[IM]

Question 1

What is infectious mononucleosis (IM)?

Answer 1

A self-limiting acute disease affecting the lymphoid tissues.

Question 2

What virus causes infectious mononucleosis?

Answer 2

Epstein-Barr virus (EBV).

Question 3

What is another name for infectious mononucleosis?

Answer 3

Pfeiffer’s disease or the kissing disease.

Question 4

What age group is most commonly affected by IM?

Answer 4

Young adults and children.

Question 5

What are the typical symptoms of IM?

Answer 5

Fever, malaise, sore throat, lymphadenopathy.

Question 6

What type of immune cells are primarily affected in IM?

Answer 6

Lymphocytes.

Question 7

What are Downey cells?

Answer 7

Enlarged atypical lymphocytes observed in a blood smear.

Question 8

What is the primary serologic test used to diagnose IM?

Answer 8

Detection of IgM heterophile antibodies.

Question 9

What type of antibodies are detected in the IM test?

Answer 9

Heterophile antibodies.

Question 10

Who discovered the heterophile antibodies in IM patients?

Answer 10

Paul & Bunnell.

Question 11

What reagent is used in the IM slide test?

Answer 11

Stabilized horse RBCs and latex particles.

Question 12

What is the principle of the IM rapid slide test?

Answer 12

Heterophile antibodies in the patient’s serum react with horse RBCs, causing agglutination.

Question 13

What type of RBCs are used in the IM test reagent?

Answer 13

Horse RBCs.

Question 14

What specimen is required for the IM test?

Answer 14

Serum.

Question 15

What is a positive result in the IM rapid slide test?

Answer 15

Visible red cell agglutination.

Question 16

What are the false positive causes of the IM test?

Answer 16

Cytomegalovirus (CMV), Toxoplasmosis, acute HIV, malignancies, autoimmune diseases.

Question 17

What is the sensitivity of the IM test after the first week?

Answer 17

90-95% after the first week.

Question 18

What is the specificity of the IM test?

Answer 18

94%.

Question 19

Why is the IM test no longer recommended by the CDC?

Answer 19

Due to false positives and false negatives.

Question 20

What test improves the specificity of the IM heterophile antibody test?

Answer 20

Davidsohn differential absorption test.

Question 21

What is the principle of the Paul-Bunnell test?

Answer 21

Mixing inactivated patient serum with sheep RBCs and observing agglutination.

Question 22

What are the limitations of the Paul-Bunnell test?

Answer 22

Not specific; reacts with Forssman and serum sickness antibodies.

Question 23

What test did Davidsohn develop to improve specificity?

Answer 23

An absorption method to remove Forssman antibodies and improve specificity.

Question 24

What are the materials provided in the IM test kit?

Answer 24

IM reagent, positive and negative control sera, IM diluent, pipettes, test cards.

Question 25

How should the IM reagent be stored?

Answer 25

Refrigerated but brought to room temperature before use.

Question 26

Why must the IM test reagents be brought to room temperature before testing?

Answer 26

To ensure optimal antigen-antibody reaction.

Question 27

How is the IM rapid slide test performed?

Answer 27

Mix patient serum with IM reagent, observe for visible agglutination.

Question 28

What control samples are used in the IM slide test?

Answer 28

Positive and negative control sera.

Question 29

How long should the slide be mixed before reading results?

Answer 29

Tilt slide for 30 seconds, leave undisturbed for 90 seconds.

Question 30

What is the quantitative test for IM antibodies?

Answer 30

A method for determining antibody titer using serum dilutions.

Question 31

What dilutions are used in the quantitative IM test?

Answer 31

1:2, 1:4, 1:8, 1:16.

Question 32

How is the IM antibody titer determined?

Answer 32

Reciprocal of the highest dilution showing agglutination.

Question 33

What is the Monospot test used for?

Answer 33

Rapid differential test for detecting IM heterophile antibodies.

Question 34

What is the principle of the Monospot test?

Answer 34

Absorption of serum with antigens followed by reaction with horse RBCs.

Question 35

What RBCs are used in the Monospot test?

Answer 35

Horse RBCs.

Question 36

How is agglutination interpreted in the Monospot test?

Answer 36

Strong agglutination indicates IM.

Question 37

What is the role of guinea pig kidney antigen in IM testing?

Answer 37

Absorbs Forssman antibodies but not IM antibodies.

Question 38

How does the Davidsohn differential test distinguish IM from other conditions?

Answer 38

Differentiates IM antibodies from Forssman and serum sickness antibodies.

Question 39

What does an eightfold reduction in the Paul-Bunnell titer indicate?

Answer 39

Presence of IM-specific antibodies.

Question 40

What diseases can give false-positive results in the IM test?

Answer 40

CMV, Toxoplasmosis, Acute HIV, Leukemia, Burkitt’s Lymphoma, Serum sickness.

Question 41

What is the role of beef erythrocytes in IM differential testing?

Answer 41

Absorbs IM heterophile antibodies for differentiation.

Question 42

How are heterophile antibodies related to IM diagnosis?

Answer 42

They cross-react with EBV antigens, aiding in IM diagnosis.

Question 43

What is the role of Epstein-Barr virus (EBV) serology in IM diagnosis?

Answer 43

Detects IgM and IgG antibodies against EBV-specific antigens.

Question 44

What are alternative laboratory tests for IM besides heterophile antibody tests?

Answer 44

EBV-specific IgM and IgG serology, PCR.

Question 45

What is the incubation period of infectious mononucleosis?

Answer 45

4-6 weeks.

Question 46

How long do IM heterophile antibodies persist after infection?

Answer 46

Persist for months to a year.

Question 47

What complications can arise from IM?

Answer 47

Splenic rupture, hepatitis, neurological complications.

Question 48

How can IM be differentiated from CMV infection?

Answer 48

CMV lacks heterophile antibodies; requires PCR or CMV-specific IgM.

Question 49

Why is it important to confirm IM diagnosis with specific EBV tests?

Answer 49

EBV-specific tests confirm the diagnosis and rule out other causes.

Question 50

How should IM test results be reported?

Answer 50

Reported as positive (agglutination present) or negative (no agglutination).