Viral Pathogens

Question 1

transient infection

Answer 1

-short term

Question 2

chronic latent infections

Answer 2

• virus remains in cell without actively replicating (long term)
• usually DNA viruses

Question 3

chronic productive infections

Answer 3

-long term, actively replicating viruses

Question 4

transforming infections

Answer 4

• viruses can be carcinogenic

- usually DNA viruses

Question 5

common cold viruses

Answer 5

• rhinoviruses
• cornaviruses
• respiratory droplet
• acute, self-limited infection
• symptoms: fever, cough, nasal congestion, minor aches and pains, headache, sneezing
• no vaccine

Question 6

rhinovirus

Answer 6

• naked, (+) ssRNA
• over 100 distinct serotypes
• most common virus in humans

Question 7

coronaviruses

Answer 7

• enveloped, (+) ssRNA

- SARS (sever acute respiratory syndrome)

Question 8

rubella virus (German measles)

Answer 8

• enveloped, (+) ssRNA
• respiratory droplet
• mild, self-limited disease (may have a rash)
• destructive fetal pathogen*
• live, attenuated vaccine

Question 9

rubella virus: congenital infection

Answer 9

• fetal deafness
• cataracts
• glaucoma
• heart defects
• mental retardation
• salt and pepper retinopathy

Question 10

west nile virus

Answer 10

• flavivirus
• enveloped, (+) ssRNA
• mosquito vector
• symptoms: asymptomatic, headache, myalgia, maculopapular rash
• no vaccine
• rare complications (1% of cases): hepatitis, myocarditis, pancreatitis, acute flaccid paralysis

Question 11

measles

Answer 11

• enveloped, (-) ssRNA
• paramyxovirus
• respiratory droplet
• symptoms: fever, URI, maculopapular rash, Koplik spots*, subacute sclerosing panencephalitis (rare)
• live vaccine

Question 12

mumps

Answer 12

• enveloped (-) ssRNA
• paramyxovirus
• respiratory droplets
• symptoms: parotitis, pancreatitis, orchitis in adult males, meningoencephalitis
• live, attenuated vaccine

Question 13

respiratory syncytial virus (RSV)

Answer 13

• enveloped, (-) ssRNA
• paramyxovirus
• transmission: respiratory droplet (100% exposure), direct contact, fomite (5 hrs on counter)
• clinical manifestations: cold-like symptoms, bronchiolitis (2-3% of cases)
• treatment: palliative

Question 14

influenza virus

Answer 14

• enveloped, (-) ssRNA
• two main groups: A and B
• 200-500k deaths annually
• respiratory droplet
• clinical manifestations: chills, fever, headache, muscle aches, general malaise, pneumonia*
• seasonal, inactivated vaccine (trivalent or quadrivalent)

Question 15

surface proteins involved in antigenic drift and shift

Answer 15

hemagglutinin, neuraminidase

Question 16

antigenic drift

Answer 16

• random mutations

- slow, gradual, not a big change from year to year

Question 17

antigenic shift

Answer 17

• co-infection
• hybrid virus
• new surface Ag (H1N1)
• quick, significant, virus acquires new surface antigen different from previous strains

Question 18

Zika virus

Answer 18

• enveloped, (+) ssRNA
• flaviviridae
• transmission: mosquito bites, sex, mother to fetus
• clinical manifestations: usually mild (fever, rash, HA, joint and muscle pain, conjunctivitis), Guillain-Barre syndrome?
• fetal microcephaly
• treatment: palliative

Question 19

viral hemorrhagic fevers

Answer 19

• enveloped, RNA viruses
• Lassa fever, Rift Valley fever, Ebola virus, Marburg virus, yellow fever, Dengue
• transmission: insect bite/inhalation/direct contact
• fever and hemorrhage: endothelial cell infection, platelet and endothelial dysfunction, hemorrhage and necrosis in multiple organs

Question 20

herpes virus

Answer 20

• enveloped, dsDNA
• transmission: kissing, sex
• manifestation: fluid-filled vesicles
• HSV type I: cold sores, encephalitis (rare)
• HSV type II: genital herpes, meningitis (rare)
• no vaccine

Question 21

latent herpesvirus infections

Answer 21

• virus lays dormant in respective ganglion, integrating into host genome
• HSV I: trigeminal ganglion
• HSV II: sacral root ganglion
• recurrence: head trauma, stress, fever, UV light, menstrual cycles, immunosuppression

Question 22

herpes keratitis

Answer 22

• latent infection on cornea
• dendritic epithelial ulcer
• recurrent HSV keratitis: corneal scarring, thinning, neovascularization, decreased corneal sensation, vision loss
• treatment: topical and oral antivirals

Question 23

varicella-zoster virus (VZV)

Answer 23

• enveloped, dsDNA
• droplet or direct contact
• chickenpox/varicella
• self limiting infection
• vesicular rash
• meningitis (rare)
• pneumonia (rare)
• latent in dorsal root ganglia
• live, attenuated vaccine

Question 24

shingles

Answer 24

• recurrence of herpes zoster virus
• lies dormant in dorsal root ganglion
• usually infect only one dermatome
• severe nerve pain, which can persist even after infection ends

Question 25

herpes zoster ophthalmicus

Answer 25

- shingles on the face and can involve eyes - Hutchinson's sign (lesion on tip of nose- precursor to ocular involvement bc nasociliary nerve supplies nose and cornea) - clinical manifestations: conjunctivitis, scleritis (rare), iritis, pseudodendrites, neurotrophic keratitis, elevated IOP - treatment: topical and oral antivirals - special consideration: post-herpetic neuralgia

Question 26

epstein-barr virus

Answer 26

- enveloped, dsDNA - transmission: saliva, selectively infects B cells - infectious mononucleosis: kissing disease, benign, self-limited - clinical presentation: lymphadenopathy, fatigue, fever, sore throat, splenomegaly - Burkitt's Lymphoma - no vaccine

Question 27

cytomegalovirus (CMV)

Answer 27

- enveloped, dsDNA - transmission: direct contact with bodily fluids, kissing - congenital infections: CNS dysfunction - CMV retinitis in AIDS patients

Question 28

human papillomavirus (HPV)

Answer 28

- papillomavirus - naked, dsDNA - transmission: skin or genital contact - clinical manifestations: skin warts, genital warts, anal warts - carcinogenesis: subtypes 16 and 18, inactivates p53 - common cancer sites: cervical cancer*, vulva, vagina, penis, anus, oropharynx - subunit vaccine

Question 29

hepatitis

Answer 29

- clinical manifestations: jaundice, fever, anorexia, malaise, fibrosis (chronic), cirrhosis (chronic), hepatocellular carcinoma (chronic) - causes: toxins, autoimmune diseases, hepatitis viruses A, B, C, D, E

Question 30

hepatitis A virus

Answer 30

- picornaviridae virus - nonenveloped, (+) ssRNA - transmission: fecal-oral route - clinical manifestations: acute, viral hepatitis, asymptomatic in 90% of infected children - treatment: palliative - prevention: sanitation, hygiene, inactivated virus vaccine, gamma-globulin shot

Question 31

hepatitis B virus

Answer 31

- hepadnavirus family - enveloped, dsDNA (+) reverse transcriptase - pararetrovirus, partially double-stranded - transmission: blood borne, sexual, vertical - pathogenesis: cytotoxic T lymphocytes eliminate infected cells - clinical manifestations: acute, viral hepatitis, fulminant hepatic failure, chronic hepatitis (cirrhosis, carcinogenic) - treatment: interferon therapy, antiviral medications - prevention: subunit vaccine

Question 32

hepatitis C virus

Answer 32

- flaviviridae family - enveloped, (+) ssRNA - many different genotypes - transmission: blood borne, sexual, congenital - acute infection (20% of cases): asymptomatic, mild hepatitis (15%), spontaneous resolution (10-50% of cases) - chronic infection (80% of case): cirrhosis* (10-30%), liver failure, hepatocellular carcinoma*, portal hypertension - treatment: interferon therapy, anitviral medications - no effective vaccine

Question 33

adenovirus

Answer 33

- adenoviridae family - nonenveloped, dsDNA - transmission: respiratory droplet, fecal-oral route, fomites - common clinical manifestations: URI, gastroenteritis, conjunctivitis - severe clinical manifestations: meningitis, encephalitis, pneumonia - prevention: vaccine, hygiene

Question 34

adenoviral conjunctivitis

Answer 34

- frequently associated with URI - most common cause of viral conjunctivitis - auto-inoculation - clinical manifestations: hyperemia, chemosis, epiphoria, decreased acuity, eyelid edema, corneal infiltrates, subconjunctival petechiae, follicles, pseudomembranes, palpable preauricular node - treatment: palliative, betadine treatment - diagnosis: RPS adeno detector - often spreads to other eye