micro sheet # 13- Shatha Al- S3oodi

 Main subjects of this lecture:
• Enteroviruses ,
• Polioviruses .

Enteroviruses: there are more than 71 serotypes, some of them are more imp than others, y3ni ; there are at least 3 or 4 imp groups of enteroviruses which are associated with Gastroenteritis or Enteritis or other complications that could be recognized in relation to the CNS , mostly in the form of Aseptic meningitis , Meningio-encephalitis , Oral ulceration.
Pathogenesis ;
Enteroviruses are very similar, all of them mainly have the same mechanism , which is => attatchment to the respiratory mucosa or intestinal mucosa .
That means ; the infection could start in the upper respiratory tract & later on reachs the lymph system, then to the blood stream & finally reaches the intestine, OR it may start in the intestine by the long ingestion of contaminated water with these viruses, after that these viruses attatch to the mucosa of the intestine…carried to the mesentric lymph nodes (in the intestine )… cross the blood barrier & reaches blood stream , then the infection will spread to all organs of the body, "especially the CNS".
Polioviruse…Viruse Structure:
Circular in shape , there are polypeptides on its surface as part of the capsule , these polypeptides are very similar to each other & its not easy to distingiush between them by molecular techniques , but if we do investigation by sequensing (as Amino- acid sequnsing) ,we may recognise some differents, but generally all of them are similar.
Morphological structure :
Can be seen only by the electron microscope , like .. polioviruse , coxsakeiviruse , ekoviruses.
Clinical symmetry ; considered as Ecosahedral symmetry , that means it have many faces & all of them have repeated type of polypeptide.
Epidimiology ;
Most of enteroviruse infections are common in developing countries , like in our country. Especially in relation to standard of hygien & the presence of enough clean water , which can contribute to a lot of infections with these viruses .
Most of these viruses can survive in surface water like river …etc . Now, the water can be contaminated by fecal materials which is excreted from humans or animals . So , if the water in any community is cleaned & chlorinated , you can recognise less incidence of these enteroviruses . And in relation to HYGIEN … during wars for example, due to crowded conditions ,low standard of hygien & less presence of clean water .. all of these conditions leads to spread of such viruses easily . Also the atmospheric temprature plays an imp rule in the spread of enteroviruses , bcoz most of them are more active in summer months , more than in winter months.
Up to 90% of all cases pf enteroviruses infection can be considered as asymptomatic, its rarely associated with clinical features , which can be identified as headach , vomiting , diarrhea …etc.
Remmeber….. most of them are asymptomatic , but you may observe in some cases mild elevation in the body temprature for 1 to 2 days associated with diarrhea /mostly.. watery diarrhea [like in case of infection with vibrio-cholera ] not bloody diarrhea , y3ni ,, its not associated with inflammation to the intestine , like in cases of shigilla or toxigenic E.coli bacterial infection .
Enteroviruse infection mainly recognised in children /especialy in young children & infant/, in the form of pharyngitis , like in rhinoviruse & others…
It might be associated with skin rashes , problems in the CNS –Aseptic meningitis - , or might produce inflammation in the conjunctiva [such manifestation is in the case of rhinoviruse infection , its not part of enteroviruses ,but could produce conjuctivitis] , and leads to bleeding in the eye .. Acute Hemorrhagic Conjunctivitis.
So, there is no 100% features which can be associated with this viruse or other viruses of this group /Enteroviruses/ , by that we can say that thses viruses are very similar to each other than any other types of viruses . But one or two of these viruses can be recognized in association with something called "Paralysis" ,Muscle Paralysis,,, which can be so sever leading to damage for the cranial nerve system , as spinal cord nerves , resulting in Flaccid Paralysis (شلل رخوي) -in relation to poliomylitis.
Some of thses viruses may manifeste ulcerations /esp. in the oral cavity/. Such patients have vesichles of ulceration or papules (elevation in the mucosa /skin ) without the presence of fluid or true inflammation , which called "Hand-Foot-Mouth disease", it might be recognized in children .
Generally, let us say ; that these viruses are more imp. & associated in clinical features to infants & young children more than adults . Whyyyyy?????
Because.. normally by asymptomatic infection , the body will develop specific humoral antibodies , as will as localized antibodies in relation to intestinal tract , which always results in the form of immunity.
SoOoOo,, generally immunity is aquired during contact with these viruses , and most of us has been exposed to some doses of these viruses at the first 5 yrs of old , by that we have gained immunity , so we will not have any problems with these viruses later on.
Poliomylitis , as a disease is caused by poliovirus , for this virus there are 3 serotypes (capsid protien) /causes asymptomatic Enteritis & they are similar in the antigenic structures , but there are some differents between them in some shapes of antigenc structure.
The Serotypes can be divided into ;
1) Serotype 1 : responsible for the infection outbreak , Epidemic Poliomylitis . which is the most common type.
2) Serotype 2 : less associated with out break of epidemic poliomylitis , rarely associated with infection .
3) Serotype 3 : recently dicovered \means in the last 30 yrs\ as imp. causative agent of epidemic poliomylitis .
In the past , in the 60's there was only one serotype , responsible for the common features of poliomylitis , and after 10 yrs they have been dicovered the serotype , and in the 80's they discovered the 3rd serotype .
Environmental conditions…
Polioviruses cosidered as the most resistant enteric viruses , the most one that resist the environmental factors , it can survive in contaminated water ,sewage water ,also it can survive in surface water like rivers , and in contaminated food articles .
Route of infection for poliovirus …
Its most commonly adapted to humans(intestinal tract) , but animals could be included by means of artificial infection in the form of infection,But not similar to human infection, means that they use expirment ……… in order to recognise them in clinical feature of the virus. So , the polioviruses are considered as human viruses , adapted to human body & produce infection in relation to…….. .
Routes of infection ;
1- Ingestion of contaminated water or food .
2- Close contact with infected person , by hands or contact with infaected materials of other persons ,saliva …etc.
Might result in upper respiratory tract infection , its not infection followed by inhalation of infected organisms like in infleunza virus , adenovirus or others. Here the infection should be transmitted by direct contact to result with infection & once the poliovirus attatch to the mucosa of the respiratory tract , it will rapidly enter the lymph system /can’t survive for along time in Respiratory Tract/ , then cross the blood brain barrier to the stream & produce infection in blood " Viremia " , later on reaches the intestine – mesentric lymph nodes .
That was one route of infection , the second one is ….
If the infection started in the intestinal tract - mucosa - it will multiply in the mesentric lymph nodes there ,then goes to blood stream ….. distributed all over the body reaching the CNS.
Incubation period ….
Depends on the doses , y3ni.. the number of viruse particles exist in the intestine , this period could be between few days up to 3 weeks .
Also it depends on , Age /as exception for poliovirus/ children are less susceptible to get infection than adults , because children have specific antibodies for this virus .
generally this infection started at early childhood , by that the childs' body will produce antibody which will protect him later on during his life. But if he hasn't get infection at that period for any reason , he will be more suceptible to infection in adulthood , then the clinical features appears to be more sever & associated with more complications .
Most of the cases with this infection , are associated with subclinical features /Asymptomatic infection /, that means … you might have the infection but you don't know about it . In this case you may have simple manifestations like fever , headach & mild diarrhea. But the existence of such features isn't enough to say that you have poliovirus infection.
The clinical features of poliovirus infection are divided into 3 parts :
1) Asymptomatic poliomylitis , associated with 95% of all children , they have Mild infection … may be recognized with mild symptoms like in case of infleunza disease. Mostly ended with recovery & even without knowning that the person was infected. Majority of cases are children , at the age of 10 yrs.
Only about 1% of asymptomatic features are associated with Aseptic Meningitis (it can be easily recognised).
2) Aborative poliomylitis , 1 - 4 % , there is incomplete clinical picture of the poliomylitis , in this case you might recognise Non-specific illness (fever , headach, sore throat, meningitis , tonsilitis, …etc.) , In addition to CNS disorders like neck stiffness, back pain , aseptic meningitis.

According to these two features [Asymptomatic & Aborrative ] …
They are followed with rapid recovery within 1 to 2 weeks , also they are not associated with sever damage to the CNS & brain stem.
The end result is developing of specific antibodies & immunity for the rest of your life, which protects u against reinfection of paralysis.

3) Paralytic poliomylitis (شلل الاطفال), which is very dangerous & rare disease, Often recognized in older children and about 1/1000 children might develop paralytic poliomylitis (these children are not immunized with the vaccine.) , in adults 1/75 may develop this disease.
Paralytic Poliomylitis means , that at the beginning there is aseptic meningitis & later on it will result in more damage to the CNS , especially in spinal cord & brain stem cells resulting in Muscle weakness.
Muscle Weakness  depends mainly on destruction of the lower motor neurons , & with increasing the severity + destruction this will leads to damage in the gray matter of spinal cord with more damage in brain stem cells, which results in something called " bulbar poliomylitis " , flaccid paralysis الشلل الرخوي paralysis for the muscles of the lower limbs , so the patient will not have the ability to walk properly on his legs, such cases of flaccid paralysis, are not recognized widely in our country & most countries in the world.

In the past, for studying such cases that have this disease/flaccid paralysis/ they use a simple & accurate way , by asking specific persons to count people who walk in the streets & appears to have problems in walking/problems in there legs/, this gives an accurate number for individuals who suffer from such disorder .
This way has been recognized in the 40's – 50's , but later in the 70's-80's the vaccine was introduced, so the incidence of acute flaccid paralysis was reduced to about 1/100,000 of population .
Now , back to Bulbar Poliomylitis ; it means sever form of polio. Infection, which is associated with sever damage to the brain stem cells , sever pain in the muscles , also might result in Respiratory Paralysis (the patient in this case can't breath very well,because of the collapse in the lungs)  ended by the death of the infected person.
This type "bulbar polio." Is rare disease , but that is after the administration of the vaccine.

*** Pregnancy & poliomylitis infection…
• Polio-maternal infection can be aquired late in pregnancy , but not associated with it like in rubella virus(can be aquired early in pregnancy), associated with Mild poliomylitis infection , can't be Accompanied with flaccid paralysis.
• Pregnant women could produce antibodies (IgG & IgA) ,and these antibodies to a some extent protects the baby , it can cross the placenta and resulted in immunity for him,,, just keep in mind also other persons in -natural conditions- who are infected with poliovirus will produce antibodies.
There are 3 types of immunoglobulins, one is related to the respiratory and intestinal tract mucosa in the form of (IgA), the two types are IgG & IgM, but the most imp of them IgG & IgA, why???
Because IgA prevents reinfection through Oral cavity or Respiratory tract , IgG can prevent the damage which is associated with the multiplication of the virus in the CNS  at the end there will be a permenet localized immunity in the body.
Vaccination ,
There are 2 types of vaccine;
1) The first one is develop, by a scientist called salk ,USA this vaccine is inactivated polio vaccine they make damage to the living virus so it can't survive in infected tissue .
Was introduced in 1957 , this vaccine has been not used widely , bcoz it used to be given by intramuscular injection, at that time not all the countries have the ability to buy the vaccine and the needles (it was very expensive ), but nowadays its cheap.
2) The second one , is Sabin vaccine [according to Albert Sabin ] in England , which is attenuated vaccine , for live oral poliomyelitis , they have managed it after 2 yrs, after 1958-1959 , to produce this oral vaccine . this vaccine was succefull in 2 features ;
The ease of administration for this vaccine, dropping the vaccine as fluid in the oral cavity.
More immunogenic than salk vaccine , bcoz its an attenuated vaccine , can multiply in the intestinal tract of the child and from the weak step of virus multiplication it can produce more globulins ,more IgG & IgA .
Sabin vaccine more effective and easy to be given ,more effective in Eradicating most of Poliomyelitis infection cases, SooOo it has been recommended by most of worlds organizations. Including our country of course.
♣ Both (Salk & Sabin) vaccines contained 3 serotypes/in the past they have only one serotype/..They are Type 1, 2&3, these vaccines should be given to child by the age of 1 month, can be started with the association of Triple vaccine. Also can be given with association of MMR vaccine [Measles Mumps Rubella], but its preferred to be given with Triple vaccine, why??? MMR and Sabin are attenuated vaccines, so the children shouldn't be exposed to 4 types of attenuated vaccines; they might suffer from several complications like fever, diarrhea …etc.
About Sabin vaccine …
Should be given after medical examination, the physician (with the help of the mother) must be sure that the child has no diarrhea or fever. Bcoz if he has one of these complications , the vaccine will not result in the production of immune response . So the child should be free from diarrhea & fever at the day of vaccine administration .
This vaccine should be kept at cold temperature –at the refragitor في الثلاجه- if the vaccine placed for more than 2 hours at room temperature it might loss 50% of its activity, & if placed for more than 24 hours all of its activity will be loss. So always keep it at cold temperature.
Concerning the immune response , about 99% of the vaccinated children with polio-vaccine will produce the two types of immunoglobulin's (IgG & IgA) this will give protection for the long period.
But for complete protection, any child receives at least 3 doses, during the 2 yrs of his life.
In some countries, between the 1st & 2nd doses there is an interval of 1-2 months and also the same between the 3rd & 4th doses.
Also can be given in the 1st year 2 doses and in the 2nd year the other 2 doses.
The WHO still try to eradicate poliomyelitis from the world, and they could do that due to the fact that polioviruses causes infection in relation to human mostly not animals, so eradication is possible.

Notes:
• Virus structure  Single stranded +ve RNA , Rigid capsule .
• Enteroviruses causes Mild Asymptomatic Enteritis.
• Poliovirus : 3 serotypes, capsid protein , Type 1 50% homology, More common , causes more Paralytic diseases. Type 2 & 3 Mild Human Poliomyelitis.
• Asyptomatic & Aborative poliomyelitis ; results in :
1) Rapid recovery within one week .
2) Develop immunity _ life long protection against reinfection & disease.
• Poliovirus present in Summer months, but Rotavirus & Astrovirus presents in Winter months.


وَالله لوعــاش الفتى في عمرِه ألفاً من الأعوام مالِكُ أمرهِ
متنعِمــاً فــيهــــا بكل لذيــــذةٍ متشَرِفاً فيها بِسُكنى قصرِهِ
مــا كَان ذلِك كلُه في أن يـَـفي فيها بِأوَلِ ليلةٍ فـــي قــــبرِهِ

THE END
Done By :
Shatha Al- S3oodi 

tz no 13 i guess