RESUMEN
OBJECTIVE: This study had two aims: (1) to investigate the prevalence of familial Mediterranean fever (FMF) and Behçet's disease (BD) in school students in Denizli, a province in western Turkey; and (2) to determine whether the previously suggested "zero patient design" was reliable for use in a prevalence survey. METHODS: The field survey was performed in two stages. In the first stage 7,389 students (3,847 females and 3,542 males) were asked to fill out a questionnaire in the classroom. In the questionnaire, filtering questions for FMF (the presence of recurrent attacks of fever accompanying abdominal pain, joint pain/swelling, and/or chest pain) and BD (presence of aphthous stomatatis) were asked. The second stage consisted of two parts. In the first, 3225 questionnaires were completed by 1778 female and 1447 male students calculated according to the zero patient design, who were selected randomly from among 7389 students for evaluation. Students with any suspicion of FMF and Behçet's disease were called to the hospital for detailed investigation. In the second step the remaining students were evaluated. RESULTS: Out of 3225 children questioned in the first step, 156 claimed recurrent abdominal pain and/or chest pain, and/or joint pain/swelling with accompanying fever, which might suggest the presence of FMF However, this diagnosis was excluded after further clinical evaluation. In the second step 152 students were called for detailed investigation: 2 patients, one 10 years and the other 12 years old, were diagnosed as having FMF. None were diagnosed to have Behçet's disease. CONCLUSION: The prevalence of FMF in Turkey in general is about 0.093%. The prevalence rate found in this survey was lower (0.027%) which may be due to the historic background of the region. This is the first study that has shown that the "zero patient design" can be used in an epidemiological survey.