DD 02-26-14 08-10am Common Viral Pathogens - Curtis Flashcards

Question

HSV-1/-2 Diagnosis:

Answer 1

Often clinical Dx If need definitive Dx: - Tzanck smear - HSV culture - Direct Fluorescent Antigen stain - PCR of lesions

Answer 2

- sunlight - stress - febrile illness - menstruation - immunosuppression

Answer 3

Severe HSV infections: <-- IV acyclovir = for neonatal HSV, HSV in immunocompromised hosts, encephalitis/meningoencephalitis Oral antiviral therapy (acyclovir or related antiviral) = for oral or genital outbreaks = standing Rx for ppl w/ frequent outbreaks not on suppressive therapy, so they can fill it & start treatment at very onset of reactivation / outbreak

Answer 4

- direct specimen (scrape base of lesion) - put specimen on slide & stain - look for multinucleated giant cells - not specific for HSV (also VZV and CMV) - rarely used in favor of easier & more sensitive / specific testing

Answer 5

Prophylactic Acyclovir - in lower doses than used for treatment - difficult to maintain Used for pts with: - frequent outbreaks of oral / genital lesions - recurrent keratitis & encephalitis

Answer 6

- NO vaccine available - Hand hygiene - Physical barriers: gloves, condoms - Avoid contact

Answer 7

VZV causes 2 clinical syndromes of importance: • Chickenpox (varicella) • Shingles (zoster)

Answer 8

= Varicella, or Chicken pox

Answer 9

1. Fever, malaise, headache, +/- cough 2. Rash develops, in successive waves - Typically lasts 7 days - No longer contagious when lesions all crusted over

Answer 10

- itchy - vesicular - “dew drop on rose petal” = clear fluid + red base - Usually starts on trunk & spreads to face & limbs - Lesions appear in successive waves, so lesions will be in various stages on physical exam

Answer 11

1. Virus gains entry via respiratory tract 2. Spreads to regional lymphoid system & replicates over next 2-4 days 3. Causes primary viremia (~4-6 days after incoc.) 4. Replicates in liver, spleen & other organs causing secondary viremia. 5. Secondary viremia spreads viral particles to skin 14-16 days after initial exposure & causes typical vesicular rash.

Answer 12

- common childhood disease - highly contagious - incubation of 10-21 days - preventable by vaccination (introduced in 1995)

Answer 13

- Typically self-limited & requires no treatment - Treatment accelerates resolution of chickenpox & decreases symptoms - Immunocompromised patients should always receive treatment

Answer 14

Varicella vaccine: is a live-attenuated vaccine - Beware in immunocompromised hosts - 2-dose series at 12-15 mo & 4-6 yo - Can be used post-exposure in certain situations Varicella-zoster immune globulin (Varizig) - for reducing severity of varicella in high-risk individuals if given w/in 4 days of exposure = pooled Abs from ppl w/ high VZV Ab titers

Answer 15

- Latent in cranial, dorsal root and/or trigeminal ganglia = Only herpes virus w/out asymptomatic viral shedding in normal hosts - Reactivation is ALWAYS SYMPTOMATIC - Reactivates in ganglion & tracks down sensory nerve to skin innervated by the nerve - Causes dermatomal rash that is pathognomonic for Zoster

Answer 16

- in up to 30% of population - 1st symptom is pain at site where vesicles will erupt in a few days. Lesions - develop in single dermatome. - itchy, but main symptom is pain - usually crust over within 2 weeks

Answer 17

- Similar to Varicella - Secondary skin infections - VZV ophthalmicus - Encephalitis - CNS vasculitis - Myelitis (spinal cord inflammation) - Cranial-nerve palsies: Ramsay-Hunt syndrome, Bell’s palsy - Peripheral nerve palsies - Post-herpetic neuralgia (PHN): can be very debilitating & last weeks to months after lesions resolve

Answer 18

- Cell-mediated immunity is crucial to maintaining latency & preventing reactivation of VZV - Cell-mediated immunity decreases w/ age & is often affected by immunosuppression and HIV

Answer 19

Secondary infection: - Group A Strep - Necrotizing fasciitis - Pneumonia (bacterial or viral) - Encephalitis or encephalomyelitis - Hepatitis - Congenital varicella (TORCH infection, severe) Adolescents & adults have more severe disease Pregnant / immunocompromised ppl have higher morbidity / mortality from primary VZV

Answer 20

Acyclovir - decreases number & duration of lesions - decreases pain PAIN = often worst part of shingles - can be treated w/ NSAIDS & opiates, occasionally with steroids

Answer 21

- Live-attenuated vaccine, Zostavax (ZOS) - One dose age 60+ recommended by ACIP - Boosts immune response to VZV, thereby preventing reactivation - Can also use acyclovir for people w/recurrent shingles (usually the immunocompromised)

Answer 22

- very common (almost all ppl infected by age 40) - primary infections often occur in early childhood - either asymptomatic or are a mild febrile illness - incubation period is 4-6 weeks - Transmission via saliva: kissing, sharing utensils/food/drink

Answer 23

= clinical syndrome that occurs when older child, adolescent or adult gets primary EBV infection (or less commonly CMV) = in ~40-50% of primary infections in this age group = “kissing disease” Symptoms include: - fever - sore throat - swollen lymph nodes - fatigue Physical exam: - Exudative tonsillitis - Enlarged cervical nodes - Splenomegaly, occasionally hepatomegaly Symptoms usually resolve in 4-8 weeks

Answer 24

1. Infects nasopharyngeal epithelium 2. Results in cell lysis & viral spread to adjacent structures (salivary glands, oropharyngeal lymphoid tissue, etc.) 3. Viremia occurs w/ distribution to liver, spleen, & infection of B lymphocytes 4. Remains dormant/latent in nasopharyngeal epithelium & B cells 5. Periodically, can reactivate (normally asymptomatic) & is commonly found intermittently in saliva of infected persons

Answer 25

- Often clinical diagnosis - Atypical lymphocytes on peripheral blood smear & often are >10% on the differential - Monospot/heterophile tests - If definitive Dx needed, can do EBV serology

Answer 26

- Detects presence of Abs that agglutinate horse / sheep / cattle RBCs - After acute infection w/EBV, 75-90% of pts develop Abs that cross-react & agglutinate RBCs - Heterophile Abs highest during 1st four weeks of infection

Answer 27

- used if definitive Dx of EBV is needed - measures development of Abs to EBV antigens: EBNA and VCA (viral capsid antigen) IgM response to VCA indicates recent infection: - appears early in infection & disappears in 4-6 wks - seen by the time symptoms appear IgG response to VCA indicates prior infection: - appears at 2-4 weeks after symptoms begin & persists for life EBNA (IgG) indicates past infection: - infection at least a few months back - NEVER positive in an acute infection

Answer 28

- NO vaccine available | - Prevention of primary infection through preventing contact w/ infectious saliva

Answer 29

- Not part of a primary infection, but occur later Burkitt’s Lymphoma: - endemic in Africa & sporadic elsewhere - B cell tumor often affecting the jaw Hodgkin’s lymphoma Nasopharyngeal carcinoma: esp. in Chinese Lymphoproliferative disease: - in immunocompromised patients <-- uncontrolled proliferation of EBV-infected B cells

Answer 30

In normal hosts - treated supportively (fluids, antipyretics) Steroids - for pts w/impending tonsillar enlargement threatening to occlude airway - for pts w/ severe hepatitis In immunocompromised hosts - very difficult to treat - mainstay is restoring immune function (reducing immunosuppression) if possible

Answer 31

Transmission through contact w/ infected body fluids - Saliva, milk, sexual contact, blood, tears, urine - Blood transfusions & organ transplantation Infected pregnant women can pass the virus to their unborn babies (in utero or perinatally)

Answer 32

- Usually diagnosed clinically | - can use Direct IFA, PCR, or culture

Answer 33

1. Infects epithelial cells of salivary gland or genital tract 2. Persistent infection & intermittent viral shedding * All cells where CMV becomes latent UNKNOWN 3. Likely viremia causing wide distribution of virus to other organs & tissues * Infection of GU system leads to shedding in urine

Answer 34

In most healthy persons acquiring CMV after birth: - Almost always asymptomatic - Sometime mild febrile illness - Sometimes mono-like syndrome (similar to EBV) w/ fever, swollen lymph nodes, & mild hepatitis - no longterm consequences Incubation period 2 weeks to 2 months

Answer 35

- serious & can infect most organs - severity parallels degree of impairment of cell-mediated immunity - severe disease most common in pts with organ / marrow transplants or HIV (w/very low CD4 counts) - -> CMV pneumonia, colitis, retinitis, hepatitis, encephalitis - -> CMV retinitis & colitis in HIV patients

Answer 36

- Most common in utero infection in US - When pregnant woman develops primary CMV infection, 3-5% chance that child will be born w/ congenital CMV infection. - Infection of fetus can also occur if pregnant women reactivates CMV, but much lower risk (<1% infected & even fewer symptomatic)

Answer 37

- Most congenitally infected infants asymptomatic - Only 10-15% have symptoms at birth (this is 3-5% of infants born to mothers w/ primary infections) Syndrome: - Low birth weight - Microcephaly - Hearing loss - Mental impairment - Hepatosplenomegaly & Jaundice - Skin rash (blueberry muffin spots) - Chorioretinitis

Answer 38

- Latent in monocytes & lymphocytes | - May reactivate from time to time, during which infectious virions appear in urine & saliva

Answer 39

- can lead to vertical transmission (mom to fetus) | - more common in mothers w/ primary infection

Answer 40

- In developed countries w/ high standard of hygiene, 50-80% of entire population is infected by 40 yo - In developing countries, over 90% are infected

Answer 41

- may produce serious disease w/ high morbidity & mortality Disease can be... - non-focal viral syndrome - organ-specific infection (ex:hepatitis, pneumonitis)

Answer 42

- Serology (CMV IgM & IgG) - Viral culture (easy to grow, takes several days) - PCR - Direct fluorescence test - Tissue histology

Answer 43

- asymptomatic | - BUT virus is being shed in bodily secretions

Answer 44

"Owl's Eye" appearance of infected cells = densely staining body surrounded by a halo - due to intranuclear inclusion bodies (viral proteins or particles) Intracytoplasmic inclusions (multiple smaller inclusions) are also seen in CMV infection

Answer 45

No treatment indicated

Answer 46

- Some protection offered by immunoglobulin preparation w/ high titer of CMV Abs (CMV-IG)

Answer 47

- Gancyclovir in infants w/congenital CMV is currently being studied - NEW standard of practice will likely be treatment of symptomatic congenital CMV infection for first 6 mos of life w/ oral valganciclovir

Answer 48

- NO vaccines available In Immunocompromised pts at very high risk for severe CMV disease: - IV CMV-IG once a month as prophylaxis - Ganciclovir or valganciclovir as prophylaxis in some circumstances (ex: post-transplant)

Answer 49

- Paramyxoviridae family - Enveloped - ssRNA genome - 2 important surface proteins: G-protein & F-protein

Answer 50

G-protein - for viral attachment to host cells F-protein (Fusion protein) - fusion of infected cells to neighboring cells to form syncytia (multinucleated giant cells)

Answer 51

- Usually Symptomatic - lasts 7-21 days - Acute respiratory disease in patients of all ages - Bronchiolitis: children <1 yr of age - Viral pneumonia: young children & elderly - Upper respiratory tract infection: children & adults

Answer 52

- By contact w/ droplets (respiratory secretions) on fomites, with subsequent contact w/eye, nose, or mouth - By aerosol droplets also possible - Incubation period is 5 days

Answer 53

Most frequent cause of bronchiolitis & viral pneumonia Almost all children infected at least once by 2yo Symptoms include: - fever - runny nose - cough - wheezing w/ involvement of lower respiratory tract

Answer 54

- Seasonal illness, peaking in Winter | - Up to 125,000 hospitalizations annually

Answer 55

- In adults and older children - Rarely Asymptomatic - Generally resembles severe cold - Usually confined to upper respiratory tract

Answer 56

1. URI w/ congestion, sore throat, fever 2. Cough deepens & becomes more prominent 3. Lower respiratory tract involvement develops w/ - increased respiratory rate - intercostal muscle retraction - wheezing Wheezing in child <2 yr of age is most likely bronchiolitis

Answer 57

1. Entry through mucosa of eye & nose 2. Infects respiratory tract locally 3. Cell-to-cell transfer of virus leads to spread from upper to lower respiratory tract 4. Syncytia formed through fusion of adjacent cell membranes

Answer 58

Bronchiolitis results from: - Mucosal edema - Cell necrosis & sloughing - Increased mucous secretion & plugging of bronchiolar lumina w/ epithelial debris & mucous Airway hyper-reactivity & bronchoconstriction also occur as a result of inflammation --> wheezing

Answer 59

Infants at high risk for severe RSV bronchiolitis - Premature infants (< 32 weeks gestation) - Pts w/ Chronic lung disease - Pts w/Complicated congenital heart disease Adults & older children at high risk for severe RSV disease are those w/significant immunosuppression (bone marrow or solid organ transplant)

Answer 60

High risk (premature) infants: - 8-10 x higher hospitalization rates - Higher need for ICU care & mechanical ventilation - 2-6 x higher Mortality rates

Answer 61

- Treat with gancyclovir or valganciclovir | - Choice of med & duration of treatment depends on the disease

Answer 62

-Mostly supportive Can use inhaled bronchodilators (albuterol) Ribavirin = only antiviral available for Tx of RSV - Currently limited use (only in dire circumstances -- bone marrow transplant, complicated congenital heart disease, etc.) - Controversial efficacy / safety - Modest effects in studies - Given as an aerosol - VERY Expensive

Answer 63

- Humoral immunity (antibodies) - NO licensed vaccine available - Primary prevention via avoiding infected secretions

Answer 64

Infants w/ high levels of maternal Abs to RSV are less likely to be infected RSV F-protein mAb prep - can be given IM to high risk infants - -> ~50% reduction in hospitalizations due to RSV - Administered monthly during RSV season - Very expensive

Answer 65

Reoviridae family Double stranded RNA virus w/ segmented genome --> Allows for reassortment & genetic diversity ``` Several serotypes (strains) of rotavirus - 5 strains responsible for >90% of rotavirus disease in the U.S. ```

Answer 66

- usually clinical - Viral culture - Serology - Direct fluorescent antibody

Answer 67

- Fecal oral transmission most common - Kids excrete 100 billion rotavirus particles per mL of feces - Infectious dose is 10-100 virus particles - 43% of rotavirus virions survive on human fingers for 60 minutes - Rotavirus in feces may survive for days to weeks on environmental surfaces

Answer 68

1. Infects mature absorptive epithelial cells or enterocytes (at tips of villi) in proximal 2/3 of ileum 2. Cell death leads to: - Reduced absorptive surface area of sm. intestine - Loss of enzymes that break down complex sugars - Increased fluid & osmotic load --> diarrhea Regeneration of villi takes 7-10 days (recovery period)

Answer 69

- 1st infections --> severe gastroenteritis - Subsequent infections --> milder or asymptomatic - Protective immunity develops after each infection which protects against symptomatic disease

Answer 70

- Leading single cause of severe diarrhea and/or gastroenteritis in infants & young children - Prior to vaccine, nearly every child had been infected at least once w/ rotavirus by age 5

Answer 71

- No antivirals available - Supportive management = Attention to fluids (Pedialyte, 50/50 Gatorade / water, IV fluids for severe dehydration)

Answer 72

2 oral, live-attenuated rotavirus vaccines licensed for use in infants: - RotaRix (2 doses): monovalent human - RotaTeq (3 doses): pentavalent human-bovine reassortment Both vaccines roughly equivalent in safety & efficacy Both highly protective in prevention of moderate & severe rotavirus disease - ~90% reduction in all types of health care visits

Answer 73

ELISA on stool samples

DD 02-26-14 08-10am Common Viral Pathogens - Curtis Flashcards

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