A pediatric study from Croatia suggests that the recent resurgence of parvovirus B19 across Europe has been marked by an increased frequency of atypical skin manifestations in children, particularly petechial and purpuric rashes associated with higher levels of viremia. The findings, published in Viruses, offer new insight into how viral load and immune response may shape clinical presentation during post-pandemic outbreaks .
Researchers retrospectively analyzed 102 children with laboratory-confirmed parvovirus B19 infection treated at a national tertiary infectious diseases center in Zagreb between January and August 2023, a period coinciding with elevated B19 circulation reported across Europe. The median age was 10 years, and nearly 90% of patients were older than five. Only 7.8% required hospitalization, and most children were otherwise healthy.
Rash was the dominant clinical feature, occurring in more than 90% of patients. While erythema infectiosum—the classic “slapped cheek” rash—was common, approximately one-third of children presented with petechial or purpuric eruptions. These atypical rashes were more frequently observed in older children and were evenly distributed across the trunk and extremities, differing from the sharply demarcated acral patterns seen in papular-purpuric gloves and socks syndrome.
Laboratory analyses revealed clear differences between rash phenotypes. Children with petechial rash had significantly lower platelet counts and higher inflammatory markers than those with classic erythema infectiosum, though severe thrombocytopenia was not observed. Most notably, petechial rash was strongly associated with higher viral loads. In multivariate analysis, viral load emerged as the only independent predictor of petechial rash, with each tenfold increase in viremia significantly raising the odds of this presentation.
Serologic patterns further supported a temporal relationship between immune response and rash type. Children with classic erythema infectiosum were more likely to have detectable anti–parvovirus B19 IgG antibodies, while those with petechial eruptions often lacked IgG and showed evidence of ongoing high-level viral replication. The authors interpret this as reflecting different stages of infection: petechial rash may correspond to an earlier viremic phase, whereas erythema infectiosum signals transition to an immune-mediated phase.
Despite frequent atypical presentations, the overall disease course was mild. Severe anemia occurred in only one child, who had an underlying hematologic disorder. Co-infections were identified in about 20% of cases and were usually viral; elevated C-reactive protein levels were more suggestive of co-infection than parvovirus severity itself.
The authors note that reduced viral circulation during the COVID-19 pandemic may have created an “immunity gap,” potentially contributing to delayed immune clearance and higher viral loads during subsequent outbreaks. They conclude that parvovirus B19 should be considered in well-appearing children with fever and petechial rash and emphasize the need for further studies examining age-related immune responses and viral kinetics in post-pandemic settings.