Central Nervous System Pathogens

Question 0

What are the Host Defenses of CNS ?

3 things

Answer 0

1) skin & mucous membranes
(Physical, chemical, immunological defense against entering blood stream)

2) Blood and Lymph
( leukocyte & immunological defense against microbes)
3) Blood/ Brain Barrier ( second layer of cell surrounding capillaries in brain to increase difficulty of penetrating into tissue of CNS)

Question 1

What is Meningitis ?

Answer 1

Is inflammation of the lining ( meninges) surrounding the brain and the spinal cord

Question 2

What are the microbial strategies to Bypass CNS defenses ? (2)

Answer 2

1) IgA protease ( degrades IgA= antibody involved with mucosal defense )
2) Antiphagocytitic Capsules ( prevent phagocytosis & destruction by Leukocytes ) &( allows pathogens to survive and cross Blood: Brain barrier )

Question 3

What is the type of Meningitis?(2)

Answer 3

1) Viral Meningitis
2) Fungal Meningitis
3) Bacterial Meningitis

Question 4

What is the Viral Meningitis?

Answer 4

• Aseptic Meningitis

- Normally resolves without CNS damage

Question 5

What are the Pathogens that Causes the most of the Viral Meningitis?

Answer 5

1) Enterovirus (90%) of all cases of Viral Meningitis

Question 6

What are the Most Common Bacterial pathogens that Causes Meningitis? (3)

Answer 6

Common Bacterial pathogens:-
1) Streptococcus pneumoniae 
2) Neisseria meningitidis 
3) Hemophilis influenza Type B ( in Countries without Hib Vaccination) 
***
Rare complication of Pharyngitis

Question 7

How the Bacterial pathogens that causes Meningitis transmitted and what kind of mode is it?

Answer 7

• Reservoir ( Asymptotic Human)

- Mode of Transmission
droplet mode, fomites, direct contact

Question 8

What are the Clinical signs and symptoms of bacterial Meningitis?
( Early and Late )

Answer 8

1- Early ( sore throat, fever, headache)
( stiff neck, drowsiness, Nausea/ vomiting are more serious problems)
2- Late ( Coma , Neurological disorder and or death)

Question 9

Provide the Etiology Of Streptococcus pneumniae that Causes the Bacterial Meningitis?

Answer 9

1- Gram+ streptococcus
2- Antiphagocytitic Capsule
3- IgA protease
( Mortality 30-40% .. Complications = Seizures, Deafness , and Blindness)

Question 10

Provide the Etiology Of Neisseria meningitidis that Causes the Bacterial Meningitis?

Answer 10

1- Gram -/ Diplococcus
2- Antiphagocytitic Capsule
3- IgA protease
4- Carried Asymptotically in 20% of the Population
( Mortality 100% untreated)( 5-10% treated)
** Complications ( Rashes: DIC( dissminte intravascular Couglultion ) No Permeant CNS damage.

Question 11

Provide the etiology of the Bacterial pathogens Hemophilis influenza Type B that causes the Meningitis?

Answer 11

1) Gram- / Rod shaped
2) Type B has Antiphagocytitic capsule
3) IgA protease
4) Children 6 months to 3 years

Mortality 6%
** Complications = Retardation; Seizure

Question 12

How the Bacterial Meningitis can be Diagnosed?

Answer 12

1) Spinal Tap To Remove CSF
- Microscopy for Leukocytes and Bacteria
- Gram Staining
- Antigen testing for Pathogens
- Culture to confirm diagnosis

Question 13

How does the Bacterial Meningitis can be Treated?

Answer 13

** Immediate ( Before pathogens identified)

Uses of Ampicillin or Rifamycin

Question 14

How can you Prevent the Bacterial Meningitis ?

• Streptococcus pneumoniae
• Neisseria meningitidis ( Prophylatic rifampicin treatment)
• Hemophilis influenza type B (Hib vaccination)

Answer 14

1) Vaccines
2) ( Vaccine targeted to regional serotype )( Prophylatic rifampicin treatment )
3) Vaccine Hib Vaccine

Question 15

What is the Rabies ?

Answer 15

An acute viral infection affecting the CNS of animals

Lethal except for one recent case

Question 16

What Causes the Rabies ?

Answer 16

Rhabdovirus

Question 17

Provide the etiology of the Rhabdovirus that Causes Rabies in animals?

Answer 17

• ssRNA ( - sense )
• Bullet shaped capsid
• Envelope with spike like projections

Question 18

How does Rhabdovirus that Causes the Rabies is transmitted? And the mode of transmission?

Answer 18

• Reservoir ( wild animals population)
• Mode of transmission
  ( Primarily Parental Route)
  bite of infected animals ( Dogs#1)
  Saliva from infected animals ( needs to be introduced under the skin of the new host)

Question 19

What are the Clinical signs and symptoms of Rabies?

Answer 19

Low fever 
Pain at the site of bite 
anxiety, stress and tension 
Excitability 
Drooling 
Loss of muscle function 
Convulsion and Seizure 
Respiratory Failure

Question 20

How The Rabies can be Diagnosed?

Answer 20

Post Mortem examination of the brain tissue

***( Nigre Bodies in Brain Neurons indicates Rabies Virus Replication )

Question 21

How would you treat The Rabies infection that caused by Rhabdovirus?

Answer 21

• Post exposure Vaccination ( virus replicate in CT for 4-13 weeks)

Immune response in 2 weeks
@@ Vaccination successful if started early after infection

Question 22

How you can prevent Rabies infection?

Answer 22

1) Vaccination ( Domestic Pets )
( Human bat researchers )

** cautious around ill domestic and wild animals **