In a study recently published in the journal Eurosurveillance, a team of researchers from the Netherlands reported on the recent surge of Mycoplasma pneumoniae infections in the country and compared them with previous trends nationwide and across Europe.
Studie: Erhöhte Inzidenz von Mycoplasma pneumoniae-Infektionen und Krankenhauseinweisungen in den Niederlanden, November bis Dezember 2023. Bildquelle: Kateryna Kon / Shutterstock
Mycoplasma pneumoniae is one of the most common pathogens causing upper and lower respiratory tract infections across all age groups. The bacterium causes recurrent epidemics worldwide, with the last epidemic occurring in Europe between 2019 and 2020. Infections with M. pneumoniae also lead to encephalitis and mucosal lesions known as erythema exsudativum multiforme.
The incidence of M. pneumoniae infections in the Netherlands has been low for several years. However, a regional hospital recently reported a sudden increase in cases of M. pneumoniae infections, prompting researchers to question whether a similar trend in incidence could be observed nationwide and across Europe.
In the present study, researchers utilized data from the Regional Public Health Laboratory Kennemerland, the diagnostic center of the Spaarne Gasthuis Regional Hospital, to gain insights into the recent surge of M. pneumoniae infections in the hospital. The data included the number of confirmed cases of M. pneumoniae infections and hospitalizations from 2017 to 2023, as well as demographic information of all patients, such as age, gender, intensive care unit admissions, and duration of hospitalizations.
Hospitalizations were attributed to M. pneumoniae infections if they were preceded by the detection of M. pneumoniae through a polymerase chain reaction (PCR) test using an oropharyngeal or nasopharyngeal swab, up to two days before admission.
Additionally, national trends in M. pneumoniae infections were determined using information from across the Netherlands obtained from a surveillance system of the Dutch National Institute for Public Health and the Environment, which receives data on the nature and number of detected pathogens from the Dutch Working Group for Clinical Virology of the Netherlands Society for Clinical Microbiology. These data do not include information on the methods of pathogen detection or demographic information of the patients.
Furthermore, the researchers also utilized data from a digital surveillance system collecting information on respiratory symptoms from voluntary participants 16 years and older belonging to the general population of the Netherlands since 2020.
The National Institute for Public Health in the Netherlands also instructed subgroups of individuals with respiratory complaints to perform oropharyngeal or nasopharyngeal swabs, which were analyzed weekly. The data from these PCR tests also contributed to the assessment of nationwide trends in M. pneumoniae infections.
The results suggest that the regional hospital Spaarne Gasthuis and the Netherlands as a whole experienced a significant increase in the number of M. pneumoniae infections since October 2023. The number of associated hospitalizations M. pneumoniae infections in the national hospital also increased during this period. Additionally, the average age of patients was significantly lower (28 years) compared to the 2019-2020 epidemic, where the average age was 40 years.
The study found that out of the 133 patients admitted to the regional hospital due to M. pneumoniae infections, 55 were under 18 years old, with 27 patients aged 5 to 11 years. The majority of patients in the adult population also fell into younger age groups of 18 to 29 years and 30 to 39 years. In comparison, there were a total of 68 cases of M. pneumoniae infections during the previous 2019-2020 epidemic, with a significantly higher average age of patients. Similar trends were observed by the researchers in Denmark.
While the reason for this sudden surge in M. pneumoniae infections is not yet known, the researchers speculated that it could be due to either a shift in the dominant M. pneumoniae strain or as a result of a decline in social interactions and other nonpharmaceutical interventions implemented during the 2019 Coronavirus Disease (COVID-19) pandemic. They anticipate that these interactions may have weakened herd immunity against M. pneumoniae.
Overall, the results suggest a sudden increase in the incidence of M. pneumoniae infections in the Netherlands since October 2023. Additionally, the average age of patients, at 28 years, was significantly lower compared to the previous epidemic, indicating that younger individuals appeared to be more susceptible to this strain. The researchers believe that further data on the severity of illness M. pneumoniae strains is needed to understand this current trend of M. pneumoniae infections.
- Bolluyt, Dita C, Euser, Sjoerd M, Souverein, D., Rossum, van, Kalpoe, J., Westreenen, van, Goeijenbier, M., Snijders, D., Eggink, D., Jongenotter, F., Lelyveld, van, & Houten, van. (2024). Erhöhte Inzidenz von Mycoplasma pneumoniae-Infektionen und Krankenhauseinweisungen in den Niederlanden, November bis Dezember 2023. Euroüberwachung29, 4. DOI: 10.2807/1560-7917.ES.2024.29.4.2300724, https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2024.29.4.2300724