Long-term surveillance of invasive group A streptococcal disease in The Netherlands, 1994-2003
B J M Vlaminckx1, W van Pelt, L M Schouls
1National Institute of Public Health and the Environment (RIVM), the Netherlands.
Abstract:
A nationwide laboratory-based surveillance study of invasive group A streptococcal (GAS) infections was conducted in The Netherlands from May 1994 until December 2003 (average population during this period was 15 729 704). Microbiologically invasive isolates were obtained from 1504 patients, with most (70%) isolates cultured from blood. There was a clear seasonal pattern in invasive streptococcal infections, with an estimated annual incidence that peaked in 1996 (4.0 cases/100 000 individuals/year) and was at its lowest in 1999 (2.0 cases/100 000 individuals/year). Twenty-eight different M-types were identified, of which the most frequent were M1 (339/1504, 23%), M3 (187/1504, 12%), M89 (174/1504, 12%), M28 (164/1504, 11%), M12 (109/1504, 7%) and M6 (55/1504, 4%). There was a high degree of variation in the relative annual contributions of the predominant M-types, but variations in M1 and M3 combined correlated with overall changes in the annual incidence. The contribution of the patient group aged > or = 56 years to all cases of invasive GAS disease increased during the study period, whereas that of the group aged 0-20 years decreased. A peak in the incidence of invasive GAS disease among the patient group aged 30-34 years did not vary during the study period, indicating that the high incidence of invasive GAS disease in this age group was age-specific rather than cohort-related.
Insights
Invasive group A streptococcal (GAS) infections in The Netherlands showed seasonal patterns and shifts in M-type prevalence. Older adults experienced increased GAS disease incidence, while younger age groups saw a decrease.
Area of Science:
- Epidemiology
- Infectious Diseases
- Microbiology
Background:
- Invasive group A streptococcal (GAS) infections pose a significant public health concern.
- Understanding the epidemiology and M-type distribution of GAS is crucial for effective surveillance and control.
Purpose of the Study:
- To analyze the incidence, seasonality, M-type prevalence, and demographic trends of invasive group A streptococcal infections in The Netherlands.
- To identify age-specific patterns and potential cohort effects in invasive GAS disease.
Main Methods:
- A nationwide laboratory-based surveillance study was conducted from May 1994 to December 2003.
- Invasive GAS isolates were collected and M-typed from 1504 patients.
- Incidence rates, seasonal patterns, and age-specific trends were analyzed.
Main Results:
- The annual incidence of invasive GAS peaked in 1996 and was lowest in 1999, with a clear seasonal pattern.
- M-types M1, M3, M89, M28, M12, and M6 were the most frequent, with M1 and M3 contributions correlating with overall incidence changes.
- The proportion of cases in individuals aged 56 years and older increased, while the 0-20 years age group decreased. A consistent incidence peak was observed in the 30-34 years age group.
Conclusions:
- Invasive GAS infections exhibit distinct seasonal patterns and fluctuating M-type prevalence.
- Shifting demographics show an increasing burden of invasive GAS disease in older adults.
- The persistent incidence peak in 30-34 year olds suggests an age-specific susceptibility rather than a cohort effect.
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