|Micro lec # 24
Date : 15/4/2012
In the last lecture we talk about the control of malaria … we wall talk briefly about the diagnosis of malaria then we will start talking about new things …
** To diagnose luminal parasites : we look for cysts or trophozoites in stool .
**To diagnose tissue parasites : we take blood sample and do serology ( look for Ab for certain organism ) but in some cases we take tissue biopsy from the lesion in the skin as in the case of nashmania or we take biopsy from the liver , spleen o bone marrow (if it was infected) as in the case of ( kanagar and viscera nashmanitis ) ??? not sure the record was not clear
** malaria parasite plasmodium : by the examination of blood smear … we take a blood sample (2-3 time in different occasion ) especially if we have fever …. One time isn’t enough
we have tow type of smear :
1-thick smear : to detect the presence of plasmodium
2-thin smear : to notice the morphology and differentiate between the 4 species of parasites .
Now we will start talking about Ectoparasites :
Ectoparasites : parasites live on the body (outside not in the lumen and tissue )
Endoparasites : parasite live inside the body and it’s tow type 1-luminal 2- tissue … we talked about it before like malaria , …
First type of ectoparasites louse .
1- Louse :
3 types :
Head louse ( pediculosis capitis )
Body louse ( pediculosis corporis )
Crab louse ( pubic louse )
Head louse and Body louse are very similar they have the same morphology ,they only differ in the area they live in .
The Louse live on the body , feed on the blood and produce eggs (nits)
**Nits : ( the egg of louse ) it stick to the hair and clothes ,and it’s white in color.
1-head louse :
Very common between school children
transmitted from one to another
not always associated with bad hygiene
after infection the person will have sensitivity to louse saliva and he will suffer from itching >> excoriation >> secondary infection
It’s easier to look for nits than looking for louse … we look for nits (eggs) by using UV light as nits fluoresce under UV light
always associated with bad hygiene
the louse live in the clothes and put their eggs on it
It can be transmitted to other people
It cause itching >> excoriation >> secondary infection
It can transmite diseases like Tephos , Rectcia
live in pubic hair
mostly it transmitted by sexual contact
Now we will take about the second type of ectoparasites
2- Sarcoptis scabiei :
Feed on the skin and it produce something like tunnel on the skin after a period of time the patient will become allergic and start scratching and get excoriation
The most common area we find them in :
1-between fingers 2-palmar aspect of the wrist 3-axillary region 4-inguinal region ( very rare on the face )
transmission: by contact and it can be transmitted sexually
The third type of ectoparasites
3- Bedbug ( cimex lectularius ) :
Feed on the blood
don’t stay on the body
They live in beds , roof , walls and at night they come out and feed on the blood
If you killed them blood will get out and it has nasty smell
Site of bite will irritate because of allergy …. The bite of bedbug more inflamed and more itching than mosquito bite .
Transmission : through clothes and furniture
there is no risk of spread of infection ( not like body louse )
we have tow type of metazoan :
Platyhelminthes ( flatworm ) : It divide into tow type
Nematode B- cestode
most of them don’t need intermediate host except tissue parasite ( Filarias )
most of them produce eggs
we have many types of nematode :
1- Pinworms ( enterobiusis )
very small about 1cm in length
live in the large intestine
they only live for 6 weeks
The eggs of pinworms don't lay in the lumen . The Female worm produce eggs in the lumen then the eggs migrate through anal canal and lay on the perianal skin
the eggs mature in the perianal skin , producing embryo and become infective
Transmission : the child will scratch the perianal skin and the eggs will stick to their hands and under nails then either it transmitted to other people or reinfect himself ( when the eggs ingested by other or by the child himself ) .
If reinfection doesn’t occur the person will cure rapidly because the worm live only for 6 weeks .
Usually not very serious disease except when it cause pruritus ani ( intense itching to the anal region )
In heavy infection the worms will appear in feces ,and the mother may note the worm on the perianal region .
Diagnosis : Transparent adhesive tape ( Scotch Tape) applied on the anal area will pick up deposited eggs, and diagnosis can be made by examining the tape with a microscope , and the eggs under microscope will appear like almond , flat on one side and convex on the other side .
treatment : all the family should take the treatment and it’s favorable to repeat the treatment after 4 weeks to make sure that they get rid of all worms and there is no reinfection .
2-whipworms ( trichuris trichiura )
The anterior part of the worm is thin and the posterior part is thick
4-5 cm in length
live in small intestine
slender anterior end ( sharp head ) help the worm to anchor itself to the wall of intestine especially to the cecum
Feed on the fluid from intestine
The eggs shape is lemon shape or tea tray shape , Compressed from tow side and wide in the center
Life cycle of the worm : Eggs are deposited from human feces to soil , in soil after (2-5) weeks they become embryonated ( mature eggs ) and enter the infective stage. These embryonated infective eggs are ingested and hatch in the human small intestine .
If the human ingest the eggs before maturation they will not cause disease .
Diagnosis : by detecting the eggs in stool examination
sign and symptoms : usually asymptomatic but if the infection was heavy the person will suffer from :
pain 2- diarrhea with blood 3- rarely the person will suffer from anemia
The whipworm can live for about 3 years in human intestine .
3-Ascaris lumbricoides :
look like earthworm , it's pink-gray in color
up to 30 cm in length
live in small intestine
very muscular , their muscular structure help them to keep squeezing themselves in the lumen between the villi of intestine and stay there .
Life cycle : the female worm produce eggs that will pass with feces and deposited in the soil , in soil after (2-4) weeks they become embryonated ( mature eggs ) and enter the infective stage .
The eggs hatch in small intestine and then penetrate the wall of small intestine and enter the blood circulation , circulate in the systemic circulation until it reach the lung . in the lung they trap there and break into the alveoli and get out with mucus secretion , the person well swallow them again and the worm will bake to small intestine .
Diagnosis : By detecting the eggs in stool examination
The ascaris can live for 1-1.5 years in human intestine
treatment : Piperazine >> paralyze the muscle of worm so it can’t stay in the lumen and get out of the body
sign and symptoms : Usually asymptomatic . The most common way for presentation when the worm get out from the mouth and umbilicus ( in case of meckel diverticulum) and observation of live worms in stools .
2-enlargement of the liver and hepatitis
3- heavy worm infestation may cause nutritional deficiency
Done by: Bayan Saleh …
We must accept finite disappointment, but never lose infinite hope.