OSPE
Objective Structured Practical Exam
Total Marks 30Divided as follows:
10 specimens: Slides, jar &/or box
5 specimens : -Identification
-Mention 2 main characteristic features
(20 marks)
(10 marks)
(1 mark each)
Identification only
Slides, jar &/or box
(2 marks each)
(1 mark each)
Time allowed to identify each specimen is one minute
Time allowed to identify each specimen is one minute
Time allowed to write 2 characteristics is another minute
Jars of Trematodes
Adult F.giganticaAdult F.hepatica
Leaf-like flat worm
Lateral borders
are parallel
Lateral borders
are converging
Jars of Trematodes
Adult Fasciola in bile ducts
Liver tissue
A piece of liver infected with Fasciola
Jars of Cestodes
Single Hydatid cyst
Spherical cyst surrounded by fibrous layer
Jars of Cestodes
Hydatid cysts in the liver
Cysts of different sizes in liver tissue
Fibrous tissue lining the cavities
Solitary cyst in the liver tissue
Jars of Cestodes
Hydatid cyst of lung
Lung tissue is consolidated
Solitary cystMultiple cysts
Taenia segments
Jars of Cestodes
Flat segmented worm, tape-like
Some segments are broader than
long, then segments
become squarish then longer than
broad
Jars of Cestodes
Cysticercus bovis in heart muscle
Section of heart showing cysticercus bovis
Piece of heart muscle Slice of heart
muscle
Cysticercus bovis appear as oval body )1X0.5 cm in size(
Cysticercus bovis appear as oval body )1X0.5 cm in size(
Jars of Nematodes
Adult ♀ Ascaris worm
Creamy-white in colour
Cylindrical, about 20 cm long
Adult Ascaris worms
Creamy-white in colour
Cylindrical, about 20 cm long
♀ & ♂Ancylostoma
Cylindrical worms
with bursa
Cylindrical worms with pointed end
Adult Ancylostoma attached to mucosa of small intestine
Jars of Nematodes
Jars for Nematodes
Adult Trichuris trichiura attached to mucosa of caecum
Thin portion of the worms are embedded in
caecal mucosa
Thick portion of the worms are hanging
in the lumen
The worms are whip-like
Jars for Nematodes
Elephantiasis of the skin
Thick, wrinkled skin
Fissured skin
Boxes of Flies
Wohlfahtria Sarcophaga
Abdomen is dotted
In both: Mouth is sucking
In both: Body is composed of head, thorax & abdomen
Abdomen is chess-board
like
Boxes of Flies
Musca domestica
Abdomen with median dark band
In both: Body is composed of head, thorax & abdomenIn both: Mouth is sucking
Lucilia
Metallic green in colour
Fleas
HABITS:
Temporary ectoparasites.
Both sexes are blood suckers.
They are host specific.
Increase in spring and autumn.
Medically Important Fleas
Is a vector of diseases:1- Plague:
Pulex irritans
Human Flea
2- Endemic or murine typhus:
Anterior station
Posterior station
Multiplication of Yersinia
Multiplication in epithelial
cells
caused byYersinia pestis.
caused by Richettsia mooseri.
Mechanism: Propagative transmission
Mode of infection
Skin contamination by flea faeces
Inhalation of dried faeces
Crushing of infected flea
Skin lesions caused by flea bite
Animal Fleas
Dog flea
Intermediate host of parasitic diseases:
I.H. for H.nana and H.diminuta )rat flea(I.H. for D.caninum )dog flea(
Rat fleaCat flea
Infected stool on the ground
Adult ♀flea
Flea egg
H.nana egg
H.diminuta egg
D.caninum egg capsule
Flea larvaFlea pupa Cysticercoid nana
Cysticercoid diminutaCysticercoid caninum
Infected flea
How can fleas transmit infection to man?
Fleas found in animal hairs
Tunga penetrans
In dusty soil
Causes Chigger’s or Jigger’s disease.
Found in South America.
It attacks humans walking bare-footed on dusty soil
Has angular head
Control of Fleas
Human fleas:
Insecticides and vacuum cleaner to clean floors and carpets from eggs and larvae of fleas.
Dog and cat fleas:Dusting animals and their resting places with insecticides.
Rat fleas:Dusting rat holes with insecticides.Using rodenticide )warfarin(.
Strict quarantine measures against ships by fumigation.
Lice Lice infecting man:Pediculus humanus capitis )head louse(.Pediculus humanus corporis )body louse(.Phthirus pubis )pubic louse(.
Habits:Permanent ectoparasites.Spread epidemics of louse-borne diseases.Season: winterTransmitted by combs, brushes, hats and clothes.
Male Female Female Male
Pediculus humanus capitis )head louse(
Cause the following lesions
Adult lice hanging to human hair
Skin lesions from lice bitesLice attach their
eggs to human hair
Body louse is a vector of the following diseases
1- Epidemic typhus: caused by R. prowazekii.
Source of the epidemic:a case of typhusa case of Brill-Zinsser disease
Posterior station
2- Trench fever: caused by R. quintana.
Posterior station
3- Epidemic relapsing fever: caused by B. recurrentis.
Disappear from gut to body
cavity )crushing(gut
Body cavity
Mechanism of disease transmission:
Propagative
)faeces, dried faeces
or crushing)
)faeces or crushing(
A human carrying R.prowazekii in a dormant form for years then disease appeared on him due to depressed immunity
Body louse cause Pediculosis
Also called: vagabond’s disease
Occurs in persons who had lice for long periods
Phthirus pubis )Pubic louse( Found attached to pubic hairs, axillary hair and eye lashes.
Blepharitis )inflammation of lid margin(.Eggs of Phthrirus pubis
Skin becomes thickened & dark coloured
Control of Lice
Boiling the underwear.Shaving pubic and axillary hairs.Removal of lice from eyelashes by forceps and
application of yellow oxide of mercury ointment.
Body louse:Bathing and boiling of clothes.
Head louse: Spraying of hair by synthetic pyrethrum )Licid(.
Pubic louse:
Bed Bugs )Cimex lectularius(
Cimex on bed matress
Female Male
Habits: Temporary ectoparasites.Feed only on blood )Nocturnal feeders(
Give a characteristic odour.
Cimex lectularius )Bed bugs(
Cimex on human skin
Cimex bite on skin
Medical importance:
Persistent biting by night causes insomnia and nervous irritability.
Mechanical carriers of human diseases.
May transmit hepatitis B virus.
Control:
Application of insecticides to hiding places. Fumigation.
Collection and destruction of bugs.
Winged Bugs)Cone-nosed, kissing, Assassin and Barber’s bug(
Vector of Trypanosoma cruzi that causes Chagas’
disease.
Egg
Romana’s sign
larva
nymph
adult
Habits:Temporary ectoparasites.
Nymphs and adults are blood suckers.
Nocturnal feeders.
Attack face with no pain.
Medical Importance:
Mechanism of disease transmission by winged bug T.cruzi in human blood
Epimastigote form
Short stumpy metacyclic
trypanosomes )infective stage(
Amastigote form
Pass out with faeces
Cyclopropagative transmission
Alimentary canal of
bug
A patient presenting with corneal ulcer
a b c
1 -Which of the following parasites can cause corneal ulcer?
E.histolytica trophozoite
Acanthamoeba trophozoite
Trypanosoma cruzi
A patient presenting with corneal ulcer
a b c
2 -Which of the following represents the mode of infection by the
causative protozoa?
Contamination by Triatoma faeces
Use of contaminated contact lens
Flies standing on eyes & face
A patient presenting with corneal ulcer
a b c
3 -How can you confirm your diagnosis?
Corneal scraping to detect the
parasite
CSF examination to detect the
parasite
Sample suspension in fresh water
A patient presenting with swollen eye-lid
1 -Which of the following parasites can cause swollen eye?
a b c
Toxoplasma gondii
trophozoite
Acanthamoeba trophozoite
Trypanosoma cruzi
A patient presenting with swollen eye
a b c
2 -Which of the following represents the mode of infection by the
causative protozoa?
Contamination by Triatoma faeces
Use of contaminated contact lens
Flies standing on eyes & face
A patient presenting with swollen eye
a b c
3 -How can you confirm your diagnosis?
Corneal scraping to detect the
parasite
Blood film examination
Sample suspension in fresh water