Abstract

Generally considered to be a benign viral disease in childhood, varicella infection presents a wide range of complications. We report here the case of a 27 month-old boy admitted for typical ataxia in the benign course of varicella, without any other neurological disorders.

Clinical survey of dark urine and conjunctive jaundice lead us to serum controls detecting normocytic anemia with initially hypo-reticulocytosis and low haptoglobin, moderate leukocytosis and normal platelet count.

Hemolytic anemia is well tolerated; lowest Hb count (6.2 g/dl) was found on day four after admission, and red cell transfusion is not required. Normal reticulocyte response and normal colored urine was found from day six, and the neurological disorder disappeared after day eight.

Clinical cerebellitis with typical varicella motivated us to use intravenous Acyclovir treatment, we rejected prednisone therapy because of the complicated course of chicken pox and rapid hematologic improvement.

Serologic tests for mycoplasma, CMV, HAV, HBV, HCV and HIV were negative, EBV showed mild reactivation. Both direct and indirect Coombs test and cold agglutinin antibodies were positive, confirming mixed autoimmune hemolytic anemia caused by varicella infection.

Hemolisis is caused by virus induced polyclonal antibodies of class M for the complement-activating cold agglutinin pathway and antibodies of class G for normathermic agglutination against red cell membrane antigens.

To the best of our knowledge, only three pediatric and three adult cases of autoimmune hemolytic anemia in chicken pox have been reported in literature and no specific epidemiologic data is available. Our observation reveals a very rare but potentially dangerous complication of varicella infection.