MT 639 - Clinical Parasitology Lecture First Shifting

Chapter 1: Introduction to Medical Parasitology PERMANENT Remains on the body of the host its
entire life.
Definition of Terms TEMPORARY Lives on the host for a short period of
time
DEFINITION OF TERMS SPURIOUS Free-living, passes through the
PARASITOLOGY Area of biology concerned with the digestive tract without infecting the
phenomenon of dependence of one host. Ex. Zoonotic parasites
organism on another.
MEDICAL Concerned with parasites that affect According to: MODE OF DEVELOPMENT
PARASITOLOGY humans and their medical OBLIGATE Needs a host at some stage of their
importance. life cycle to develop and propagate.
TROPICAL Branch of medicine that deals with Ex. tapeworms
MEDICINE tropical diseases and other special FACULTATIVE May exist in a free-living state or
medical problems of tropical regions. become parasitic when the need
TROPICAL An illness indigenous to or endemic arises.
DISEASE in a tropical area. ERRATIC Found in an organ that is not its
• May occure in sporadic or usual habitat.
epidemic proportions in
non-tropical areas. Hosts
• Many are parasitic o Classified based on their role in the life cycle of a
diseases. parasite
o Humans are not always the final host
HOSTS
Symbiotic Relationships DEFINITIVE/ Where parasite attains sexual
SYMBIOSIS FINAL maturity.
o Living together of unlike organisms. o Ex. Taeniasis – humans
o May involve protection or other advantages to one or are the definitive host.
both organisms. INTERMEDIATE Harbors the asexual or larval stage.
o Ex. Taeniasis – pigs and
SYMBIOTIC RELATIONSHIPS cattle
COMMENSALISM Two species live together and one Schistosoma spp. – snail
species benefits while the other is PARATENIC The parasite does not develop
neither benefited nor harmed. further to later stages.
o EXAMPLE: E. coli in the o Ex. Paragonimus
intestine is supplied with metacercaria – raw wild
nourishment. boar meat, infective to
MUTUALISM Both species benefit from each other humans
o EXAMPLE: Termites with Importance: widens the parasite
flagellates in their distribution, bridge the gap bet.
digestive System. definitive and intermediate host.
Flagellates synthesize RESERVOIR Animals that harbor the parasite.
cellulase to aid in Allow the parasite life cycle to
breakdown of wood. continue
PARASITISM The parasite depends on the host o Ex. PIGS: Balantidium coli
for survival while the host is being –
harmed. o FIELD RATS: Paragonimus
o EXAMPLE: E. histolytica westermani
derives nutrition from the o CATS: Brugia malayi
human host and causes
amebic dysentery. Vectors
o Responsible for transmitting the infection
Parasites
o Often describes according to habitat or mode of VECTORS
development. BIOLOGIC Transmits the parasite only when it
has completely developed in the
According to: HABITAT host.
ENDOPARASITE Inside the body of the host. Essential part to the parasite’s life
o Causes infection cycle.
ECTOPARASITE Outside the body of the host. o Ex. Aedes mosquito – sucks
o Causes infestation blood from a patient with
ERRATIC Found in an organ that is not its filiarisis.
usual habitat. MECHANICAL/ Transports only the parasite
ACCIDENTAL/ Establishes itself in a host where it PHORETIC o Ex. Flies and cockroaches
INCIDENTAL does not ordinarily live.
o Ex. B. coli

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 MT 639 - Clinical Parasitology Lecture First Shifting
Exposure and Infection Modes of Transmission (MoT)
o Majority of parasites are pathogens. o Most likely portal of entry is mouth (due to food and
water)
DEFINITION OF TERMS
CARRIER Harbors a particular pathogen a. ORAL (foodborne)
without manifesting signs and o Cestodes, Trematodes, Intestinal Protozoans
symptoms. o Taenia solium (pork)
EXPOSURE Process of inoculating an infective o Taenia saginata (beef)
agent. o Diphyllobotrium latum (raw salmon)
INFECTION Establishment of the infective agent o Clonorchis, Opistorchis, Haplorchis (raw fish)
in the host. o E. histolytica and Giardia lamblia (food and
INCUBATION Period between between infection water contaminated with mature cysts)
PERIOD and evidence of symptoms. b. Skin Penetration
Also known as clinical incubation o Hookworms and Strongyloides – exposure of
period skin to soil, common to farmers
o Schistosoma – skin to water
PRE-PATENT Period between infection or c. Arthopod bites
PERIOD acquisition of parasite and evidence o Serve as vectors
or demonstration of infection o malaria, filiarisis, leishmaniasis,
Also known as biologic incubation trypanosomiasis, babeisiosis
period d. Congenital Transmission
AUTOINFECTION An infected individual becomes his o Toxoplasma gondii – trophozoites can cross
own direct source of the infection. the placental barrier.
o Ex. Enterobiasis – hand- e. Transmammary
to-mouth transmission, due o Through the mother’s milk
to constant scratching of o Ancylostoma and Strongyloides
the perianal area where f. Sexual Intercourse
gravid females lay eggs. o Trichomonas vaginalis
o Ex. Capillaria philippinensis g. Inhalation of eggs
– multiplies internally o Enterobius
SUPERINFECTION/ When the infected individual is
HYPERINFECTION further infected. Nomenclature
o Ex. Strongyloides – life o International Code of Zoological
cycle alteration leads to Nomenclature
large increase in worm o PCOFGS: Phylum-Class-Order-Family-
burden. Genus-Species
o -idae: added to the stem of genus type to
form family.
Sources of Infection
o Generic name: capitalized initial letter 1 word
o Most common source: contaminated soil and water.
o Specific name: lowercase letter
o Genus and Species: italicized and
PARASITE SOURCE
underlined.
Ascaris lumbricoides o Lack of sanitary
Trichuris trichuria toilets
Life Cycle
Strongyloides stercoralis o Use of night soil
o The more complicated life cycle = less chance of
hookworms (human excreta as
survival
fertilizer)
o Perpetuation depends on ability to ensure
Cysts of amebae and o Contaminated water transmission.
flagellates
Cercariae of Schistosoma Epidemiologic Measures
Trematodes o Food
Cestodes DEFINITION OF TERMS
Malaria and Filarial o Arthropods EPIDEMIOLOGY Study of patterns, distribution, and
parasites (mosquitoes) occurrence of disease.
Trypanosoma cruzi o Triatoma bugs INCIDENCE Number of new cases in a population
(Chagas disease) (Reduviid bugs) in a given period of time.
Leishmania spp. o Sand flies PREVALENCE Number (in %) of individuals
(Phlebotomus spp.) estimated in a population infected by
Toxoplasma infection o Cats the parasite.
Hymenolapis nana o Rats CUMULATIVE % of individuals infected with at least
E. histolytica o Another person or PREVALENCE one parasite
Capillaria philippinensis the person
Enterobius vermicularis himself/herself INTENSITY OF Burden of infection
Hymenolapis nana (beddings, clothings, INFECTION Number of worms per person
Strongyloides stercoralis self, environment) Also known as worm burden
MORBIDITY Clinical consequences of infection

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 MT 639 - Clinical Parasitology Lecture First Shifting
Treatment Host-Parasite Relationships
o Adaptation of parasites is essential to survival.
DEFINITION OF TERMS o More specialized parasites shown greater changes.
DEWORMING Use of anthelminthic drugs
CURE RATE Number of previously positive a. Locomotory and Digestive organs
subjects found to be egg negative o Protozoans in Phylum Apicomplexa have
EGG REDUCTION Percentage fall in egg counts after no locomotory organelles; mostly parasitic.
RATE (ERR) deworming. o Free-living flatworms: cilia on epidermis,
SELECTIVE Individual-level deworming organs of attachment (hookers and suckers)
TREATMENT Used in whole population or defined o Cestodes and Trematodes: no cilia, obtain
risk groups nutrients through their tegument
b. Size and Shape
TARGETED Group-level deworming o Adult Ascaris worms: maintain position by
TREATMENT constant movement.
UNIVERSAL Population-level deworming o Intestinal flukes: spine-covered tegument to
TREATMENT prevent abrasion.
PREVENTIVE Regular, large-scale, systematic o Ova, larvae, cysts – special covering during
CHEMOTHERAPY intervention its free-living state, aid in resisting digestive
Administration of one or more drugs juices.
to selected groups c. Reproductive Systems
Aim: reduce morbidity o Flatworms – highly elaborate and
complicated.
COVERAGE Proportion of target population
o Tapeworms and flukes (except
reached by intervention
Schistosoma spp.) are hermaphroditic (they
EFFICACY Effect of drug against an infective
contain complete set of male and female
agent
organs)
EFFECTIVENESS Measure of the effect of a drugs in an
o Flukes – asexual reproduction
agent living in a host
d. Biochemical Adaptations
Cure rate and ERR are indicators
o Streamlining – loss of certain metabolic
Qualitative and quantitative
pathways. Exemplified by hemoflagellates
DRUG Loss of susceptibility to a drug in a and helminth parasites.
RESISTANCE parasite population e. Mechanisms for Entry
o E. histolytica trophozoites – secrete
cysteine proteases which allows it to
Prevention and Control penetrate the mucosa and adhere.
o Cercariae of Schistosoma – contain
DEFINITION OF TERMS penetration glands (produces enzyme that
MORBIDITY Avoidance of illness can digest skin)
CONTROL
INFORMATION- Health education strategy Effects of the Parasite on the host
EDUCATION- Aims to encourage people to adapt a. Interference with vital processes of the host
COMMUNICATION and maintain healthy life practices. o Most common
(IEC) o Through parasitic enzymes
ENVIRONMENTAL Planning, organization, performance, o Metabolizes nutrients from the host
MANAGEMENT and monitoring of activities for o E. histolytica trophozoites – secrete cysteine
modification/manipulation of proteases (degrades epithelial membrane,
environment factors. facilitates tissue invasion)
ENVIRONMENTAL Interventions to reduce b. Invasion and destruction of host tissue
SANITATION environmental health risks. o Plasmodium – invades RBC
o Schistosoma japonicum – deposition of eggs
SANITATION Provision of access to adequate in the liver stimulates granuloma formation
facilities for the safe disposal of and fibrosis – leads to portal hypertension –
human excreta. massive hemorrhage.
o Hookworms – cutting plates that attaches to
mucosa and destroys intestinal villi.
Eradication vs. Elimination o Ascaris – tangled masses, causes intestinal
ERADICATION ELIMINATION obstruction, may invade other organs.
o Permanent o Reduction to zero of c. Deprive the host of essential nutrients and substances
reduction to zero the incidence of a o Heavy hookworm infection – massive
of the worldwide specified disease in intestinal bleeding, blood loss, leading to
incidence. a geographic area. iron-deficiency anemia
o Once achieved, o Continued o Diphyllobotrium latum – competes for
continued intervention is Vitamin B12, causes megaloblastic anemia.
measures are no required.
longer needed.

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 MT 639 - Clinical Parasitology Lecture First Shifting
Effects of the Host on the Parasite Host-Immune Response
a. Genetic Makeup o Rely on humoral and cell-mediated actions.
o P. falciparum (malaria) – sickle-cell traits o Response begins when the body detects and
confers protection eliminates the pathogen.
o P. vivax – Duffy blood factor increases o Phagocytosis - macrophages
susceptibility. o Dendritic cells – oxidative killing and use of toxic
b. Nutritional status of the host peptides.
o Protein-rich diet – not suitable for intestinal o Cell-mediated immune mechanisms required for
protozoans parasites that enter macrophages. (Leishmanis spp.,
o Low-protein diet – favors symptoms of Toxoplasma gondii, T. cruzi)
amebiasis. o Toll-like receptors – recognize specific molecules that
o High-carb diet – favors development of some are nonnative to the body. 10 are TLRs are identified.
tapeworms
c. Immune Processes Parasite Evasion Mechanisms
o Immunity to infection – rarely after protozoan o Factors include:
infection, never with helminths. o Parasite size
o Complicated life cycle
IMMUNOLOGY OF PARASITIC INFECTIONS o Location within the body
o Antigenic Complexity
OUTCOMES OF PARASITE IN A HOST a. Resistance to Immune Response
a. Parasite fails to become established in the host. o Cuticle and integument of helminths make
b. Parasite becomes established and the host eliminates them resistant to the cytotoxic effects of
the infection. neutrophils and macrophages
c. Parasite becomes established, and the host begins to b. Immune Suppression
overcome the infection but is not successful. o Certain parasites reduce immune function of
d. Parasite becomes established and the host harms macrophages. (Plasmodium spp,)
itself while trying to eliminate the parasite. o Surface glycoproteins – produces by
e. Parasite becomes established and kills the host. trypomastigotes of T. brucei.
o E. histolytica – suppresses macrophage
Host-Parasite Interactions respiratory burst and nitric oxide production.
c. Antigenic Variation
BARRIERS TO ENTRY/ESTABLISHMENT OF PARASITES o Parasite changes its antigenic profile to
1. Natural physical barriers of the body resist host response.
o Skin – provides surface protection d. Host Mimicry
o Strongyloides, filariform larvae of hookworm o Antibodies fail to recognize parasites
– synthesize protein that aids entry to skin. containing antigens similar to that on the
o Schistosoma spp. Cercariae – secrete lytic body.
enzymes from glands in its anterior part for e. Intracellular Sequestration
skin penetration. o Parasites multiply intracellularly.
2. Mucous membrane lining
o Tight junctions between epth. cells prevent
passage. Adverse Effects of the Immune Response in the Host
3. Low pH of vaginal secretions and gastric juices
o T. vaginalis trophozoites – can’t survive in - The normal immune response might contribute to
the acidic environment of the vagina. tissue damage as one of four types:
o Giardia lamblia – reduced motility due to o TYPE 1: Immediate type hypersensitivity
intestinal secretions. o TYPE 2: Immune Complex Formation
o Giardia lamblia – reduced motility due to o TYPE 3: Cytotoxic reactions of antibody
intestinal secretions. o TYPE 4: Delayed-type hypersensitivity
o Cysts and eggs are covered with thick walls
to protect them from acidity. GROUPS OF PARASITES WITH MEDICAL IMPORTANCE
4. Chemical components of body fluids
o Lipase in breast milk – toxic to Giardia Protozoa
lamblia o Infection due to unicellular protozoan or multicellular
o Lysozyme in tears and saliva – destroys metazoan.
microorganisms along with IgA o Provided with nucleus, cytoplasm, outer limiting
immunoglobulins. membrane, and organelles (cellular elaborations).
5. Physiologic functions of the body o Require a wet environment.
o Peristalsis, cilia motion, human reflexes – o Form infective stages called cysts and vegetative
expel parasites stage called trophozoite.
o Coughing – expectoration of adult Ascaris o Fall under Kingdom Protista
lumbricoides and eggs of Paragonimus o Majority of pathogenic protozoans belong to Phylum
westermani Sarcomastigaphora, P. Ciliophora, P. Apicomplexa,
o Flushing action of urine – decreases no. of T. and P. Microspora
vaginalis.

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 MT 639 - Clinical Parasitology Lecture First Shifting
Phylum Sarcomastigaphora METAZOAN PARASITES
o Differentiated by means of locomotion o Metazoan parasites are either helminths or arthropods
that fall under Kingdom Animalia.
SUBPHYLUM SARCODINA o Helminths causing infection fall under 3 groups:
Function Unique Feature Significant spp. annelids (leeches), nematodes, and flatworms
Locomotion Pseudopodia – Acanthamoeba
hyaline foot like castellani
extrusions from Endolimax nana
the ectoplasm E. coli
E. dispar
E. gingivalis
E. histolytica
Iodamoeba
butschlii
Naegleria fowleri
SUBPHYLUM MASTIGAPHORA
Locomotion Flagella – whip- Atrial Flagellates
like structure Chilomastix
arising from the mesnili
ectoplasm Dientamoeba
fragilis
Giardia lamblia
T. hominis
T. Tenax
T, vaginalis

Hemoflagellates
Leishmania spp.
Trypanosoma
brucei complex
Trypanosoma
cruzi

Phylum Ciliaphora

Function Unique Feature Significant spp.

Locomotion Cilia – hair-like Balantidium coli
projections from
the ectoplasm
COMPARISON
Phylum Apicomplexa FLATWORMS
o Have an apical complex at the anterior end which Nematodes Cestodes Trematodes
consists of polar rings, subpellicular tubules, conoid Roundworms Tapeworms Flukes
processes, rhoptries, and micronemes (involved in Cylindrical and Segmented, Leaf-like and
penetration and invasion of target cells) elongated in ribbon-like unsegmented
o All members are parasitic shape, bilateral appearance
o Very important groups fall under class Sporozoa symmetry
o Plasmodia Habitat: Small Intestines of Mesenteric veins
o Babesia (Ascaris, definitive host, (Schistosoma –
o Toxoplasma hookworms, larval stage blood flukes)
o Cystoisospora Strongyloides, encysted in Lung
o Cryptosporidium Capillaria) and tissues. parenchyma
o Cyclospora large intestine Liver
(Trichuris, Intestines
Phylum Microspora Enterobius)
o Enterocytozoon and Encephalitoxoon Transmission: ingestion of embryonated eggs; skin
o Spore-forming parasites penetration, bite of mosquito vectos, inhestion of infective
o Possess a unique extrusion apparatus which enables larvae, autoinfection, inhalation of embryonated eggs
them to inject infective material into the host cell. Complete No digestive tract, Incomplete
o The apparatus includes: digestive tract no circulatory digestive tract, no
o Highly coiled polar filament, extrudes (due to and triradiate system, circulatory
stimuli from GI tract), forms a polar tube that muscular pharynx Hermaphroditic system
penetrates host cell. Hermaphroditic
o Associated with immunocompromised states (AIDS)

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 MT 639 - Clinical Parasitology Lecture First Shifting
Amphids Scolex – main Oral sucker and a o Varying no. of chromatic granules
(anterior) and organ of ventral sucker
Phasmids attachment. called Parasite Biology
(posterior) – Neck – after acetabulum. o Most invasive of the entamoeba species
sensory organs scolex, region of Genital sucker – o Pseudopod-forming non-flagellated protozoan.
growth. Proglottids gonotyl o Only member to cause colitis and liver abscess.
(segments) o E. hartmanii – “small race” of E. histolytica due to its
nearest to the size.
neck are most
immature PARASITE BIOLOGY

Important Important Species: Important

Species: Order Species:
Trichuris, Pseudophyllidea
Trichinella, Scolex - bothria Fasciola,
Capillaria (all are Diphyllobotrium Clonorchis,
aphasmids), the Spirometa Opistorchis,
rest are Schistosoma,
phasmids. Order Paragoniums.
Cyclophillidea
Scolex – globular
w/ muscular
suckers
Taenia,
Hymenolepis

Arthropods

o With segmented and jointed appendages.

o Body is covered with chitinous exoskeleton.
o Insects, mites, ticks, spiders, scorpions, centipedes,
millipedes, crustaceans.
o Affect humans through:
o Bites
o Introduction of venom
o Exposure to arthropod allergens

Chapter 2: PROTOZOAN INFECTIONS

Intestinal Amebae
o Seven species occur in humans.
o Differentiated on size and structure, GENERALITIES
o Trophozoites divide by binary fission
o Cyst-forming amebae go through nuclear division, E. histolytica
then divide again after excystation in a new host. Trophozoite Cyst
Invasive stage Infective stage
GENERAL RULES OF AMEBAE Excystation : cyst – Encystation: trophozoite –
1. All are commensal except E. histolytica. trophozoite; occurs in the cyst; occurs in the large
2. All are capable of encystation except E. gingivalis. small intestine intestine
3. Mature cyst is the infective stage except E. gingivalis. Feeding, vegetative, motile Non-motile, infective,
4. Large intestine is the habitat except E. gingivalis (oral form resistant to environment
cavity). factors.
5.
Entamoeba histolytica Locomotion: Progressive, Highly refractive cyst wall
o Taxonomy: unidirectional, contains
o Subphylum Sacrodina pseudopodia
o Superclass Rhizopoda
o Class Lobosea Cytoplasm: clean-looking, Chromatid bar: rod-shaped /
o Order Amoebida with ingested RBC. cigar-shaped
o Family Entamoebidae Mononucleated 1-4 nuclei
o Genue Entamoeba
o Vesicular nucleus
o Central small karyosome

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 MT 639 - Clinical Parasitology Lecture First Shifting
Pathogenesis and Clinical Manifestations o Genital amebiasis should be differentiated from
o Mechanism of virulence: carcinoma, tuberculosis, chancroid,
o production of enzymes or other cytotoxic lymphanogranuloma venerum.
substances
o contact-dependent cell killing Bacillary vs. Amebic dysentery
o cytophagocytosis
o Trophozoites adhere to the colonic mucosa through a
galactose-inhibitable adherence lectin (Gal lectin).

DISEASES CAUSED
Disease Clinical Manifestation
Amebic Colitis Gradual onset of abdominal pain and
diarrhea with or without blood and
mucus in stools.
o Fever is not common.
o Children may develop
fulminant colitis with severe
bloody diarrhea, fever, and
abdominal pain.
Complication: perforation and
bacterial peritonitis
Ameboma Mass-like lesion with abdominal pain
and history of dysentery
o Mistaken as carcinoma.
o Occurs in less than 1%
o May be asymptomatic
Onset: sudden after 8-10 days of
incubation.
Amebic Liver Fever and right upper quadrant pain.
Abscess (ALA) o Most common extra-
intestinal form of amebiasis.
All acute presentation (< 2 weeks),
chronic (> 2 weeks)
Complication: rupture into the
pericardium and pleura, and Diagnosis
superinfection, o Standard method is microscopic detection in stool
specimens.

o Natural immunity include: DIAGNOSIS

o Mucin inhibition of amebic attachment to Method Category Trophozoite Cyst
the underlying mucosal cells. Stool Examined Examined
o Acquired immunity from cell-mediated Sample within 30 within 24
response. minutes. hours.
o Activated T-cells kill E. histolytica by: Appearance More in More in
• Directly lysing watery formed
trophozoites. Direct Fecal sample. sample.
• Producing cytokines which Smear Visualizing 0.85% NSS 1% Lugol’s
activate macrophages and (DFS) Stain (to visualize iodine (to
other effector cells. motility) visualize cell
• Providing helper effect for components)
B-cell antibody production. Diagnostic Detection of Observation
o Acute amebic colitis is different with bacillary Feature ingested of nucleus
dysentery (caused by Shigella, Salmonella, RBCs and
Campylobacter, Yersinia, Escherichia coli). karyosome
o Fever and elevated leukocyte count are less common to
in amebic colitis. differentiate
o Inflammatory bowel disease: amebic colitis must be from other
ruled out before starting steroid therapy to lessen the species.
risk of developing a megacolon. Concentration Visual More
o Differential diagnoses of ALA: methods: sensitive to
o Pyrogenic liver abscess FECT detection of
o Tuberculosis of the liver MIFC cysts.
o Hepatic carcinoma Polymerase To differentiate E. histolytica and E. dispar
Chain

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 MT 639 - Clinical Parasitology Lecture First Shifting
Reaction Entamoeba dispar
(PCR), o Morphologically similar to E. histolytica, but their DNA
and rRNA are different (isoenzyme pattern for E.
Treatment and Prognosis dispar)
o Two objectives: Entamoeba moshkovskii
o To cure invasive disease at intestinal and o Non-pathogenic
extra-intestinal sites. o Indistinguishable with E. histolytica and E. dispar.
o To eliminate passage of cysts from the o Differs biochemically and genetically
intestinal lumen. o Osmotolerant (grows at 25-30 degrees Celcius,
o Metronidazole: drug of choice for invasive amebiasis. survives at 0-41 degress Celcius).
o Other 5-nitroimidazole derivatives such as tinidazole
and secnidazole are also effective. Entamoeba hartmanii
o Diloxanide furoate: for asymptomatic cyst passers, o Similar to E. histolytica only that it is smaller.
also given after a course of Metronidazole.
o Percutaneous drainage of liver abscess: for patients
who do not respond to metronidazole.

EPIDEMIOLOGY
o 1-5% worldwide prevalence.
o 50 million E. histolytica infection cases, 40,000-
100,000 deaths per year due to amebiasis.
o Amebiasis: third most important parasitic disease after
malaria and schistosomiasis
o Second to malaria as top cause of mortality among Entamoeba coli
parasitic protozoans. o Most common amebae in humans.
o Transmission include:
o Fecal-oral contact Category Trophozoite Cyst
o Ingestion of food and drink contaminated Nucleus 1 nucleus 8-16 nuclei
with mature infective cysts. Locomotion Sluggish, non- n/a
directional
Prevention and Control Peripheral Thick, irregular, n/a
o Improve environmental sanitation. Chromatin large eccentric
o Provide safe drinking water and food. karyosome
o Sanitary disposal of human feces. Cytoplasm Dirty-looking with Granular
o Proper hygiene ingested bacteria
o Use of night soil should be avoided. and debris with
o Vaccines no RBCs
Chromatoidal n/a Splinter-like
bodies
COMMENSAL AMEBAE
o The presence of commensal amebae in stool may
signify:
o Mistaken E. histolytica
o Indication of fecal contamination of food and
water.

Parasite Biology
o The three genera can be differentiated through the
morphological features of their nuclei.
Genus
Entamoeba Endolimax Iodamoeba
Spherical Vesicular Large
nucleus nucleus chromatin
Nuclear rich
membrane kayrosome
with chromatin
granules
Small Irregularly
karyosome shaped
near the karyosome
center of the
nucleus
Stages: precyst, cyst, metacyst, trophozoite
except E. gingivalis.
Reproduction: binary fission of trophozoites.

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 MT 639 - Clinical Parasitology Lecture First Shifting
FREE-LIVING PATHOGENIC AMEBAE
Entamoeba polecki
o Found in the intestine of pigs and monkeys. Acanthamoeba spp,
o Motility: sluggish o Ubiquitous, free-living ameba
o Small karyosome is centrally located in the nucleus. o Etiologic agent of:
o Mononucleated o Acanthamoeba keratitis
o Chromatoidal bars: angular or pointed. o Granulomatous amebic encephalitis (GAE)
o Prominent nuclear membrane and karyosome. o Acanthopodia: thorn-like appendages of
trophozoites.
Entamoeba gingivalis o Highly resilient cyst stage.
o Found in the mouth o Aquatic organism and can survive in contact lens
o Trophozoites: solution.
o Locomotion: quick (blunt pseudopodia) o Trophozoites:
o Food vacuoles containing cellular debris o Feed on gram-negative bacteria, blue green
(mostly leukocytes) and bacteria. algae, yeasts
o Lives in the surface of the gum and teeth, o Reproduce by binary fission.
gum packets, tonsillar crypts. o Feed on corneal epithelial cells and
o No cyst stage. neurologic tissues through phagocytosis and
o Transmission: kissing, droplet spray, sharing utensils. secretion of lytic enzymes.
o Single centrally located large nucleus.
Endolimax nana o Densely staining nucleolus
o Large endosome
o Finely granulated cytoplasm
o Large contractive vacuoles
o Replicate by mitosis.
o Infective stage
o Only has two stages.
o No flagellated stage.
o Both cyst and trophozoite can gain entry to the body.
o Entry: eye, nasal passages to the lower respiratory
tract, ulcerated or broken skin.
o Opportunistic

Pathogenesis and Clinical Manifestations

DISEASES CAUSED
Iodamoeba butschlii
Disease Clinical Manifestation Symptoms
Acanthamoeba Use of improperly Severe ocular
Keratitis disinfected soft contact pain and
lenses. blurring of
vision
Immunocompromised =
more susceptible to Corneal
infection ulceration with
progressive
Scleritis, iritis, vision corneal
loss. infiltration.

Hypopyon
formation
Diagnosis
Granulomatous Occurs in Related to
o Through stool examination
Amebic immunocompromised destruction of
o Formalin ether/ethyl acetate concentration
Encephalitis hosts and those on brain tissue
technique and iodine stain
(GAE) immunosuppressive and meningeal
o For E. gingivalis, swab between gums and teeth is
agents irritation.
examined for trophozoites.
o Cysts are recovered from formed stools.
Increased
o Trophozoites are recovered from water or semi-
sleeping time,
formed stools.
severe
o Trophozoites: best demonstrated by DFS
headache,
o Cysts: best demonstrated by FECT and zinc sulfate
mental status
floatation.
changes,
epilepsy,
comatose.

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 MT 639 - Clinical Parasitology Lecture First Shifting
o Entry into the CNS is not completely understood. ▪ Found in CSF and tissue
o Route of invasion is hematogenous. o Flagellated forms
o Post mortem examination of neural tissues show: ▪ Occasionally found in CSF.
o Edematous and soft cerebral hemispheres
o Areas of hemorrhage and focal abscess. Pathogenesis and Clinical Manifestation
o Most affected areas: posterior fossa o Causative agent of Primary amebic
structures, thalamus, and brainstem. meningoencephalitis (PAM)
o Leptomeninges are opaque and exhibit o Rare but rapidly destructive and fatal.
purulent exudates and vascular congestion. o Occurs in previously healthy adults with a
o 10 days – incubation period. history of swimming.
o True pathogen
Diagnosis and Treatment o Route of entry:
▪ Through the olfactory bulb after
Disease Diagnosis Treatment accidental inhalation of water.
Acanthamoeba Epithelial biopsy Surgical excision ▪ Sustentacular cells of the olfactory
Keratitis Corneal scrapings of the infected neuroepithelium phagocytose the
Ameba isolation cornea then amebae and transport these
from contact lens corneal through the cribriform plate and into
solution of patients transplantation. the brain.
Culture and o Mechanisms:
molecular analysis Deep lamellar ▪ Cytopathic effect on host tissue.
through PCR. keratectomy – ▪ Secretion of lytic enzymes.
procedure of ▪ Membrane pore-forming proteins.
choice. ▪ Factors that induce apoptosis.
Granulomatous Usually post-mortem Amphotericin B, ▪ Direct feeding on cells.
Amebic in most cases pentamidine o Symptoms:
Encephalitis isethionate, ▪ Fever
(GAE) sulfadiazine, ▪ Nausea
flucytosine, ▪ Vomiting
fluconazole, or ▪ Headache
itraconazole. ▪ Nuchal rigidity
▪ Mental status changes
Epidemiology ▪ Rapid progression to coma and
o Protean distribution death
o Isolated from fresh and salt water, sewage, hospital o Signs:
equipment, and contact lenses and their lens solution. ▪ CSF findings: elevated WBC count
▪ Neutrophilic predominance
Prevention and Control ▪ High protein
o Its ubiquitous nature makes exposure unavoidable. ▪ Low glucose
o Robust immune system. o Post-mortem examination of infected brain:
o Meticulous contact lens hygiene. ▪ Hemorrhagic necrosis (olfactory
bulbs)
Naegleria fowleri ▪ Congestion and edema of neural
o Two vegetative forms: tissue
o Ameba (trophozoite form) ▪ Leptomeninges are inflamed and
o Flagellate (swimming form) congested.
o Dormant cyst form: when conditions are o Death occurs as a result of cerebral or
unfavorable. cerebellar herniation as a result of increased
o Two forms: intercranial pressure.
o Ameboid (only found in humans)
▪ Granular cytoplasm Diagnosis
▪ Contain many vacuoles o Persons with history of exposure.
▪ Single, large nucleus o Rapid meningoencephalitis.
▪ Large, dense karyosome o Aspirates are introduced into bacteria-seeded agar
▪ Lacks peripheral chromatin. (bacteria as prey usually Escherichia coli) will exhibit
o Ameboflagellate active trophozoites within 24 hours.
o Thermophilic – thrive best in hot springs and warm o Trophozoites are identified by:
aquatic environments. o Blunt, lobose pseudopodia
o Three stages in its life cycle: o Directionaly motility
o Cysts o PCR and immunostaining
▪ Not seen in brain tissue
o Trophozoites Treatment
▪ Replicate by promitosis o Amphotericin B in combination with clotrimazole
▪ Infect humans and animals by
penetrating the nasal mucosa and Epidemiology
migrating to the brain via olfactory o Fecal coliform contamination provides food for the
nerves. ameba.

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 MT 639 - Clinical Parasitology Lecture First Shifting
Prevention and Control o Direct fecal smear, sensitivity is increased using
o Easily killed by chlorination of water at 1ppm or concentration techniques.
higher.
TREATMENT
Blastocystis hominis o Difficult to eradicate
o Hides in the intestinal mucus and holds on to
o Lacks a cell wall intestinal membrane
o Previously classified as a yeast o Metronidazole
o Reproduction is asexual o Drug of choice
o 37 degrees celcius – optimal growth o 750mg 3x/day for 10 days
o Iodoquinol
o 650mg 3x/day for 20 days

EPIDEMIOLOGY
o 1.5 – 17.9% worldwide prevalence.
o Infection is possible through oral route.
o Occur in crowded, unsanitary conditions.
o Can be prevented by consuming safe drinking water
o Cysts can survive up to 19 days in water at normal
temperature and have shown resistance to chlorine at
standard concentrations.

CILIATES

Balantidium coli
o Initially identified as Paramecium coli.
o Causative agent of the zoonotic disease balantidiasis.
o Largest protozoan parasite affecting humans.
o Only ciliate known to cause human disease
o Attacks the intestinal epithelium.

PATHOGENESIS AND CLINICAL MANIFESTATION

o Blastocystosis
o Causes intestinal disorders
o Abdominal cramps
o Irritable bowel syndrome
o Bloating
o Flatulence
o Mild to moderate diarrhea without fecal
leukocytes of blood
o Nausea o Ingestion of food and water contaminated by the
o Vomiting, low grade fever, malaise parasite.
o Symptoms last for 3-10 days o Incubation period: 4-5 days.
o Associated with gastrointestinal symptoms.
Pathogenesis and Clinical Manifestation
DIAGNOSIS o Trophozoites are capable of attacking the intestinal
o Laboratory detection epithelium.

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 MT 639 - Clinical Parasitology Lecture First Shifting
o Create a characteristic ulcer: rounded base and wide- FLAGELLATES
neck, in contrast with the flask-shaped ulceration
created by E. histolytica. Giardia lamblia
o Hyaluronidase – lytic enyme, cause ulceration. o Also known as duodenalis/intestinalis
o Balantidiasis – 3 forms of clinical manifestations o Causes epidemic and endemic diarrhea
o Asymptomatic carriers – do not present o Giardiasis
diarrhea or dysentery but serve as parasite o Habitat: duodenum, jejunum, upper ileum of humans
reservoir. o Asexual life cycle
o Fulminant/balantidial dysentery – diarrhea o Cysts are transferred via contaminated hands, food,
with bloody mucoid stools; associated with water.
immunocompromised and malnourished o Cysts excysts in the duodenum
hosts. o Trophozoites attach to the intestinal villi
o Chronic form – diarrhea may alternate with o Trophozoites are found in the jejunum
constipation and accompanied by non-
specific symptoms.
o Can spread to extraintestinal sites (mesenteric nodes,
appendix, liver, genitourinary sites, pleura, lungs.
o Complications: intestinal perforation and acute
appendicitis.
o Mortality: intestinal hemorrhage and shock, intestinal
perforation, sepsis

Diagnosis
o Microscopic demonstration of trophozoites and cysts
in feces using direct examination or concentration
techniques.
o Biopsy specimens
o Bronchoalveolar washings

Treatment
o Tetracycline
o Adults and older children
o 500mg or 40mg/kg/dose
o 4 doses for 10 days
o Contraindicated in children > 8 y/o and
pregnant women
o Metronidazole
o 750mg 3x daily
o 35-50mg/kg body weight
o 5 days Pathogenesis and Clinical Manifestations
o Iodoquinol o Can occur with ingestion of 10 cysts.
o 650mg or 40mg/kg/dose o Pathogenicity is traced to its ability to alter mucosal
o 3 doses intestinal cells once it has attached to the apical portion
o 20 days of the enterocyte.
o Doxycycline and nitazoxanide o Attaches to the intestinal villi by its ventral sucking disc.
o No reports of drug resistance o Produces lectin – activated by duodenal secretions and
facilitate attachment.
Epidemiology o Causes alterations to the villi such as villous flattening
o Cosmopolitan, more prevalent with poor sanitation. and crypt hypertrophy.
o Close contact with pigs or pig feces. o Lead to decreased electrolyte, glucose, and
o Overcrowded institutions fluid absorption and deficiencies in
o 1% worldwide prevalence disaccharides.
o Pigs are the major hosts. o Rearrange cytoskeleton of human colonic and
duodenal monolayers.
Prevention and Control o Causes enterocyte apoptosis
o Proper sanitation o 1-4 weeks for the disease to manifest.
o Safe water supply o Half of cases are asymptomatic.
o Good personal hygiene o Symptoms (acute cases)
o Protection of food from contamination o Abdominal pain (cramping)
o Limit contact of pigs with water resources and food o Diarrhea
crops o Excessive flatus with an odor of “rotten eggs”
o Avoid use of pig feces as fertilizer due to hydrogen sulfide
o Cysts are inactivated by heat and 1% sodium o Abdominal bloating
hypochlorite. o Nausea
o Ordinary chlorination of water is not effective against o Anorexia
cysts.

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 MT 639 - Clinical Parasitology Lecture First Shifting
o Symptoms (chronic) of the vaginal epithelium followed by leukocytic
o Steatorrhea – greasy, frothy stools inflammation of the tissue layer.
o Diarrhea o Infects the surface but not the mucosa.
o Weight loss o Acute inflammation:
o Profound malaise o Liquid vaginal secretion
o Low-grade fever o Greenish or yellow in color
o Itchiness and burning sensation
Diagnosis o Chronic stage:
o Demonstration of cysts and trophozoites in stool o Increase in epithelial cells (secretions)
specimens. o Mixed bacterial flora
o Trophozoites: floating leaf-like motility o Vulvitis and dysuria
o Cysts: concentration techniques o Strawberry cervix – hemorrhage of the cervix
o Duodeno-jejunal aspiration: if parasite is not found in o In males:
feces. o Asymptomatic
o Enterotest – gelatin capsule with a nylon string. o Irritating or persistent urethritis
o Prostatitis is the most common complication.
Treatment
o Metronidazole Diagnosis
o 250mg 3x/day for 5-7 days o Saline preparation of vaginal fluid
o Cure rate: 90% o Gold standard: culture
o Tinidazole
o Single dose 2g for adults Treatment
o 50mg/kg in children o Metronidazole/Tinidazole
o Furazolidone o 2g as a single dose
o 100mg 4x/day for 10 days in adults o Both male and female must be treated.
o 6mg/kg/day in 4 divided doses for 7-10 days
o Albendazole Epidemiology
o Equally effective as metronidazole at doses o 170-190 million individuals
▪ 400mg/day for 5 days in adults o Higher among women of child-bearing age
▪ 10mg/kg/day for 5 days in children. o 5-20% women, 2-12% men
o Nitazoxanide o Reduce risk of exposure.
o Used for drug-resistant cases o Practice safe sex.

Epidemiology NON-PATHOGENIC FLAGELLATES

o Worldwide distribution
o 1.6%-22% prevalence in the Philippines Trichomonas hominis
o Poor sanitation and hygiene practices have higher o Occurs only as trophozoite
prevalence. o Habitat: cecal area of the large intestine
o Oral-anal sexual contact o Non-invasive
o Water-borne outbreaks

Trichomonas vaginalis
o Trichomoniasis (sexually transmitted)
o Incidence correlates with number of sexual partners.
o Most prevalent nonviral STI.
o Exists only in the trophozoite stage.
o Found in:
o Males: urethra, prostate, epididymis
o Females: urogenital tract, vagina, renal
pelvis
o Multiply by binary fission.
o MoT: sexual intercourse

Trichomonas tenax
o Pyriform flagellate
o Only trophozoite stage
o Smaller and slender than T. vaginalis
o 4 free equal flagella and a 5th one on the
margin of an undulating membrane.
o Single nucleus and cytostome
o Multiplies by binary fission
o Thrives on microorganisms
Pathogenesis and Clinical Manifestation o Exposure:
o Inflammation of the vaginal mucosa. o Droplet spray
o 4-28 days after introduction of the parasite to the o Habitat: human mouth (tartar around the teeth,
vagina, they cause degeneration and desquamation cavities of carious teeth, necrotic mucosal cells in the
gingival margins)

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 MT 639 - Clinical Parasitology Lecture First Shifting
o Quite resistant to changes in temperature and survive ▪ These drugs leave crystalline
for several hours in drinking water. residue.
o Diagnosis: swabbing ▪ Sample must be collected a week
o Pulmonary trichomoniasis after the last intake.
o B. Intake of antibiotics
Chilomastix mesnili ▪ Decreases number of protozoans
o Habitat: cecal region of the large intestine o C. Amount of stool to be collected
o Transmission: ingestion of cysts in food and drinks ▪ Dictated by the techniques that will
o Prevalence in the Ph: >1% be used.
o Diagnosed by: microscopic examination of feces ▪ Requires a thumb-sized specimen
o No treatment needed of formed stool.
o Prevention and control: improved sanitation and ▪ 5-6 tbsp. of watery stool
personal hygiene. o
o D. Contamination with toilet water, urine, or
soil must be prevented.
▪ These can destroy protozoan
trophozoites.
▪ May contain other free-living
organisms.
o E. Age of the stool sample
o F. Delay in examination of specimen
▪ May require preservation
o G. Temporary storage of fecal samples
▪ In a refrigerator (acceptable)
▪ Prolonged refrigeration can bring
about desiccation.
CHAPTER 7: DIAGNOSTIC PARASITOLOGY ▪ Trophozoites are killed by
refrigeration.
Examination of Stool and Body Fluids ▪ Cysts are usually not damaged.
o Most parasitic diseases cannot be established based ▪ NEVER FREEZE STOOL
on clinical signs and symptoms. SAMPLES
o Confirmation depends on the result of proper ▪ NEVER KEEP THEM IN
laboratory examination. INCUBATORS
o Done either by: Stool Preservatives
o Demonstration of parasite components o 1 part stool to three parts preservative.
▪ Possible only during the patent o Consider the preparation of permanently stained slide.
stage of infection.
o Detection of host immune response to the Preservative Description
parasites.
Formalin o All-purpose fixative
o Stool is commonly utilized.
o 5% - protozoan cysts
o 10% - helminth eggs and
Examination of Stool or Fecal Sample
larvae
o Demonstration of eggs, larvae, adults, trophozoites,
o Buffered with sodium
cysts, or oocysts in stool.
phosphate – to preserve
o Specimen is best collected in:
morphological features.
o Clean, wide-mouther containers made of
o Concentrated with FECT
waxed cardboard or plastic with a tight-fitting
Schaudinn’s o Preserve fresh stool in
lid to ensure retention of moisture and
solution preparation for staining.
prevent accidental spillage.
o Mercuric chloride – highly
o Should be submitted with the ff. information.
toxic.
▪ Patient’s name
o Problems of mercury
▪ Age
disposal.
▪ Sex
Polyvinyl alcohol o Plastic resin
▪ Date/time of collection
(PVA) o Adhere a stool sample onto
▪ Requesting physician
a slide.
▪ Requested procedure
o Incorporated in Schaudinn’s
▪ Presumptive diagnosis
solution.
▪ Prior infections
o Advantage: preservation of
▪ Travel history
protozoan cysts and
o Factors to be considered:
trophozoites.
o A. Intake of drugs/medical substances
o Disadvantage: use of
▪ Antacids
mercuric chloride
▪ Anti-diarrheals
o Can be concentrated using
▪ Barium
FECT.
▪ Bismuth
o Replace with cupric sulfate.
▪ Laxatives

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 MT 639 - Clinical Parasitology Lecture First Shifting
Merthiolate- o Contains merthiolate ▪ Plant cells/fibers
iodate-formalin (thimerosal) ▪ Pollen grains
(MIF) o Contains iodine (for staining) ▪ Starch granules
o Fixation of intestinal ▪ Vegetable spirals
protozoans, helminth eggs, o Plant and animal hairs
and larvae. ▪ Resemble helminth larvae
o Yield unsatisfactory results
Sodium acetace- o Does not contain mercuric TECHNIQUES
acetic acid chloride. A. Direct Fecal Smear (DFS)
formalin (SAF_ o Images are not as sharp as o 2mg of stool comminuted with a drop of
those fixed in PVA or 0.85% NSS and then covered with a cover
Schaudinn’s slip.
o Long shelf life o Routine method of stool examination.
o Detection of motile protozoan trophozoites.
Methods of Examination o Trophozoites appear pale and transparent.
o Specimen are submitted fresh or preserved: o Trophozoites may be stained with Nair’s
o Consistency: buffered methylene blue (BMB) sol’n
o Protozoans o Entamoeba cytoplasm will stain
▪ Formed stool – cysts pale clue
▪ Watery stool – trophozoites o Entamoeba nucleus will stain darker
o Helminth eggs and larvae blue.
▪ Can be found on both formed and o Protozoan cysts can also be seen in a DFS.
watery stool. o Weak iodine solution (Lugol’s or
▪ Reduced number of eggs in watery D’Antoni) can be used as temporary
sample – due to dilution. stain.
o Purged stools – for better chances of recovering o Iodine – cytoplasm will stain golden
protozoan trophozoites. yellow; nucleus will be pale and
o Color: refractile, glycogen will be deep
o Blood: brown
▪ Bright-red: bleeding from a more o Helminth eggs and larvae can also
distal location be detected.
▪ Dark-colored: bleeding high up in o Micrometry – measure cysts and ova
the GI tract.
o Blood and mucous in soft or watery stools B. Kato Thick Smear
may possibly yield trophozoites. o 50-60mg of stool (two mung beans) is placed
o Ingestion of certain compounds may impart over a glass slide and covered with cut
color on the stool. cellophane paper soaked in a mixture of
o Gross examination: Ascaris or Enterobius may be glycerin and malachite green solution.
found on or beneath the surface of the sample. o Glycerine – clearing solution
o Malachite green – used to give
A. Microscopic Examination color and give a pale green
o Elements found in stool: background.
o White blood cells: o Best examined in 10-20 minutes
▪ Polymorphonuclears (PMN) – o Useful in mass stool examinations.
indicate inflammation o Very good in detecting eggs with thick shells
▪ Eosinophils – immune but not eggs with thin shells.
response o Not able to detect protozoan cysts and
o RBCs trophozoites.
▪ indicate ulcerations or
bleeding C. Concentration Techniques
o Macrophages – o Separate protozoan cysts and helminth eggs
▪ present in parasitic and from a large amount of stool based on
bacterial infection; mistaken for difference in specific gravity.
amebic trophozoites o Based on either sedimentation or floatation.
o Charcot-Leyden crystals o Sedimentation – the parasite that has a
▪ Disintegration of eosinophils higher spec. grav. than the reagent will sink
▪ Presence of hypersensitivity or (vice versa)
parasitic infections (esp. o Floation – cleaner than sedimentation
amebiasis)
o Epithelial cells SEDIMENTATION
o Eggs of arthropods, plant nematodes, Technique Reagent and Parasite
spurious parasites Description Visualized
▪ Mistaken as human parasites Acid Ether 40% HCl Recovery of
o Fungal spores from Candida spp., yeast, Concentration o Can dissolve Trichuris,
and yeast-like fungi Technique albuminous Capillaria, and
▪ Mistaken as parasites (AECT) material trematode eggs,
o Elements of plant origin Ether

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 MT 639 - Clinical Parasitology Lecture First Shifting
o Dissolve esp. o Larval diff. between hookworm and Strongyloides at
neural fats in Schistosoma the rhabtidiform stage is difficult.
stool
Choice if stool material 1. Copro Culture
is from animals. o Positive stools are mixed with moistened soil or
Drawback granulated charcoal.
o Loss of o Simulates environmental condition.
parasite to the o Larvae are harvested using Baermann
plug of debris procedure.
o Possible
destruction of 2. Harada-Mori or Test Tube Culture Method
protozoan o Test tubes and filter paper strips.
cysts o (+) stool is applied to filter paper then placed into
Formalin- 10% formalin Recovery of a test tube with about 7mL of boiled or distilled
Ether/Ethyl o All-purpose helminth eggs water.
Acetate fixative and protozoan o Filariform larvae can be recovered at the bottom.
Concentratio Ether cysts.
Technique o Dissolve fats E. Egg Counting Procedures
(FECT) in stool o Correlate severity of disease with the intensity of
infection or worm burden.
o Can be done o Done to assess efficacy of anthelminthics.
with formalin
and PVA- 1. Kato-Katz Method or the Cellophane Covered
preserved Thick Smear
stools. o Stool is sieved through a wire mesh then pressed
o Most parasites under a cellophane paper soaked in glycerine-
can be malachite green solution.
recovered o Uniform amount of stool is examined using a
from formalin template.
preserved o Total egg count is multiplied with a factor depending
stools. on the amount of factor used.
o Ether is o Assess intensity of infection with:
explosive and o Schistosoma
flammable. o Ascaris
o Ethyl acetate o Trichuris
can be used in o Hookworm
place of ether. o Consistency is a determinant for sensitivity.
o Can only be done on formed stools.
FLOATATION o For Schistosoma ova: 1% eosin solution is layered
Technique Reagent and Parasite over the cellophane paper.
Description Visualized
Zinc Sulfate o 33% zinc If parasites are Formula:
(ZnSO4) sulfate exposed to high
solution specific gravity, 𝑬𝑷𝑮 (𝒆𝒈𝒈𝒔 𝒑𝒆𝒓 𝒈𝒓𝒂𝒎) = (𝒇𝒂𝒄𝒕𝒐𝒓)(𝒏𝒖𝒎𝒃𝒆𝒓 𝒐𝒇 𝒆𝒈𝒈𝒔)
o Specific thin-walled
gravity should nematode eggs 𝟏𝟎𝟎𝟎
be checked and protozoan 𝑲𝒂𝒕𝒐 − 𝑲𝒂𝒕𝒛 𝒇𝒂𝒄𝒕𝒐𝒓 =
𝒎𝒈 𝒐𝒇 𝒔𝒕𝒐𝒐𝒍
o Ideal SG = cyst distortion
1.18-1.20 and shrinkage
may occur.
Brine o Saturated Hookworm and 2. Stoll Egg Count
table salt Schistosoma o Uses 0.1 N NaOH and a stool displacement flask
solution eggs become calibrated at 56 mL and 60 mL.
o No need for shrunken. o NaOH
centrifugation o Acts as stool diluent.
since eggs Not useful for o Stoll pipette – used to measure amount of diluted
float operculated stool for egg counting. (calibrated at 0.075 and 0.15
eggs since they mL)
don’t float. o Constant used to multiply the total egg count depends
Sheather’s o Boiled sugar Coccidian on the amount of stool.
Sugar solution oocysts o Sensitivity is determined by consistency of stool.
preserved with
phenol F. Staining of Stool Specimen
o To examine nuclear characteristics of amebae.
D. Stool Culture Methods o Identification of other intestinal parasites.
o Ova of all hookworm species are similar, and o Techniques include:
speciation is impossible. o Iron-Hematoxylin

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 MT 639 - Clinical Parasitology Lecture First Shifting
o Trichrome • Hematoxylin and
o Periodic Acid Schiff (PAS) ammonium alum: main
o Chlorazol Black E stain
o Not useful for coccidian oocyst identification. • Enhances nuclear detail
(Kinyounn’s method of acid-fast staining is and morphological
best) features.
o Acid-fast staining • Could be permanently
o spreading a thin layer of stool on a glass mounted with Canada
slide. balsam.

PERIANAL SWAB o 3. Capillary Tube Methods

o Used to recover eggs of Enterobius vermicularis and o Finger-prick blood sample in heparinized
Taenia spp. capillary tube.
o When centrifuged, 3 layers are visible.
A. Cellulose Tape or Scotch Tape Method o Microfilariae and trypanosomes are
o Sampling the perianal skin using a strip of visualized in the buffy coat area.
cellulose tape attached to a glass slide. o Buffy Coat films
o Specimen is collected early in the morning ▪ Tube is broken at the white cell
before washing the perineum. layer area.
▪ Layer is spread and stained with
EXAMINATION OF BLOOD Giemsa or Wright’s stain.
o Several Helminthic parasites and protozoan parasites ▪ Trypanosomes and Leishmania are
are in the blood at some stage of their life cycle. concentrated in the area.
o Quantitative Buffy Coat (QBC)
Methods: ▪ makes use of capillary tube
o Finger-prick blood sample precoated with acridine orange and
o Sample must be free-flowing to prevent potassium oxalate.
dilution of blood with tissue fluid ▪ Cylindrical float – inserted to
o 1. Wet/Fresh Preparation enlarge layers.
o Microfilariae and trypomastigotes are large ▪ After centrifugation, tube is read
and motile. using UV microscope.
o 2. Stained Smears ▪ DNA of parasites take up acridine
o Thick films orange, causing fluorescence.
▪ 2-3 small drops of blood spread ▪ Malaria parasites, microfilariae,
over an area of 2cm. trypanosomes, Babesia.
▪ Demonstrate microfilariae and
malarial infection. B. Venous Blood - Concentrated to detect microfilariae.
o Thin films o 1. Knott’s Concentration
▪ Thick at one end and thin and o 1mL of blood is mixed with 10mL of 2%
feathery on the other end. formalin then centrifuged.
▪ Species identification of malarial o Sediment is studied, spread, and stained.
parasites. o 2. Membrane Filtration
o Stains o Useful when density of microfilariae is low.
▪ Giemsa Stain o Syringe attached to a Swinney filter holder.
• red cells stain pale red o Blood is lysed by adding distilled water.
• white cell nuclei – purple o Lysed blood is passed through Swinney
• eosinophil – bright purple membrane to recover microfilariae.
• neutrophil- deep pink
purple EXAMINATION OF SPUTUM
▪ Wright’s stain o Parasites that may be recovered:
• Contains alcohol o Migrating larvae of Ascaris lumbricoides,
• No fixation needed Strongyloides stercoralis, and hookworms
• Erythrocytes – light red o Paragonimus ova
• Leukocyte nuclei – bright o Echinococcus granulosus hooklets
blue o Protozoa
• Eosinophilic granules – ▪ E. histolytica trophozoites from
bright red pulmonary amebic abscess
• Neutrophilic granules – ▪ Cryptosporidium parvum oocysts
pink ▪ E. gingivalis, T. tenax
▪ Delafield hematoxylin stain o First morning specimen is best
o Inductants (10% NaCl or H 2O2) are used to
• Demonstrating detailed
increase amount.
features of microfilariae.
• Thick films are
dehemoglobinized in 2%
formalin with 1% acetic
acid.

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 MT 639 - Clinical Parasitology Lecture First Shifting
Methods
A. Gross or Macroscopic Examination B. Rectal Biopsy
a. Consitency – serous, mucoid, purulent, o Reveal presence of deposited Schistosoma
bloody or combination japonicum eggs.
b. Color
i. Yellow – pus
ii. Greenish tint – Pseudomonas --------------------------------------END---------------------------------------
infection
iii. Bright red- recent bleeding
iv. Rust – breakdown of hemoglobin
B. Microscopic Examination
a. Wet Mount – using saline or iodine for
protozoan trophozoites.
b. Sputum Concentration – if sputum if thick,
equal amount of 3% NaOH is added.

EXAMINATION OF URINE
o First morning specimen is best.
o For Trichomonas vaginalis parasite
o Rounded, globular, and transparent
structure.
o Jerky tumbling motion
o Wucheria bancrofti microfilariae
o Schistosoma haematobium

EXAMINATION OF TISSUE ASPIRATES

o Samples from the following have found to yield
parasites:
o Liver
o Duodenum
o Bronchial
o Lymph Node
o Skin
o In the Ph, most common aspirate comes from the liver
(hepatic amebic abscess)

A. Duodenal aspirate
o Used for the following
o Giardia lamblia
o Strongyloides stercoralis
o Intestinal intubation
o Entero Test (string test)

B. Cutaneous or String Aspirates

o Cutaneous ulcerations
o Leishmaniasis
o Oriental sore – below the ulcer bed
o (+) samples show presence of
amastigotes.

EXAMINATION OF CEREBROSPINAL FLUID

o Trypomastigotes of hemoflagellates (Trypanosoma
complex)
o Trophozoites of Naegleria
o Parastrongyliasis – CSF eosinophilia
o Trypomsstigotes perish within 20 minutes as well as
the morphology of Naegleria
o Centrifuged at 7000g for 10 minutes.

EXAMINATION OF TISSUE BIOPSY MATERIAL

A. Muscle Biopsy
o Diagnosis of Trichinella spiralis infection.
o Pieces of muscle are pressed between two glass
slides.
o Taenia – larval infection with Spirometra spp.
Can result in sparganosis.

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