Whooping cough – a recurrent epidemic

Abstract Background Whooping cough (WC), or Pertussis, is a vaccine-preventable and highly contagious infectious disease. Although it has a relatively low fatality rate, approximately 13% of reported cases develop secondary bacterial pneumonia. This was because of several recurrent epidemics across Europe in the last decades, with the latest beginning in mid-2023 and still ongoing. The Central Region of Portugal is currently being affected, and this study aims to describe the current epidemic at the regional level. Methods Data from epidemiological inquiries of confirmed and probable cases of WC pertaining to the Central Region of Portugal from January 2020 till April 2024 was gathered from the mandatory report national epidemiological surveillance system (SINAVE). Both a temporal comparison of number of cases and a statistical space-time scan with permutation were conducted (software SaTScan v10.) Results A comparison by month of reported cases shows an increase in cases from September 2023 until December 2023 followed by an exponential increase from January 2024 until April 2024 denoting an ongoing epidemic. In the statistical space-time analysis of 107 reported cases between September 2023 and April 2024, 8 nonsignificant clusters were identified with different locations involved in non-overlapping periods. Conclusions The finding of several unrelated clusters, even though nonsignificant, during a short time period indicates that Pertussis transmission is ongoing at the local level probably through asymptomatic or barely symptomatic cases that act as reservoirs. Clinicians must hold a high clinical suspicion for a timely diagnosis, treatment and report and health authorities must reinforce control measures to limit the spread of this disease. Key messages • Pertussis remains a disease of significant concern recurrent outbreaks across Europe show that public health local authorities have an important role in timely management of cases and outbreaks. • Local level transmission and intervention may play a pivotal role in the epidemiologic dynamic of Pertussis.