Transcript Lecture 1: Laboratory Diagnosis of Parasitic Infections

LABORATORY DIAGNOSIS
OF
PARASITIC
INFECTIONS
Case diagnosis
• History (Age, occupation, residency,
previous infection)
• Complaint
Provisional diagnosis
• Clinical examination
Confirm the diagnosis
• Invesigations
- Laboratory investigations
- Radiology
- Surgical intervention (Exploratory)
DIAGNOSIS
DIRECT
Urine
Stool
Sputum
Biopsy
Blood
Aspirates
INDIRECT
IHAT
LAT
IFAT
ELISA
MOLECULAR
PCR
DNA probes
URINE EXAMINATION
MACROSCOPIC
MICROSCOPIC
colour
white
Sedimentation
smoky
Chyluria
concentration
Blood
Filaria
S. haematobium
Ether
Acetic acid
Dissolve fat
M.f
RBC haemolysis
Clear ova
Membrane filtration
URINE EXAMINATION
SEDIMENTATION
CONCENTRATION
Clean conical
glass receptacle
15-20 min
Centrifuge (2 min)
URINE EXAMINATION
Membrane filtration technique
air
10 ml urine
Nucleopore filter
+ Saline
Eggs of Schistosoma
URINE EXAMINATION
HELMINTHES
PROTOZOA
ARTHROPODES
• S. haem.egg
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•
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•
E. vermic. egg
S. mansoni egg
Mf (Ov, Wb)
H sand
• T. Vag troph
• Pthirus pubis
STOOL EXAMINATION
MACROSCOPIC
•Consistency
•Colour
•Composition
OTHERS
MICROSCOPIC
Permanent
Diect saline smear
•Culture
•Cellophane tape
Temprory
Iodine smear
•Baeremann tech.
•Ova quantitaion (Stoll & Kato)
Concentration techniques
Floatation
Sedimentation
Saline
Formol ether
Sat saline
Zinc sulphate
Sheather’s sugar
STOOL EXAMINATION
MACROSCOPIC EXAMINATION
COLOUR
CONSISTENCY
Pale
-Liquid (Troph)
-Formed (Cyst)
-Semi formed (Cyst)
COMPOSITION
?? Blood ?? Mucus
(dysentry)
Adult PARASITES
*Ascaris worm
*E. vermicularis
*T. saginata
STOOL EXAMINATION
Temporary
Saline smear
Iodine smear
saline
Iodine 1%
Huge number of:
•Eggs
• Protozoal troph. Motility
(Amoeb, flagellates)
Huge number of:
•Cyst morphological details
STOOL EXAMINATION
Scanty infection
Concentration techniques
Sedimentation
• Heavy eggs (Ascaris egg)
Floatation
• Non Operculated eggs
• Operculated eggs (Trematodes)
Trematodes ( S. m.)
• Larvae (Strong sterc.)
Cestode
Nematode(Hookworms,Trichostong)
• Cysts
• Cysts
STOOL EXAMINATION
Saline sedimentation
Mesh wire gauze
Saline
Emulsify
Conical flask
10 g stool
Sediment
STOOL EXAMINATION
Permanent Stained smears
• Iron haematoxylin stain
• Trichrome stain
• Modified Ziehl Neelsen stain
(Crypto.)
STOOL EXAMINATION
Kato technique
Mesh screen
Hole
Remove the template
Template
Cellophane soaked by glycerin
(clears faeces(
Egg count/ g stool
Egg quant. Of: Ascaris, T. trich., Hookworms, S. mansoni
Stool examination
• Stoll’s technique for eggs of Ascaris, T.
trich., Hookworms, S. mansoni
• Baermann’s technique Detec. Of
Nematode L. /stool, soil
• Cultures for Nematode larvae using Filter
paper culture for Larvae of: St. stercoralis
(A,L) and Hookworms
SPUTUM EXAMINATION
MACROSCOPIC
Appearance
MICROSCOPIC
Concentration
Bloody (Parag)
Rusty brown (Parag)
NaOH
Sputum
Centrifuge
Parasites/sputum
P living in lung
• P. westermani eggs
P migrating in lung
P resulting from rupture of
• St. stercoralis
• Ascaris
• Hookworm (filariform L)
• Hydatid cyst (sand)
• Amoebic abcess (troph)
BIOPSY SPECIMEN
SKIN
MUSCLE BIOPSY
RECTAL BIOPSY
O. Volvulus mf
T. Spiralis larvae
Schistosoma egg
CSF
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•
•
•
Afr. Tryp. (trypom)
FLA (troph)
M.f. of loa loa
L. of T spiralis
Duodenal aspirates
•
•
•
•
G. lamb troph
Crypto oocyst
St sterc. Rh L.
Fasciola eggs
BM aspirates
• L. donovani a,ast.
•T. cruzi amast.
•P. falciparum.
Cutanoeus ucler
•Leishmaniasis
•Lumbar puncutre
• Centrifuge
•Examine sed.
Direct stain (amast)
NNN (promast)
BLOOD EXAMINATION
Blood films
Thin
Buffy coat films
Thick
QBC technique
Knott’s conc. tech.
BLOOD EXAMINATION
BLOOD FILMS
• Thin
• Thick
Bld drop
spread
Air dry
Circular motion
Air dry
methyl alcohol
Geimsa
Geimsa
Malaria, Babesia, Filaria, Tryp.
Indirect immunological diagnosis
• Serology – All tests
available
– IHA
– ELISA
• More useful in
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–
–
–
–
–
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Amoebiasis
Leishmaniasis
Malaria
Toxoplasmosis
Trichinosis
Filariasis
Echinococcosis
• Skin Tests –
Specificity low, cross
reactions common
– Casoni’s test
– Leishmanin test