
 Aka accidental host
 Host other than the normal one that is harboring a parasite
7. Transport host – host responsible for transferring a parasite from
one location to another
8. Carrier – Parasite-harboring host that is not exhibiting any
clinical symptoms but can infect others
B. Classification of Parasites
1. According to habitat
 Ectoparasites – those found outside of the host
 Endoparasites – those found within the host
2. According to effect in host
 Pathogenic – the parasite is able to set up a disease process
in man
 Non-pathogenic – the parasite is not able to set up a disease
process in man
 Aka “commensals”
I. WHAT IS PARASITOLOGY





It is an area of biology concerned with the phenomenon of
dependence of one living organism on another.
It is a study of a particular relationship among certain species.
Parasite – any organism that lives in or on the body of another
organism (host) for survival for food and shelter
 Parasites alter their antigenic makeup so that the host will
not recognize the modified parasites as foreign, and thus
the initiation of an immune response does not occur.
Host – any organism that harbors the parasite
 The primary function of the host is to carry on the parasite’s
life cycle
Parasitism – relationship wherein one derives the benefits and
cause harm to the host
C. Types Of Relationship Between Host And Parasite


A. Different Types of Host
1. Intermediate host - harbors the larval or asexual stages of the
parasites
 Host in which the larval asexual/juvenile phase of parasite
development occurs
 example: snail, cat, dogs, plants, sheep
2. Definitive host – aka the final host
 It harbors the adult of the sexually mature stages of a
parasite
 Host in which the adult sexual phase of parasite
development occurs
 Examples: mosquito (malaria is the parasite), cat, dog
3. Reservoir host – aka the definitive host
 It harbors the parasite in nature, they can serve as the
source of infection
 Host harboring parasites that are parasitic for humans and
from which humans may become infected
4. Vector host – usually responsible for the infection of the
vertebrate host
 Examples: mosquito (dengue: aedes; malaria: anopheles),
tick, fly (can carry amoeba)
When a parasite infects a host, symbiosis results.
This newly-formed relationship may develop into
commensalism, mutualism, or parasitism.
1. Obligatory – those that cannot survive without a host
2. Facultative – those that can survive without a host
 Parasite that is capable of existing independently of a
host
 Aka free-living parasites
 Can survive in soil (for years) then may infect accidental
hosts
3. Intermittent/temporary/periodic – so-called because they
would simply visit the host during feeding time
4. Incidental/wandering/aberrant/erratic – a parasite that
established itself in a host in which it does not usually live
5. Pseudoparasite – an object that is mistaken for a parasite
 Examples: pollen grains, vegetable fibers
D. Modes of Transmission

Mode of transmission – means whereby a parasite gains entry
into an unsuspecting host
1. Soil transmitted – those that require further development
in the soil before they become infective
2. Snail transmitted – requires further development in the
body of a snail before they become infective
 The snail serves as the intermediate host, and the
human will be the definitive host
3. Arthropod transmitted – requires further development in
an arthropod/insect
4. Food-animal transmitted – requires further development in
the flesh of animal that man utilizes as food
5. Contact transmitted – are readily infective
BSMT 2019 – FESTIN A | Page 1 of 2
BSMT2-01
1-1
E. Different Portals of Entry of Parasites
1. Oral Entry – ingestion
 Ingestion of contaminated food or drink
 Examples: Embryonated eggs, protozoan cyst, metacercaria
2. Skin – through skin penetration
 Entry via drilling through the skin
 Examples: Filariform, Cercaria, arthropod
3. Sexual – Trichomonas vaginalis, Giardia lamblia, Entamoeba
histolytica
4. Transplacental – mother to child, vertical transmission
 Example: Toxoplasma gondii
5. Intranasal – through breathing
 Example: Naegleria species
6. Transmammary – Strongyloides stercoralis
7. Airborne – Enterobious vermicularis
F. Diagnosis (Specimen Requirement)






Stool – ova, cyst, scolex
Urine – Trichomonas vaginalis, Schistosoma haematobium
Sputum – Paragonimus westermani, nematode larvae
Blood – malaria, filarial worms
Tissue biopsy – Trichinella spiralis, interstinal amoebiasis
Orifice swab – Trichomonas vaginalis, Enterobius vermicularis,
Taenia infection
 Originally, Enterobius and Taenia are only found in stool but
due to improper washing, they can be transmitted to
vagina.
II. EPIDEMIOLOGICAL TERMS




Epidemiology – the study of the occurrence and prevalence of
disease, often applied to the study of the manner of spread of
contagious disease
Epidemic – sudden increase of infection; outbreak
 H1N1, Zika Virus, Ebola, SARS
Endemic – certain infection is present constantly in low
numbers, constantly present area
 Malaria (in Palawan), elephantiasis (in Sorsogon)
Pandemic – refers to disease which spreads to several countries
and affects a large number of people
 Malaria, HIV, TB, Hepa-B
III. TEST QUESTIONS
Test 1
1. Which of the following are key discoveries that contributed to current
knowledge about parasites?
a. Consistent status quo preservation of samples
b. Techniques that indicate only the presence or absence of parasites
c. Modifications of traditional parasite identification technique
d. Decrease in parasite incidence because of global travel
2. Which of the ff people may be at risk for contracting a parasitic
infection?
a.
A toddler who attends an all-day pre-school or day care center
b. A 25-yr-old man who lives on his own in an apartment complex
c.
A 37-yr-old South American refugee
d. More than one of these _____ (specify)
INTRODUCTION TO PARASITOLOGY
3. The primary function of a host in a parasite-host relationship is to:
a.
Carry on the parasite’s life cycle
b. Provide immunologic protection for the host
c.
Carry on the host’s life cycle
d. Provide a food source for the host
4. Which of the ff key pieces of information may be extracted from the
portion of a parasite’s life cycle that occurs outside the body?
a.
Parasitic disease symptoms and disease processes
b. Epidemiology and prevention and control measures
c.
Appropriate parasite diagnosis methodologies
d. Selection of appropriate antiparasitic medication
5. Which of the ff groups of symptoms represents those most commonly
observed in parasitic infections?
a.
Diarrhea, abdominal cramping and anemia
b. Enlargement of the spleen, fever and chills
c.
Skin lesions, abdominal pain, and diarrhea
d. Abdominal cramping, abdominal pain, and diarrhea
6. Which of the ff represent examples of available treatment therapies to
combat parasitic infections?
a.
Regulated exercise plan
b. Change in diet
c.
Avoidance of vitamin supplements
7. Which of the ff are examples of possible parasite prevention and
control measures?
a.
Avoiding the use of insecticides
b. Practicing unprotected sex
c.
Practicing proper sanitation practices
8. Which of the ff specimen type is most often submitted for parasite
study?
a.
Blood
b. Sputum
c.
Urine
d. Stool
9. Which of the ff correctly represents the three major groups of clinically
significant parasites?
a.
Protozoa—worms;
metazoan—single-celled
parasites;
arthropods—insects and their allies
b. Protozoa—insects and their allies; metazoan—worms;
arthropods—single-celled parasites
c.
Protozoa—single-celled
parasites;
metazoan—worms;
arthropods—insects and their allies
d. Protozoa—single-celled parasites; metazoan— insects and their
allies; arthropods—worms
Test 2
1. The form of a parasite that enters a host
2. Two organisms of different spp living together
3. The official units of parasite measurement
4. A parasite that cannot survive outside its host
5. An insect that transports a parasite from an infected host to an
uninfected host
6. A parasite that lives on the outside surface of its host
7. Parasite-harboring host that is not affected by its presence but can shed
the parasite and infect others
8. A destructive process that has characteristic symptoms
9. Association of 2 different spp of organisms that is beneficial to one but
neutral to the other
10. A host responsible for transferring a parasite from one location to
another
Answers:
Test 1: 1. C, 2. D(A+C,), 3. A, 4. A, 5. D (but I think all choices are correct), 6. B,
7. C, 8. D, 9. C
Test 2: 1. Infective stage, 2. Symbiosis, 3. Microns, 4. Obligatory parasite, 5.
Vector, 6. Ectoparasite, 7. Carrier, 8. Disease, 9. Commensalism, 10. Transport
host
BSMT 2019 – FESTIN A | Page 2 of 2