Understanding the causes of Kawasaki disease remains one of the most complex and elusive areas of modern paediatric medicine.
Even though Kawasaki disease is well-known as an inflammatory illness, its exact cause is still unknown. What we do know is that several factors likely play a role. These include genes, infections, environmental triggers, and immune system responses. Because of this, it’s hard to find a single cause. Still, ongoing research continues to explore the most likely sources of this serious childhood condition.
Doctors have searched for answers since Dr Tomisaku Kawasaki first described the illness in 1967. Over the years, many studies have suggested that the disease may result from an abnormal immune reaction. This response likely starts after a common infection or exposure to something in the environment, especially in children who are more vulnerable due to their genetics.
1. Infectious Triggers: The Leading Theory
One of the strongest theories is that an unknown infection may trigger the disease. This is because many signs of Kawasaki disease are similar to common infections—like fever, swollen glands, and skin rashes.
Also, more cases happen in winter and early spring. This seasonal pattern makes infection a likely cause.
Experts have studied several possible germs:
- Viruses: Epstein-Barr virus (EBV), adenovirus, cytomegalovirus (CMV), and enteroviruses are all under review. These viruses can cause similar symptoms and may trigger the immune system.
- Bacteria: Some bacteria, like Staphylococcus aureus and Streptococcus pyogenes, make substances that overstimulate the immune system. These may also be involved.
So far, no single virus or bacteria has been found in all cases. But many researchers believe a common, harmless germ may cause an extreme immune reaction in children with a genetic risk.
2. Genetic Susceptibility
Genetics also play an important role. Kawasaki disease is more common in children from East Asian backgrounds, especially Japanese, Korean, and Chinese families—even if they live in other countries.
Certain genes may make a child more likely to get the disease. These include:
- ITPKC: A gene that helps control immune cell activity. Some versions of this gene may lead to more inflammation and heart problems.
- CASP3: A gene that helps control how immune cells die. Changes in this gene might affect how the immune system works.
- FCGR2A: This gene helps the immune system respond to infections. Some variations may lead to a stronger or longer immune reaction.
However, having these genes alone is not enough. The child still needs to be exposed to something—like an infection or environmental trigger—to develop Kawasaki disease.
3. Immune System Overreaction
Kawasaki disease causes strong inflammation in many parts of the body. Blood vessels, especially the ones around the heart, are often affected. If not treated, this can cause serious heart problems.
During the illness, the body’s immune cells become overactive. These cells release substances called cytokines, such as IL-6, TNF-alpha, and IL-1 beta. These chemicals cause the inflammation that leads to tissue damage.
While the trigger might be an infection, the immune system reacts much more than it should. That’s why many experts see Kawasaki disease as a temporary autoimmune condition—where the body attacks itself.
Thankfully, this immune reaction usually settles after treatment with IVIG (intravenous immunoglobulin). Most children’s immune systems go back to normal within a few weeks.
4. Environmental Factors
Some researchers believe the environment may also play a part in Kawasaki disease. Although the evidence is still weak, several possible triggers have been suggested:
- Air pollution: Breathing in tiny harmful particles may raise inflammation in some children.
- Weather: More cases happen during colder months or low humidity, which may be linked.
- Allergens: Things like dust or pollen may play a role in sensitive children.
- Toxins: Chemicals in food or water might also trigger the immune system.
On their own, these triggers are not enough to cause the disease. But when combined with genetic risk and other factors, they may help start the immune response.
5. Perinatal and Maternal Factors
Some studies suggest that events during pregnancy might affect a child’s risk later on. Possible factors include:
- Mothers with autoimmune conditions
- Infections during pregnancy
- Smoking or toxin exposure
- Poor nutrition before birth
These may affect how the baby’s immune system develops. If the immune system becomes too reactive, it could later respond too strongly to common infections or allergens. This may partly explain why some children get Kawasaki disease while others do not.
6. Vaccines and Kawasaki Disease
Some people worry that vaccines may cause Kawasaki disease. However, many studies show no proven link.
Children with Kawasaki disease are still advised to get all regular vaccines. The protection they offer far outweighs any small or rare side effects.
Sometimes, a child may get Kawasaki-like symptoms shortly after a vaccine. But this is a coincidence, not a cause. The reaction seen in Kawasaki disease is much stronger than what vaccines trigger.
Final Thoughts
The causes of Kawasaki disease are still unclear. But current evidence points to a mix of genetics, environmental exposure, and an immune overreaction to a common infection.
We haven’t found a single cause, which makes prevention difficult. Still, new discoveries about genes and immune system behaviour are helping doctors find the disease faster and treat it more effectively.
More research is needed to fully understand the causes of Kawasaki disease. Learning why some children get it—and others don’t—may lead to better treatments and even prevention in the future.
