You have to refer to the slides, since I have included the extra information only. Slide #1: Both illnesses aseptic meningitis and encephalitis can be caused by the same viruses; that viruses which cause encephalitis may be involved in meningitis or meningo And enteroviruses which cause more aseptic meningitis may be involved in Aseptic meningitis: inflammation of meninges with sterile CSF (without any causative organisms which can be grown on culture media). Myelitis: seen mostly in cases of poliomyelitis. Slide #3: Encephalitis and viral meningitis may share some clinical pictures like: headache, photophobia, fever, loss of appetite, and stiff neck. From the picture in the slide: - Mild meningitis resolves spontaneously without any complication -Fatal encephalitis = encephalopathy. -Enterovirus + mumps & LCM cause acute viral infections. Slide #4: ARBO viruses (arthropod-borne viruses) cause primary encephalitis by crossing the BBB reaching the CSF. ARBO is not a family virus. It is a group of virus families that transmitted through arthropod vectors. Secondary or post-infectious encephalitis is the result of previous infection by a certain virus followed by immune response leading to brain injury and damage. This damage is due to toxicity of cells like in rubella/ measles. Examples of Viruses which cause secondary encephalitis: Measles/ rubella/ polioma virus JC/ persistent enterovirus infection in immunocompromised patient. The virus-infected cells might present with acute infection, but 2-10 years later we can see subacute The symptoms associated with subacute encephalitis: personality change, intellectual deteriorations, myoclonal spasticity and ocular involvement. Subacute encephalitis as a result of measles and rubella is a very rare complication. P a g e 1
Persistent rubella virus infection in CNS as a result of acquiring rubella virus during fetal life leads to Post rubella encephalitis during adulthood. Progressive multifocal encephalopathy: a subacute degenerative disease of the brain that arise in immunocompromised patients, aged patients,patients with hematopoietic malignancies, and patients with autoimmune diseases who are on immunosuppressive therapy. Poliomavirus JC: acquired from multiple foci of infection within the brain of these patients. There is no specific treatment for polioma JC virus. [Most of these viruses (encephalitis viruses) don't have specific treatment. there is only supportive treatment. Enteroviruses: most of them cause acute illnesses. -meningitis resolve without any sequence, but in patients who have congenital or acquired immunodeficiency, these enteroviruses might not be cleared. and as a result, they might reside in CNS cells causing encephalitis which characterized by headache, confusions, lethargy, and seizures. -If you apply lumber puncture and take a CSF sample to examine it, you will see pleocytosis*. *pleocytosis : increased WBC count in CSF. -If you give those patients with persistent enterovirus infection type- specific immunoglobulin which you have identified by PCR, they will improve. But at the moment you stop giving them immunoglobulin, there symptoms worsen once again and the virus persist in their CNS. Slide #5: Paramyxoviridae family causes secondary Adenoviridae and rhabdoviridae cause rabies. Enteroviruses: if persisted in immunocompromized patients, they might cause Togaviridae, flavivridae, and bunyaviridae members are associated with belong to the ARBO viruses. Not all There are 2 genera of togaviridae family: 1- rube genus ( rubella) 2- alphaviruses ( eastern equine/ western equine/ Venezuelan equine). Flaviviridae: the names of viruses are acquired from the cities where their involvement in encephalitis was first recorded. There are multiple members of bunyaviridae, but not all of them are associated with They may cause febrile illness or hemorrhagic fever. P a g e 2
Slide # 6: Photophobia and neck stiffness might present in encephalitis (rare). Also, they present in case of meningo Slide # 8: Herpes simplex virus is one of the most fatal causative viruses of Herpes simplex encephalitis is a rare complication of herpes simplex infection. There are two types of herpes simplex encephalitis: 1-neonatal: -affects neonates especially during the passage of fetus through the birth canal. -at the time of birth, the neonate might acquire the virus>> spread to CNS>> -mortality is very high, nearly 100%! 2-focal: -affects neonates and adults. -high mortality rate, approximately 70% If we suspect a case of herpes simplex encephalitis, we apply lumber puncture and withdraw a sample of CSF >> PCR for diagnosis. We have to start antiviral therapy the prognosis better. Slide #11: (acyclovir) even before diagnosis in order to make As we said before, there is no specific treatment, but they found that some patients who have respiratory problems may benefit from ribavirin. Slide #12: Animals, like pigs, virus. Slide #15: which transmit the virus to humans are not the reservoir of the Line 9: Man becomes infected incidentally by insect bite especially during warmer summer months because ticks and mosquitoes are during their reproductive cycle. Slide #17: Arthropod vectors can fly long wide area. Slide #18: distances (20-30 km), so they spread the disease into P a g e 3
Not for memorizing. Slide #19: Glycoproteins E1 and E2: for attachment of the virus to the target cell. You should be familiar with the replication cycle of the +sense RNA virus: [Attachment of the virus to the target cell by E1 and E2 >>entry into the cytoplasm >> uncoating >> release of the genetic material for replication >> the +sense RNA acts as messenger RNA that translate in ribosomes into structural and nonstructural proteins >> one of the nonstructural proteins is the RNA-dependent RNA polymerase (RNA replicase) which catalyses synthesis of the -sense intermediate strand complementary to the RNA template >> this intermediate RNA is transcribed into +sense genome>> this newly formed genome with the structural proteins form the new virion >>this virion buds from the infected cell acquiring its envelope from the membrane of the cell]. Slide #22: The infection with arthropod viruses is rare in the Middle East. Slide #23: Most people have no symptoms. So, the immune system can cope with the presence of the virus by both humoral and cellular mediated immunities. Slide #26: Flaviviruses: +ssrna enveloped viruses/ icosahedral/ M protein/ capsid protein/ 1 glycoprotein (E) envelope protein. They replicate in the same manner of replication mentioned above, but they differ in that the +sense RNA which acts as messenger RNA is translated into polyprotein which cleaves further into individual proteins. P a g e 4
Slide #27: The infection of the virus, most of the time, passes unnoticed, and if the infected people develop any symptoms after the incubation period they will present with Diagnosis is by serology ( seroconversions of antibodies specific to the virus). There is no specific treatment. Slide #31: bunyaviridae members have multiple nucleocapsids : L (large) / M (medium)/ S (small). Each one has a part of the genetic material of the virus. L strand encodes for RNA dependent RNA polymerase. Slide #35: Direct detection tests- e.g. detection of antigen and nucleic acids by PCR. Slide #37: Respiratory support is one of the treatment methods. Why? Because some viruses, like hantaviruse may cause respiratory failure. I'm sorry for any mistake. P a g e 5