Sojourn through the Land of Bad Bugs

1
(No Transcript)
2
Virology Pathogenesis of viral infections JU-
2nd Year Medical Students

• By
• Dr Hamed AlZoubi Microbiology and Immunology
  Department Mutah University.
• MBBS (J.U.S.T)
• MSc, PhD medical microbiology (UK).
• FRCPath (associate, medical microbiology).
• dr_alzoubi_at_yahoo.com

3
Pathogenesis of viral infections

• Localized and generalised infection
• Some target organs
• Patterns of disease

4
Localized

• Epithelial cells Skin, conjunctiva and mucous
  membranes of the respiratory tract,
  gastrointestinal urogenital tract.
• Skin
• Poxvirus (Vaccinia orf) Papular skin
  lesions---Vesicles then pustules.
• Papilloma virus Proliferative lesions
• molluscum contagiosum. 

5

• Mucous membranes
• Spread is usually rapid, e.g respiratory
  infection such as influenza.
•  
• Conjunctiva
• Adeno 8 and entero 70

6
Generalized infection

• Mechanism (Pathogenesis spread) not very well
  known, why?
• No suitable animal model
• Dangerous virus Dangerous handling
  experimentation.
• Difficult growing virus in the lab.
• However poxvirus infection in mice (ectromelia)
  might give an idea

7
(No Transcript)
8
Target organs - Skin

• Exanthem vs enanthem (Tables 4.3 and 4.4)
• Macule
• Papule
• Maculopapular rash due to destruction of
  infected ells by T-cells
• Vesicule due to viral replication damaging the
  epithelial cells
• Pustule
• Purpuric rash low platelets
• Haemorrhagic rash DIC

9

• A macule is a flat change in the color of the
  skin.
• A papule is a solid raised lesion that has
  distinct borders and is less than 1 cm in
  diameter
• Primary lesions are physical changes in the skin
  considered to be caused directly by the disease
  process

10
(No Transcript)
11

• PURPURIC RASH-petechiae vs ecchymoses

12

• Lung
• Localized infection (influenza virus infection
  symptoms are due to immune response)
• or
• Generalized infection Measles and CMV (fatal
  giant cell pneumonia)
• Liver
• As a target (hepatitis) liver damage is immune
  mediated
• part of general infection (yellow hemorrhagic
  fever)

13

• Kidney
• Rarely but sometimes CMV and hantaviruses
• Shedding in urine
• brain
• From blood stream polio encephalitis
• Via nerves rabies, HSV, Varicella

14
Patterns of disease

• Acute non persistent
• Resolve spontaneously unless CNS involved e.g
• Early involvement polio and arboviruses
• Late involvement (2 weekspostinfection) mumps
  measles rabies virus not detected

15

• Persistent infection with acute onset
• Latent
• Inadequate immune response
• DNA viruses and retroviruses
• Immediate (HSV) late (hepatitis)
• Episomal or integrated
• Asymptomatic, reactivation and symptomatic,
  malignancies

16

• Persistent infection with acute onset
• Chronic
• Defected Immune response
• Virus is continously produced
• DNA or RNA viruses
• SSPE, Chronic active hepatitis, papillomaviruses
• Insidious infection with fatal outcomes
• Prions
• Lymphocytic choriomeningitis
• Immunological tolerance?

17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20

• The End