Micro lec # 24 Date : 15/4/2012



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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 …


Diagnosis :
** 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

 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 :

  1. Head louse ( pediculosis capitis )

  2. Body louse ( pediculosis corporis )

  3. 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



2-body louse:

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



3-Crab :

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 )


Metazoa

 we have tow type of metazoan :



  1. Metahelminthes

  2. Platyhelminthes ( flatworm ) : It divide into tow type 

  1. Nematode B- cestode


Nematode :

separated sex

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 :



  1. 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 .

complications :



1-intestinal obstruction

2-enlargement of the liver and hepatitis

3- heavy worm infestation may cause nutritional deficiency

4- toxicity
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Done by: Bayan Saleh …

We must accept finite disappointment, but never lose infinite hope. 


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