An out-of-season increase in Group A streptococcal infections, including scarlet fever, has become headline news in England and is also a source of concern elsewhere around the world. According to figures from the UK Health Security Agency (UKHSA), last updated on 15 December 2022, 74 people in all age groups have died of invasive group A streptococcus (iGAS) infections in England, including 16 children under the age of 18, during the current season, which began on 12 September 2022. The majority of cases were reported in those over 18. During the same period, there were 7,750 scarlet fever notifications. Normally, most cases of scarlet fever are reported between February and April. The last peak in Group A strep infections was during 2017 to 2018, when there was a total of 355 deaths across the entire season, which is measured from week 37 one year to week 36 the following year, including 27 deaths in children under 18. The tragedy is that all these deaths were potentially preventable, as the causative bacterium is eminently treatable with penicillin and there is no evidence for the emergence of a new strain or for the development of antibiotic resistance.
The streptococcus is a spherical bacterium or coccus, which stains violet with a stain referred to as a Gram stain in honour of its inventor. Streptococci are divided into a number of groups. These groups are distinguished by a cell wall carbohydrate antigen that is specific to each group. Group A streptococci are further differentiated into alpha, beta, and gamma variants by their capacity to produce haemolysis (destruction of red blood cells) on blood agar culture plates. The relevant variant in the current outbreak is the Group A beta-haemolytic streptococcus.
Strep A infections spread through respiratory droplets from the nose and throat of infected people, during coughing or sneezing, or by direct contact with sores or wounds on the skin. Preventing the spread of these highly contagious infections is a matter of good hygiene. Recommended practices include regular handwashing with soup and water, covering one’s mouth and nose when coughing and sneezing, and the prompt disposal of used tissues. It is important not to share contaminated utensils, cups and glass, bed linen, or towels. Spread is more likely in crowded environments, such as schools and play areas, and it has been suggested that school closures during pandemic lockdowns may have reduced population-wide immunity by preventing the social mixing of children in communal locations.
Most often, the symptoms of Strep A infections are caused by the multiplication of bacteria in the skin and throat, followed by the release of bacterial toxins. Streptococcal infections of the throat (tonsillitis and pharyngitis) result in a sore throat, which is frequently accompanied by fever, pain on swallowing, red and swollen tonsils, and painful and swollen glands in the neck. At times, white or yellow spots, patches or streaks of pus may be noted to coat the tonsils. Viral throat infections, on the other hand, are more likely to be associated with a runny nose and a dry cough. It is often difficult to distinguish between Strep A infections, which require antibiotic treatment, and viral infections, which do not, unless a throat swab is taken for rapid antigen detection and further confirmation by bacterial culture in the laboratory. This may not always be practicable and explains why “empirical” prescribing of antibiotics, based on likely symptoms but without definite proof of Strep A infection, is being recommended, notwithstanding any concerns over increasing antibiotic resistance from over-prescription. Streptococcal infections of the skin may cause red, itchy sores that leak clear fluid or pus and form yellow crusts or scabs (impetigo), or areas of spreading redness, pain, and swelling, often accompanied by fever (cellulitis).
Group A streptococcal infections are usually mild and respond well to penicillin. On rare occasions, they may progress to either invasive Group A streptococcus (iGAS) infections or to scarlet fever. Invasive infections usually produce symptoms that are indistinguishable from other forms of bacterial sepsis, including persistently high temperatures, severe muscle aches, and unexplained diarrhoea and vomiting. Severe iGAS infections may also result in either necrotising fasciitis, commonly known as the “flesh-eating disease”, or streptococcal toxic shock syndrome.
Scarlet fever, once a common childhood illness, mostly affects children between the ages of 5 and 15. It is recognised by high fever, a sore throat, a “strawberry” (bright red, swollen, and bumpy) tongue, and a characteristic skin rash that appears pink or red on white skin and has a rough or sandpapery feel, which helps detect the rash on darker skins. The rash first appears on the neck, before spreading to the rest of the body. The area around the mouth may appear pale in contrast with the adjacent flushed cheeks. The rash typically blanches on finger pressure. Health professionals are required to notify all suspected cases of scarlet fever to their local health protection teams, to allow detection of clusters of cases and better manage community outbreaks.
Group A strep infections, invasive or otherwise, must be treated promptly to prevent serious complications such as rheumatic fever, which can cause permanent damage to the heart valves, or inflammation of the kidneys, which can affect kidney function. These complications are thankfully rare in the developed world today, because of ready access to, and widespread use of, penicillin treatment.
It is important to be aware of, and to then follow, all relevant public health guidance, as and when it becomes available. When Group A strep infection is suspected, medical attention must be sought without delay, either from one’s own GP, from the online 111 service, or by calling 999 or attending the emergency department when the situation seems suitably urgent. Reports of shortages of penicillin caused by supply chain problems must not dissuade people from seeking treatment where it seems indicated. On 15 December, serious shortage protocols were issued across the UK for three key penicillin used to treat Group A strep infections, allowing pharmacists to supply alternative forms of penicillin to keep up with demand as needed. Ending on a more positive note, unlike COVID we already know a lot about Group A streptococcus and the treatments available are almost uniformly effective. It is largely a matter of high vigilance, early detection, and timely treatment.
Ashis Banerjee