| area of biology concerned with the phenomenon of dependence of one living organism on
another | Parasitology |
| – deals with the parasites that cause human infections and the diseases they
produce; broadly divided into two parts: protozoology and helminthology | Medical Parasitology – |
| Living together; the association of two living organisms, each of a different species | SYMBIOSIS |
| Association of two different species of organisms that is beneficial to one and
neutral to the other | COMMENSALISM |
| Association of two different species of organisms that is beneficial to both | MUTUALISM |
| Association of two different species of organisms that is beneficial to one at the
other’s expense | PARASITISM |
| A parasite, which lives within the body of the host.
The presence of an endoparasite causes an: INFECTION
Most of the protozoan and helminthic parasites causing human disease
are endoparasites. | ENDOPARASITE |
| Inhabit only the body surface of the host without penetrating the tissue.
(e.g. head lice, ticks)
The presence of an ectoparasite causes an: INFESTATION | ECTOPARASITE |
| Most parasites are obligate parasites; cannot exist without a host.
Need a host at some stage of their life cycle to complete their
development and to propagate their species
Depends entirely upon their host for existence
Ex. Toxoplasma gondii, Plasmodium spp. | OBLIGATE |
| May exist in a free-living state or become parasitic when the need arises
(e.g. Strongyloides) | FACULTATIVE |
| Infect an unusual host; establishes infection in a host where it does not
normally live
(e.g. Echinococcus granulosus, Dipylidium caninum, Dirofilaria immitis,
Ancylostoma caninum) | ACCIDENTAL/INCIDENTAL |
| Remain in or on the host for its entire life
Ex. Strongyloides, Loa loa, Taenia solium | PERMANENT |
| Live in the host for a short time (e.g. Plasmodium spp.) | TEMPORARY |
| Passes digestive tract of humans without infecting them (e.g. Eimeria
sardinae) | SPURIOUS |
| Infect a host where they cannot develop further (e.g. Toxocara canis) | ABERRANT |
| Female parasite capable of reproducing eggs without being fertilized by
a male and whose eggs contain larva that immediately hatches (e.g.
Strongyloides | PARTHENOGENETIC |
| Usually protozoans; able to multiply in fecal matter outside human body | COPROPHILIC |
| Lives inside red blood cells (e.g. Plasmodia, Babesia, Leishmania) | HEMATOZOIC |
| Lives inside cells or tissues (e.g. Trichinella spiralis) | CYTOZOIC |
| Lives in body cavities (Mansonella spp.) | COELOZOIC |
| Resides in intestines (Tapeworms, Entamoeba histolytica) | ENTEROZOIC |
| ACCORDING TO PATHOGENECITY, Capable of causing disease | PATHOGENIC |
| Commensals; incapable of causing disease (e.g. Trichomonas tenax,
Entamoeba gingivalis) | NONPATHOGENIC |
| CLASSIFICATION OF HOSTS
Host in which the adult parasite lives and undergoes sexual
reproduction
May be human or any other living being however in majority of
human parasitic infections, humans are the final hosts (e.g. filarial,
roundworm, hookworm | DEFINITIVE/FINAL |
| CLASSIFICATION OF HOSTS, Host in which the larval stage of the parasite lives or the asexual
multiplication takes place.
If there are more than one IH, these can be classified as 1st and 2nd
IH. | INTERMEDIATE |
| CLASSIFICATION OF HOSTS
Parasite does not develop further to latter stages
Parasite remains alive and is able to infect other susceptible host
Harbors the parasite; will only serve as a transport medium; no
further development occurs.
Ex. Paragonimus metacercaria in raw wild board meat
Diphyllobothrium latum plerocercoid larva in big carnivorous fish | PARATENIC |
| CLASSIFICATION OF HOSTS
Harbors parasite; allows the parasite life cycle to continue and
become additional sources of infection
Ex. Pigs – reservoir host of Balantidium coli
Field Rats – reservoir host of Paragonimus westermani
Cats – reservoir host of Brugia malay | RESERVOIR |
| Host in which the parasite is not usually found (e.g. man in
echinococcosis) | ACCIDENTAL |
| CLASSIFICATION OF VECTORS
A vector, which not only assists in the transfer of parasites but
the parasites undergo development or multiplication in their
body as well; also called as true vectors. | BIOLOGIC |
| A vector, which assists in the transfer of parasitic form
between hosts but is not essential in the life cycle of the
parasite.
Ex. Housefly – Amebiasis
Cockroach - Ascariasis | MECHANICAL/PHORETIC |
| Harbors pathogen and is asymptomatic | CARRIER |
| Period between the entry of parasite in the host and
subsequent recovery of the form/s of parasite in samples | PRE-PATENT PERIOD/
BIOLOGIC INCUBATION |
| Period between infection to development of symptoms | CLINICAL INCUBATION PERIOD |
| Individual becomes infected by his/her own
Nematodes: Capillaria philippinensis, Enterobius
vermicularis, Strongyloides
Cestodes: Taenia solium, Hymenolepis nana
Protozoan: Cryptosporidium hominis, Cryptosporidium
parvum | AUTOREINFECTION |
| Already infected individuals are further infected with same
species (e.g. Strongyloides) | SUPERINFECTION/HYPERINFECTION |
| SOURCES OF INFECTION
Most common
Lack of sanitary toilets and the use of night soil or human
excreta as fertilizer allow the eggs to come in contact with the
soil and form the development of specific parasites
Ex. Hookworm, Ascaris lumbricoides, Trichuris trichiura,
Strongyloides stercoralis (HATS) | SOIL |
| SOURCES OF INFECTION
Cysts of amebae or flagellates; cercaria of schistosomes | WATER |
| SOURCES OF INFECTION
Trematodes (Flukes) and Cestodes (Tapeworms) | FOOD |
| SOURCES OF INFECTION
Mosquitoes – Malaria, Filarial worms
Triatoma bugs – Trypanosoma cruzi
Phlebotomus sandflies – Leishmania spp | ARTHROPODS |
| SOURCES OF INFECTION
Cats – direct sources of Toxoplasma infection
Rats – may be infected with Hymenolepis nana | ANIMALS |
| SOURCES OF INFECTION
Asymptomatic carriers of Entamoeba histolytica working as
food handlers. | ANOTHER INDIVIDUAL |
| MODES OF TRANSMISSION, Most common method
Cestodes, Trematodes, Intestinal Protozoans are foodborne | ORAL (FECAL-ORAL) |
| Another important mode of transmission
Hookworm and Strongyloides stercoralis enter upon exposure
to soil
Schistosoma spp. is acquired when cercariae in water
penetrate the skin | SKIN PENETRATION |
| Transmit parasites through their bites
Malaria, Filariasis, Leishmaniasis, Trypanosomiasis,
Babesiosis | ARTHROPODS |
| Toxoplasma gondii
Trophozoites can cross the placental barrier during pregnancy
TRANSMAMMARY INFECTION
Ancylostoma and Strongyloides - may be transmitted through
mother’s milk | CONGENITAL TRANSMISSION |
| MODES OF TRANSMISSION, Enterobius vermicularis | INHALATION OF AIRBORNE EGGS |
| MODES OF TRANSMISSION, Trichomonas vaginalis | SEXUAL INTERCOURSE |
| Seen in case of transfusion malaria and toxoplasmosis after
organ transplantation | IATROGENIC TRANSMISSION |
| – most commonly submitted sample for examination of parasites
The most common procedure performed is the examination of a stool specimen for Ova and Parasites
(O&P). | Stool |
| All-purpose fixative; buffered with sodium phosphate to preserve
morphological characteristics
- 5% concentration: recommended for protozoan cysts
- 10% concentration: recommended for helminth eggs and larvae
- When the stool specimen is added to the vial, the final ratio of stool to
preservative is 1:3
- Preserved stool can be concentrated using Formalin-Ether/Ethyl Acetate
Concentration Technique (FECT/FEACT) | FORMALIN |
| - Used to preserve fresh stool/fresh fecal specimen in preparation for staining the
stool smears
- Provides excellent preservation of protozoan trophozoites and cysts
- For many years, considered as the “gold standard”
- Contains mercuric chloride which is highly toxic to humans | SCHAUDINN’S
SOLUTION |
| - Plastic resin that serves to adhere a stool sample onto a slide
- Normally incorporated into the Schaudinn’s solution
- Main advantage: preservation of protozoan cyst and trophozoites for
permanent staining
- Stool preserved in PVA can be concentrated using FECT
- Modified PVA: using non-mercuric compounds such as copper sulfate or zinc
sulfate (used with trichrome stain)
- Disadvantage: use of mercuric chloride | POLYVINYL
ALCOHOL (PVA) |
| - Components both fix and provide stain color
- Contains Merthiolate (Thimerosal) and Iodine that act as staining
components
- Formalin acts as a preservative
- Useful for fixation of intestinal protozoans, helminth eggs, and larvae
- Disadvantages: Contains mercury compounds (thimerosal)
Staining of preserved stools in MIF yields unsatisfactory results or
not as good as Schaudinn’s fluid | MERTHIOLATE
IODINE-FORMALIN
(MIF) |
| - Advantage: Does not contain mercuric chloride; long shelf-life
- Disadvantage: Images are not as sharp after staining as compared with those
fixed in PVA or Schaudinn’s solution | SODIUM ACETATEACETIC ACID
FORMALIN (SAF) |
| Both the concentration and permanent stained smear can be prepared
- It is also possible to perform fecal immunoassay procedures from some of these
vials. | SINGLE-VIAL
COLLECTION
SYSTEMS |
| - 2 mg of stool + 1 drop of 0.85% NaCl (NSS) + coverslip
- Routine method of stool examination
- Can be stained with Nair’s Buffered Methylene Blue (BMB) solution
- Micrometry is used to measure cysts and ova (ex. differentiation between cysts
of Entamoeba histolytica and E. hartmanni is based entirely on their sizes)
- LPO (x100) of entire 22x22 mm coverslip & HPO (x400) of at least 1/3 of the
coverslip area of both saline and iodine
- OIO (x1000) is not recommended (organism morphology is not clear)
- The use of iodine is optional
Eggs of helminths are also readily seen.
o Rhabditiform larvae of Strongyloides stercoralis are detected in
freshly passed stool | DIRECT FECAL
SMEAR |
| 50-60 mg of stool is placed over a glass slide; covered with cellophane paper
soaked in a mixture of glycerin and malachite green solution
- GLYCERIN: clearing solution
- MALACHITE GREEN: gives a pale green color minimizing the brightness of the
microscopic field
- Best examined within 10-20 minutes
- Useful in mass stool examination; technique is simple and economical
- Very good in detecting eggs with thick shells (e.g. Ascaris and Trichuris) but
not eggs with thin shells (e.g. Hookworm)
- Not able to detect protozoan cysts and trophozoites | KATO THICK
SMEAR |
| BEST technique for
the recovery of:
-Schistosoma
(heavy spine)
-Operculated eggs
- Trematode eggs
- Cestode eggs
- T. trichiura eggs
- C. philippinensis | SEDIMENTATION
CONCENTRATION |
| - Main Reagents:
o 40% HCl: dissolve albuminous material
o Ether: dissolve neutral fats/lipids and CHO in the stool
- Recommended for the recovery of Trichuris, Capillaria, and trematode eggs,
especially Schistosoma
- Choice if stool material comes from animals like cats and dogs
- Disadvantage: destruction of protozoan cysts | SEDIMENTATION
CONCENTRATION, ACID ETHER CONCENTRATION TECHNIQUE (AECT) |
| Main Reagents:
o 40% HCl: dissolve albuminous material
o Ether: dissolve neutral fats/lipids and CHO in the stool
- Recommended for the recovery of Trichuris, Capillaria, and trematode eggs,
especially Schistosoma
- Choice if stool material comes from animals like cats and dogs
- Disadvantage: destruction of protozoan cysts | SEDIMENTATION
CONCENTRATION, ACID ETHER CONCENTRATION TECHNIQUE (AECT) |
| Most commonly used
- Main Reagents:
o 10% Formalin: all-purpose fixative
o Ether: dissolve neutral fats/lipids and CHO in the stool; explosive and
flammable
o Ethyl Acetate: alternative for ether | FORMALIN-ETHER/ETHYL ACETATE CONCENTRATION TECHNIQUE
(FECT/FEACT |
| Useful in the recovery of both helminth eggs and protozoan cysts
- FECT can be done with formalin-preserved and
PVA-preserved samples
- More parasites can be recovered from formalin-preserved samples
- Morphology is also better preserved in formalin than in PVA
- Sediments from FECT can be stored for a long period of time. | FORMALIN-ETHER/ETHYL ACETATE CONCENTRATION TECHNIQUE
(FECT/FEACT) |
| BEST technique for
recovery of:
- Protozoan cysts
- Nematode eggs
except for T.
trichiura and C.
philippinensis
(heavy due to
bipolar mucus
plugs) | FLOTATION
CONCENTRATION |
| - operculated and/or very dense eggs such as unfertilized Ascaris eggs do not
concentrate well in the flotation method; sedimentation technique is recommended
- Main Reagent: 33% Zinc Sulfate solution
- Specific Gravity Range: 1.18-1.20
- FRESH STOOL SPECIMEN: 1.18
- FORMALIN PRESERVED SPECIMEN: 1.20
- If parasites are exposed to high specific gravity, distortion and shrinkage of
protozoan cyst and thin nematode eggs may occur
- To ensure detection of all possible organisms, both the surface film and the
sediment must be examined. | ZINC SULFATE FLOTATION |
| uses saturated table salt solution; stools are directly mixed with the brine solution
(SG: 1.20)
- Helminth eggs like Hookworm and Schistosoma become badly shrunken
- Not useful for operculated eggs like Clonorchis, Opistorchis, and Heterophyids
because these do not float in brine solution. | BRINE FLOTATION |
| Boiled sugar solution with phenol
- Best for recovery of coccidian oocysts mainly Cryptosporidium, Cyclospora, and
Cytoisospora | SHEATHER’S SUGAR FLOTATION |
| Stools positive for
Hookworm ova or
Strongyloides
rhabditiform larva
can be cultured
until filariform larva
develop | STOOL CULTURE |
| - Positive stools are mixed with moistened soil or granulated charcoal.
- Larvae are harvested using the Baermann procedure
- Baermann procedure: based on active migration or movement of larvae from
feces suspended in water
- Advantage: greater amount of fresh stool used; better chance of larval recovery | COPRO CULTURE AND BAERMANN FUNNEL TECHNIQUE |
| Uses test tubes and filter paper strips
- Positive stool (0.5-1g) is smeared in the middle third of the filter paper
and placed into a test tube with 7 mL (3-4 mL) (1/2 inch) of boiled
or distilled water
- Keep the tube at room temperature in the dark for 7-10 days; examine daily | HARADA-MORI OR THE TEST TUBE CULTURE METHOD |
| - Filariform larvae will move downwards and be recovered from the water at the
bottom of the tube
- Strongyloides larvae may instead move upwards and accumulate at the upper
end of the strip
- Caution must be exercised in handling the filter paper | HARADA-MORI OR THE TEST TUBE CULTURE METHOD |
| - More sensitive
- 2 g of fresh stool is placed in the center of the agar plate
- Plates are sealed with tape to prevent accidental infection and placed in RT for 2
days
- In positive cases, larvae will crawl over the agar, making visible tracks over it.
- Examine microscopically for the evidence of larvae at the ends of tracks away
from the stool | AGAR PLATE CULTURE FOR Strongyloides stercoralis |
| Boeck and Drbohlav’s diphasic medium (modified by Dobell and Laidlaw)
- Balamuth’s monophasic liquid medium (amebae and other intestinal protozoa)
- Cleveland Collier’s Medium
- Diamond’s Medium (for T. vaginalis)
NNN (Novy-McNeal-Nicolle) Medium for Leishmania and Trypanosoma
Schneider’s Insect Tissue Culture Medium – recommended in vitro culture of
Leishmania; more sensitive than NNN; uses cells of Drosophila | CULTURE MEDIA FOR INTESTINAL PROTOZOA |
| Recommended method of WHO
- Uses a measured amount of stool which has been sieved through a wire mesh
- Uniform amount of stool is examined through the use of a template with a
uniform-sized hole in the middle.
- Allow the cellophane coverslips to soak in the glycerin mixture for about 24 hours
- Allow the preparation to stand for 1 hour at RT to allow clearing of fecal material
- Do not overclear; thin shelled hookworm eggs may disappear
- Clearing time extended to 24 hours for S. mansoni eggs | KATO-KATZ METHOD OR CELLOPHANE-COVERED THICK SMEAR |
| Uses 0.1 N NaOH that acts as a stool diluent; saponifies fat and frees eggs from
debris
- The amount of diluted stool used for egg counting is measured by stoll pipettes
- Total egg count is multiplied by a factor depending on the amount of stool used
- Routine: 4 g feces; multiply by factor 100 to obtain # of eggs/gram stool
- Sensitivity is determined by the consistency of the stool | STOLL DILUTION EGG COUNT |
| - Easiest to use
- 2 mg of stool is smeared
- Egg counts on direct smear are reported as eggs/smear | DIRECT SMEAR METHOD OF BEAVER |
| - Eggs in 20 mg stool are concentrated by salt flotation on the squared grid on the
roof of the chamber which can be counted | MCMASTER’S EGG COUNTING CHAMBER |
| - Most reliable
- The two most commonly used are the Wheatley modification of the Gomori
tissue trichrome stain and the iron-hematoxylin stain
- Permanent stained smears are examined using oil immersion objectives
(×600 for screening, ×1000 for final review of 300 or more oil immersion fields)
- The permanent stained smear is the most important procedure performed to
confirm the diagnosis of intestinal protozoan infections.
- MODIFIED ACID-FAST: recommended for intestinal coccidia
- MODIFIED TRICHROME: recommended for intestinal microsporidia | PERMANENT STAINED SMEARS |
| Fixative: PVA
- Expected results: Background debris will be green and protozoa will show
blue-green to purple cytoplasm. The nuclei and inclusions will be red or
purple-red and sharply delineated from background. | WHEATLEY’S TRICHROME STAIN FOR FECAL SPECIMENS |
| Oldest method (created over a century ago) but more difficult
- Reveals excellent morphology of the intestinal protozoa
- In some cases, the nuclear detail of organisms is considered to be stained clearer
and sharper than when stained with trichrome
- Modifications:
> Spencer-Monroe method
> Tompkins-Miller method: longer method; uses 2% phosphotungstic acid
as decolorizer | IRON HEMATOXYLIN STAIN |
| Expected results:
> Protozoa cytoplasm: blue to purple
> Protozoa nuclear material: dark blue to dark purple
> Debris and background material: light blue, sometimes with pink tint | IRON HEMATOXYLIN STAIN |
| Fixative: 5-10% Formalin or SAF
- Expected results: Spores: ovoid, refractile; spore wall is bright pinkish red
Polar tube: seen as a stripe or as a diagonal line across the spore
Bacteria and debris: stain green, some stain red | MODIFIED TRICHROME STAIN FOR MICROSPORIDIA (WEBER-GREEN) |
| Specimen: Fresh stool or fixed (5-10% Formalin or SAF)
- Expected results: Spores: ovoid, refractile; spore wall is bright pinkish red
Polar tube: seen as a stripe or as a diagonal line across the spore
Bacteria and debris: stain blue, some stain red
- If the stool is semi-formed or formed, the amount of artifact material is much
greater, and the spores are much harder to detect and identify.
- The number of spores varies according to the stool consistency (the more
diarrheic the stool, the more spores that are present). | MODIFIED TRICHROME STAIN FOR MICROSPORIDIA (RYAN-BLUE) |
| - Kinyoun’s Method of Acid-Fast Staining is recommended
- Weaker decolorizer (2% H2SO4) compared to the original Acid-Fast Staining
method
- The oocyst of the coccidians stain pink to red with a blue or green background | MODIFIED ACID-FAST FOR COCCIDIANS |
| Rarely requested and no longer clinically relevant
- Requires mixing a small amount of feces with water and straining the mixture
through a series of wire screens (graduated from coarse to fine mesh) to look for
scolices and proglottids | RECOVERY OF
THE
TAPEWORM
SCOLEX |
| - The appearance of scolices after therapy is an indication of successful
treatment.
- If the scolex has not been passed, it may still be attached to the mucosa; the parasite
is capable of producing more segments from the neck region of the scolex, and the
infection continues.
- If this occurs, the patient can be retreated when proglottids begin to reappear in
the stool | RECOVERY OF
THE
TAPEWORM
SCOLEX |
| Used to recover Enterobius vermicularis, Taenia spp., and Schistosoma mansoni eggs | PERIANAL SWAB |
| moves out through the anus at night time and deposits eggs on the
perianal skin | Enterobius gravid female |
| can crawl out of the anus and in the process, ova are
squeezed out of the segment and are deposited on the perianal skin | Taenia spp. gravid segments |
| A piece of transparent adhesive tape is pressed firmly against perianal skin, and the adhesive
surface of the tape is spread on a glass slide | CELLULOSE TAPE OR SCOTCH TAPE METHOD |
| The slide is then placed under microscope and observed for parasitic eggs.
o A drop of toluene or xylol may be placed between the tape and the slide to clear the preparation.
o The specimen should be collected for 3 consecutive days at early in the morning before the
patient has taken a bath or before the patient has washed the perineum; can also be obtained late
at night when patient have already slept for several hours
o At least 4 to 6 consecutive negative tapes are required to rule out the infection. | CELLULOSE TAPE OR SCOTCH TAPE METHOD |
| Next to feces, the largest number of parasites are found in the | BLOOD |
| Several species of helminthic parasites (e.g. filariae) and protozoan parasites (e.g. Plasmodium,
Trypanosoma, Babesia) are in the blood at some stage of their life cycle.
Blood films can be prepared from fresh, whole blood collected containing no anticoagulants,
anticoagulated blood, or sediment from the various concentration procedures | BLOOD |
| often used to stain the microfilarial sheath | Delafield’s hematoxylin stain |
| Microfilariae and Trypanomastigotes are large and motile in fresh blood
preparations. Their presence can be easily detected
- Species identification is not possible. | WET/FRESH PREPARATION |
| Larger quantity of blood can be tested
- Increased volume of blood present on thick film may allow the malaria parasite to
be detected even with low parasitemia.
- Compared with a thin film, a thick film is about 30 times more sensitive and can
detect about 20 parasites/μL of blood.
- The examination should be performed at low magnification to detect
microfilariae. | STAINED SMEAR: THICK FILMS |
| A search for malarial organisms and trypanosomes should be completed using
oil immersion (at least 300 fields)
- The thick blood film is prepared by spreading a few drops of blood (using a circular
motion) over an area approximately 2 cm in diameter.
- If whole blood is used: examiner should continue stirring about 30 seconds to
prevent the formation of fibrin strands.
- The blood films must be laked before or during staining (rupture of all RBCs); the
only structures that are left on the blood film are white blood cells, platelets, and
parasites.
- The disadvantages are that the red cells are lysed (dehemoglobinized) and the
morphology of the parasites is distorted, so that species identification becomes
difficult.
- The WBCs on the stained blood film serve as the quality control
- Reporting (Paniker) | STAINED SMEAR: THICK FILMS |
| - The initial screening should be done with the low-power microscope objective
- Microfilariae are carried with the smear during preparation and typically are
located at the edges or feathered end of the thin film.
- Before a smear is reported as negative for the presence of parasites, a minimum
of 300 fields should be examined. | STAINED SMEAR: THIN FILMS |
| The thin blood film is routinely used for parasite identification to the species level.
- The WBCs on the stained blood film serve as the quality control
- If the smears are prepared from anticoagulated blood, which is more than an hour
old, the morphology of both parasites and infected RBCs may not be typical.
- Slides are fixed with methanol before staining. | STAINED SMEAR: THIN FILMS |
| - Thick smear is first dehemoglobinized and the two are then stained together.
- Do not allow the methanol to contact the thick film when fixing the thin film.
- The stained thin smear is examined first. If the thin smear is negative, the thick
smear should be searched for parasites. | STAINED SMEAR: COMBINED THICK AND THIN FILMS |
| Collected using
heparinized
capillary tube
Centrifuged;
microfilariae
and
trypanosomes
are visualized at
the buffy coat
area examined
under a
microscope | CAPILLARY
TUBE
METHOD |
| Capillary tube is broken at the area of the white cell layer after centrifugation and
then stained with Giemsa or Wright’s stain.
- L. donovani, trypanosomes, and H. capsulatum (a fungus with intracellular
elements resembling those of L. donovani) occasionally may be detected in the large
mononuclear cells found in the buffy coat
- With L. donovani, the nuclear material stains dark red-purple, and the cytoplasm
is light blue.
- H. capsulatum appears as a large dot of nuclear material (dark red-purple)
surrounded by a clear halo.
- Trypanosomes in the peripheral blood also concentrate with the buffy coat cells. | BUFFY COAT FILMS |
| - Capillary tube precoated with Acridine Orange and Potassium Oxalate. After
centrifugation, the tube is read using a UV microscope.
- The DNA of the parasite takes up Acridine Orange (fluorochrome) stain causing
fluorescence | QUANTITATIVE BUFFY COAT (QBC) |
| May be
concentrated
to detect
microfilariae | KNOTT’S CONCENTRATION |
| - In cases of low microfilaremia
- 1 mL of blood is mixed with 10 mL of 2% Formalin
- Supernatant is discarded
- Sediment is studied (smeared and stained)
- The disadvantage of the procedure is that the microfilariae are killed by the
formalin and therefore are not seen as motile organisms. | KNOTT’S CONCENTRATION |
| - Useful when density of microfilariae is low
- Uses Swinney membrane filter where microfilariae is recovered
- Membrane filtration recovers most species of microfilariae; however, because of
their small size, Mansonella perstans and M. ozzardi may not be recovered.
- This is the most sensitive method of detecting small numbers of microfilariae, but
it is expensive for routine use.
- The blood is passed through a polycarbonate filter that contains a 2-μm pore.
- Distilled water is passed through the filter, lysing the red blood cells and
improving the visualization of the parasites. | MEMBRANE FILTRATION |
| Migrating larvae of Ascaris lumbricoides, Strongyloides stercoralis, and Hookworm spp.
A-S-H: Heart-To-Lung Migration | SPUTUM |
| sputum may be viscous, streaked with blood, and tinged with
brownish flecks, which are clusters of eggs (“iron filings”) | Paragonimus westermani ova |
| Migrating larvae of Ascaris lumbricoides, Strongyloides stercoralis, and Hookworm spp.
A-S-H: Heart-To-Lung Migration
B. Paragonimus westermani ova – sputum may be viscous, streaked with blood, and tinged with
brownish flecks, which are clusters of eggs (“iron filings”)
C. Echinococcus granulosus hooklets from pulmonary hydatid cysts: Pulmonary Hydatid Disease | SPUTUM |
| Protozoa such as:
1. Entamoeba histolytica trophozoites from pulmonary amebic abscess
2. Cryptosporidium parvum oocyst
3. Nonpathogenic Entamoeba gingivalis and Trichomonas tenax | SPUTUM |
| Very good specimen for the diagnosis of Trichomonas vaginalis (most frequent parasite) | URINE AND UROGENITAL TRACT SPECIMENS |
| rounded and globular structure exhibiting jerky, tumbling motility | Trichomonas vaginalis: |
| in the Philippines, the most common aspirate submitted for parasitic diagnosis comes from the
liver to rule out hepatic amebic abscess caused by Entamoeba histolytica
Also used in the recovery of Echinococcus granulosus hydatid cyst composed of hydatid sand and
scolices | TISSUE ASPIRATES |
| is used in the diagnosis of Giardia lamblia and Strongyloides stercoralis
▪ Giardia’s “falling leaf” motility is rarely seen; Strongyloides larvae are very motile
▪ Centrifugation of the specimen before examination is important
▪ If the specimen cannot be completely examined within 2 hr after it is taken, any remaining
material should be preserved in 5% to 10% formalin. | Duodenal aspirate |
| is a simple, convenient method for collecting
duodenal contents.
▪ The terminal end of the yarn should be yellow-green, indicating that it was in the duodenum.
▪ After 4 hours, the yarn is retrieved and the mucoidal material clinging to the yarn is examined
for parasites including S. stercoralis, G. lamblia, Cryptosporidium spp., microsporidia,
and the eggs of Clonorchis sinensis
▪ If the specimen cannot be completely examined within 1 hr after removal of the yarn, the
material should be preserved in 5% to 10% formalin or PVA-mucus smears should be
prepared. | the Duodenal Capsule Technique (Entero-Test) |
| must be centrifuged at 7000 g for 10 minutes,
Trypomastigotes of Trypanosoma cruzi, Trypanosoma brucei rhodesiense, Trypanosoma
brucei gambiense
Trophozoites of Naegleria and Parastrongylus larvae
must be within 20 minutes since trypomastigotes perish and the
morphology and motility of Naegleria trophozoites are affected within the time period | CSF |
| Useful in the diagnosis of Trichinella spiralis infection
Useful in the diagnosis of larval infection with Taenia solium resulting in cysticercosis or
larval infection with Spirometra spp. resulting in sparganosis | MUSCLE BIOPSY |
| reveal the presence of deposited eggs of Schistosoma
japonicum
Schistosoma mansoni, Schistosoma japonicum | Rectal Biopsy |
| obtained to diagnose subcutaneous filariasis (Onchocerca & Mansonella)
or leishmaniasis by grasping with a forceps or elevating a portion of skin with the tip of needle.
Tip of the small cone of the skin is then sliced with a sharp blade or razor. | SKIN SNIP |
| Wet mount preparation of lymph node aspirate and chancre fluid are used as rapid methods for
demonstration of trypanosomes.
o Biopsies from liver, spleen, bone marrow, and lymph nodes are taken in visceral leishmaniasis for
demonstration of Leishman Donovan (LD) bodies.
o All biopsy tissues must be submitted to the laboratory without the addition of formalin fixative. If
there is delay in transport or processing, the specimen should be placed in polyvinyl alcohol fixative
o Adult filarial worms can sometimes be found in section of biopsied lymph node.
o Corneal scrapings are useful in diagnosis of acanthamoeba keratitis. | SKIN BIOPSY |
