Medical Parasitology: An Observation of the Basic Morphology of
Parasitic Protozoa and Helminths
GAVRIL M. RELUCIO
BSN- G1B
MICROBIOLOGY AND PARASITOLOGY
JUNE 6, 2021
Introduction
Medical parasitology is the branch of sciences that delves into the world of parasites
which infect humans, the diseases they cause, clinical picture and the reaction that is made by
human as a response to them [parasites]. It is also concerned with the various methods of
diagnosis, treatment, and their prevention and control (Pikarski, 2010). According to Centers for
Disease Control and Prevention, there are essentially three different types of parasites; the
protozoa (Single-celled organism that can be free-living or parasitic in nature, they are able to
multiply in humans that could allow serious infections to develop), the helminths (Multicellular
organisms that can normally be seen by the naked eye in their adult stage as worms, may also be
either free-living or parasitic in nature), and lastly the ectoparasite (which is a term that normally
collectively refers to organisms such as ticks, fleas, lice, mites that rely on living, attaching, or
eating from an external portion of host. Parasites are organisms that live inside or on a host,
which serves as the resource to supply its life cycle (Biggers, 2018). While some parasites don’t
noticeably affect their host, others grow, reproduce, or invade organ systems that make their host
sick, resulting in a parasitic infection (Marcin, 2018).
It is important to study medical parasitology because it can negatively affect humans by
causing issues such as; wasting (cachexia, spoliatrices), superinfections, production of toxic
compounds, immunodepression, allergic reactions, anaphylactic shock, mechanical damage, etc.
(Opperdoes, 2000). According to the World Health Organization (2020) “approximately 1.5
billion people are infected with soil-transmitted helminths worldwide”. While according to Berhe
(2019) “Protozoan infections are amongst the leading causes of morbidity and mortality
throughout the world with more than 58 million diarrheal cases detected each year” which just
shows how important is it to study and understand the morphology, behavior, and other relevant
information regarding parasites. This will help people learn how to combat or prevent the spread
of parasite related infections and diseases.
This diagnostic activity will enable proponents to test their diagnostic skills by engaging
in diagnostic exercise through the use of a virtual microscope. This experiment aims to allow the
proponents to identify and differentiate various specimens through the virtual microscope.
Specifically, this experiment aims to satisfy the following objectives, (1) To allow the
proponents to observe different samples of protozoan and helminth parasites under the virtual
microscope, (2) To identify each specimens morphological qualities (i.e size, shape, color,
appendages, etc.), and lastly (3) To identify which subgroup does each specimen of helminth or
protozoa belong to (i.e nematodes, cestodes, intestinal amoeba, etc.).
Material and Methods
A. Materials
There were no materials specifically mentioned that is to be used in the virtual
activity however, there will be usage of a virtual microscope and the following specimens;
plasmodium vivax, plasmodium malaria, plasmodium malaria, plasmodium falciparum,
plasmodium ovale, Giarda duodenalis (Giarda lambia), Balantidium Coli, Entamoeba
Histolytica, Ascaris Lumbricoides, Enterous Vermicularis, Schistoma Japonicum, Paragominus
Westermani, Diphyllobothrium Latum, Taenia Solium. There are also settings provided in the
virtual labs such as; labels, magnification, view, and images).
B. Methods
The specimens that were given to be examined can be found through the link of the
virtual simulation. The name of each specimen can be selected and it will automatically
appear from the view of the microscope. A photo screen shot of each specimen were taken,
then the labels were also enabled, so as to see the names and definition of microorganisms.
Results and Discussions
PROTOZOA
Plasmodium
Vivax
(Malaria)
Image
a. Ring
Definition/Discussion

Young trophozoite, no
Schuffner dots.

Has large chromatid dots
and cytoplasm ( can
become ameboid as they
develop)
b. Trophozoite


c. Gametocytes


Plasmodium
Falciparum
(Malaria)
a. Ring




b. Gametocyte


Immature schizont with
schuffner dots, erythrocytes
deformed and enlarged.
Shows ameboid cytoplasm,
large chromatid dots, and
have fine yellowish dots
that appears finer that those
of P. ovale (Supported by
data from Laboratory
Identification of Parasites
of Public health concern)
Mikrogametocytes (male),
all colored reddish, nulcei
not distinguishable.
Round with scattered
brown pigments and may
almost fill the rbc. Scuffner
dots maay appear finer that
those seen in P. ovale.
Thin and delicate,
measures an average of 1/5
the diameter of the red
blood cell.
Possesses one chromatin
dot.
Located at the periphery of
the red blood cell.
Typical young trophozoite.
Shape is comparable to that
of a sausage.
Microgametocyte (male)
 Cell that
undergoes 6-8
mature male sex
cells or malarial
parasite. They can
be located in
human blood cells
and are only
acquired through
a mosquito bite.

Plasmodium
Malariae
(Malaria)
Cytoplasm of
male
microgametocytes
are usually more
pale in color.
a. Trophozoite




Young trophozoite,
ameboid alteration, no dots
in the erythrocyte.
Erythrocyte rather
shrunken in size.
Have compact cytoplasm
and large chromatin dots.
Occasional bands form
and/or occurs with a
coarse, dark-brown
pigment.
b. Schizont

Have 6-12 merozoites with
large nuclei, clustered
around a mass of coarse
dark-brown pigment.
 Merozoites
can
occasionally
be arranged as
a rosette
pattern.
a. Ring
Plasmodium
Ovale
(Malaria)


b. Trophozoite


c. Schizont


Balantidium
Coli
(Intestinal
flagellates and
ciliates)



Very young rings,
developing Scuffner dots.
Has sturdy cytoplasm and
large chromatin dots.
Young trophozoite, strong
schuffner dots, erythrocyte
enlarged, slightly
deformed.
Has sturdy cytoplasm,
large chromatin dots, and
can be compact to slightly
irregular.
Quite mature schizont, 812 merozoite
Has large nuclei, clustered
around a mass of darkbrown pigment.
Cysts are smaller than
trophozoites,
measuring 40-60 mm
across. Cysts are round
and have a tough, heavy
cyst wall made of one or
two layers. Usually only
the macronucleus and
perhaps cilia and
contractile vacuoles are
visible in the cyst.
The cyst is the infective
stage of Balantidium coli
life cycle.
Balantidium coli is the
largest protozoan parasite
for humans.
Giarda
Duodenalis
(Giarda
Lambia)
(Intestinal
flagellates and
ciliates)

Entamoeba
Histolytica
(Intestinal
Amoeba)






HELMINTHS
Ascaris
Lumbricoides
(Nematodes)
A fully mature cyst is oval
or ellipsoidal in shape and
measures 8-12µm in length
and 7-10µm in breadth
Cyst is surrounded by a
thick cyst wall. Cytoplasm
is granulated and is
separated from the cyst
wall by clear space.
Cyst contains 4 nuclei.
This is the infective stage
of the protozoa.
The cysts are spherical
measuring 10-15 µm in
diameter and have 4 nuclei.
Cysts and trophozoites are
passed in feces. The cysts
are usually found in
formed stool, while the
trophozoites are usually
found in diarrheal stool.
Infection happens through
the ingestion of mature
cysts (which may originate
from contaminated water,
food, and hands)



Fertilized egg,
broadly oval with
a thick,
mammilated coat,
usually golden
brown.
Fertile eggs range
from 45 to 75 µm
in length.
Adult worms live
in the small
intestine and
lumen.


Enterobius
Vermicularis
(Nematodes)



Schistoma
Japonicum
(Trematodes)


Paragominus
Westermani
(Trematodes)




Unfertilized eggs
may be ingested
but are not
infective.
Adult worms can
live between 1- 2
years.
Oval, compressed
laterally and
flattened on the
one, with
developed
infective larvae.
Measure 50—60
µm by 20—30 µm
Transparent as it
lacks any visible
color.
Oval, minute
lateral spine, in
most views not
clearly visible,
nonoperculated,
containing
miracidium.
Eggs are relatively
large compared to
other species,
measures 70-100
µm long by 55-64
µm wide.
Ovoid,
operculated,
opercular
shoulders,
brownish yellow,
and thick shell.
Eggs range from
80-120 µm long
by 45-70 µm
wide.
Asymmetrical
with one end
slightly flattened.
At the bigger end,
the operculum is
visible
Diphyllobothrium
Latum
(Cestodes)



Taenia Solium/
Taenia Saginata
(Cestodes)





Broadly oval,
operculated, and
brownish color.
Eggs are oval/
ellipsoidal. Sizes
occur anywhere
between 55 to 75
µm by 40 to 50
µm.
On one side there
is an operculum
which can barely
be visible and on
the other end there
is a small knob
that can also be
difficult to
identify.
Spheroidal,
yellow-brown,
thick-shelled
containing
oncosphere, T.
saginata egg not
distinguishable
from T. solium
egg.
Eggs of Taenia
spp. are not
distinguishable
from one another,
this goes the same
for other members
of Taeniidae.
Eggs measure
anywhere between
30-35 µm in
diameter.
Radially striated.
Internal
oncosphere
contain six
refractile hooks.
Summary and Conclusion
In conclusion, the experiment revealed that the specimens are composed of helminths and
protozoa species. This group of helminths and protozoa was categorized into three other
subgroups to further specify their categories. The protozoa were split into three subgroups;
malaria (P. Vivax, P. Falciparum, P. Malariae, and P. Ovale), intestinal flagellates and ciliates
(Balantidium Coli and Giarda Duodenalis/Giarda Lambia), and lastly the intestinal amoeba
(Entamoeba Histolytica). The Helminths were also split into three subgroups; nematodes
(Ascaris Lumbricoides and Enterobius Vermicularis), trematodes ( Schistoma Japonicum and
Paragominus Westermani), and lastly the cestodes ( Diphyllobotrium Latum and Taenia
Solium/Taenia Saginata. The experiment was also able to characterize the different morphology
each specimens (noting the color, size, shape, maturity, etc.). It was also found out that specimen
Taenia Solium and Taenia Saginata cannot be distinguished from one another due to similarity in
morphology. The experiment, however, failed at identifying adult helminth specimens as no such
organism appeared in any of the sample provided and no trophozoite was found in amongst the
sample of P. falciparum as well. The objectives provided at the beginning of the experiment were
also satisfied upon the conclusion of the experiment/report.
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