Infectious Anemia

Question 1

What is macrocytic anemia?

Answer 1

Anemia where red blood cells are larger than their normal volume

Question 2

What is microcytic anemia?

Answer 2

Anemia where you have small, often hypochromatic red blood cells

Question 3

What is normocytic anemia?

Answer 3

Anemia where you have normal sized red blood cells but a small number of them.

Question 4

What is Megaloblastic anemia?

Answer 4

A condition in which the bone marrow produces unusually large, structurally abnormal, immature red blood cells (megaloblasts)

Question 5

What is hemolytic anemia?

Answer 5

Anemia caused by the abnormal breakdown of red blood cells.

Question 6

What is aplastic anemia?

Answer 6

A rare anemia in which the bone marrow and the hematopoietic stem cells that reside there are damaged. This causes a deficiency of all three blood cell types (pancytopenia): red blood cells (anemia), white blood cells (leukopenia), and platelets (thrombocytopenia).

Question 7

What is pancytopenia?

Answer 7

A deficiency of all three blood cell types (RBC, white blood cells, thrombocytes)

Question 8

What is pure red cell anemia (PRCA)?

Answer 8

A type ofanemia affecting the precursors toredbloodcellsbut not white bloodcells. Can be caused by Parvovirus B19 in patients with pre-existing high RBC turnover rates (sickle cell, thalassemia. spherocytosis).

Question 9

What is autoimmune hemolytic anemia?

Answer 9

When the body’s immune system creates antibodies ( IgG) directed at RBC surface proteins

Question 10

What are some infectious agents that can cause aplastic anemia?

Answer 10

Hepatitis virus, CMV, EBV and HSV viral infections

Question 11

How does babesia and plasmodium cause hemolytic anemia?

Answer 11

They directly infect RBC leading to cell lysis.

Question 12

How does Leishmania cause hemolytic anemia?

Answer 12

Infects the reticuloendothelial system which causes the production of oxidative metabolic products that lyse RBCs.

Question 13

How does Clostridium perfringens cause hemolytic anemia?

Answer 13

Produces alpha toxin which lyses RBCs.

Question 14

How does Haemophilus influenza type B cause hemolytic anemia?

Answer 14

The capsular polysaccharide (PRP) binds to the red blood cell surface and anti-PRP antibodies lyse the cell.

Question 15

What infectious agents can cause autoimmune hemolytic anemia?

Answer 15

EBV, CMV, or HIV infections.

Question 16

What is microcytic hypochromic anemia associated with?

Answer 16

Microcytic hypochromic anemia (iron deficiency anemia) is caused by blood loss. Infectious agents that can cause this include parasites like hook worm.

Question 17

What is an infectious agent that can cause megaloblastic anemia?

Answer 17

D. Latum through the accompanying B12 deficiency.

Question 18

What are the only two known human pathogens in the Parvoviridae?

Answer 18

Parvovirus B19 and Bocavirus.

Question 19

What is the tropism of parvovirus B19?

Answer 19

Erythroid precursor cells and erythroblasts.

Question 20

Why must parvovirus B19 infect erythroid precursor cells?

Answer 20

Because it must infect mitotically active cells as it does not encode the means to stimulate cell growth or a polymerase.

Question 21

What disease does parvovirus B19 cause in children?

Answer 21

Fifths disease/erythema infectiosum.

Question 22

What disease does parvovirus B19 cause in adults?

Answer 22

Acute aseptic arthritis.

Question 23

Approximately what percentage of the adult population has been infected with parvovirus B19 by age 40?

Answer 23

65%

Question 24

What is the target receptor for parvovirus B19?

Answer 24

Erythrocyte P antigen

Question 25

What is the overview of parvovirus B19 replication?

Answer 25

After binding to the erythrocyte blood group P antigen (globoside) and its internalization, the virion is uncoated, and the single-stranded DNA genome is delivered to the nucleus. Factors available only during the S phase of the cell's growth cycle and cellular DNA polymerases are required to generate a complementary DNA strand.

Question 26

What can a chronic parvovirus B19 infection cause in immunocompromised patients?

Answer 26

PRCA Pure red cell aplasia

Question 27

What can an acute parvovirus B19 infection cause in those with pre-existing high RBC turnover rates? (sickle cell, thalassemia, spherocytosis)

Answer 27

Transient Aplastic Crisis | TAC

Question 28

Why is hydrops fetalis rare?

Answer 28

Most adult women have antibodies to parvovirus B19 (65% of the adult population infected before age 40)

Question 29

What is transient aplastic crisis (TAC)?

Answer 29

The abrupt cessation of erythropoiesis characterized by reticulocytopenia, absent erythroid precursors in the bone marrow, and precipitous worsening of anemia

Question 30

What does a CBC look like in patients with transient aplastic crisis?

Answer 30

- Low reticulocyte count ( 0-1%) - Drop in hemoglobin levels by 2g/dL - IgM antibodies by day 3 of illness - IgG antibodies at time of recovery of erythrogenesis - PCR will demonstrate high level viremia during TAC

Question 31

What are two example of hookworms?

Answer 31

Ancylostoma duodenale and Necator americanus

Question 32

What other symptoms can hookworms cause other than microcytic/ hypochromic anemia?

Answer 32

- vague gastro intestinal complaints - “ground-itch” rash - Respiratory symptoms (eosinophilic pneumonitis) due to migration of the larvae - Pallor, weakness, fatigue, edema

Question 33

How are hookworms (nematodes) transmitted?

Answer 33

Transmission is by direct penetration of skin by the filariform larvae. Usually through bare feet in fecal contaminated areas.

Question 34

What is the parthenogenesis of hookworm infection?

Answer 34

Adult worms adhere to mucosa and suck blood which causes iron deficiency anemia due to chronic blood loss.

Question 35

What is the importance of Vitamin B12 and folate?

Answer 35

They are required for required for thymine synthesis, a building block for DNA

Question 36

What is megaloblastic anemia characterized by?

Answer 36

Large (macrocytic) & oval red blood cells and low reticulocyte count. Possibly nucleated RBCs in circulation

Question 37

How does Diphyllobothrium latum cause megaloblastic anemia?

Answer 37

Heavy vitamin B12 uptake by the parasite causes impaired DNA synthesis and normal hemoglobin accumulation.

Question 38

What are the virulence factors of Haemophilus influenzae B?

Answer 38

- Anti-phagocytic Polyribose Phosphate (PRP) Capsule | - IgA1 protease

Question 39

What are some differentials for Haemophilus influenzae B?

Answer 39

- Fails to grow on MacConkey agar and BAP. - V Factor (NAD) requirement - X factor requirement - Grows on “Chocolate” agar well