L11 - INFECTIONS OF THE NERVOUS SYSTEM : VIRAL INFECTIONS

Question 1

What is the name given to teh infection at brain?

Answer 1

Encepahlitis

Question 2

What is the name given to the infection of meninges?

Answer 2

Meningitis

Question 3

What is the name given to the infection of Spinal cord?

Answer 3

Myelitis

Question 4

What is the name given to the infection of peripheral nerves

Answer 4

Neuritis/ Neuropathy

Question 5

What are the two pathogenesis of viral CNS disease?

Answer 5

Direct invasion of the CNS

Post infectious syndromes; Acute disseminated encephalomyelitis (ADEM)

Question 6

What are the laboratory diagnosis of viral infection?

Answer 6

Virus detection (Clinical specimens, CSF, Brain (biopsy, autopsy), throat swab (mumps, enteroviruses); stool (enteroviruses))

Serology
Clinical specimens: serum & CSF

Question 7

What is the limitation in virus limitation?

Answer 7

Isolation rate in CSF of encephalitis is very low

Question 8

When is PCR used for diagnosis of CNS infeciton?

Answer 8

Herpes simplex encephalitis
CMV encephalitis/ myelitis
VZV encephalitis/ meningitis/ myelitis

Question 9

In what way can serology be applied in diagnosis?

Answer 9

Rising antibody titres
IgM
Intra-thecal (in CSF) antibody synthesis

Question 10

When is rising antibody titres (serology) used for diagnosis?

Answer 10

Flu A/B, VZV, HSV, entero, mycoplasma (mumps, meales)

Question 11

When is IgM antibody used for diagnosis?

Answer 11

JE, EBV

Question 12

What is intra-thecal (in CSF) antibody?

Answer 12

It is used in the diagnosis by serology. However, it is only detectable later in illness. Paired serum or CSF specimens can be used as antibody index

Question 13

What is the aetiology of viral meningitis?

Answer 13

Enteroviruses (ECHO, Coxackie A/B)

Herpes simplex type 2

Question 14

What is the aetiology of Hand Foot and mouth disease?

Answer 14

Enterovirus (Cox A, EV 71)

Question 15

What is the aetiology of viral encephalitis?

Answer 15

H. simplex type 1 (HSV 2 in neonates)
Enteroviruses
Varicella-zoster virus

Question 16

What is the location of herpes simplex encephalitis in our brain?

Answer 16

Lesions characteristically in temporal lobe or orbital surface of frontal lobe. Ajdacent frontal, parietal or occipital lobes and cingulate gyri may also be involved

Question 17

What are the clinical features of viral encephalitis?

Answer 17

History: Altered consciousness, headache, seizures, vomiting, memory loss

Clinical findings: fever, PERSONALITY CHANGE, dysphasia, autonomic dysfunction, ataxia, hemiparesis, seizures, cranial nerve deficits

Question 18

What is the method used to diagnose herpes encephalitis?

Answer 18

HSV DNA detection by PCR in CSF is method of choice

Question 19

What is the mortality of untreated herpes encephalitis?

Answer 19

70%

Question 20

What is the treatment of herpes encephalitis?

Answer 20

Acyclovir

Question 21

What is the treatment for relapse of HSE?

Answer 21

14 to 21 days acyclovir therapy

Question 22

What is the prognosis of Japanese encephalitis?

Answer 22

For those who are symptomatic, the mortality is 10-30% and many of the survivors have permanent brain damage

Question 23

What is the reservoir of the virus of Japanese encephalitis?

Answer 23

Zoonotic infection maintained in an animal

Question 24

How is the virus of japanese encephalitis transmitted?

Answer 24

Transmission between animals is by a mosquito typically associated with rice fields

Question 25

What is the causative agent for myelitis/ neuropathy?

Answer 25

``` Enteroviruses (EV71, Polio, other) VZV EBV CMV Exanthems mumps HSV 2 Japanese encephalitis ```

Question 26

What is the reservoir for rabies?

Answer 26

Anmial reservoir (Dogs, cats) and other mammals (Fox, wolves, jackals, mongoose)

Question 27

When is the last case of rabies in Hong Kong?

Answer 27

1981 for human | 1987 for animals

Question 28

What is the parthenogenesis of rabies?

Answer 28

- Virus replicates in striated muscle at the site of the bite --> enters nerve ending - Carried by axonal transport to the brain/ spinal cord. Hence bites on the face usually have a shorter incubation period - virus has less distance to travel - After replication in brain (encephalitis), the virus travels down the peripheral nerves to salivary glands (virus present in saliva), skin, muscles

Question 29

What is the incubation period of Rabies encephalitis?

Answer 29

20-90 days, maybe more than a year

Question 30

How is rabies encephalitis diagnosed?

Answer 30

``` Viral antigen by immunofluroescence Inclusion bodies (Negri bodies) ```

Question 31

How are animal bites managed?

Answer 31

Wound toilet: clean with soap/ water, good debridement, instill antiseptics, avoid suturing if possible. Manage other potential complcaitions e.g. tetanus and other bacterial infections Assess rabies risk

Question 32

How is the risk of animal bites assessed?

Answer 32

What animal? Endemic area? Behaviour of animal Is animal available for observation

Question 33

If risk of rabies exposure is present, what is the further action of prevention?

Answer 33

Active immunisation: human diploid cell vaccine, 6 doses | Passive immunisation: Human rabies immune globulin

Question 34

What is an isoform

Answer 34

Same amino acid sequence but different 3D conformation

Question 35

What is a prion

Answer 35

Infectious protein

Question 36

What are the characteristics of encephalopathies of prion

Answer 36

Associated with accumulation of Prion-related protein in brain Loss of neurons Spongiform vacuolation of brain Lack of an inflammatory reaction or immune response Long incubation period

Question 37

What are the symptoms of Spongiform encephalopathies

Answer 37

Rapidly progressive dementia, loss of memory and intellect, personality changes, unsteadiness/ clumsiness, myoclonic jerks

Question 38

What are the causative agents of spongiform encephalopathies

Answer 38

Kuru | Creutzfeldt-Jakb disease (CJD)

Question 39

How is prion transmitted in contaminated medical instruments?

Answer 39

Electrodes in brain | Neurosurgical instruments in brain

Question 40

List four effective disinfectants method

Answer 40

Chlorine Sod hydroxide Propriatary enzymatic and alkaline detergents Formic acid

Question 41

Give two ways of effective processes of disinfecting prion contacted instruments

Answer 41

Immerse in 1M NaOH for 2 hrs plus autoclave 121C for 30 min in downward displacement displacement autoclave Autoclave (134C for > 18 min (prevacuum); 132C for 60 min (gravity))