U of U PA School Intro to Viral Diseases and Human Herpes Viruses

How are viruses grouped?

STRUCTURE:
- DNA vs RNA
- Enveloped vs non-enveloped
- Single stranded vs double stranded

Life cycle of a virus

Virus enters cell
Begins replication
Buds off of cell
Spreads through blood/lymph
Clinical symptoms develop (based on area of infection)
Recovery
Viral shedding

Immune response to virus

Interferons released to inhibit viral replication
Antigen presenting cells activate immune T/B cells

General diagnosis practice for viruses

Clinical history and exam
Antigen testing
ELISA
Serology - antibodies IgM, IgG
PCR
Cultures

Treatment for viruses

Largely supportive care
Some antivirals
Vaccines

What are the clinically important HHVs?

Herpes simplex viruse (HSV) - 1 and 2
Varicella-Zoster (VZV)
Epstein Barr - EBV
Cytomegalovirus (CMV)
Human Herpes 6 (HHV6 aka Roseola)

HSV 1/2 diseases

Very similar
Orofacial infections
Genital
Gingivostomatitis
Conjunctivitis
Neonatal diseases
Corneal ulcers
Encephalitis

HSV 1/2 properties

DNA
Spread by skin to skin contact
Infect nerve cells into ganglia where latency occurs
Reactivate due to stimulus

Epidemiology of HSV 1/2

Both can spread without lesions

HSV1 - acquired earlier in life (6months - 3 years), 80-90% of adults have antibodies for HSV1

HSV2 - 40-60 million infected individuals in the USA

HSV1/2 clinical disease in adults

Orofacial infections - cluster of vesicular lesions on lip
-Herpes labialis, pharyngitis, tonsilitis

Prodrome of numbness, tingling, burning before eruption

First episode is worst, recurrence varies

HSV1/2 clinical disease in peds

Orofacial infections - vesicular lesions on lips and mucosa
-pharyngitis, gingivostomatitis, fever, sore throat
Lasts for 2 weeks

HSV1/2 clinical disease keratoconjunctivitis

Keratoconjunctivitis - infection of iris, conjunctive that can cause blindness
-Dendritic lesions on corneal stain

HSV1/2 clinical disease encephalitis

Infection of brain - RAPID fever, headache, AMS, seizure/neurologic symptions
High morbidity and mortality
Can be due to primary or recurrent flare ups
Most commonly caused by HSV1

Genital herpes

Usually HSV2
Vesicular, ulcerative lesions of genitalia
Prodrome of fever, malaise
Transmissible without lesions

Herpetic whitlow

HSV1/2 skin infection
Enters via skin abrasion
Causes vesicular lesions of hands/fingers

Herpes gladiatorum

HSV1 common in wrestlers
Lesions on head and neck

HSV1/2 diagnosis

Clinical history
Lesions
PCR/NAAT swab of blood, CSF, tissue

HSV1/2 treatment/prevention

Antivirals acyclovir, valacyclovir, famciclovir
PO for cold sores or genital herpes
IV for encephalitis
Ophthalmic drops for eyes

No screenings/vaccines

VZV

Chicken pox and herpes zoster (shingles)

VSV properties

DNA
Replication in upper respiratory and spreads via lymph node

VSV epidimiology

Worldwide
Respiratory spread human - human
Chickenpox is primarily a childhood disease, decreased incidence with vaccine

VZV clinical disease - chicken pox

2 week incubation
Prodrome of fever, rash, malaise
3-5 days later maculopapular rash with vesicles and erythema
-last 1-2 weeks

Can cause encephalitis in immunocompromised

VZV clinical disease - herpes zoster/shingles

Disease of adults
Latent infection of chicken pox
Prodrome of burning skin 3-5 days prior to outbreak
Vesicular rash that does not cross midline, dermatomal distribution. Very painful

VZV diagnosis

Clinical diagnosis from history and exam
Rash examination
Swab with PCR/NAAT to confirm

VZV treatment/prevention

Chicken pox -
Self limiting
Supportive care, limit itching
Vaccine @12 months old, booster @4-6 years, may repeat as adult if needed

Singles -
Antivirals - Acyclovir, valacyclovir, famciclovir
NSAIDs, opiates, gabapentin
Shringrix vaccine >50 years, 2 shot series

CMV properties

DNA
Wide array of diseases, more severe in immunocompromised
Latency in multiple cell trypes
Seen in most body fluid

CMV epidimiology

Most infections asymptomatic
40-100% seroprevalence in adults

CMV disease

Congenital CMV

Mononucleosis

Pneumonia

Retinitis

Congenital CMV

Mom to fetus
If at birth - mainly asymptomatic
Intrauterine - growth retardation, hearing loss, 20% mortality rate

CMV mononucleosis

Milder than EBV
Fever, lymphadenopathy, pharyngitis, profound fatigue

CMV pneumonia

Mild for healthy, severe for immunocompromised
Cough, fever, malaise

CMV retinitis

Retinal inflammation causing vision disturbances

CMV diagnosis

Clinical

Noted infection in mother via PCR/Antibodies

Mononucleosis - clinical diagnosis

Pneumonia/retinitis - PCR/history

CMV treatment

Recognition
Supportive care
Ganciclovir

EBV properties

DNA
Latent infection
Can cause lymphoma

EBV epidemiology

95% of the world's population is exposed to the virus
Transmitted primarily by close contact with saliva or blood

EBV diagnosis

Clinical presentation
Serology -
-acute= + IgM, IgG
-past= -IgM, +IgG
PCR

EBV treatment

Supportive care
Mono - no sports with splenomegaly
No antivirals, vaccine

HHV-6 properties

Roseola or Sixth disease
DNA
Grows in T-lymphocytes
Lifelong persistence

HHV-6 epidimiology

90% worldwide have had virus and have antibodies
Primary spread via saliva
Most common in young children, reactivation in immunocompromised

HHV-6 disease

3 day fever
Exanthem subitem (roseola) - rash after fever - 1-5mm papules that blanche with pressure, start on trunk then legs/arms

HHV-6 diagnosis

Clinical
History of fever than exanthem subitem

HHV-6 treatment

Self limiting, benign rash
Supportive care
Immunocompromised - gancicylovir if severe