Seroprevalence of Hand, Foot and Mouth Disease Among Children and Adolescents in Türkiye

Background/Objectives: Hand, foot and mouth disease (HFMD) has recently emerged as a serious health threat, as certain serotypes can cause severe illness. Serotype distribution vary by region, and seroprevalence studies helps in developing preventive strategies. This study aimed to determine the seroprevalence of enterovirus type 71 (EV-A71), Coxsackievirus A16 (CV-A16), Coxsackievirus A10 (CV-A10), and Coxsackievirus A6 (CV-A6), the main causative agents of HFMD and to investigate risk factors for seropositivity. Methods: This multicenter, cross-sectional study was conducted across five major cities in Türkiye. Children (6 months–17 years) who presented to outpatient clinics for any reason were included between May 2024 and January 2025. Neutralizing antibodies were measured using a microneutralization assay. Statistical analyses included descriptive methods, appropriate group comparisons (Chi-square/Fisher’s Exact), and backward logistic regression to identify factors associated with HFMD seropositivity. Results: The study included 998 participants (mean age: 8.6 ± 5.2 years; 51.3% male). CV-A6 antibodies were detected in 68.5%, EV-A71 in 66.5%, CV-A10 in 60.2%, and CV-A16 in 46.0% of samples. No viral antibodies were detected in 5.3% of serum samples (All-Negative group); antibodies against at least one HFMD agent were detected in 94.7% (Any-Positive group). HFMD seropositivity increased significantly with age. Handwashing habits did not differ between the groups. The any-positive group more often had a household member aged 12–18 years, a mother with lower education, and higher kindergarten attendance. In logistic regression analysis, age, average monthly household income, and mother’s education level were the factors influencing seropositivity. Conclusions: The seroprevalence of HFMD-causing viruses in Türkiye is high from six months of age onward. Beyond promoting personal protective measures, the implementation of a vaccination program should also be considered.