Invasive streptococci researchers: This is how a dangerous disease spreads

Group A streptococcal infections are increasing in Sweden and can lead to serious illnesses such as sepsis. Magnus Rasmussen, an infectious disease physician at Scania University Hospital and professor at Lund University, has been researching streptococci for 30 years. He sees similarities to outbreaks in previous seasons.

– We know a lot about the properties of bacteria themselves, but we still find it difficult to predict who will get seriously ill and who will not, says Magnus Rasmussen.

To get closer to answering this question, he is currently studying an invasive group A streptococcus outbreak last winter in Scania. It is almost always a specific type of invasive group A streptococcus, called emm type-1, that causes severe cases of the disease. But last winter it was joined by another bacteria, type 12. This year, the latter has been replaced by streptococci type 22.

Different types of streptococci have different characteristics that affect how they spread. I think these newcomers, emm-12 and 22, don't come back after one season of infection because people have time to develop immunity to them. But the common type, emm-1, may be so powerful that it can continue to spread year after year.

Vaccine development
Magnus Rasmussen hopes his research will lead to a better understanding of what is more important for the spread of infection – the properties of bacteria or the human immune system?

-This knowledge could be valuable in developing a vaccine against invasive streptococci. The vaccines being developed target specific types of the disease, but the most effective is a vaccine that covers all types.

Greater range
Although there are similarities to last year's outbreak, there is still a big difference: scale. In 2023, nearly 1,300 cases were reported in the country, compared to about 350 in 2022. The number of serious streptococcal infections has been low during the pandemic, and this is likely to have contributed to low immunity in the population, says Magnus Rasmussen. .

– Now is also the season for the spread of various winter viruses such as influenza, and this increases the risk of the spread of streptococcal infections.

Streptococcus can cause crib fever
He has another ongoing research project on Streptococcus, with his research group analyzing about a hundred cases in Skåne County of puerperal fever during the years 2014-2020, when a newly born woman develops, among other things, fever, chills and abdominal pain. In some cases, bed fever can lead to serious illness.

Here too, group A streptococcus is the culprit – and in many cases, the spread of infection has been between employees, who can be carriers of the disease without showing symptoms, and the patient. Preliminary results of the study show that there is often more than one infected patient in the same maternity ward.

– If the maternity ward has a patient suffering from puerperal fever, you should be on your toes. It is important to get to the bottom of existing bacteria, so that the spread of the infection can be stopped as quickly as possible.

Scientific publications:
On the immune system against streptococci in invasive infections.

A study on risk factors for serious illness in invasive streptococcal infections.

Summary of a study on an outbreak of puerperal fever in Scania.

Facts: Invasive group streptococci

• Group A Streptococcus is a bacteria that can cause strep throat, pigpox, and scarlet fever, among others. In rare cases, it can cause sepsis and other serious infections. You can also carry the bacteria without getting sick or showing any symptoms.
• Signs of serious illness are, for example, general malaise, high temperature, decreased consciousness, difficulty taking fluids, severe redness of the skin or confusion. In this case, it is important to seek care quickly.
• Streptococcus is spread through direct person-to-person contact, or indirectly via objects or through droplet infection, for example when someone sneezes. Good hand hygiene is important, and staying home when you are sick to avoid infecting others.

  Source: 1177.se

For more information please contact:
Magnus Rasmussen, infection specialist at Skane University Hospital and professor at Lund University. [email protected], tel. 046-17 70 47