10 [KAYA MO TO, PAPASA KA] Viral Diseases

• Large family of viruses

• Cause latent, recurrent infections

Herpesviridae

Herpesviridae Characterisitics

dsDNA, icosahedral or cubic symmetry, with a spiked envelope

Herpesviridae Examples

• Herpes simplex virus (HSV), types 1 and 2 • Varicella-zoster virus (HHV-3) • Epstein-Barr virus (HHV-4) • Cytomegalovirus (HHV-5) • Human herpesvirus-6 to 8 (HHV-6, HHV-7, HHV-8)

types 1 and 2

Herpes simplex virus (HSV)

(HHV-3)

Varicella-zoster virus

(HHV-4)

Epstein-Barr virus

(HHV-5)

Cytomegalovirus

(HHV-6, HHV-7, HHV-8)

Human herpesvirus-6 to 8

Herpes Causative Agent

HSV-1 (oral) and HSV-2 (genital)

Occurs in childhood

HSV-1

acquired from sexual activity)

HSV -2

Herpes Transmission

direct contact with vesicular discharge

Herpes Mechanism

Virus from active lesions enter through cracks or cuts in the skin or through mucous membranes • Reproduce in epithelial cells • May remain latent in nerve cells » recurrence • Reactivation triggered by a variety of stimuli

fetus is infected in utero / during or after birth

Neonatal herpes

Herpes Manifestations

• Gingivostomatitis

• Painful, itchy skin lesions • Lips (fever blisters or cold sores) • Genitalia

• Flu-like symptoms

• Neonatal herpes: “cigarette burn” lesions

Herpes Complications

Meningitis, Encephalitis, Keratitis (corneal blindness) Eczema herpeticum

Herpes Diagnosis

• Microscopic examination: Tzanck cells • Presence of lesions • Pap smear » cytopathic effects • Antibody testing

Herpes Prevention

• Use of condoms • Abstinence • Mothers with cold sores should be careful in handling newborns

Herpes Treatment

• Acyclovir, Valacyclovir and Famciclovir

Chickenpox

Varicella

Shingles

Herpes Zoster

Chickenpox and Shingles Causative Agent

Varicella zoster virus (VZV or HHV-3)

Chickenpox and Shingles Transmission

respiratory route / transmission through vesicular fluid

Chickenpox and Shingles Mechanism

• Spread through respiratory droplets; close contact with active lesions • Virus enters the respiratory tract, attaches to mucosa and invades the bloodstream » reaches skin • Remain latent in nerve cells • Primary infection: Chickenpox; Reactivation: Shingles

Primary Infection

Chickenpox

Reactivation

Shingles

Chickenpox and Shingles Most often seen in

Children

But Chickenpox and Shingles is typically more severe in

adults

• (IP: 10 – 21 days): lesions on the back and trunk that spread to the face, neck, limbs

Macules » papules » thin-walled, fluid-filled vesicles » vesicles turn cloudy, dry up and crust over (heal without scarring)

Chickenpox

localization of lesions along a band of skin that is innervated by a single sensory nerve; the rash is very painful

Shingles

Chickenpox and Shingles Diagnosis

• Microscopic examination: Tzanck cells • Presence of lesions • Antibody testing

Chickenpox and Shingles Prevention

• Immunization for all children (live, attenuated vaccine for chickenpox is recommended for all children, starting at 1 year of age) • More potent form of the vaccine » people older than 19

Chickenpox and Shingles Treatment

• Typically self-limiting

• Relief of symptoms with paracetamol, antihistamines

• Acyclovir: used in severe cases; may provide relief for shingles

Why is Aspirin NOT given to children/adolescents

Aspirin should NOT be given to children/adolescents  Reye’s syndrome

Mono, Kissing disease

Infectious Mononucleosis

Infectious Mononucleosis CA

Epstein-Barr Virus (EBV or HHV-4),

Type of herpesvirus of EBV

a gamma herpesvirus

Infectious Mononucleosis Transmission

respiratory route

Infectious Mononucleosis Mechanism

• Spread through direct oral contact; contamination with saliva • Infects epithelial cells of the throat or salivary glands • Enters the blood, invades B lymphocytes » latency (incorporates in cell DNA) • Suppresses apoptosis of B cells » immortal B cells

• Age at the time of infection is a determining factor: adolescent (teens) develop symptomatic disease

Infectious Mononucleosis Manifestations

• Seldom result to disease • Aggressive cellular immunity: Infectious Mononucleosis (severe sore throat and fever, disseminated lymphadenopathy, pharyngitis, splenomegaly, rash) • Poor immunity: Cancer of the lymphatic system (Burkitt’s lymphoma, Hodgkin lymphoma)

Infectious Mononucleosis Diagnosis

• Blood work: Large, lobed B lymphocytes with atypical nuclei • Monospot test – based on the detection of cross-reactive, heterophile antibodies

Infectious Mononucleosis Treatment

• Relief of symptoms • Chemotherapy

Cytomegalovirus Disease CA

Cytomegalovirus (CMV)

Type of herpesvirus Cytomegalovirus (CMV)

a beta herpesvirus

Cytomegalovirus Disease Transmission

• Carried in bodily secretions (saliva, semen, breastmilk) • Sexual contact, in utero, vaginal birth, blood transfusion, organ transplants • Congenital transmission • Achieve latency in leukocytes

Cytomegalovirus Disease Manifestations

• Most are asymptomatic • Fetuses, newborns: Enlarged liver, spleen, jaundice, anemia, birth defects • Immunocompromised: pneumonia, CMV retinitis, CMV mononucleosis

Cytomegalovirus Disease Diagnosis

• Microscopic examination of kidney biopsy tissue  abnormally enlarged cells and inclusions within nuclei (“owl’s eyes”) • Serology (IgM)

Cytomegalovirus Disease Treatment

• Ganciclovir OR Valganciclovir • Foscarnet OR Cidofovir for the resistant CMV • CMV immune globulin for prophylaxis of CMV associated with organ transplantation

Roseola Other name

aka Roseola infantum, Exanthem Subitum, or Sixth disease

Roseola CA

HHV-6, sometimes HHV7

HHV-6, sometimes HHV7 herpesvirus type

beta herpesvirus

Roseola Transmission

through saliva

Roseola Manifestations

• Abrupt fever, sore throat, lymphadenopathy • Pink rash on the face, neck, trunk, thighs • Self-limiting

Roseola causes what in young children

Febrile seizures

Does Roseola Reactivate frequently in highly immunocompromised hosts?

Yes

Roseola Treatment

No therapy has been shown to be effective for HHV-6 or HHV-7, but both viruses are sensitive to Ganciclovir, Foscarnet and Cidofovir in vitro

Kaposi’s Sarcoma CA

HHV-8, aka Kaposi sarcoma-associated herpesvirus (KSHV)

Persisting in latently infected B lymphocytes

Kaposi’s Sarcoma

Kaposi’s Sarcoma Transmission

Sexual contact; contact with infected blood

Kaposi’s Sarcoma Manifestation

Tumors under the skin with or without organ involvement (for PLHIV)

• Largest animal viruses

Poxviridae

Poxviridae Characteristics

dsDNA, brick-shaped, multilayered capsid, with envelope

Poxviridae Replication

Replication occurs in the cytoplasm

Poxviridae Examples

• Variola virus (25 to 50% mortality rate) • Vaccinia virus

• First human disease to be eradicated globally in nature (WHO, 1980)

Smallpox

Smallpox CA

Variola virus aka Human poxvirus

Smallpox Transmission

similar to Chickenpox virus (IP: 12 to 16 days)

Smallpox Manifestations

Chills, fevers, headache, back pains; skin lesions filled with pus and often a dimple in the center

Smallpox Prevention

Vaccination based on the Vaccinia virus (cowpox, monkeypox)

Hepatotropic DNA viruses

Hepadnaviridae

Hepadnaviridae Characteristics

dsDNA, icosahedral virus with envelope

Hepadnaviridae Examples

Hepatitis B virus

Viral Hepatitis Manifestations

• Jaundice, abdominal pain and distention, dark urine, light-colored stools • Loss of appetite, nausea, vomiting, fever, weight loss • Chronic hepatitis: liver cirrhosis, liver failure, liver cancer

fulminant hepatitis; may cause meningitis or relapse (15%)

Hepatits A

acute and chronic hepatitis; hepatocarcinoma and cirrhosis

Hepatitis B and C

superinfection or coinfection with HBV

Hepatitis D

protracted and chronic hepatitis only in immunosuppressed patients

Hepatitis E

Hepatitis A (Infectious Hepatitis)

• Can survive on fomites

Typically causes an acute, self-limited illness, more often symptomatic in adults

Hepa A Transmission

Fecal-oral route, sexual contact

Hepa A Virulence

Generally, of low virulence; does not cause chronic infection

Hepa A Diagnosis

IgM anti-HAV antibodies, HA antigen or virus in stool samples

Hepa A Prevention

Inactivated viral vaccine (Havris®); Passive immune globulin (IM) for short term immunity

• The growth of the virus first results in systemic symptoms • One to two weeks later, the patient may develop jaundice (since bilirubin increases) • As the virus grows in the hepatocytes, the liver cells die.

Acute Viral Hepatitis

In acute viral hepatitis

The concentration of liver-function enzymes increases:

• Aspartate aminotransferase (AST) • Alanine aminotransferase (ALR) • Gamma-glutamyl transpeptidase (GGT) • Alkaline phosphatase

• Dane particles – intact viruses

Hepatitis B (Serum Hepatitis)

Hepatitis B (Serum Hepatitis) Transmission

virions shed in saliva, semen, vaginal secretions

Hepatitis B (Serum Hepatitis) Transmission

• Sexual transmission, contaminated needles, childbirth

T/F Hepa B May enter latency in some patients

T

Hepatitis B (Serum Hepatitis) Diagnosis

Detection of anti-HBV antibodies

Viral Hepatitis Treatment and Prevention

• Vaccination with recombinant vaccines (Recombivax B®, Engerix B®) • Passive immunization with Hepatitis B immune globulin (HBIG) • Interferon, Lamivudine, Adefovir, Entecavir

Hepatitis C (Non-A, Non-B Hepatitis; Chronic Hepatitis) Transmission

Sexual transmission, via contaminated needles

Hepa C other name

Chronic hepatitis

– large percentage of the population is affected with no symptoms

“Silent Epidemic”

Hepa C Diagnosis

Serology to test for antibodies to the virus

Hepa C Treatment

• No vaccine available • Pegylated interferon, Ribavirin

Utilizes Hepatitis B capsomeres

• Coinfection with HBV or Superinfection of HBV carrier

• More severe acute disease

Hepatitis D