23- Systemic infections

Question 1

triad of symptoms for infectious mononucleosis

Answer 1

fever
tonsillar pharyngitis
lymphadenopathy (symmetric and generalised)
- extra: white/gray/green/necrotic tonsils; palatal petechiae

Question 2

who is the major reservoir for EBV

Answer 2

humans

Question 3

T/F approx 90-95% of adults are EBV positive

Answer 3

T

Question 4

T/F EBV acquired during childhood is often subclinical

Answer 4

T

Question 5

peak incidence of EBV

Answer 5

15-24

Question 6

is infectious mono more common in children or adults

Answer 6

Children

Question 7

how does EBV shed

Answer 7

salivary secretions for 6 months after the onset of the illness

Question 8

T/F EBV is a very contagious disease

Answer 8

F

Question 9

incubation period for EBV lasts

Answer 9

4-8 Weeks

Question 10

rare complications of mono

Answer 10

peritonsillar abscess or airway occlucsion (1%), due to edema of soft palate and tonsils

Question 11

is splenomegaly common in mono

Answer 11

yes, 50-60%. recedes after 3rd week of illness

Question 12

is mono related to a rash

Answer 12

yes, generalised maculo-papular rash, often post ampicillin, amoxicillin

Question 13

T/F absence of cervical lymphadenopathy and fatigue make mono unlikely

Answer 13

T

Question 14

DX of mono

Answer 14

atypical lymphocytes and lymphocytosis

• heterophile antibodies (produced by abnormal B cells- called monospot test) react to unrelated antigens (paul bunnell - latex agglutination using horse RBC)
• ELISA
• IgM VCA; acute infection
• IgG VCA: persistant infection

Question 15

tx for mono

Answer 15

supportive care

Question 16

T/F CMV in a competent host is asymptomatic or presents as mono

Answer 16

T

Question 17

CMV transmission route

Answer 17

• sexual exposure
• close contact: urine, upper resp
• blood or tissue
• perinatal exposure

Question 18

can CMV have a rash

Answer 18

yes, maculopapular with 1/3 of ppl exposed to ampicillin

Question 19

dx of CMV

Answer 19

antibodies, PCR

Question 20

Tx of CMV

Answer 20

most cases are asymptomatic, and if they have symptoms its self limited with a recovery in days to weeks

Question 21

toxoplasmosis is due to

Answer 21

intracellular protozoan parasite

Question 22

infection with T gondii sx

Answer 22

asymptomatic

in immunocompromised theres acute systemic infection or posterior uveitis

Question 23

toxoplasmosis reactivation results in

Answer 23

multiple CNS abscess like, round processes with ring enchancement

Question 24

how can people become infected with T gondii

Answer 24

• eating undercooked meat of animals harboring tissue cysts
• consuming food or water contaminated with cat feces
• blood transfusion or organ transplantation
• mother to fetus

Question 25

congenital toxoplasmosis appears as

Answer 25

- look normal on prenatal US Intracranial calcifications, ventricular dilatation, hepatic enlargement, ascites, increased placental thickness - later symptoms are potential vision loss, mental disability, seizures

Question 26

if a person has a new infection which antibody is present first

Answer 26

IgM

Question 27

tx for toxoplasmosis

Answer 27

is usually self limited, - treat those with severe or longer symptoms - treat pregnant women with pyrimetamine and sulfadiazine

Question 28

leptospirosis is due to

Answer 28

spirochete bacteria

Question 29

transmission of leptospira

Answer 29

by contact of urine of infected animals to mucous membranes; conjunctiva, skin cuts, abrasions of humans Bacteria can survive for weeks to months in urine contaminated water and soil There are outbreaks after heavy rainfall

Question 30

which disease can be biphasis

Answer 30

leptospirosis First phase: acute febrile bacteremic phase for 2-9 days Second phase: immune phase with renewed fever (here the bacteria is absent from the blood but present in the urine) Can occur with jaundice and renal failure (Weils disease). pulmonary hemorrhage, ARDS, uveitis, myocarditis

Question 31

sx of leptospira

Answer 31

MOST INFECTIONS ARE ASYMPTOMATIC - fever, rigors, myalgias, headache - conjunctival suffusion and redness, and subconjunctival hemorrhages

Question 32

tx of leptospira

Answer 32

for mild sx: doxycycline or azithromycin, ampicillin, amoxicillin severe dx: IV penicillin and ceftriaxone

Question 33

The majority of reactive lymphocytes in pts with infectious mononucleosis are

Answer 33

CD8 cytotoxic t cells

Question 34

What is an IgG avidity assay in CMV

Answer 34

To measure the binding strength between IgG antibodies and virus It helps distinguish primary CMV infection from past infection - Following a primary infection IgG have low binding strenght (low avidity) and 2-4 months after they have high avidity

Question 35

a serious complication of leptospirosis is

Answer 35

severe pulmonary disease with pulmonary hemorrhage