Out-of-season increase of puerperal fever with group A Streptococcus infection: a case-control study, Netherlands, July to August 2018

• Published in: Euro surveillance : bulletin européen sur les maladies transmissibles 2020-10, Vol.25 (40), p.8
• Main Authors: van den Boogaard, Jossy, Hahné, Susan Jm, Te Wierik, Margreet Jm, Knol, Mirjam J, Balasegaram, Sooria, de Gier, Brechje
• Format: Article
• Language: English
• Subjects: Adult; Case-Control Studies; Disease Notification; Disease Outbreaks - statistics & numerical data; Disease Transmission, Infectious - statistics & numerical data; Female; Fever - etiology; Humans; Impetigo; Impetigo - epidemiology; Impetigo - microbiology; Infections; Natural gas; Netherlands - epidemiology; Nosocomial infections; Outbreaks; Pharyngitis - epidemiology; Pharyngitis - microbiology; Postpartum Period; Pregnancy; Puerperal Infection - epidemiology; Puerperal Infection - microbiology; Risk factors; Scarlet Fever - epidemiology; Scarlet Fever - microbiology; Seasons; Social networks; Streptococcal Infections - complications; Streptococcal Infections - epidemiology; Streptococcus infections; Streptococcus pyogenes - isolation & purification
• ISSN: 1560-7917; 1025-496X; 1560-7917
• DOI: 10.2807/1560-7917.ES.2020.25.40.1900589

We observed an increase in notifications of puerperal group A (GAS) infections in July and August 2018 throughout the Netherlands without evidence for common sources. General practitioners reported a simultaneous increase in impetigo. We hypothesised that the outbreak of puerperal GAS infections resulted from increased exposure via impetigo in the community.We conducted a case-control study to assess peripartum exposure to possible, non-invasive GAS infections using an online questionnaire. Confirmed cases were recruited through public health services while probable cases and controls were recruited through social media. We calculated odds ratios (OR) and 95% confidence intervals (95% CI) with logistic regression analysis.We enrolled 22 confirmed and 23 probable cases, and 2,400 controls. Contact with persons with impetigo were reported by 8% of cases and 2% of controls (OR: 3.26, 95% CI: 0.98-10.88) and contact with possible GAS infections (impetigo, pharyngitis or scarlet fever) by 28% and 9%, respectively (OR: 4.12, 95% CI: 1.95-8.68). In multivariable analysis, contact with possible GAS infections remained an independent risk factor (aOR: 4.28, 95% CI: 2.02-9.09).We found an increased risk of puerperal fever after community contact with possible non-invasive GAS infections. Further study of this association is warranted.