Viral Infections

Question 1

Varicella Etiology

Answer 1

Double stranded DNA Herpes Virus that enters the respiratory tract. Chicken pox- childhood; Zoster older adults

Question 2

Types of Varicella

Answer 2

Chicken pox- primary infection (highly infective); Zoster- secondary infection (development not always a/w exposure to chicken pox or zoster)

Question 3

Other reservoir for the virus

Answer 3

None, circulates exclusively in humans

Question 4

Transmission of Varicella

Answer 4

respiratory route and requires close contact

Question 5

Symptoms of Varicella (chicken pox)

Answer 5

A mild prodrome and fever precede vesicular rash (small erythmatous papules) Hall mark of Chicken pox is that lesions at all stages of development are all found together. Complete healing in 10-14 days (establishes life long latent infection)

Question 6

Sypmtoms of Varicella Zoster

Answer 6

Presents with localized infection /eruption, a long the course of one or more dermatomes, most commonly thoracic or lumbar. Preceded with localized pain. Vesicles coalesce into large, confluent blisters.

Question 7

Dx of Varicella

Answer 7

chicken pox- clinical dx; zoster- dx is more difficult (culture virus from open vessicle and PCR

Question 8

Complications of Varicella

Answer 8

sinvolvement of pulmonary veins and nervous system (pneumonia, encephalitis) w/ zoster- G. Barre and Opthalmic keratinitis

Question 9

Tx of Varicella

Answer 9

Acyclovir (oral), IV if severe

Question 10

Prevention of Varicella

Answer 10

live attenuated vaccine (~100% preventative of serious disease) Recommended for all over the age of 12 mo.

Question 11

Transmission of EBV

Answer 11

oropharyngeal secretions of assymptomatic shedders, blood transfusion, bone marrow transplant

Question 12

Acute infectious mononucleosis

Answer 12

vigorous humoral and cellular immune response to rabildy proliferating EBV infected B cells.

Question 13

Pathogenesis of mononucleosis

Answer 13

infectious B cells and illness manifestations are the result of vigorous T cell and NK cell inflammatory response

Question 14

Signs and symptoms of mononucleosis

Answer 14

fever, sore throat and lymphadenopaty (classic triad)

Question 15

Complications of mononucleosis

Answer 15

acute: splenic rupture, neurologic syndromes and ariway obstruction. chronic: hairy leukoplakia, B cell lymphoma, NK cell lymphoma and sarcomas

Question 16

Dx of mononucleosis

Answer 16

heterophil antibody agglutination test is 90% positive for primary disease. The monospot test may be negative, especially early in the course of the disease. Titer of IgM antibody to viral capsid antigen is the most sensitive and specific test. Elevated at time of infection, then decreases and IgG rises and persists for life.

Question 17

Tx for mononucleosis

Answer 17

supportive care, if severe give acyclovir

Question 18

Antigenic Drift

Answer 18

changes in hemagglutinin and neuraminidase proteins resulting from genetic mutation. Changes structure by genetic mutation

Question 19

Antigenic Shift

Answer 19

reassortment (exchange of genomic segments with other virus strains)- occurs in influenza A

Question 20

Strains of influenza that commonly cause human disease

Answer 20

Influenza a and b both cause epidemics; A can cause pandemics

Question 21

Special surface proteins of influenza

Answer 21

Special surface proteins: hemagglutinins (HA) and Neuramidases (NA);

Question 22

Signs and symptoms of influenza

Answer 22

abrupt onset of fever, shaking chills, head ache, myalgias, pharyngitis and rinorrhea. Complications: viral pneumonia, superinfection, Reyes syndrom (a/w asprin use)

Question 23

Dx of Influenza

Answer 23

Predominance of systemic symptoms; Rapid influenza test- sensitivity is variable depending on source and quality of specimen

Question 24

When to initiate tx for influenza

Answer 24

most effective when administered soon after onset of infection

Question 25

Tx of influenza

Answer 25

two NA inhibitors, zanamavir and oseltamavir, highly effective in inhibiting A and B

Question 26

Who should get and influenza vaccine

Answer 26

groups at risk for influenza complications (>65, in nursing homes, chronic pulmonary of CV problems, under 18 and on aspirin, pregos in 2/3 trimester) AND those at risk or transmitting to high risk individuals (health care, employees of nursing homes, home care providers)

Question 27

Signs and symptoms of HSV 1 and 2

Answer 27

initial infection- lesions usually ulcerative and exudative, and may involve extensive areas of the lips, oral cavity, pharynx and peritoneal skin. Heal in 2 weeks with out scarring; SECONDARY infection- fever blisters (vesicular , ulcerative lesions- most commonly at vermillion boarder of lips), much less severe. BOTH ARE PAINFUL AND ITCHY

Question 28

Complications of HSV

Answer 28

HSV1- personality changes, obtundation and seizures; Herpes keratinitis can cause blindness (leading cause), cutaneous dissemination can occur in eczema patients.

Question 29

Dx for HSV

Answer 29

dewdrop on a rose petal; culture of vesicle fluid is highly sensitive and specific. Direct staining for HSV antigens can also be used. PCR of CSF is BEST

Question 30

Tx for HSV

Answer 30

acyclovir

Question 31

Laboratory test to confirm CMV

Answer 31

most reliable test is a rise in CMV IgG titer (4x baseline), Detection of IgM is also strong evidence of acute infections.

Question 32

Tx for CMV

Answer 32

None, ganciclovir or foscarnet if severe or organ specific disease