SARS-CoV-2 seroprevalence in children and their family members, July-October 2020, Brussels.

The aim of this study was to estimate the seroprevalence of SARS-CoV-2 antibodies in a pediatric population after the first pandemic wave in Belgium. All patients requiring a blood sample between 1 July 2020 and 31 October 2020 in our institution were invited to participate. Their parents and siblings could also participate to estimate familial transmission and the congruence between serological statuses. A questionnaire was completed for each participant to identify symptoms consistent with COVID-19 in the previous months. Blood samples were tested for SARS-CoV-2-specific immunoglobulin G using ELISA. The final population included 112 children, 24 siblings of these children, and 36 adults. The seroprevalence of cases was 6.9% before 8 September, a date that corresponds to 1 week after the beginning of the second wave in Belgium and 22.5% afterwards (OR = 3.89, 95% CI (1.20; 12.58), p-value = 0.03). Twenty-five percent of children were asymptomatic, and none experienced severe disease. The symptoms associated with SARS-CoV-2-positive antibodies were diarrhoea (OR = 9.9, 95% CI [2.88; 33.87.65] p-value < 0.01), fever (OR = 3.8, 95% CI [1.44; 10.22] p-value < 0.01), rhinitis (OR = 3.9, 95% CI [1.38; 10.90] p-value = 0.01), or anosmia (OR = 31.5, 95% CI [1.45; 682.7], p-value = 0.02). A child was the first symptomatic household member in 50% of the familial clusters.Conclusion: Seroprevalence in children was comparable to that of the general population. Children could represent the source of infection in the household. What is Known: • COVID-19 infection is generally mild or asymptomatic in children and adolescents. • Belgian strategy of testing was focused on symptoms. • Adults are believed to be responsible for most of familial clusters. What is New: • Serological testing gives a more accurate view of the rate of infected children. • Based on serological results, children have been infected as frequently as adults during the first and second wave in Belgium. • Seventy-five percent of SARS-CoV-2 IgG-positive children presented a mild symptomatology, and 25% were totally asymptomatic. • Children could represent the source of infection within household.

Refractory Trichophyton rubrum infection in lamellar ichthyosis.

A 10-month-old boy with congenital lamellar ichthyosis presented with a chronic Trichophyton rubrum infection. There was no history of atopy or immunosuppression, and examination revealed high total immunoglobulin E (IgE) with a positive specific IgE for T. rubrum. Multiple treatments with fluconazole were necessary to control the infection. T. rubrum is present worldwide and is responsible for the vast majority of chronic dermatophytosis. Lamellar ichthyosis is a risk factor for chronic dermatophytosis because of excessive keratin and the barrier defect. A delayed-type hypersensitivity reaction to T. rubrum is associated with cure, whereas immediate hypersensitivity and IgE are not protective and may lead to chronic infection. Atopy and the Th2 profile therefore seem to be associated with chronic dermatophytosis. The association between ichthyosis and atopy is well documented. T. rubrum also has an interesting ability to evade immunity, which helps explain the chronic infection. Finally, in ichthyosis, it is likely that fluconazole has difficulty penetrating the acanthotic stratum corneum, which explains treatment failure. We report this case to alert clinicians to the possible association between lamellar ichthyosis and chronic dermatophytosis and to report the difficulties of management.