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BackgroundAlthough pertussis has been considered a disease of childhood, it is also recognized as an important respiratory tract infection in adolescents and adults. However, in countries with routine vaccination against pertussis with high coverage, pertussis is not usually taken into consideration for the etiology of prolonged cough in adults. Previous studies in a variety of populations in developed countries have documented that pertussis is quite common, ranging from 2.9 to 32 % of adolescents and adults with prolonged cough. The anticipation and early recognition of this change in the epidemiology is important because the affected adolescents and adults act as reservoirs of the disease and source of infection to the vulnerable population of infants, for whom the disease can be life threatening. We conducted a prospective study to determine the prevalence of pertussis in Thai adults with prolonged cough.MethodsSeventy-six adult patients with a cough lasting for more than 2 weeks (range, 14–180 days) were included in the present study. The data regarding medical history and physical examination were carefully analyzed. Nasopharyngeal swabs from all patients were obtained for the detection of deoxyribonucleic acid of Bordetella pertussis by the polymerase chain reaction (PCR) method. Paired serum samples were collected and tested for IgG antibody against pertussis toxin by using an ELISA method.ResultsOf 76 adult patients, 14 patients (18.4 %) with the mean age of 59 (range, 28–85) years and the mean duration of cough of 34 (range, 14–120) days had laboratory evidence of acute pertussis infection. One patient was diagnosed by the PCR method, while the rest had serological diagnosis. Whooping cough is a significantly associated symptom of patients with chronic cough who had laboratory evidence of pertussis. (p < .05, odds ratio 3.75, 95 % confidence interval: 1.00,14.06)ConclusionPertussis is being increasingly recognized as a cause of prolonged, distressing cough among adults in Thailand. This result addresses the need of pertussis vaccination in Thai adults for preventing transmission to a high risk group such as newborn infants.

This study determined the presence of anti-SARS-CoV-2 antibodies in 4964 individuals, comprising 300 coronavirus disease-19 (COVID-19) prepandemic serum samples, 142 COVID-19 patients, 2113 individuals at risk due to their occupations, 1856 individuals at risk due to sharing workplaces or communities with COVID-19 patients, and 553 Thai citizens returning after spending extended periods of time in countries with a high disease prevalence. We recruited participants between May 2020 and May 2021, which spanned the first two epidemic waves and part of the third wave of the COVID-19 outbreaks in Thailand. Their sera were tested in a microneutralization and a chemiluminescence immunoassay for IgG against the N protein. Furthermore, we performed an immunofluorescence assay to resolve discordant results between the two assays. None of the prepandemic sera contained anti-SARS-CoV-2 antibodies, while antibodies developed in 88% (15 of 17) of the COVID-19 patients at 8–14 days and in 94–100% of the patients between 15 and 60 days after disease onset. Neutralizing antibodies persisted for at least 8 months, longer than IgG antibodies. Of the 2113 individuals at risk due to their occupation, none of the health providers, airport officers, or public transport drivers were seropositive, while antibodies were present in 0.44% of entertainment workers. Among the 1856 individuals at risk due to sharing workplaces or communities with COVID-19 patients, seropositivity was present in 1.9, 1.5, and 7.5% of the Bangkok residents during the three epidemic waves, respectively, and in 1.3% of the Chiang Mai people during the first epidemic wave. The antibody prevalence varied between 6.5 and 47.0% in 553 Thai people returning from high-risk countries. This serosurveillance study found a low infection rate of SARS-CoV-2 in Thailand before the emergence of the Delta variant in late May 2021. The findings support the Ministry of Public Health’s data, which are based on numbers of patients and contact tracing.