Viral Dz

Question 1

CMV:

Answer 1

1. Member of Herpes viridae family
2. > 60% of US has been exposed→latent & reactivation pattern
3. Asymptomatic infection usually
4. Symptomatic = mononucleosis syndrome in immunocompetent pts (may have maculopapular rash)
5. Effects almost every organ in body
6. Associated w/ progression of AIDS and death while receiving HAART
7. Transmission: close contact.
8. Congenital CMV transmission (mother w/ acute infection during pregnancy→neuro abnormalities & deafness)
9. CMV Pneumonia: <50. CMV Nephritis: associated w/ acute glomerular injury
10. IgM level elevated w/ recent CMV infection or 4-fold increase in IgG titers
11. Anti-CMV immediate early Ag Monoclonal Ab Test →detect CMV 3 hrs into infection
12. Owl’s Eyes” in cytopathology
13. Best Tx = ganciclovier & valganciclovir (2nd line = foscarnet or cidofovir)
14. Ganciclovir used in prophylactic tx in transplant recipients

Question 2

Epstein-Barr Virus:

Answer 2

1. Transmission: intimate contact w/ body fluids
2. Infects B cells in oropharyngeal epithelium - circulating B cells spread infection thru entire reticular endothelial system
3. T-lymphocyte cellular response determines clinical expression
4. Rapid & efficient response = control of primary EBV→lifelong suppression
5. Ineffective response = B-lymphocyte malignancies
6. 1-2 month incubation then fatigue sets in→Gradually resolves in 3 months
7. Classic Presentation Triad = fever, pharyngitis, & lymphadenopathy
8. Mortality is rare → splenic rupture & hepatic necrosis)
9. Post transplant lymphoproliferative disorder (PTLD) is associated w/ EBV
10. Haglund Sign – bilateral upper-lid edema (lasts few days)
11. Labs: heterophile Ab test (peak @ 2-6 wks after infection and last up to a year), latex agglutination assay
12. Tx:
    • monitor for adenoid/tonsillar enlargement for airway obstruction
    • steroids if impending airway obstruction
    • short course corticosteroids (if anemia, thrombocytopenia, CNS involvement, extreme tonsil involvement)

Question 3

Erythema Infectiosum:

Answer 3

1. Usually benign childhood condition→slapped-cheek & lacy exanthema
2. Caused by HPV B19 → only parvovirus causing dz in humans
3. Transmission: respiratory secretions, fomites, vertical transmission to fetus, blood transfusions
4. Incubation = 7-10 days
5. Ag-Ab complexs in skin & jnts cause derm & rheum symptoms
6. Symmetric polyarthritis, transient bone marrow suppression, anemia
7. Phase 1 = bright red, raised, slapped cheek rash w. circumoral pallor
8. Phase 2 (1-4 days later) = erythematous maculopapular rash on arms & trunk (lace reticular pattern)
9. Phase 3 = recurrence of lacy rash for wks or months
10. Labs: CBC, IgM Ab (detect w/in 3 days of onset of symps), IgG Ab (confirms previous infection)
11. Children are NOT infectious, may attend school→ No longer infectious when rash disappears

Question 4

Herpes Simplex

Answer 4

1. HSV-1 = orofacial dz
2. Ab to HSV-1 start in childhood, based on socioeconomic status
3. HSV-1 invades trigeminal ganglia
4. Acute Herpetic Gingicostomatitis – primary HSV-1 in children 6mo-5yr, adults less severe posterior pharyngitis
5. Acute Herpetic Labialis – MC form of recurrent HSV-1
6. HSV-2 = genital dz
7. Ab to HSV-2 emerge @ puberty w/ sexual acts
8. HSV-2 invades sacral nerve root ganglia
9. HSV-2 reactivates 8-10x’s more than 1. Endemicity = latent infection w/ periodic reactivation
10. 80% are asymptomatic
11. Dissemination can occur w/ impaired T-cell immunity

Question 5

Primary Genital Herpes:

Answer 5

1. Women: more severe, herpetic vesicles on external genitalia, moist area vesicles rupture, dysuria in severe
2. Men: herpetic vesicles on glans penis, scrotum, and thighs; dry areas progress to pustules & crust, urethritis & dysuria in severe
3. Recurrent Genital Herpes: heal w/in 7-10 days
4. HSV Best Workup: isolation of the virus in tissue culture. Immunogluorescent staining can distinguish between types, Tzank smear
5. PCR used to detect encephalitis and viral shedding.
6. DFA distinguishes between type 1 and 2
7. Complications: bacterial/fungal superinfection, candidal vaginitis, eczema herpeticum, Herpetic whitlow, meningitis, ganglionitis, encephalitis
8. Tx: Life threatening = high dose IV acyclovir. Then anything that ends in –clovir

Question 6

Human Immunodeficiency Virus (HIV)

Answer 6

1. Blood-borne, sexually transmitted virus
2. Co-infection w/ Hep B, C, and HHV8 common
3. HIV-2 – slightly lower risk of transmission, progresses more slowly to AIDS
4. HIV related health info considered separate from other health info
5. Produces immune deficiency d/t decline in CD4 helper T cells, inversion of CD4/CD8 T-cell ratio
6. Clinical Phases: acute seroconversion→asymptomatic infection→AIDS (CD490% w/ death in 8-10 yrs from infection. Once progressed from AIDS, survivial
   <2 yrs untreated.

Question 7

Human Papillomavirus (HPV)

Answer 7

1. Epithelial tumors of the skin & mucous membranes
2. Anogenital HPV is the MC STI in the US!
3. Transmission: virus enters basal epithelial layer of skin and replicates in superficial skin
4. Cofactors for CA: tobacco use, UV light, pregnancy, folate deficiency, immune suppression
5. Malignancy Risk Factors: oral contraceptives, chewing Indian betel quid, UV & X-ray irradiation
6. Presentations:
   • Nongenital Cutaneous HPV: common cutaneous warts on keratinized skin
   • Palmoplantar Warts: acral surfaces of feet & hands, notable thickness, solitary, become black/painful
   • Flat Warts: occur in groups of small plaques
7. Laryngeal Papillomatosis: HPV 6, 11, 16 implicated. Incubation period of 3 months. Age of onset is 2-4 yrs
   • Hoarseness, voice changes, croupy cough, stridor
   • Dx: laryngoscopy
   • Tx: direct sx resection
8. Most dx made clinically, examine genital lesions w/ acetic acid
9. PAP smear (liquid based = best)
10. Tx: no single curative tx →excision/chemical ablation/cryotherapy.
11. Meds: imiquimod. Interferon alfa, cytotoxic agents

Question 8

Influenza:

Answer 8

1. One of the MC infectious dzs
2. Highly contagious airborne dz, causes acute febrile illness
3. Each year, vaccine contains influenza A strains from H1N1 & H3N2 along w/ influenza B strain
4. Viral RNA polymerase lacks error checking mechanism (why each year is an antigenic shift)
5. Incubation = 2 days w/ abrupt onset commonly
6. Sx: Fever, chills, sore throat, frontal/retro-orbital headache, ptosis, mayalgias, rhinitis, weakness, severe fatigue, nonproductive cough, diarrhea (in children)
7. Acute encephalopathy w/ influenza A virus
8. Complications: pneumonia, secondary bacterial pneumonia, myocarditis, pericarditis
9. Work Up: viral culture (nasopharyngeal/throat samples), rapid dx test available, CBC & lytes, PCR tests, serologic tests
10. Tx: antivirals (oseltamivir, zanamivir). Provenecid. Agents must be administered w/in 40 hrs of onset
11. H5N1: tx w/ oseltamivir for 6-8 dyas from onset to decrease mortality
12. Prevention
    • Trivalent vaccines - effective 7-10 days after administration & good for >6 months
    • Quadravelent vaccines – nasal (only for people ages of 2-50)

Question 9

Measles:

Answer 9

1. One of the most contagious infectious dzs
2. Incubation = 10-12 days (communicable 1-2 days before onset of symps)
3. Marked by: prodromal fever, cough, conjunctivitis, Koplik spots, then rash on day 3-7
4. 1st sign = unusually high fever (>104)
5. Triad: conjunctivitis, cough, coryza
6. Infection = lifelong immunity (maternal Ab protects up to 1 year)
7. Vaccine given to child >1 yr (give second dose for non-responders)
8. Winter-spring
9. Transmission: respiratory droplets
10. May predispose pts to secondary opportunistic infections (MC bronchopneumonia) & fatal giant cell pneumonia
11. Prognosis: major cause of childhood blindness
12. Complications:
    • Reactivation of latent infections by bacterial pathogen
    • More common in pts 20 yrs, immune deficient, malnutrition, under-vaccinated
    • Pneumonia is MC complication
    • Acute encephalitis, subacute sclerosing panencephalitis (SSPE), premature labor, spontaneous abortion
13. Labs:
    • Dx by clinical picture of the classic triad.
    • Confirm w/ serological testing: IgG & IgM isolation, isolation of virus,
    • RT-PCR
    • CBC (for leucopenia)
    • LFTs (for hepatitis)
    • CXR (r/o pneumonia)
    • CSF (r/o encephalitis)
14. Tx: supportive – IV hydration, Vit. A, abx for secondary infection, MMR vaccine, Ribavirin

Question 10

Molluscum Contagiosum:

Answer 10

1. MC virus causes a benign viral infection almost exclusively limited to humans
2. Characteristic skin lesions→rounded, dome shaped, pink, waxy papules which contain a caseous plug
3. Inoculate along minor skin trauma
4. Types:
   • Orthopoxvirus: resembles small pox & vaccinia
   • Parapoxvirus: orf & milker’s nodule viruses
5. Distribution:
   • Children: face, trunk, extremities
   • Adults: groin & genitalia
6. Histology: cup-shaped indentation, Henderson-Paterson bodies (membrane bound sacs that contain numerous molluscum contagiosum virions
7. Spontaneous resolution, recurrences in 35% after initial clearing
8. With HIV, direct correlation between increasing severity of dz & lower CD4 counts
9. Tx: antiviral tx
   • Curettage: most effective, low ADRs
   • Cantharidin: less effective, moderate ADRs
   • Topical Keratolytic: too irritating for children
   • Topical Imiquimod: more effective than cantharidin but expensive
   • Multiple Tx Sessions Necessary: d/t recurrence &/or appearance of new lesions by autoinoculation

Question 11

Mumps

Answer 11

1. An acute, self-limited, systemic viral illness characterized by the swelling of one or more salivary glands (MC –parotid)
2. Transmission of virus into kidneys = glomerulonephritis possible
3. Prognosis is excellent in uncomplicated mumps. Death rare even in more complicated mumps
4. Presentation: fever (x7 days), ear pain (near lobe), sudden hearing loss, thyroiditis, orchitis, oophoritis, aseptic meningitis, morbilliform rash, erythema & edema @ Stenson’s/Wharton’s duct, sour taste
5. Workup: dx typically clinical
   • Serum amylase (parotitis = amylase-S, pancreatitis = amylase-P/lipase)
   • Viruria
   • PCR assay of CSF
   • Confirm w/ IgG and IgM titers
   • Audiology in children
6. Tx: supportive care, low acidic foods, ice packs for parotid gland, analgesix/antipyretics, isolation x5 days, vaccine coverage→unimmunized: no school until 26 days after start of infection

Question 12

Rabies:

Answer 12

1. A viral dz that affects the CNS
2. After inoculation, enters peripheral nerves & incubates 20-90 days
3. Amplification occurs until nucleocapsids enter motor & sensory axons (prophylaxis is futile! Mortality 100%)
4. Multiplication in ganglion heralded by onset of pain, paresthesias, itching @ site of inoculums (1st symptoms)
5. Spreads quickly (can have rapidly progressive encephalitis), then to periphery & salivary glands
6. Segregated from immune system so NO Ab response
7. Presentation
   • Prodromal Period: virus enters CNS (2-10 days) → paresthesia, pain, itching → malaise, anorexia, H/A, chils, pharyngitis, N&V, diarrhea, anciety, agitation, insomnia, depression
   • Acute Neurologic Period: 2-7 days. Muscle fasiculations, convulsions. Pts may die immediately or progress to paralysis
   • Coma: 10 days of onset, duration varies
   • Respiratory depression, arrest, & death occur shortly after
8. After Exposure
   • Washing >10 mins & wound debridement @ time of bite = essential
   • Abx prophylaxis should be considered
   • Rabies vaccine IM

Question 13

Roseola

Answer 13

1. HHV-6, replication of virus occurs in leukocytes and salivary glands
2. Classic presentation is 9-12 month old w/ acute onset high fever, febrile seizure→72 hrs later rapid defervescence w/ onset of morbilliform rash. Lack of GI or URI symptoms.
3. Enanthem (Nagayama spots) – erythematous papules on mucosa of soft palate & base of uvula (starting 4th day)
4. Peak age of infection is 9-21 months
5. May cause M&M in immunocompromised pts (esp. AIDS and transplant recipients)

Question 14

Rubella:

Answer 14

Latin for “little red”/3rd dz

1. Generally a benign communicable exanthematous dz cause by rubella virus
2. Young Children – mild symptoms, rash, suboccipital adenopathy
3. Older Children/Adults – complicated by arthralgia, arthritis, thrombocytopenic purpura
4. Pregnant Women – teratogenic effects when contract dz esp in early wks of gestation (congenital defects, abortion, stillbirths)
5. Portal of Entry: respiratory epithelium of nasopharynx via aerosolized particles
6. Spreads hematogenously to regional & distal lymphatics & replicates in reticuloendothelial system
7. 2nd viremia 6-20 days after infection (LNs, urine, CSF, breask milk, synovial fluid, lungs)
8. Incubation = 14-21 days
9. Congenital Rubella Syndrome: Classic Triad = sensorineural hearing loss (MC manifestation), ocular abnormalities, CHD
10. S&S appear 1-5 days before onset of rash
11. Forchheimer Sign: enanthem observed during prodromal period, pinpoint or larger, occurs on soft palate
12. Postnatal Rubella: exanthema, pruritic rash, “3-day measles” (starts initially on face/neck & spreads to trunk/extremities), fever 4-fold) between acute & convalescent serum specimens drawn 2-3 wks apart
13. Prevention: Vaccinate! Immunize immunosupressed pts! (benefit outweighs ADRs), infants w/ HIV w/o severe immunosuppresion. Consider 2nd dose as soon as 28 days after 1st

Question 15

Varicella-Zoster Virus Infections (aka – Chickenpox):

Answer 15

1. Caused by reactivation of VZV after primary infection→ associated w/ aging, immunosuppression, & intrauterine exposure
2. Transmission: inhalation of airborne respiratory droplets
3. Remains latent in dorsal ganglion cells of sensory nerves, reactivation in shingles
4. Incubation = 10-21 days
5. Presentation
   • Onset of exanthema (infection 1-2 days prior to this)
   • Small, erythematous macules w/ intense pruritis→ infectious 4-5 days after rash develops
6. Complications→Secondary Bacterial Infection: MC pathogens are staph & strep.
7. CNS: Reye syndrome, Guillain-Barre syndrome, acute cerebellar ataxia, encephalitis
8. In Utero VZV Infection: primary maternal chickenpox during pregnancy may produce latent VZV in fetus
9. Workup: Tzank smear of vesicular fluid (better w/ direct immunofluorescence & PCR)
10. Tx: clip nails, antihistamines, abx for secondary infections
11. Varicella-zoster immune globulin – immunocompromised w/in 96 hrs of exposure
12. Live attenuated varicella vaccine for prophylaxis use in health children & adults