Denmark: SSI Reports Sharp Rise In Strep A Infections

 

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For several months we've been watching the sharp rise in Strep A - primarily scarlet fever  - along with Invasive Group A Strep (aka iGAS) in the UK, the United States, and other parts of Europe (see partial list below). 

CDC HAN #0484: Increase in Pediatric Invasive Group A Streptococcal Infections

WHO Risk Assessment On Rise Of Strep A Infections In Europe & UKHSA Weekly Update

UK: Unseasonable & Robust Increase In Scarlet Fever/iGAS Cases

Scarlet fever is caused by the same bacteria that causes `strep throat’ - Streptococcus pyogenes - and is characterized by fever, a very sore throat, a whitish coating or sometimes `strawberry’ tongue, and a `scarlet rash’ that first appears on the neck and chest.

Once greatly feared and the cause of numerous epidemics, scarlet fever can today be  successfully treated by modern antibiotics and is usually a mild disease (although rare fatalities still occur). 

Far less common, albeit considerably more serious, is a related illness called iGAS (invasive Group A Strep), which indicates infection of the bloodstream, deep tissues, or lungs, and may result in severe (and frequently fatal) cases of necrotizing fasciitis and streptococcal toxic shock syndrome.

While this latest surge may be due to increased social contacts following the end of pandemic lockdowns, scarlet fever has been on the ascendant for more than a decade - first in Asia (see Hong Kong: Scarlet Fever In 2012) - and then about 8 years ago in the UK, reaching its peak in 2018 (see UK: `Exceptional' Scarlet Fever Season Continues) which was followed by a deadly outbreak of iGAS in Essex in 2019.

Bacteria can evolve over time creating more infectious, antibiotic resistant, or more  pathogenic strains. Strep A strains are identified by changes in their M-protein gene sequence (emm types) – and within these types new variants can emerge.

But as of of a month ago, the WHO reported:

In light of the moderate increase in cases of iGAS, GAS endemicity, no new emm gene sequence type identified and no reports of increased antibiotic resistance, WHO assesses that the risk for the general population posed by iGAS infections is low at present.

Yesterday, running a couple of months later than the US and UK, Denmark's SSI (Statens Serum Institut) reported their own surge in Strep A cases, releasing a detailed report and Risk Assessment.  The English language summary follows:

Sharp increase in the number of streptococcal infections

There is currently a sharp increase in cases with group A streptococci (GAS) in Denmark, including an increased incidence of invasive cases (iGAS), figures from the Statens Serum Institut show.

Last edited on January 20, 2023

Sore throat, scarlet fever and children's ulcers. More and more people in Denmark are currently being diagnosed with an infection with group A streptococci, and the increase has now reached a level that far exceeds the normal for the time of year.

At the same time, there has been a tripling of invasive cases (iGAS) in one month, which are cases where streptococci have spread and caused serious conditions, for example blood poisoning. In December, 68 cases were thus registered, but the number in November was 22.

This shows figures that the Statens Serum Institut (SSI) has drawn from the Danish microbiology database (MiBa).


"It is SSI's expectation that the number of positive cases may continue to rise for some time to come. Usually there are the most invasive cases in the months January to March, but there are also signs of many positive tests in January so far", says department head and department doctor Peter Henrik Andersen from SSI

 

Most severe cases are seen in older people over the age of 65, but there are also a smaller number of invasive cases detected in children under 5 years of age.

An increasing number of deaths are recorded within 30 days of detection of iGAS, but it is not proportionally more than usual. Abroad, there have been reports of cases among children that have had a fatal outcome, but SSI finds no evidence of increased mortality among children.

Rises throughout Europe

Group A streptococci are a common cause of infections, and most frequently cause diseases such as strep throat, otitis media, scarlet fever and canker sores. In certain cases, and especially in the elderly and people with poor immune systems, the infection can spread and cause serious conditions such as blood poisoning, meningitis and toxic shock syndrome.

The increase in the number of infections comes at the same time that since December there have been reports from other European countries about an increased incidence of infections with group A streptococci.

The fact that we in Denmark - and all over Europe - are seeing such a sharp increase right now may possibly be due to the bacterium making a comeback after being kept down under the covid-19 restrictions, says Peter Henrik Andersen from SSI.

"Infections with this type of bacteria have been at a lower level during the first long part of the corona pandemic. It seems that the increase that we have also seen for some other infections after society was opened up again is now also happening for group A streptococci”, he explains.

SSI has prepared a risk assessment

Based on the increased incidence, SSI has prepared a risk assessment, in which it is assessed that the probability of further spread of infection among children is very high, but that the consequence of this is very low, and that the risk to children of continued spread of infection is therefore assessed as low.

For the elderly, the probability of the spread of infection is moderate, the consequence of this will be moderate, and that the overall risk of continued spread of infection is therefore assessed as moderate.

"It is important that doctors pay attention. It is the invasive infections among the older part of the population that we are most worried about", says Steen Hofmann, head of the Department for Bacteria, Parasites & Fungi at SSI.

SSI will continue to follow developments closely, both in Denmark and internationally.

SSI has issued the newsletter EPI-NYT with a description of the situation and with advice from the relevant doctors. SSI will also create an outbreak page where data will be updated regularly.

Link to " Risk assessment - Group A streptococci in Denmark, 2023 " (pdf)