Seroprevalence of Hand, Foot and Mouth Disease Among Children and Adolescents in Türkiye
by
, , , , ,
Adem Karbuz
1,2, 
Tuğce Tural-Kara
3,
Ümit Çelik
4,
Belgin Gülhan
5,
Ayşegul Elvan-Tüz
6,
Yasemin Coşgun
7,
Çigdem Kirmaci
1,
Ayşe Kübra Açık
3,
Merve Kılıç-Çil
4,
Saliha Kanık-Yüksek
5,
Dilek Yılmaz-Çiftdoğan
6,8,9,
Merve Zerey-Albayrak
7,
Vildan Şahin
1,
Tuğba Erat
5,
Şilem Özdem-Alataş
6,
Ekrem Sağtaş
7,
Erdem Öksüzoğlu
1,
Muhammed Emin Demirkol
10 and
Ateş Kara
11,12,* 1
Pediatric Infectious Diseases Clinic, Prof. Dr. Cemil Taşcıoglu City Hospital, 34384 Istanbul, Türkiye
2
Department of Pediatric Infectious Diseases, Cerahpaşa Medical Faculty, Istanbul University Cerrahpaşa, 34320 Istanbul, Türkiye
3
Department of Pediatric Infectious Diseases, Faculty of Medicine, Akdeniz University, 07070 Antalya, Türkiye
4
Pediatric Infectious Diseases Clinic, Adana City Hospital, 01230 Adana, Türkiye
5
Pediatric Infectious Diseases Clinic, Ankara Bilkent City Hospital, 06800 Ankara, Türkiye
6
Pediatric Infectious Diseases Clinic, İzmir City Hospital, 35540 Izmir, Türkiye
7
Virology Reference Laboratories, General Directorate of Public Health, Republic of Türkiye Ministry of Health, 06100 Ankara, Türkiye
8
Department of Child Health and Diseases, Faculty of Medicine, İzmir Katip Çelebi University, 35620 Izmir, Türkiye
9
Pediatric Infectious Diseases Clinic, University of Health Sciences, Izmir Tepecik Training and Research Hospital, 35020 Izmir, Türkiye
10
Directorate of Public Health, Republic of Türkiye Ministry of Health, 06100 Ankara, Türkiye
11
Department of Pediatrics, Pediatric Infectious Diseases, Faculty of Medicine, Hacettepe University, 06100 Ankara, Türkiye
12
Türkiye Vaccine Institute, 06270 Ankara, Türkiye
*
Author to whom correspondence should be addressed.
Vaccines 2026, 14(6), 470; https://doi.org/10.3390/vaccines14060470
Submission received: 3 April 2026
/
Revised: 6 May 2026
/
Accepted: 14 May 2026
/
Published: 25 May 2026
(This article belongs to the Section Vaccines Against Tropical and Other Infectious Diseases)
Abstract
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.
Keywords:
hand; foot; and mouth disease; seroprevalence; EV-A71; CV-A16; CV-A10; CV-A6; risk factors; children; adolescents; Türkiye1. Introduction
Hand-foot-and-mouth disease (HFMD) is a common contagious illness primarily affecting children under the age of five, though older children and adults can also be infected. HFMD is characterized by a papulovesicular or maculopapular rash, blisters on the hands, soles, and buttocks, and painful ulcerative lesions in the mouth [1,2]. It is generally self-limited, but a small proportion of children may experience severe complications such as meningitis, encephalitis, acute flaccid paralysis, and cardiopulmonary failure. In the past few decades, epidemiological and clinical studies have revealed that the disease may be associated with potentially fatal complications, thereby altering the initial understanding and drawing greater attention to HFMD [1,2]. Recently, HFMD has emerged as a serious health hazard, especially in Asia-Pacific countries. HFMD outbreaks, seen in many countries worldwide, have reported serious complications and deaths [3].
Currently, there is no specific treatment for HFMD. Symptomatic and supportive treatment is applied, patients are isolated to prevent cross-infection, and good oral and skin care is provided [3]. Vaccination is considered the most effective and cost-effective approach to controlling the incidence of HFMD. Currently, monovalent and polyvalent vaccines against the HFMD pathogen are available, and vaccine studies are ongoing [3,4].
HFMD is caused by enteroviruses (EVs), which belong to the genus Enterovirus within the family Picornaviridae. The most frequently implicated pathogens are members of the Enterovirus A (EV-A) species. Among the various EV-A species associated with HFMD, the most known are enterovirus type 71 (EV-A71) and Coxsackievirus A16 (CV-A16). HFMD due to other viruses such as Coxsackievirus A10 (CV-A10) and Coxsackievirus A6 (CV-A6) has also been reported [2]. HFMD is typically diagnosed clinically without microbiological tests. However, identifying the specific viral serotype is crucial, as certain serotypes can cause severe illness and serotype distribution may vary across regions. Increased global travel may contribute to the spread of different serotypes. Effective and continuous surveillance, or at least the identification of circulating serotypes through seroepidemiological studies, is essential in combating the disease. Accurate identification of causative serotypes supports public health efforts, informs preventive strategies, and aids vaccine development [4]. In this context, this study aimed to determine the seroprevalence of EV-A71, CV-A16, CV-A10, and CV-A6, which are the main causative agents of HFMD, and to investigate risk factors for seropositivity among children and adolescents in Türkiye. Thus, we believe that determining the frequency of exposure to these agents in our country will provide valuable data to policymakers regarding vaccination strategies.
2. Materials and Methods
2.1. Design
This multicenter, cross-sectional study was conducted in five hospitals across five major cities in Türkiye (Ankara, Antalya, Adana, İzmir, and İstanbul) between May 2024 and January 2025. The characteristics of the study areas are summarized in Appendix A Table A1.
Hospital-based recruitment was selected to facilitate data collection from participants who met the eligibility criteria. Cities were selected to optimize geographical representation, and study hospitals were chosen based on their strong willingness to participate, as well as their capability and resources to conduct the study. The locations of study centers in Türkiye are shown in Figure 1. The cities where the study was conducted account for about one-third of the country’s population (36.25%).
The mean summer (July) and winter (January) temperatures of the relevant cities are presented in Appendix A in Figure A1. The highest temperatures in summer are in Adana, and the lowest temperatures in winter are in Ankara.
2.2. Participants
Children aged 6 months to 17 years who presented to outpatient clinics for any reason and required blood collection were included in the study. Individuals who had difficulty obtaining blood samples due to previous conditions such as coagulation abnormalities or hematomas, or petechiae after intramuscular injections or venipuncture, patients with autoimmune disease or immunodeficiency/immunosuppression (including but not limited to congenital immunodeficiency, systemic lupus erythematosus, ankylosing spondylitis, autoimmune thyroid disease, anaplasmosis, absent functional spleen, Human Immunodeficiency Virus [HIV] infection), patients with serious neurological disorders (e.g., epilepsy, convulsions, or seizures), psychiatric diseases or a family history of psychiatric disorders, those who had participated in any other clinical trial within the last six months, those who had received immunosuppressive or other immunomodulatory therapy within the last year, or those who had used immunoglobulin or other blood products within the last year were excluded. Participants were required to be available throughout the study period.
In Türkiye, healthcare services are provided free of charge for individuals under 18 years of age; therefore, no direct payment was required from the families of the participating children. In addition, no promotional or incentive-based recruitment strategies were employed, and participation was entirely voluntary.
The study was approved by the Clinical Research Ethics Committee of Ankara Bilkent City Hospital (Approval Number: E2-24-6875; Date: 20 March 2024). Written informed consent was obtained from the participant or parent/guardian/legal representative.
2.3. Procedure
Information on participants who met the inclusion and exclusion criteria was recorded in case report forms (Supplementary File S1: Case Report Form of the Study in Turkish). Blood samples collected in clotted blood tubes were centrifuged 2000–4000× g for 15 min at room temperature. The resulting sera were aliquoted into two clearly labeled cryovials, each containing approximately 500 microliters of serum, designated as the main sample and backup sample. Serum samples were stored at −20 °C or below until testing. All samples were transferred to the central laboratory (Turkish Ministry of Health, General Directorate of Public Health National Reference Laboratory) for analysis. Neutralizing antibodies against EV-A71, CV-A16, CV-A10, and CV-A6 were measured using a microneutralization assay. Seropositivity was defined as a neutralizing antibody titer of ≥1:8. Laboratory studies were conducted in accordance with the standard operating procedures of the World Health Organization [5].
2.4. Statistical Analysis
The sample size was calculated assuming that the overall seroprevalence of neutralizing antibodies against EV-A71 is 20%. Based on a 95% confidence interval (CI) with a width of 5%, a sample size of 1022 participants was calculated using PASS 15.0 (NCSs, LLC. Kaysville, UT, USA). Considering other factors (such as time or logistical limits), around 1000 participants were planned to be enrolled. Thus, the study aimed to recruit 200 participants from each center, with 50 individuals allocated to each of the following age groups: 6 months–2 years, 3–5 years, 6–11 years, and 12–17 years.
Statistical analysis was performed using PASW 18.0 for Windows (SPSS, Inc., Chicago, IL, USA). Descriptive statistics were presented as numbers and percentages for categorical variables, and as means and standard deviations for numerical variables. The normality of data was tested using visual (histogram and probability graphs) and analytical methods (Kolmogorov–Smirnov/Shapiro–Wilk tests). For comparisons of categorical variables between two or multiple groups, Fisher’s Exact test was used when the assumptions of the Chi-Square test were not met. To determine the factors affecting seropositivity for HFMD, a logistic regression analysis was performed using the backward method on a model created with clinically and/or statistically significant variables (p < 0.200). Statistical significance level was accepted as p < 0.05.
3. Results
The study included 998 participants from 5 centers. The mean age of the participants was 8.6 ± 5.2, and 51.3% were male. General characteristics of the participants are shown in Table 1.
Viral antibody test results are shown in Figure 2. No viral antibodies were detected in 53 (5.3%) of the serum samples. Single viral antibodies were detected in 180 (18.0%) samples, dual in 252 (25.3%) samples, triple in 330 (33.1%) samples, and quadruple in 183 (18.3%) samples.
Viral antibody test results by age group are presented in Table 2. As age increased, a significant increase was observed in the likelihood of exposure to viruses associated with HFMD. The frequency of quadruple viral antibodies was found to be 4.8% in the 6–8-month age group and 25.3% in the 12–17-year age group.
When viruses were considered separately, it was observed that CV-A6 antibodies were detected in 684 (68.5%) of the samples, EV-A71 in 664 (66.5%), CV-A10 in 601 (60.2%), and CV-A16 antibodies in 459 (46.0%). The seroprevalence of EV-A71, CV-A16, CV-A10, and CV-A6 among all participants and by age group is presented in Figure 3.
The distribution of viral antibody-positive samples by age group is shown in Table 3. CV-A16 antibody positivity was found at similar rates across age groups. EV-A71, CV-A6, and CV-A10 antibody positivity was found to be highest in the 12–17 age group.
No significant difference was found between centers in terms of CV-A6 and CV-A10 antibody positivity. The highest CV-A16 antibody positivity rate was found in Adana (66.5%) and the lowest in Istanbul (24.2%). EV-A71 antibody positivity was found to be highest in Ankara (74.2%) and the lowest in Istanbul (53.4%) (Table 3).
Serotype distribution by age groups and study sites is shown in detail in Appendix A Table A2.
The participants showing no antibodies against any HFMD pathogen (All-Negative group, n = 53) were compared with those showing antibodies against any HFMD pathogen (Any-Positive group, n = 945) in terms of certain characteristics. A significant increase in HFMD seropositivity was found with increasing age. Handwashing habits did not differ between the two groups. The any-positive group had a higher frequency of having a household member aged 12–18 years and of having a mother with a lower education level. Attending kindergarten was significantly higher in the any-positive group (Table 4).
In the logistic regression analysis, a model was created using the variables of age, sex, nursery attendance, kindergarten attendance, household’s average monthly income, mother’s and father’s education level. Factors influencing seropositivity were identified as follows: a 1-unit increase in age (1.177 times), a household’s average monthly income between 50,000 and <75,000 TL (4.056 times), a household’s average monthly income ≥75,000 TL (5.640 times), and a mother being a high school graduate (3.419 times) (Table 5).
4. Discussion
The first case of HFMD was identified in 1948, and in the 1970s, outbreaks of EV-associated HFMD were reported in many regions worldwide. In the 1990s, outbreaks of EV-associated HFMD, accompanied by complications, permanent sequelae, and deaths, were reported from Asian countries. Outbreaks continue to be reported from many regions from the 2000s to the present [6]. In the past, HFMD received little attention, as it was considered a self-limiting disease. However, with increasing reports of outbreaks and cases involving serious complications, it has emerged as a significant public health concern [6]. Identifying the circulating HFMD agents is important, as certain serotypes, especially EV-A71, are associated with severe outcomes [7]. When recent outbreaks are examined, it has been noted that EV-A71 and CV-A16 tend to be gradually replaced by CV-A6 and CV-A10 as the main pathogens of HFMD, and the incidence of CV-B3 and CV-B5 infections is increasing [6]. Continuous monitoring of this changing trend in the causative serotypes is necessary to take effective preventive measures for HFMD infection [8]. Seroprevalence studies reveal past infections and help identify the prevalent serotypes in a given area. These data also inform the selection of candidate serotypes for vaccine development. Among recent studies, a seroprevalence study conducted in 220 children (7 months–15 years old) in Korea found EV-A71 and CV-A6 to be suitable candidate serotypes for vaccine development, while further studies were needed for CV-A10 and CVA-16. The highest seropositivity in all age groups was detected for CV-A6 (73.6%), followed by EV-A71, (64.1%), CV-A10 (47.7%), and CV-A16 (34.5%) [9]. Similarly, the highest seropositivity was observed for CV-A6 (65.80%), followed by EV-A71, (59.61%), CV-A10 (58.96%), and CV-A16 (40.07%) in a seroprevalence study conducted in China among healthy individuals (n = 307) across various age groups [10]. Analysis of HFMD cases reported in China between 2009 and 2023 confirmed that CV-A6 gradually emerged as the dominant serotype, while the prevalence of EV-A71 and CV-A16 declined over time [11]. In a seroprevalence study conducted in the United Kingdom, the overall seropositivity rate was determined as 80% for CV-6 and 74% for EV-A71 in archive serum samples from all age groups from 2006 (n = 514), 2011 (n = 498), and 2017 (n = 561) [12]. On the other hand, in a seroprevalence study involving 600 children aged 6–71 months in Indonesia, EV-A71 immunoglobulin G (IgG) positivity was found to be quite high (99.3%) [13].
In Türkiye, the published manuscripts on HFMD have generally focused on the clinical aspects of the disease or on case reports [14,15,16,17,18,19]. A study conducted in Istanbul analyzed 27 patient samples collected between 2015 and 2017. Laboratory testing using RT-PCR revealed the presence of enterovirus in 12 samples. Among these, CV-A16 was detected in 3 cases and CV-A6 in 9, supporting the observation that CV-A6-related cases are increasing in frequency [20]. A seroprevalence study conducted among preschool children (n = 380) in Sakarya showed the EV-A71 IgG antibody positivity was 57.9% and CV-A16 IgG antibody positivity was 57.4% [21]. Our study, conducted in different regions of Türkiye, is the first of its kind to conduct a comprehensive seroprevalence study. Neutralizing antibodies against at least one HFMD agent were detected in 94.7% of serum samples collected from 998 children aged 6 months to 17 years. Antibodies to CV-A6 (68.5%) and EV-A71 (66.5%) were the most prevalent, followed by CV-A10 (60.2%) and CV-A16 (46.0%). Our findings are consistent with global seroprevalence patterns observed in recent studies mentioned above.
Seropositivity rates were evaluated separately in the 6 month–2 year, 3–5-year, 6–11-year, and 12–17-year age groups. CV-A16 seropositivity remained relatively consistent across all age groups, whereas the highest antibody positivity rates for EV-A71, CV-A6, and CV-A10 were observed in the 12–17-age group. This age-related increase in antibody prevalence likely reflects cumulative exposure, as HFMD primarily occurs in early childhood. On the other hand, most participants had more than one antibody detected, and when all serotypes were considered together, the rate of at least one antibody positivity was 90.5% (n/N = 19/21) even in children aged 6–8 months. Comparing individuals seronegative for HFMD with those who had at least one antibody positivity for any HFMD, the seroprevalence rate was shown to increase with age. Of the any-positive individuals (n = 945), 2% were in the 6–8-month age group, while 33.1% were in the 12–17-year age group (p < 0.001).
There are environmental factors that affect disease epidemiology. Climatic characteristics such as ambient temperatures and humidity have found to be associated with the incidence of HFMD [22,23,24,25,26]. When seroprevalence rates were examined by region in our study, the highest CV-A16 antibody positivity rate was found in Adana (66.5%) and the lowest in Istanbul (24.2%). The highest EV-A71 antibody positivity rate was found in Ankara (74.2%) and the lowest in Istanbul (53.4%). No difference was found between regions in terms of CV-A6 and CV-A10 seroprevalence. Our findings have confirmed that certain HFMD-associated agents exhibit variable frequencies of occurrence, which appear to be influenced by regional and climatic factors. Socioeconomic factors are also closely related to the epidemic and severity of HFMD [27,28]. In our study, the HFMD seropositive group had a higher frequency of having a household member aged 12–18 years and of having a mother with a lower education level.
Due to the absence of a specific treatment for HFMD and the diversity of its causative agents -with reinfection remaining a possibility- preventive measures are essential for effective disease control [29]. Enteroviruses, the principal pathogens responsible for HFMD, are thought to be transmitted primarily via the fecal-oral route, respiratory droplets and aerosols, or through close personal contact [6]. Personal hygiene, hand washing, household crowding, and nutritional habits are associated with the risk of HFMD [6,30,31,32]. For these reasons, personal hygiene and improving environmental factors play an important role in disease prevention. In our study handwashing habits did not differ between the seronegative and seropositive groups. Although the literature identifies handwashing habits as a risk factor, our finding may not align with this expectation, likely because handwashing information was obtained through self-report. Moreover, given the high seroprevalence, widespread exposure to the virus may have overshadowed the measurable effect of personal hygiene in this particular cross-sectional snapshot. On the other hand, attending kindergarten was significantly higher in the seropositive group, highlighting the role of close contact in transmission. In logistic regression analysis, age, average monthly household income, and mother’s education level were found to be factors influencing seropositivity.
Within the scope of personal prevention, vaccine research is ongoing. Effective results have been reported with the EV-A71 vaccine, which was introduced in China in 2015 [33,34]. The overall EV-A71 vaccine effectiveness was reported to be 90.8% for all cases, and it reached 100% against severe cases [33]. Ongoing research efforts are also directed toward the development of multivalent formulations, such as the EV-A71/CV-A16 bivalent vaccine, the EV-A71/CV-A6/CV-A10 trivalent vaccine, and the EV-A71/CV-A16/CV-A6/CV-A10 tetravalent vaccine [34].
Our study has some limitations. Since it is based on admissions to outpatient clinics rather than a population-based screening, caution is warranted when generalizing the findings to the broader population. However, the fact that the hospitals where the study was conducted are located in five major cities and serve about a third of the country’s population (36.25%) is valuable in terms of representativeness. The exclusion of patients with chronic illnesses such as autoimmune diseases or immunodeficiency/immunosuppression may also have contributed to a bias. However, our study is valuable as it represents the first large-scale seroprevalence investigation conducted in Türkiye. We believe that our findings regarding circulating HFMD serotypes will serve as a guide in shaping prevention strategies.
5. Conclusions
The seroprevalence of HFMD-causing viruses in Türkiye is high from six months of age onward, underscoring the urgent need for nationwide preventive strategies. Nationwide strategies should be developed to address associated risk factors. To reduce transmission, policymakers should prioritize strengthening routine surveillance systems, integrating seroepidemiological data into public health planning, and promoting hygiene education programs in schools and childcare facilities. In addition to promoting personal protective measures, the implementation of a vaccination program should also be considered as part of a comprehensive national strategy. These measures would contribute to reducing the burden of HFMD in the population.
Supplementary Materials
The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/vaccines14060470/s1, Supplementary File S1: Case Report Form of the Study in Turkish.
Author Contributions
Conceptualization, A.K. (Adem Karbuz), T.T.-K., Ü.Ç., B.G., D.Y.-Ç. and A.K. (Ateş Kara); methodology, Y.C., M.Z.-A. and E.S.; validation, A.K. (Adem Karbuz), T.T.-K., Ü.Ç., B.G., D.Y.-Ç. and A.K. (Ateş Kara); investigation, All authors; writing—original draft preparation, A.K. (Ateş Kara); writing—review and editing, All authors; supervision, A.K. (Adem Karbuz), T.T.-K., Ü.Ç., B.G., D.Y.-Ç. and A.K. (Ateş Kara); project administration, A.K. (Ateş Kara). All authors have read and agreed to the published version of the manuscript.
Funding
The present study was sponsored by Sinovac Biotech (Singapore) PTE. Ltd., Beijing, P.R.C., grant number PRO-EV71-MA4002-TUR.
Institutional Review Board Statement
The study was conducted in accordance with the Declaration of Helsinki, and approved by the Clinical Research Ethics Committee of Ankara Bilkent City Hospital (Approval Number: E2-24-6875; Date: 20 March 2024).
Informed Consent Statement
Written informed consent was obtained from the participant or parent/guardian/legal representative involved in the study.
Data Availability Statement
Due to the provisions outlined in the informed consent form (ICF), the raw data are not publicly available. However, specific portions of the data may be shared upon reasonable request to the corresponding author, subject to appropriate justification and approval.
Acknowledgments
The statistical analysis and medical writing support was conducted by Omega CRO, Ankara, Türkiye and was funded by Sinovac Biotech (Singapore) PTE. Ltd., Beijing, P.R.C.
Conflicts of Interest
The sponsor had no role in the data analysis, interpretation of the results, or preparation of the manuscript.
Abbreviations
The following abbreviations are used in this manuscript:
| HFMD | Hand, foot and mouth disease |
| EV-A71 | Enterovirus type 71 |
| CV-A16 | Coxsackievirus A16 |
| CV-A10 | Coxsackievirus A10 |
| CV-A6 | Coxsackievirus |
| EUROSTAT | The Statistical Office of the European Union |
| NUTS | The Nomenclature of Territorial Units for Statistics |
| HIV | Human Immunodeficiency Virus |
| CI | Confidence Interval |
| SD | Stanadard Deviation |
| IgG | Immunoglobulin G |
Appendix A
Table A1.
Demographic, climatic, and socio-economic characteristics of study sites.
| City | Ankara | Antalya | Adana | İzmir | İstanbul |
|---|---|---|---|---|---|
| Study site | Ankara Bilkent City Hospital | Akdeniz University Medical Faculty Hospital | Adana City Hospital | İzmir City Hospital | Prof. Dr. Cemil Taşcıoğlu City Hospital |
| EUROSTAT NUTS-1 Region | TR5-West Anatolia | TR6-Mediterranean | TR6-Mediterranean | TR3-Aegean | TR1-İstanbul |
| Temperature-Mean, January | 0.3 °C | 10.6 °C | 10.0 °C | 8.8 °C | 5.5 °C |
| Temperature-Mean, July | 23.4 °C | 28.0 °C | 28.1 °C | 27.0 °C | 23.6 °C |
| General population by city 2024 | 5,864,049 | 2,722,103 | 2,280,484 | 4,493,242 | 15,701,602 |
| Population <18 y by city 2024 | 1,332,868 | 643,299 | 628,383 | 931,178 | 3,714,755 |
| Population <12 y by city 2024 | 845,530 | 409,861 | 404,984 | 593,953 | 2,394,700 |
| Percentage of population at risk for HFMD (<18 y) | 22.7% | 23.6% | 27.6% | 20.7% | 23.7% |
| Socio-Economic status | Developed | Touristic | Agricultural | Developed | Dynamic |
Table A2.
Serotypes distribution by age groups and study sites.
| Ankara | Antalya | Adana | İzmir | İstanbul | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| N | n (%) | N | n (%) | N | n (%) | N | n (%) | N | n (%) | |
| CV-A16 | ||||||||||
| 6–8 months | 8 | 3 (37.5) | 3 | 2 (66.7) | 3 | 2 (66.7) | 4 | 2 (50.0) | 3 | 0 (0.0) |
| 9–11 months | 8 | 3 (37.5) | 6 | 2 (33.3) | 1 | 0 (0.0) | 8 | 5 (62.5) | 0 | 0 (0.0) |
| 12–14 months | 1 | 0 (0.0) | 8 | 5 (62.5) | 1 | 0 (0.0) | 11 | 5 (45.5) | 3 | 0 (0.0) |
| 15–17 months | 4 | 2 (50.0) | 5 | 3 (60.0) | 6 | 3 (50.0) | 5 | 0 (0.0) | 2 | 0 (0.0) |
| 18–20 months | 7 | 5 (71.4) | 5 | 1 (20.0) | 7 | 5 (71.4) | 5 | 2 (40.0) | 3 | 0 (0.0) |
| 21–24 months | 4 | 1 (25.0) | 4 | 2 (50.0) | 5 | 4 (80.0) | 0 | 0 (0.0) | 4 | 0 (0.0) |
| 25–35 months | 14 | 8 (57.1) | 14 | 7 (50.0) | 13 | 7 (53.8) | 11 | 5 (45.5) | 4 | 0 (0.0) |
| 3–5 years | 38 | 21 (55.3) | 44 | 12 (27.3) | 39 | 26 (66.7) | 33 | 22 (66.7) | 33 | 11 (33.3) |
| 6–11 years | 55 | 25 (45.5) | 59 | 23 (39.0) | 60 | 42 (70.0) | 57 | 31 (54.4) | 74 | 19 (25.7) |
| 12–17 years | 55 | 21 (38.2) | 50 | 23 (46.0) | 71 | 48 (67.6) | 47 | 28 (59.6) | 93 | 23 (24.7) |
| EV-A71 | ||||||||||
| 6–8 months | 8 | 8 (100.0) | 3 | 1 (33.3) | 3 | 3 (100.0) | 4 | 2 (50.0) | 3 | 2 (66.7) |
| 9–11 months | 8 | 6 (75.0) | 6 | 3 (50.0) | 1 | 1 (100.0) | 8 | 6 (75.0) | 0 | 0 (0.0) |
| 12–14 months | 1 | 1 (100.0) | 8 | 5 (62.5) | 1 | 1 (100.0) | 11 | 4 (36.4) | 3 | 0 (0.0) |
| 15–17 months | 4 | 3 (75.0) | 5 | 1 (20.0) | 6 | 3 (50.0) | 5 | 3 (60.0) | 2 | 2 (100.0) |
| 18–20 months | 7 | 7 (100.0) | 5 | 4 (80.0) | 7 | 5 (71.4) | 5 | 4 (80.0) | 3 | 2 (66.7) |
| 21–24 months | 4 | 4 (100.0) | 4 | 2 (50.0) | 5 | 1 (20.0) | 0 | 0 (0.0) | 4 | 2 (50.0) |
| 25–35 months | 14 | 8 (57.1) | 14 | 9 (64.3) | 13 | 5 (38.5) | 11 | 10 (90.9) | 4 | 3 (75.0) |
| 3–5 years | 38 | 17 (44.7) | 44 | 35 (79.5) | 39 | 19 (48.7) | 33 | 27 (81.8) | 33 | 11 (33.3) |
| 6–11 years | 55 | 43 (78.2) | 59 | 43 (72.9) | 60 | 44 (73.3) | 57 | 41 (71.9) | 74 | 31 (41.9) |
| 12–17 years | 55 | 47 (85.5) | 50 | 42 (84.0) | 71 | 45 (63.4) | 47 | 34 (72.3) | 93 | 64 (68.8) |
| CV-A6 | ||||||||||
| 6–8 months | 8 | 4 (50.0) | 3 | 2 (66.7) | 3 | 0 (0.0) | 4 | 1 (25.0) | 3 | 1 (33.3) |
| 9–11 months | 8 | 5 (62.5) | 6 | 2 (33.3) | 1 | 1 (100.0) | 8 | 4 (50.0) | 0 | 0 (0.0) |
| 12–14 months | 1 | 0 (0.0) | 8 | 6 (75.0) | 1 | 0 (0.0) | 11 | 5 (45.5) | 3 | 1 (33.3) |
| 15–17 months | 4 | 0 (0.0) | 5 | 3 (60.0) | 6 | 2 (33.3) | 5 | 3 (60.0) | 2 | 0 (0.0) |
| 18–20 months | 7 | 4 (57.1) | 5 | 0 (0.0) | 7 | 2 (28.6) | 5 | 1 (20.0) | 3 | 1 (33.3) |
| 21–24 months | 4 | 4 (100.0) | 4 | 2 (50.0) | 5 | 4 (80.0) | 0 | 0 (0.0) | 4 | 0 (0.0) |
| 25–35 months | 14 | 5 (35.7) | 14 | 6 (42.9) | 13 | 7 (53.8) | 11 | 5 (45.5) | 4 | 1 (25.0) |
| 3–5 years | 38 | 20 (52.6) | 44 | 31 (70.5) | 39 | 25 (64.1) | 33 | 21 (63.6) | 33 | 13 (39.4) |
| 6–11 years | 55 | 40 (72.7) | 59 | 44 (74.6) | 60 | 47 (78.3) | 57 | 44 (77.2) | 74 | 48 (64.9) |
| 12–17 years | 55 | 42 (76.4) | 50 | 46 (92.0) | 71 | 64 (90.1) | 47 | 43 (91.5) | 93 | 74 (79.6) |
| CV-A10 | ||||||||||
| 6–8 months | 8 | 4 (50.0) | 3 | 1 (33.3) | 3 | 0 (0.0) | 4 | 0 (0.0) | 3 | 1 (33.3) |
| 9–11 months | 8 | 5 (62.5) | 6 | 3 (50.0) | 1 | 1 (100.0) | 8 | 3 (37.5) | 0 | 0 (0.0) |
| 12–14 months | 1 | 0 (0.0) | 8 | 6 (75.0) | 1 | 0 (0.0) | 11 | 1 (9.1) | 3 | 0 (0.0) |
| 15–17 months | 4 | 1 (25.0) | 5 | 2 (40.0) | 6 | 1 (16.7) | 5 | 3 (60.0) | 2 | 0 (0.0) |
| 18–20 months | 7 | 4 (57.1) | 5 | 1 (20.0) | 7 | 0 (0.0) | 5 | 2 (40.0) | 3 | 1 (33.3) |
| 21–24 months | 4 | 4 (100.0) | 4 | 1 (25.0) | 5 | 1 (20.0) | 0 | 0 (0.0) | 4 | 1 (25.0) |
| 25–35 months | 14 | 8 (57.1) | 14 | 11 (78.6) | 13 | 3 (23.1) | 11 | 7 (63.6) | 4 | 2 (50.0) |
| 3–5 years | 38 | 14 (36.8) | 44 | 27 (61.4) | 39 | 20 (51.3) | 33 | 20 (60.6) | 33 | 10 (30.3) |
| 6–11 years | 55 | 33 (60.0) | 59 | 35 (59.3) | 60 | 39 (65.0) | 57 | 41 (71.9) | 74 | 39 (52.7) |
| 12–17 years | 55 | 41 (74.5) | 50 | 39 (78.0) | 71 | 57 (80.3) | 47 | 33 (70.2) | 93 | 75 (80.6) |
Figure A1.
The mean summer (July) and winter (January) temperatures (°C) of the cities.
References
- Cox, B.; Levent, F. Hand, foot, and mouth disease. JAMA 2018, 320, 2492. [Google Scholar] [CrossRef] [PubMed]
- Zhu, P.; Ji, W.; Li, D.; Li, Z.; Chen, Y.; Dai, B.; Han, S.; Chen, S.; Jin, Y.; Duan, G. Current status of hand-foot-and-mouth disease. J. Biomed. Sci. 2023, 30, 15. [Google Scholar] [CrossRef]
- Nayak, G.; Bhuyan, S.K.; Bhuyan, R.; Sahu, A.; Kar, D.; Kuanar, A. Global emergence of Enterovirus 71: A systematic review. Beni Suef Univ. J. Basic Appl. Sci. 2022, 11, 78. [Google Scholar] [CrossRef]
- World Health Organization—Regional Office for the Western Pacific. A Guide to Clinical Management and Public Health Response for Hand, Foot and Mouth Disease (HFMD); WHO Regional Office for the Western Pacific: Manila, Philippines, 2011; Available online: https://iris.who.int/handle/10665/207490 (accessed on 3 March 2026).
- World Health Organization—Department of Immunization; Vaccines and Biologicals. Polio Laboratory Manual, 4th ed.; World Health Organization: Geneva, Switzerland, 2024; Available online: https://polioeradication.org/wp-content/uploads/2017/05/Polio_Lab_Manual04.pdf (accessed on 29 April 2026).
- Huang, C.Y.; Su, S.B.; Chen, K.T. A review of enterovirus-associated hand-foot and mouth disease: Preventive strategies and the need for a global enterovirus surveillance network. Pathog. Glob. Health 2024, 6 118, 538–548. [Google Scholar] [CrossRef]
- Li, Y.; Yang, J.; Liang, L.; Wang, K.; Turtle, L.; Li, P.; Zhou, Y.; Shen, Y.; Cui, P.; Zhou, C.; et al. Clinical characteristics and severity of hand, foot, and mouth disease by virus serotype: A prospective hospital-based cohort study. PLoS Negl. Trop. Dis. 2025, 19, e0013039. [Google Scholar] [CrossRef]
- Shrestha, S.; Malla, B.; Haramoto, E. Evaluation of the Enterovirus serotype monitoring approach for wastewater surveillance of hand foot and mouth disease using secondary epidemiological surveillance data. Sci. Total Environ. 2025, 969, 178896. [Google Scholar] [CrossRef]
- Kim, S.; Bae, K.S.; Kim, J.H.; Kang, J.H.; Choi, U.Y. Seroprevalence of neutralizing antibodies against candidate serotypes of enterovirus vaccines among Korean Children. Viral Immunol. 2021, 34, 62–67. [Google Scholar] [CrossRef] [PubMed]
- Wang, J.; Wu, W.; Wang, W.; Zhang, J.; Xiao, J.; Cai, M.; Guo, J.; Li, R.; Zhu, S.; Zhang, W.; et al. Seroprevalence of neutralizing antibodies against HFMD associated enteroviruses among healthy individuals in Shanghai, China, 2022. Virol. Sin. 2024, 39, 694–698. [Google Scholar] [CrossRef]
- Wu, B.; Zhang, X.; Fu, M.; Ji, X. Epidemiological trends of hand, foot, and mouth disease in children under age 10, Jiangning District, Jiangsu, China (2009–2023). BMC Infect. Dis. 2025, 25, 886. [Google Scholar] [CrossRef] [PubMed]
- Kamau, E.; Nguyen, D.; Celma, C.; Blomqvist, S.; Horby, P.; Simmonds, P.; Harvala, H. Seroprevalence and virologic surveillance of Enterovirus 71 and Coxsackievirus A6, United Kingdom, 2006–2017. Emerg. Infect. Dis. 2021, 27, 2261–2268. [Google Scholar] [CrossRef]
- Girsang, R.T.; Rusmil, K.; Fadlyana, E.; Setiabudiawan, B.; Adrizain, R.; Mulyadi, R.P.; Budiman, A.; Utami, R.K.; Mardiah, B.Z.; Dwi Putra, M.G.; et al. A serosurvey study of hand, foot and mouth disease in healthy children aged 6 to 71 months old in West Bandung and Bandung Region, Indonesia. BMC Infect. Dis. 2025, 25, 124. [Google Scholar] [CrossRef]
- Ekinci, A.P.; Erbudak, E.; Baykal, C. A significant increase in the frequency of hand-foot-mouth disease in Istanbul in June 2012. Turkderm-Turk. Arch. Dermatol. Venereol. 2013, 47, 192–193. (In Turkish) [Google Scholar]
- Akkoyunlu, Y.; Ceylan, B.; Aslan, T. Hand, foot, and mouth disease in an adult. Braz. J. Infect. Dis. 2014, 18, 227–228. [Google Scholar] [CrossRef] [PubMed]
- Demirhan, B.I.; Demirbaş, Z.E.; Sari, T.; Toprak, A.; Navruz, M. Hand-foot-mouth disease in 14 years-old: A Case Report. Turk. J. Fam. Med. Prim. Care 2016, 10, 51–53. (In Turkish) [Google Scholar] [CrossRef][Green Version]
- Bucak, İ.H.; Tepe, B.; Almiş, H.; Köse, A.; Turgut, M. Joint diagnosis of pediatric and dermatology clinics: Prospective observation of thirty-nine patients with hand, foot and mouth disease. Turkderm-Turk. Arch. Dermatol. Venereol. 2017, 51, 41–45. (In Turkish) [Google Scholar] [CrossRef]
- Kiratli, K.; Topal, Y.; Saat, B.; Kemer, S.; Cevik, E. Hand-foot-mouth disease in an immunocompetent adult. Causapedia 2017, 6, 1–4. (In Turkish) [Google Scholar]
- Kara, M.; Sütçü, M.; Kılıç, Ö.; Gül, D.; Tural Kara, T.; Akkoç, G.; Baktır, A.; Bozdemir, Ş.E.; Özgür Gündeşlioğlu, Ö.; Yıldız, F.; et al. Propolis as a treatment option for hand, foot, and mouth disease (HFMD) in children: A prospective randomized clinical study. Children 2025, 12, 695. [Google Scholar] [CrossRef]
- Ceylan, A.N.; Turel, O.; Gultepe, B.S.; Inan, E.; Turkmen, A.V.; Doymaz, M.Z. Hand, foot, and mouth disease caused by Coxsackievirus A6: A preliminary report from Istanbul. Pol. J. Microbiol. 2019, 68, 165–171. [Google Scholar] [CrossRef]
- Cinar, E.M.; Kosecik, M.; Aslan, F.G.; Buyukavcı, M.; Koroglu, M.; Elmas, B.; Altındis, M. The seroprevalence of hand-foot-mouth disease in preschool children. J. Pediatr. Infect. Dis. 2019, 14, 171–175. [Google Scholar] [CrossRef]
- Cheng, Q.; Bai, L.; Zhang, Y.; Zhang, H.; Wang, S.; Xie, M.; Zhao, D.; Su, H. Ambient temperature, humidity and hand, foot, and mouth disease: A systematic review and meta-analysis. Sci. Total Environ. 2018, 625, 828–836. [Google Scholar] [CrossRef] [PubMed]
- Bo, Z.; Ma, Y.; Chang, Z.; Zhang, T.; Liu, F.; Zhao, X.; Long, L.; Yi, X.; Xiao, X.; Li, Z. The spatial heterogeneity of the associations between relative humidity and pediatric hand, foot and mouth disease: Evidence from a nation-wide multicity study from mainland China. Sci. Total Environ. 2020, 707, 136103. [Google Scholar] [CrossRef] [PubMed]
- Zhang, R.; Lin, Z.; Guo, Z.; Chang, Z.; Niu, R.; Wang, Y.; Wang, S.; Li, Y. Daily mean temperature and HFMD: Risk assessment and attributable fraction identification in Ningbo China. J. Expo. Sci. Environ. Epidemiol. 2021, 31, 664–671. [Google Scholar] [CrossRef] [PubMed]
- Rui, J.; Luo, K.; Chen, Q.; Zhang, D.; Zhao, Q.; Zhang, Y.; Zhai, X.; Zhao, Z.; Zhang, S.; Liao, Y.; et al. Early warning of hand, foot, and mouth disease transmission: A modeling study in mainland, China. PLoS Negl. Trop. Dis. 2021, 15, e0009233. [Google Scholar] [CrossRef] [PubMed]
- Tang, Z.; Sun, Q.; Pan, J.; Xie, M.; Wang, Z.; Lin, X.; Wang, X.; Zhang, Y.; Xue, Q.; Bo, Y.; et al. Air pollution’s numerical, spatial, and temporal heterogeneous impacts on childhood hand, foot and mouth disease: A multi-model county-level study from China. BMC Public Health 2024, 24, 2825. [Google Scholar] [CrossRef]
- Wang, Y.; Zhao, H.; Ou, R.; Zhu, H.; Gan, L.; Zeng, Z.; Yuan, R.; Yu, H.; Ye, M. Epidemiological and clinical characteristics of severe hand-foot-and-mouth disease (HFMD) among children: A 6-year population-based study. BMC Public Health 2020, 20, 801. [Google Scholar] [CrossRef]
- Li, P.; Rui, J.; Niu, Y.; Xie, F.; Wang, Y.; Li, Z.; Liu, C.; Yu, S.; Huang, J.; Luo, L.; et al. Analysis of HFMD transmissibility among the whole population and age groups in a large city of China. Front. Public Health 2022, 10, 850369. [Google Scholar] [CrossRef]
- Zhou, H.; Yao, Y.; Long, Q.; Deng, C. Epidemiological characteristics and influencing factors of hand, foot and mouth disease reinfection cases in Jiulongpo District, Chongqing, China, 2009–2023. Front. Public Health 2025, 13, 1543450. [Google Scholar] [CrossRef]
- Lin, H.; Sun, L.; Lin, J.; He, J.; Deng, A.; Kang, M.; Zeng, H.; Ma, W.; Zhang, Y. Protective effect of exclusive breastfeeding against hand, foot and mouth disease. BMC Infect. Dis. 2014, 14, 645. [Google Scholar] [CrossRef]
- Zhang, D.; Li, Z.; Zhang, W.; Guo, P.; Ma, Z.; Chen, Q.; Du, S.; Peng, J.; Deng, Y.; Hao, Y. Hand-washing: The main strategy for avoiding hand, foot and mouth disease. Int. J. Environ. Res. Public Health 2016, 13, 610. [Google Scholar] [CrossRef]
- Guo, N.; Ma, H.; Deng, J.; Ma, Y.; Huang, L.; Guo, R.; Zhang, L. Effect of hand washing and personal hygiene on hand food mouth disease: A community intervention study. Medicine 2018, 97, e13144. [Google Scholar] [CrossRef]
- Zhang, Y.; Cui, J.; Liu, F.; Song, Y.; Wang, Q.; Liu, Y.; Zhang, Y.; Li, Z.; Chang, Z. Effectiveness of Enterovirus 71 inactivated vaccines against hand, foot, and mouth disease: A test-negative case-control study. Hum. Vaccin. Immunother. 2024, 20, 2330163. [Google Scholar] [CrossRef] [PubMed]
- Yan, X.; Liu, Y.; Chen, F.; Chang, Z.; Zhang, Z.; Pons-Salort, M.; Grassly, N.C. The efficacy and effectiveness of enterovirus A71 vaccines against hand, foot, and mouth disease: A systematic review and meta-analysis. PLoS ONE 2025, 20, e0323782. [Google Scholar] [CrossRef]
Figure 1.
Study center locations and their share of the national population. Note: Percentages indicate each city’s share of the national population.
Figure 1.
Study center locations and their share of the national population. Note: Percentages indicate each city’s share of the national population.
Figure 2.
Viral antibody test results.
Figure 3.
Seroprevalence of EV-A71, CV-A16, CV-A10, and CV-A6 in all participants and by age group.
Table 1.
General characteristics of participants.
| Study City | Ankara N = 194 | Antalya N = 198 | Adana N = 206 | İzmir N = 181 | İstanbul N = 219 | Total N = 998 |
|---|---|---|---|---|---|---|
| Age, year, mean ± SD (%95 CI) | 8.08 ± 5.41 (7.31–8.84) | 7.79 ± 5.12 (7.07–8.50) | 8.95 ± 5.29 (8.22–9.68) | 7.77 ± 5.27 (6.99–8.54) | 10.10 ± 4.70 (9.48–10.73) | 8.59 ± 5.22 (8.26–8.91) |
| Age Group, n (%) | ||||||
| 6 months–2 years | 46 (23.7) | 45 (22.7) | 36 (17.5) | 44 (24.3) | 19 (8.7) | 191 (19.0) |
| 3–5 years | 38 (19.6) | 44 (22.2) | 39 (18.9) | 33 (18.2) | 33 (15.1) | 188 (18.7) |
| 6–11 years | 55 (28.4) | 59 (29.8) | 60 (29.1) | 57 (31.5) | 74 (33.8) | 305 (30.6) |
| 12–17 years | 55 (28.4) | 50 (25.3) | 71 (34.5) | 47 (26.0) | 93 (42.5) | 316 (31.7) |
| Sex, n (%) | ||||||
| Male | 111 (57.2) | 104 (52.5) | 111 (53.9) | 97 (53.6) | 89 (40.6) | 512 (51.3) |
| Female | 83 (42.8) | 94 (47.5) | 95 (46.1) | 84 (46.4) | 130 (59.4) | 486 (48.7) |
Table 2.
Viral antibody test results by age group.
| Negative | Positive | Total | |||||
|---|---|---|---|---|---|---|---|
| Single | Dual | Triple | Quadruple | ||||
| Age group | n (%) | n (%) | n (%) | n (%) | n (%) | n (%) | p |
| 6–8 months | 2 (9.5) | 6 (28.6) | 7 (33.3) | 5 (23.8) | 1 (4.8) | 21 (100.0) | <0.001 |
| 9–11 months | 2 (8.7) | 4 (17.4) | 7 (30.4) | 8 (34.8) | 2 (8.7) | 23 (100.0) | |
| 12–14 months | 5 (20.8) | 7 (29.2) | 6 (25.0) | 3 (12.5) | 3 (12.5) | 24 (100.0) | |
| 15–17 months | 0 (0.0) | 11 (50.0) | 9 (40.9) | 2 (9.1) | 0 (0.0) | 22 (100.0) | |
| 18–20 months | 3 (11.1) | 7 (25.9) | 9 (33.3) | 6 (22.2) | 2 (7.4) | 27 (100.0) | |
| 21–24 months | 2 (11.8) | 3 (17.6) | 7 (41.2) | 4 (23.5) | 1 (5.9) | 17 (100.0) | |
| 25–35 months | 5 (8.9) | 13 (23.2) | 16 (28.6) | 16 (28.6) | 6 (10.7) | 56 (100.0) | |
| 3–5 years | 16 (8.6) | 46 (24.6) | 46 (24.6) | 52 (27.8) | 27 (14.4) | 187 (100.0) | |
| 6–11 years | 15 (4.9) | 51 (16.7) | 79 (25.9) | 99 (32.5) | 61 (20.0) | 305 (100.0) | |
| 12–17 years | 3 (0.9) | 32 (10.1) | 66 (20.9) | 135 (42.7) | 80 (25.3) | 316 (100.0) | |
Table 3.
Serotypes by age group and study sites.
| Serotypes | |||||
|---|---|---|---|---|---|
| CV-A16 | EV-A71 | CV-A6 | CV-A10 | ||
| Age Group | N | n (%) | n (%) | n (%) | n (%) |
| 6 months–2 years | 190 | 84 (44.2) | 121 (63.7) | 82 (43.2) | 78 (41.1) |
| 3–5 years | 187 | 92 (49.2) | 109 (58.3) | 110 (58.8) | 91 (48.7) |
| 6–11 years | 305 | 140 (45.9) | 202 (66.2) | 223 (73.1) | 187 (61.3) |
| 12–17 years | 316 | 143 (45.3) | 232 (73.4) | 269 (85.1) | 245 (77.5) |
| p | 0.777 | 0.004 | <0.001 | <0.001 | |
| Study Sites | N | n (%) | n (%) | n (%) | n (%) |
| Ankara | 194 | 89 (45.9) | 144 (74.2) | 124 (63.9) | 114 (58.8) |
| Antalya | 198 | 80 (40.4) | 145 (73.2) | 142 (71.7) | 126 (63.6) |
| Adana | 206 | 137 (66.5) | 127 (61.7) | 152 (73.8) | 122 (59.2) |
| İzmir | 181 | 100 (55.2) | 131 (72.4) | 127 (70.2) | 110 (60.8) |
| İstanbul | 219 | 53 (24.2) | 117 (53.4) | 139 (63.5) | 129 (58.9) |
| p | <0.001 | <0.001 | 0.084 | 0.846 | |
Table 4.
Baseline characteristics and medical history stratified by test result.
| All-Negative (N = 53) | Any-Positive (N = 945) | OR (95% CI) | p | |
|---|---|---|---|---|
| n (%) | n (%) | |||
| Age group | ||||
| 6–8 months | 2 (3.8) | 19 (2.0) | <0.001 * | |
| 9–11 months | 2 (3.8) | 21 (2.2) | 1.10 (0.14–8.63) | |
| 12–14 months | 5 (9.4) | 19 (2.0) | 0.39 (0.06–2.32) | |
| 15–17 months | 0 (0.0) | 22 (2.3) | - | |
| 18–20 months | 3 (5.7) | 24 (2.5) | 0.84 (0.12–5.56) | |
| 21–24 months | 2 (3.8) | 15 (1.6) | 0.78 (0.09–6.27) | |
| 25–35 months | 5 (9.4) | 51 (5.4) | 1.07 (0.19–6.01) | |
| 3–5 years | 16 (30.2) | 171 (18.1) | 1.12 (0.24–5.27) | |
| 6–11 years | 15 (28.3) | 290 (30.7) | 2.03 (0.43–9.55) | |
| 12–17 years | 3 (5.7) | 313 (33.1) | 10.9 (1.73–69.7) | |
| Routine vaccination status by age | ||||
| Complete | 44 (83.0) | 892 (94.5) | 0.003 * | |
| Incomplete | 9 (17.0) | 41 (4.3) | 4.45 (2.03–9.73) | |
| Unknown | 0 (0.0) | 11 (1.2) | - | |
| Daily handwashing | ||||
| Never | 2 (4.1) | 11 (1.2) | 0.329 * | |
| Very rarely | 15 (30.6) | 311 (35.2) | 3.76 (0.76–18.5) | |
| Rarely | 23 (46.9) | 427 (48.4) | 3.37 (0.70–16.1) | |
| Occasionally | 9 (18.4) | 134 (15.2) | 2.70 (0.51–14.1) | |
| Handwashing after playtime | ||||
| Never | 7 (13.2) | 130 (13.8) | 1.000 * | |
| Sometimes | 31 (58.5) | 541 (57.2) | 0.93 (0.40–2.18) | |
| Always | 15 (28.3) | 267 (28.3) | 0.95 (0.38–2.40) | |
| Unknown | 0 (0.0) | 7 (0.7) | - | |
| Handwashing before meals | ||||
| Never | 7 (13.2) | 89 (9.4) | 0.692 * | |
| Sometimes | 26 (49.1) | 497 (52.6) | 1.50 (0.63–3.56) | |
| Always | 20 (37.7) | 356 (37.7) | 1.39 (0.57–3.41) | |
| Unknown | 0 (0.0) | 3 (0.3) | - | |
| Total number of household members | ||||
| 1–3 | 17 (32.7) | 211 (22.6) | 0.221 * | |
| 4–6 | 34 (65.4) | 690 (74.0) | 1.63 (0.89–2.98) | |
| 7 or more | 1 (1.9) | 32 (3.4) | 2.57 (0.33–20.0) | |
| Household members aged 0–5 years | 29 (55.8) | 484 (51.9) | 0.85 (0.48–1.49) | 0.584 ** |
| Household members aged 6–11 years | 27 (51.9) | 605 (64.8) | 1.70 (0.97–2.98) | 0.060 ** |
| Household members aged 12–18 years | 11 (21.2) | 415 (44.5) | 2.98 (1.51–5.88) | 0.001 ** |
| Mother’s education level | ||||
| Primary education | 13 (24.5) | 412 (43.6) | 0.048 * | |
| High school graduate | 25 (47.2) | 352 (37.2) | 0.44 (0.22–0.88) | |
| Bachelor’s degree and above | 14 (26.4) | 174 (18.4) | 0.39 (0.18–0.85) | |
| Illiterate | 1 (1.9) | 7 (0.7) | 0.22 (0.02–1.92) | |
| Father’s education level | ||||
| Primary education | 15 (28.3) | 245 (25.9) | 0.045 * | |
| High school graduate | 24 (45.3) | 471 (49.8) | 1.20 (0.61–2.33) | |
| Bachelor’s degree and above | 13 (24.5) | 229 (24.2) | 1.07 (0.50–2.31) | |
| Illiterate | 1 (1.9) | 0 (0.0) | - | |
| Household’s average monthly income, TL | ||||
| <20,000 | 12 (22.6) | 133 (14.1) | 0.061 * | |
| 20,000–<50,000 | 21 (39.6) | 279 (29.6) | 1.19 (0.57–2.50) | |
| 50,000–<75,000 | 13 (24.5) | 341 (36.2) | 2.36 (1.05–5.31) | |
| ≥75,000 | 7 (13.2) | 190 (20.1) | 2.44 (0.93–6.38) | |
| Any history of HFMD | 3 (5.7) | 124 (13.1) | 2.51 (0.77–8.19) | 0.113 ** |
| Any history of other rash illnesses | 13 (24.5) | 196 (20.7) | 0.82 (0.43–1.57) | 0.640 ** |
| Nursery attendance | 10 (18.9) | 235 (24.9) | 1.42 (0.70–2.87) | 0.323 ** |
| Kindergarten attendance | 11 (20.8) | 432 (45.7) | 3.21 (1.63–6.32) | <0.001 ** |
| Kindergarten attendance without prior nursery | 4 (9.3) | 266 (37.5) | 5.84 (2.06–16.5) | <0.001 ** |
* Fisher Exact Test; ** Chi-Square Test. HFMD: Hand, foot and mouth disease.
Table 5.
Factors influencing seropositivity-logistic regression analysis.
| OR (95% CI) | p | |
|---|---|---|
| Age | 1.177 (1.098–1.262) | <0.001 |
| Household’s average monthly income (<20,000 TL) | - | |
| Household’s average monthly income (20,000–<50,000 TL) | 1.336 (0.605–2.948) | 0.474 |
| Household’s average monthly income (50,000–<75,000 TL) | 4.056 (1.667–9.872) | 0.002 |
| Household’s average monthly income (≥75,000–100,000) | 5.640 (1.973–16.123) | 0.001 |
| Mother’s education level (Bachelor’s degree and above) | - | |
| Mother’s education level (High school graduate) | 3.419 (1.479–7.907) | 0.004 |
| Mother’s education level (Primary education) | 1.078 (0.521–2.230) | 0.839 |
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2026 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.
Share and Cite
MDPI and ACS Style
Karbuz, A.; Tural-Kara, T.; Çelik, Ü.; Gülhan, B.; Elvan-Tüz, A.; Coşgun, Y.; Kirmaci, Ç.; Açık, A.K.; Kılıç-Çil, M.; Kanık-Yüksek, S.; et al. Seroprevalence of Hand, Foot and Mouth Disease Among Children and Adolescents in Türkiye. Vaccines 2026, 14, 470. https://doi.org/10.3390/vaccines14060470
AMA Style
Karbuz A, Tural-Kara T, Çelik Ü, Gülhan B, Elvan-Tüz A, Coşgun Y, Kirmaci Ç, Açık AK, Kılıç-Çil M, Kanık-Yüksek S, et al. Seroprevalence of Hand, Foot and Mouth Disease Among Children and Adolescents in Türkiye. Vaccines. 2026; 14(6):470. https://doi.org/10.3390/vaccines14060470
Chicago/Turabian StyleKarbuz, Adem, Tuğce Tural-Kara, Ümit Çelik, Belgin Gülhan, Ayşegul Elvan-Tüz, Yasemin Coşgun, Çigdem Kirmaci, Ayşe Kübra Açık, Merve Kılıç-Çil, Saliha Kanık-Yüksek, and et al. 2026. "Seroprevalence of Hand, Foot and Mouth Disease Among Children and Adolescents in Türkiye" Vaccines 14, no. 6: 470. https://doi.org/10.3390/vaccines14060470
APA StyleKarbuz, A., Tural-Kara, T., Çelik, Ü., Gülhan, B., Elvan-Tüz, A., Coşgun, Y., Kirmaci, Ç., Açık, A. K., Kılıç-Çil, M., Kanık-Yüksek, S., Yılmaz-Çiftdoğan, D., Zerey-Albayrak, M., Şahin, V., Erat, T., Özdem-Alataş, Ş., Sağtaş, E., Öksüzoğlu, E., Demirkol, M. E., & Kara, A. (2026). Seroprevalence of Hand, Foot and Mouth Disease Among Children and Adolescents in Türkiye. Vaccines, 14(6), 470. https://doi.org/10.3390/vaccines14060470
Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.
