[Serological diagnosis of pertussis in older persons.]

The aim of the work was to assess the effectiveness of serodiagnosis of pertussis in people over 50 who complained of prolonged cough. The study included 30 patients over the age of 50 who applied to the consultative diagnostic center complaining of a prolonged cough in the period from 2015 - 2020. Blood serum samples were investigated in enzyme immunoassay with the definition of antitussive antibodies of three classes - IgM, IgG, IgA in the commercial test system RIDASCREEN (R-Biopharm AG, Germany). It was found that in the serum samples of individuals over the age of 50, IgM antibodies above the threshold level were not detected. Patients were divided into two groups - with IgG and IgA antibodies above the threshold level (group 1) and below the threshold level (group 2). In the first group, in 83.3% and 61.1% of patients, the levels of antibodies of the IgG and IgA class significantly exceeded the threshold level (189.8 ± 16.7 U / ml and 290 ± 20 U / ml, respectively), which indicated a pertussis infection; in 5.6% and 38.9% of patients, IgG and IgA class antibodies slightly exceeded the threshold level (20 U / ml and 43 ± 2.3 U / ml, respectively), which indicated a dying infection. In the second group, in 100% of patients, antibodies of the IgM and IgA classes were determined below threshold levels, and IgG antibodies were detected in 58.3% of individuals at low rates, which corresponded to the natural immunological background of individuals not infected with pertussis pathogen. Therefore, in the presence of a prolonged cough in adults, it is advisable to study blood serum samples for the presence of antitussive antibodies of three classes, which is especially important when people of older age live in families with young children and pregnant women.