Haemophagocytic lymphohistiocytosis (HLH) is a clinico-pathologic entity caused by increased proliferation
and activation of benign macrophages with haemophagocytosis throughout the reticulo-endothelial system.
Virus-associated HLH is a well-recognised entity. Although majority of parvovirus B19 associated HLH does not
require any specific treatment and carries good prognosis, outcome of children is worse than adults. We report
here a case of HLH associated with acute parvovirus B19 infection in a young healthy patient with underlying
hereditary spherocytosis, with bone marrow findings typical of parvovirus infection. Although this patient
had spontaneous recovery of cell counts, he succumbed due to complication from prolonged ventilation.
Unexpectedly, his immunoglobulin levels were inappropriately normal despite on-going ventilator associated
pneumonia, which reflects inadequate humoral immune response towards infection.
The association between pure red cell aplasia (PRCA) and autoimmune haemolytic anaemia (AIHA) has rarely been reported. PRCA represents an isolated process, characterized by normochromic, normocytic anaemia, reticulocytopenia and erythroid hypoplasia in the bone marrow, and may be attributable to infection with Parvo virus B19. AIHA is a condition in which peripheral red blood cell destruction is induced by the presence of autoantibodies. However, the co-existence of these conditions is very rare, since only few cases of PRCA and AIHA associated with malignant lymphoma (ML) were reported. A case of PRCA and AIHA was detected and described, for the first time in Malaysia, in a 10-year-old child suffering from non-Hodgkin lymphoma from the Department of Haematology, Universiti Sains Malaysia. Following the induction course of chemotherapy, the patient turned anaemic, with tendency for red cell clumping, reticulocytopenia and anisocytosis. AIHA was suspected in spite of the weak Coomb reaction obtained. The bone marrow aspirate revealed the presence of giant pronormoblasts, suggesting PRCA. Serological tests for Parvo virus and other viruses were negative.
A seroepidemiological study carried out on 800 stored serum samples collected between January 1999 to December 2000 derived from an urban population in Malaysia showed that the overall seropositive rate of human paravovirus B19 infection was 37.6%, with an overall geometric mean titre (GMT) of 18.3 IU. The seropositive rates of B19 among the male and female populations were 39.0% and 36.3% respectively. The seropositive rates among the racial groups were 37.2%, 38.2%, 38.1% and 29.4% respectively for the Malays, Chinese, Indians and other races. There was no statistical significant gender and racial differences in the B19 seropositive rates. When compared with the seroprevalence of B19 infection in other Asian countries, the seropositive rate of B19 in Malaysia was low in the younger age group and increased steadily with age. The unusual finding in this study was the presence of a high seropositive rate in those between six months to five years of age, especially in children in the one year old age group.