B19 infections play a significant role in the etiology of severe anemia in this area of malarial endemicity. Given the high levels of morbidity and mortality associated with severe anemia in such regions, the prevention of B19 infection with a vaccine might be a highly effective public health intervention.

BackgroundDuring acute Human parvovirus B19 (B19) infection a transient reduction in blood haemoglobin concentration is induced, due to a 5-7 day cessation of red cell production. This can precipitate severe anaemia in subjects with a range of pre-existing conditions. Of the disease markers that occur during B19 infection, high IgM levels occur closest in time to the maximum reduction in haemoglobin concentration. Previous studies of the contribution of B19 to severe anaemia among young children in Africa have yielded varied results. This retrospective case/control study seeks to ascertain the proportion of severe anaemia cases precipitated by B19 among young children admitted to a Kenyan district hospital.MethodsArchival blood samples from 264 children under 6 years with severe anaemia admitted to a Kenyan District Hospital, between 1999 and 2004, and 264 matched controls, were tested for B19 IgM by Enzyme Immunosorbent Assay and 198 of these pairs were tested for B19 DNA by PCR. 536 samples were also tested for the presence of B19 IgG.Results7 (2.7%) cases and 0 (0%) controls had high B19 IgM levels (Optical Density > 5 × cut-off value) (McNemar's exact test p = 0.01563), indicating a significant association with severe anaemia. The majority of strongly IgM positive cases occurred in 2003.10/264 (3.7%) cases compared to 5/264 (1.9%) controls tested positive for B19 IgM. This difference was not statistically significant, odds ratio (OR) = 2.00 (CI95 [0.62, 6.06], McNemar's exact test p = 0.3018. There was no significant difference between cases and controls in the B19 IgG (35 (14.8%) vs 32 (13.6%)), OR = 1.103 (CI95 [0.66, 1.89], McNemar's exact test, p = 0.7982), or the detection of the B19 DNA (6 (3.0%) vs 5 (2.5%)), OR = 1.2 (CI95 [0.33, 4.01], McNemar's exact test p = 1).ConclusionsHigh B19 IgM levels were significantly associated with severe anaemia, being found only among the cases. This suggests that 7/264 (2.7%) of cases of severe anaemia in the population of children admitted to KDH were precipitated by B19. While this is a relatively small proportion, this has to be evaluated in the light of the IgG data that shows that less than 15% of children in the study were exposed to B19, a figure much lower than reported in other tropical areas.

Parvovirus B19 (B19) is a common childhood infection that has recently been found to be associated with severe anemia in Papua New Guinean children. Population surveys were performed in 15 villages in Maprik district, East Sepik Province, Papua New Guinea in 2005. Plasma samples collected from children less than 10 years of age were tested for IgM and IgG antibodies to B19 by enzyme immunoassay. The prevalence of IgG antibody to B19 was 53.8% and ranged from 20% in those less than one year of age to 85.5% in those nine years of age. Considerable variation in IgG prevalence was observed between study areas, indicating complex patterns of transmission. Prevalence of IgM antibody to B19 was 1.5%. This study confirms that B19 infection is common among children in this tropical area. With 19.5% of children one year of age showing evidence of previous infection, any preventive measures should be targeted at the very young.