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Medicine II: Infectious Disease > Viral Infections > Flashcards

Flashcards in Viral Infections Deck (32):
1

Varicella Etiology

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

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Types of Varicella

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

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Other reservoir for the virus

None, circulates exclusively in humans

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Transmission of Varicella

respiratory route and requires close contact

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Symptoms of Varicella (chicken pox)

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)

6

Sypmtoms of Varicella Zoster

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.

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Dx of Varicella

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

8

Complications of Varicella

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

9

Tx of Varicella

Acyclovir (oral), IV if severe

10

Prevention of Varicella

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

11

Transmission of EBV

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

12

Acute infectious mononucleosis

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

13

Pathogenesis of mononucleosis

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

14

Signs and symptoms of mononucleosis

fever, sore throat and lymphadenopaty (classic triad)

15

Complications of mononucleosis

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

16

Dx of mononucleosis

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.

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Tx for mononucleosis

supportive care, if severe give acyclovir

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Antigenic Drift

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

19

Antigenic Shift

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

20

Strains of influenza that commonly cause human disease

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

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Special surface proteins of influenza

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

22

Signs and symptoms of influenza

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

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Dx of Influenza

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

24

When to initiate tx for influenza

most effective when administered soon after onset of infection

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Tx of influenza

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

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Who should get and influenza vaccine

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)

27

Signs and symptoms of HSV 1 and 2

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

28

Complications of HSV

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

29

Dx for HSV

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

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Tx for HSV

acyclovir

31

Laboratory test to confirm CMV

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

32

Tx for CMV

None, ganciclovir or foscarnet if severe or organ specific disease