Richard, an 18 year old student, complains of lethargy and weakness which have b

Question

Richard, an 18 year old student, complains of lethargy and weakness which have become more prominent since he first became ill three days ago, with general malaise, a fever, a runny nose, and an irritating cough. Today he has also noticed some shortness of breath after climbing the stairs in his home. He has had no serious illness in the past and is on no regular medication. His mother and his sister both suffer from an uncharacterized hemolytic anemia. On examination, Richard is pale and his resting pulse is 90/min. He has a palpable spleen. A full blood count is performed and the following results are received: Hb 5.0 g/dl; MCV 86 fl; no reticulocytes seen; white cell count 2.2 x 10 9/l; platelets 80 x 10 9/l. Based on these results, the physician orders a bone marrow aspirate. The bone marrow report shows marked erythroid hypoplasia. Granulopoiesis and megakaryopoiesis are active but mildly reduced.

Richard is observed carefully over the next few days. His hemoglobin, white cell, and platelet counts gradually begin to rise. However, nine days after his initial presentation, an erythematous maculopapular rash (figure 1) develops on his face, trunk, and limbs, and the next day he complains of pain in the small joints of his hands. Richard's rash lasts four days and his joint symptoms, initially relieved by Tylenol, also disappear. On follow up, his full blood count shows an Hb of 11.3 g/dl, a white cell count of 5.4 x 10 9/l and a platelet count of 180 x 10 9/l. Subsequent investigations confirm a diagnosis of chronic hemolytic anemia due to pyruvate kinase deficiency.

1. Although Richard suffers from chronic hemolytic anemia as do other members of his family, his initial febrile illness was not caused by the anemia. What was the etiologic agent of the febrile illness and the rash nine days after initial presentation?

2. What is the common name of the disease resulting in Richard’v s rash?

3. How did Richard’s initial infection exacerbate his existing chronic hemolytic anemia? Describe what the infectious agent did in the body to worsen his anemia.

4. Are Richard’s mother and sister at risk of catching the disease while Richard has the rash? Explain your answer.

5. Is this infection rare? Explain.

Extra Credit (1 pt)

Is Richard’s dog at risk of catching this infection from him at any point during the disease (before, during, or after the rash)? Explain.

Explanation / Answer

1 chikungunya, caused by  RNA virus that belongs to the alphavirus genus of the family Togaviridae.

2.

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