In an editorial published in the journal New bacteria and new infectionsresearchers have pinpointed the possible reasons for a sudden rise in cases of group A streptococcal infections among children in the UK and other European countries.
Study: Group A streptococcal infections (GAS) in children in Europe: stemming the rising tide. Image credit: MyFavoriteTime / Shutterstock
Background
A sharp increase in group A streptococcal infections and associated mortality was seen in children in the UK in December 2022. An increase in cases was also seen in other European countries, including Ireland, France, the Netherlands, Spain and Sweden.
The UK, the worst-hit country, reported more than 6,600 cases of scarlet fever and 652 cases of invasive group A strep infection in just 12 weeks. Scarlet fever is a contagious infection caused by group A streptococci in children. In the same period, around 60 infection deaths have been reported in the UK.
The average mortality rate was estimated at 10%. The highest ratio was observed in children aged 10 to 14, followed by adults aged 75 and over.
The number of confirmed cases and deaths from group A streptococcal infections (for both scarlet fever and invasive forms combined). CFR: case fatality. According to ECDC/WHO (European Centers for Disease Prevention and Control/World Health Organization), Ireland, Great Britain, France, the Netherlands and Sweden are the countries experiencing an increase in SGA notifications. Spain was removed from this list by ECDC based on a comparison with previous years. SGA notifications are said to be higher in Germany and Slovenia based on reports by local epidemiologists in newspapers. Note that the authors remain neutral regarding the territorial representations used in the map. Data source: The Ministry of Health in the respective countries.
What is a group A streptococcal infection?
Group A beta-hemolytic streptococci (Streptococcus pyogenes) is an aerotolerant, gram-positive bacterium commonly found in the throat and skin. The bacterium is known to colonize the pharynx in asymptomatic people. The highest incidence is seen in asymptomatic school children with an infection rate of approx. 8-12% in developed countries and 15-20% in developing countries.
According to the World Health Organization (WHO) report, more than 18 million people worldwide are affected by group A streptococcal infections. In addition, an annual induction of cases and mortality has been estimated at over 1.7 million and 500,000, respectively.
The bacterium is spread by several routes, including large respiratory droplets, nasal secretions, sputum, dust particles, direct skin contact, contaminated surfaces and biological vectors such as insects.
The most common symptoms of group A strep infection include high fever with sore throat, scarlet fever, headache, nausea, vomiting and abdominal pain. In some cases, autoimmune reactions may develop after infection. Invasive group A streptococcal infection, most commonly characterized by bacteremia and cellulitis, is associated with a high mortality rate of 8–23%.
Therapeutic and preventive measures
Penicillin antibiotic therapy is considered the gold standard for group A streptococcal infections. Amoxicillin, macrolides, cephalexin, and co-trimoxazole are potent antibiotics in people who are allergic or intolerant to penicillin.
The sudden increase in group A streptococcal infections in the UK and European countries has led to a shortage of antibiotics. The public health authorities in the affected countries have advised against prescribing antibiotics without a correct diagnosis. This can lead to further shortages of antibiotics as well as the development of antibiotic resistance.
To prevent the misuse of antibiotics, the Royal College of General Practitioners (RCGP), the Royal College of Paediatrics and Child Health (RCPCH) and the Royal College of Emergency Medicine (RCEM) have stated that asymptomatic or mildly symptomatic group A streptococcal infection is common and treated in children. These infections are mostly self-limiting and do not require antibiotic treatment.
Considering the clinical presentations, the authorities have recommended a shorter antibiotic treatment of 5 days for children with symptomatic infection. Children can remain contagious for 10 to 21 days if left untreated. However, contagious infections usually disappear 24 to 48 hours after the start of antibiotic treatment.
What are the reasons for a sudden increase in group A strep infection in the UK?
According to the report by the British Health Safety Agency, no new strains of group A streptococcus have been detected in the country recently. The report also states: “Current emm types have been circulating for five years after the documented emergence of M1United Kingdom in 2016.”
The Emm type of group A streptococci is determined from the amino acid sequence of the bacterial cell wall protein, namely the M protein.United Kingdom is a mutant strain belonging to the emm1 family. The strain was discovered in 2019 but has been circulating since 2010.
As noted by Professor Shiranee Sriskandan of the Center for Bacterial Resistance Biology at Imperial College London, the rapid expansion and dominance of bacterial strains with better evolutionary fitness than circulating strains may account for this sudden increase in cases.
Due to the ongoing coronavirus disease 2019 (COVID-19) pandemic, a reduction in social and work interactions and an induction of personal hygiene and protective measures have been observed worldwide. This has significantly reduced the overall incidence of viral and bacterial infections, especially in children.
However, pandemic-related restrictions have resulted in an overall reduction in herd immunity due to lack of exposure and reduced immune stimulation. This greatly increased the proportion of susceptible people. With the lifting of post-pandemic restrictions, these susceptible people, including children, suddenly experience a period of exposure and thus develop infections more quickly. This may be another reason for the outbreak of group A strep infection.
Public health measures, including good personal hygiene and limiting crowded gatherings, should be continued to reduce the course of cases of group A strep infection. In addition, increased genetic surveillance is needed to identify clusters of infection.
Adequate testing, contact tracing and isolation of infected individuals as well as early initiation of antibiotic treatment are the essential measures to be taken to reduce the transmission of infection.