Research into Long-Term Symptoms Following Infections
Have you experienced persistent symptoms after Lyme disease, Q fever, sepsis, or COVID? For example, severe fatigue, pain, dizziness, a racing heart, sleep problems, difficulty thinking, or worsening symptoms after exertion?
If so, you know how much these symptoms can affect your daily life. Yet it is often still unclear why some people recover fully, while others continue to experience symptoms, have relapses, or remain limited in what they can do.
Persistent symptoms following an infection are known as post-acute infection syndromes (PAIS). The symptoms associated with PAIS are very similar to those experienced by people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).
As part of the PAIS & ME studies, we are investigating what happens in the body when people experience persistent symptoms following an infection. We are looking for people with persistent symptoms after Lyme disease, Q fever, sepsis, or COVID. We are also looking for people who have recovered after an infection and people who have not developed persistent symptoms.
By taking part, you can contribute to the knowledge needed to better recognise and understand persistent symptoms following infections. This knowledge may help lead to better diagnosis and treatment.
What Are We Investigating in PAIS & ME?
Some people recover after an infection. Others continue to experience symptoms and remain limited in what they can do. We still do not fully understand why this happens.
That is why, within PAIS & ME, we are investigating what happens in the body. We are looking not only at which symptoms people experience, but also at the biological processes that may play a role in these symptoms.
These include the immune system, inflammation, metabolism, the nervous system, and hormonal regulatory systems. These processes can also influence one another. That is why we do not focus on a single measurement, but look at the bigger picture.
Study 1
Signals in the blood
The first study focuses on post-COVID in relation to ME/CFS and other PAIS, such as persistent symptoms following Lyme disease, Q fever, COVID, and sepsis.
In this study, we will measure more than 5,400 proteins in the blood. Proteins perform many different functions in the body. For example, they can provide information about inflammation, the immune system, metabolism, the nervous system, and recovery processes.
By measuring these proteins in different groups of participants, we are looking for patterns. For example, we will investigate whether certain patterns occur more often in people with persistent symptoms than in people who have recovered or in healthy people.
Because many people with different PAIS experience similar symptoms, such as post-exertional worsening, we will also investigate whether there are protein signals specifically associated with these types of symptoms. This approach links biological findings to symptoms, also known as symptom clusters, regardless of the underlying diagnosis. It is a promising approach for research into ME/CFS and PAIS.
In this way, the study may help us better understand which biological processes may play a role in persistent symptoms following infections.
Study 2
Symptoms, Disease Course, and Biological Signals
The second study focuses on ME/CFS and PAIS.
In this study, we will assess participants in several ways. We will look at their symptoms: which symptoms they experience, how severe they are, and how much they affect daily life.
We will also look at the course of the illness. When did the symptoms begin? How have they developed over time? Do they remain the same, improve, or change over time?
In addition, we will examine biological signals in the body. These include substances in the blood and other measurable indicators that may provide information about inflammation, the immune system, metabolism, and hormonal regulatory systems.
The aim is to bring symptoms, disease course, and biological signals together. This will help us better understand how ME/CFS and PAIS are similar, how they differ, and which biological processes may be associated with specific symptoms.
This may help us better understand why some people continue to experience symptoms or experience relapses after an infection.
Why Are Different Groups Compared?
Persistent symptoms following infections can be similar. However, this does not necessarily mean that the same processes are occurring in the body in everyone.
That is why PAIS & ME compares different groups of participants, including people with persistent symptoms following COVID, Lyme disease, Q fever, or sepsis. People who have recovered and people who have not developed persistent symptoms will also take part.
By comparing these groups, researchers can better identify what they have in common and how they differ. This can reveal patterns that may not be visible when looking at a single group alone.
What Does This Mean for the Future?
PAIS & ME is not a study that will directly lead to treatments or enable these conditions to be diagnosed. You will therefore not automatically receive individual results or medical advice.
The aim of the research is to build knowledge. This knowledge is needed to better recognise and understand persistent symptoms following infections. It may also help guide future research into diagnosis and treatment.
This is a step-by-step process. First, we need to better understand which processes in the body may play a role. Further research can then investigate what these findings could mean for patients and healthcare
We hope to show that ME/CFS and PAIS are not as different as they may appear. This could help us join forces and make a stronger case to scientists, healthcare professionals, and policymakers.