DNA Viruses

Question 1

Varicella-Zoster

Answer 1

• chicken pox, skin vesicular eruptions
• latent in dorsal ganglion–shingles in older patients (herpes zoster)
• pain in single dermatome in shingles–localized painful vesicular eruption.
• neutrophil filled vesicles.
• fever, malaise, rash

Question 2

Smallpox (Variola virus)

Answer 2

• Epidemiology: ancient disease. named after latin “varius” meaning “pimple/spot”. Common in Europe. Arrived in the new world by explorers and decimated native populations. Edward Jenner (1796) performed first vaccination by innoculating child with lymph from hand of milkmaid infected with cowpox. WHO began eradication campaign in 1967 leading to eradication in 1978 (Somalia last endemic cases). CDC and Russia still have virus stockpiled.
• Etiology: Spread between infected and susceptible hosts via droplets or aerosol of infected saliva. Virus highly stable and remains infective for long periods outside human host. Variola major (Asia and parts of Africa–prototypical) and Variola minor (Africa, South America, and Europe–minor systemic toxicity and lesions).
• Pathology: Skin vesicles of variola show reticular degeneration and areas of ballooning degeneration. Guarnieri bodies (eosinophilic, intracytoplasmic inclusion bodies) are seen, but not specific to smallpox (most poxviral infections). Vesicles also occur in palate, pharynx, trachea, and esophagus. Severe cases produce gastric and intestinal involvement, hepatitis, and interstitial nephritis.
• Clinical Features: Incubatin period: 12 days (7-17 days). Spreads to regional lymph nodes to produce viremia. Abrupt malaise, fever, vomiting, and headache manifest. Characteristic rash (face and forearms) follows in 2-3 days. After eruptions on lower extremities, rash spreads central during next week to trunk. Lesions: macules–>papules–>pustular vesicles–>scabs–>scars. Fatality rate is 30% in unvaccinated.

Question 3

Monkeypox

Answer 3

• similar to smallpox, milder.
• fever, headache, lymphadenopathy, malaise, myalgia, back ache.

Question 4

Human Parvovirus B19

Answer 4

• Epidemiology: spreads person to person by respiratory route. Infection common and occurs in outbreaks, mostly among children.
• Pathology: gains entry to erythroid precursor cells via P erythrocyte antigen and produces certain cytopathic effects: enlarged nuclei with peripheral chromatin displacement and eosinophilic material nuclear inclusion bodies.
• Clinical Features: Mild exanthematous illness (rash) known as erythema infectiosum, accompanied by interruption of erythropoiesis (mostly asymptomatic). Potentially fatal anemia caused in hosts with chronic hemolytic anemia–transient aplastic crisis. Fetal infection leads to severe anemia, hydrops fetalis, and death in utero (10% of maternal infections).

Question 5

Human Papillomavirus

Answer 5

• person to person contact (STD) -genital warts + cervical cancer (common manifestations)
• depressed cell-mediated immunity with spread of HPV lesions
• koilocytosis: large squamous cells with shrunken nuclei in large cytoplasmic vacuoles.

Question 6

Herpes Simplex Virus 1 and 2

Answer 6

• HSV1: oral secretions
• HSV2: genital secretions
• painful ulcerating lesions on skin or mucous membranes
• Herpes encephalitis and hepatitis (rare HSV1)
• neonatal Herpes–serious complication of maternal genital herpes (high mortality)
• acyclovir effective

Question 7

Epstein-Barr Virus

Answer 7

• infectious mononucleosis: fever, malaise, pharyngitis, splenomegaly
• lymphadenopathy–spleen and lymph nodes (cervical)
• atypical lymphocytes
• heterophilic antibody–distinguishing lab test

Question 8

Cytomegalovirus

Answer 8

• infects lymphocytes and monocytes–Infectious Mononucleosis
• symptomatic in immune suppressed patients (as is EBV)
• encephalitis, pneumonitis, GI hemmorhage

Question 9

Adenovirus

Answer 9

• Pathology: necrotizing bronchitis and bronchiolitis, with sloughed epithelial cells and inflammatory infiiltrate (lymphocytic) fill damaged bronchioles. Interstitial pneumonia is characterized by areas of consolidation with extensive necrosis, hemorrhage, and mononuclear inflammatory infiltrate. Intracellular inclusions, smudge cells and Cowdry type A inclusions involve bronchiolar epithelial cells and alveolar lining cells.
• Clinical Features: necrotizing bronchitis and bronchiolitis. Adenovirus type 40 + 41 infect colonic and small intestinal epithelial cells–cause diarrhea in both immunocompetent and compromised victims. AIDS patients susceptible to Adenovirus type 35–urinary tract infections.