Metropolitan residents were overrepresented, which is not unexpected given that the fairgrounds are located in a metropolitan county. facilitating larger seroepidemiologic studies. A total of 104 adults and children were enrolled to provide a finger stick blood sample for serologic testing and to take a written survey regarding recent cough illness and pertussis vaccination. The survey was used to distinguish between antibodies induced by vaccination and pertussis infection. Elevated antibodies suggestive of recent infection were found among two adults. The prevalence of undetectable antibodies, suggestive of susceptibility, was 72.3% (95% CI 59.6, 85.1%) among 717 year olds, 53.8% (95% CI 26.7, 80.9%) among 16 year olds, and 23.3% (95% CI 8.2, 38.5%) among adults. Our ability to rapidly enroll participants and collect satisfactory specimens suggests that seroepidemiologic studies with 10002000 participants could efficiently be completed over the Nefazodone hydrochloride 12-day course of the Minnesota State Fair. This setting raises the possibility of efficiently conducting annual population-based seroepidemiologic studies to supplement traditional public health surveillance in estimating disease prevalence, monitoring vaccine impact, and identifying at-risk groups. Keywords:Serology, Infectious diseases, Vaccination, Pertussis == Introduction == Seroepidemiologic studies, which measure sera antibody levels produced in response to infection and/or vaccination, can be valuable tools for gaining insight on population level dynamics of infectious diseases [1]. The use of seroepidemiologic studies in pertussis research illustrates their contribution to COL1A1 estimating population susceptibility and infection prevalence. Pertussis (whooping cough) is a bacterial respiratory infection with illness characterized by paroxysmal coughing that may be followed by vomiting and a whooping noise upon inhalation. Compared to unvaccinated children, adults and previously vaccinated children may experience Nefazodone hydrochloride less severe illness [2,3]. Surveillance in the United States, which consists of case reports from health care providers and laboratories, underestimates true pertussis incidence by primarily capturing clinically apparent disease. Infections that remain undetected have contributed both Nefazodone hydrochloride to the persistence of cyclic pertussis outbreaks every 25 years and to the resurgence of pertussis following near elimination in the 1970s [4,5]. In various populations, seroepidemiologic studies have been conducted to identify adults as a common source of unrecognized transmission [68]. Additionally, seroepidemiologic studies have been used to identify age groups with low pertussis antibody levels suggestive of susceptibility due to waning of vaccine-acquired immunity [9]. Because vaccination records cannot capture the unobserved effects of vaccine failure, waning immunity, and natural boosting (boosting of immunity in partially immune individuals exposed to infection), serologic data can complement vaccination records and provide a more accurate measure of population immunity [10,11]. Pertussis seroepidemiologic studies have previously been conducted to identify potential areas for public health intervention and to assess vaccine impact on population immunity; however, seroepidemiologic studies are commonly restricted to one time point, limiting their ability to elucidate temporal trends [8,9,12]. Campbell et al. conducted serologic testing at three time points (1997, 2002, and 2007) that coincided with different phases of the epidemic cycle of pertussis [13]. They found that an increased prevalence of undetectable antibody levels among children preceded a record pertussis outbreak in Australia. Though Campbell et al. measured population antibody levels at three time points that coincided with different points of the pertussis epidemic cycle, the surveys were conducted in non-consecutive years and spanned 10 years, during which time changes were made to both the pertussis vaccine composition and schedule. Nefazodone hydrochloride To build upon previous seroepidemiologic research, one would ideally conduct a study that sampled a single population annually in consecutive years over the full epidemic cycle of pertussis, which typically lasts 25 years years. Understanding demographic-specific temporal trends in susceptibility and undetected infections as they relate to the recurrence of outbreaks would highlight opportunities for targeted interventions to disrupt sustained transmission. Nefazodone hydrochloride However, seroepidemiologic studies can be expensive and logistically difficult to conduct. Consequently, seroepidemiologic studies are not routinely used to assess population-based temporal trends of infectious diseases [14]. The main challenge presented by prospective seroepidemiologic studies that aim to monitor changes in population-level immunity over time is collecting sera samples from a wide range of age groups drawn from the same population. Specimen collection for serologic testing is generally expensive,.