i. background - med.mui.ac.irmed.mui.ac.ir/sites/default/files/users/microbiology/herpes...
TRANSCRIPT
I. Background
25 viruses in the family Herpetoviridae-
a number of these are known to infect man:
– herpes simplex virus (HSV)
– Epstein-Barr virus (EBV)
– cytomegalovirus (CMV)
– varicella-zoster virus (VZV)
– human herpes 6 & 7 (exanthum subitum & roseola infantum)
– HHV 8 (Kaposi’s sarcoma-associated).
II. Classification
Viruses of Humans Common Name Subfamily
Human herpesvirus 1 Herpes simplex type1 alpha
Human herpesvirus 2 Herpes simplex type 2 alpha
Human herpesvirus 3 Varicella -zoster alpha
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Virus Subfamily primary terget cell Site of Latency Spread
Herpes Simplex Virus I a mucoepithelial Neuron close contact
Herpes Simplex Virus II a mucoepithelial Neuron close contact
Varicella Zoster Virus a mucoepithelial Neuron close contact,
respiratory droplets
Human Herpesviruses
IV. Neurovirulence and Latency in
HSV
– Virus lies dormant for a period of time but may become reactivated even in the presence of neutralizing antibodies.
– Sensory ganglia are the source of virus that produces recurrent skin lesions-
– trigeminal ganglia in type 1
– sacral ganglia in type 2
Three manifestations of HSV
latencyKey Feature: there is a wide spectrum of clinical
presentations
•Some individuals (5 - 10%) have frequent clinical
reactivation
•Most individuals reactivation is clinically asymptomatic
•In ALL cases, virus is shed
Clinical findings:
HSV-1
1) acute Gingivostomatits
2) herpes Labialis( fever blisters or cold sores)
3) Keratoconjunctivitis
4) Encephalitis
5)Herpetic withlow
Eczema herpeticum
6)Disseminated infections in immunocompromised patients( s.a. esophagitis, pneuminia)
HSV Disease:
Recurrent Infection
Cold sores (labialis)
Genital lesions (herpes genitalis)
Keratoconjunctivitis
Encephalitis
Meningoencephalitis
Herpes Simplex Virus type 2
•Infects the genital tract
•Is sexually transmitted
•Complicates childbirth
Diagnosis of Herpes Simplex Virus
Infections:
•Viral Culture
•Tzanck prep
•Culture with monoclonal antibody staining
•Serology
•Polymerase chain reaction (PCR)
Two Unique Features of VZV:
•Airborne spread or skin to skin contact
•More severe infection if primary infection
occurs as an adult
Complications of Varicella
•Reye’s Syndrome
•Bacterial Superinfection of lesions (more common in younger
patients)
•Varicella pneumonia
•Neonatal varicella -- disseminated, 30% mortality
Varicella patients at risk
•ADULTS
•PREGNANCY (3rd trimester)
•IMMUNOCOMPROMISED
•The mortality rate for varicella pneumonia in leukemic
children receiving chemotherapy is 1,000 times higher than
in healthy children.
Note: Children with isolated agammaglobulinemia are not at risk!
Complications of Zoster
Postherpetic Neuraligia
•Affects 25 - 50% of zoster patients over 50
•Pain may persist for months or even years
Varicella Vaccine
•Prevents 40 - 70% of chickenpox occurrence
•Greatly reduces the severity in the rest
•Attenuated virus
•Can still establish latency and reactivate
Question: How long will immunity last?