What Is Kawasaki Disease?
Kawasaki disease also known as mucocutaneous lymph node syndrome or Kawasaki syndrome is a disease that causes blood vessels to become inflamed. It is common children under 5 years and is one of the leading causes of heart disease in kids.
It is an acute febrile illness of unknown cause. The disease was first described in Japan by Tomisaku Kawasaki in 1967, and the first cases outside of Japan were reported in Hawaii in 1976. Clinical signs include fever, rash, swelling of the hands and feet, irritation and redness of the whites of the eyes, swollen lymph glands in the neck, and irritation and inflammation of the mouth, lips, and throat.
The disease affects boys more than girls, with people of Asian ethnicity, particularly Japanese and Korean people, most susceptible, as well as people of Afro-Caribbean ethnicity. The higher incidence in Asian populations is thought to be linked to genetic susceptibility. Incidence rates vary between countries.
Currently, Kawasaki syndrome is the most commonly diagnosed pediatric vasculitis in the world. By far, the highest incidence of Kawasaki disease occurs in Japan, with the most recent study placing the attack rate at 218.6 per 100,000 children less than five years of age (about one in 450 children). At this present attack rate, more than one in 150 children in Japan will develop Kawasaki syndrome during their lifetimes.
However, its incidence in the United States is increasing. About 2,000-4,000 cases are identified in the U.S. each year (9 to 19 per 100,000 children younger than five years of age). In the continental United States, Kawasaki disease is more common during the winter and early spring, boys with the disease outnumber girls by ≈1.5–1.7:1, and 76% of affected children are less than years of age.
In the United Kingdom, prior to 2000, it was diagnosed in fewer than one in every 25,000 people per year. Incidence of the disease doubled from 1991 to 2000, however, with four cases per 100,000 children in 1991 compared with a rise of eight cases per 100,000 in 2000. By 2017, this figure had risen to 12 in 100,000 people with 419 diagnosed cases of Kawasaki disease in the United Kingdom.
In Japan, the rate is 240 in every 100,000 people.
The disease was first reported by Tomisaku Kawasaki in a four-year-old child with a rash and fever at the Red Cross Hospital in Tokyo in January 1961, and he later published a report on 50 similar cases. Later, Kawasaki and colleagues were persuaded of definite cardiac involvement when they studied and reported 23 cases, of which 11 (48%) patients had abnormalities detected by an electrocardiogram. In 1974, the first description of this disorder was published in the English-language literature. In 1976 it was described in 16 children in Hawaii.
Kawasaki disease is now recognized worldwide. Why cases began to emerge across all continents around the 1960s and 1970s (possible explanations could include confusion with other diseases such as scarlet fever, and easier recognition stemming from modern healthcare factors such as the widespread use of antibiotics) is unclear. In the United States and other developed nations, Kawasaki disease appears to have replaced acute rheumatic fever as the most common cause of acquired heart disease in children.
Since April 2020, a slight increase in childhood illnesses similar to the Kawasaki syndrome has been observed in the USA and some European countries; the WHO is examining a possible link with SARS-CoV-2 infections.
Kawasaki disease causes
Scientists haven’t found an exact cause for Kawasaki disease. It might be linked to genes, viruses, bacteria, and other things in the world around a child, such as chemicals and irritants.
The disease probably isn’t contagious, but it sometimes happens in clusters in a community. Kids are more likely to get it in the winter and spring.
Three things are known to increase the risk of developing Kawasaki disease in children.
- Age: Children under 5 years old are most at risk of Kawasaki disease.
- Sex: Boys are slightly more likely than girls are to develop Kawasaki disease.
- Ethnicity: Children of Asian or Pacific Island descent, such as Japanese or Korean, have higher rates of Kawasaki disease.
Kawasaki Disease Symptoms
Kawasaki disease comes on fast, and symptoms develop in 3 phases over a 6-week period.
Phase 1 – Acute phase (Weeks 1 to 2)
Symptoms will appear suddenly and may be severe and very irritable. Signs you will see are:
- High fever (Above 101 F) that lasts more than 5 days. This symptom will not go down even if a child takes medication that usually works on fever.
- Rash and/or peeling skin. This occurs often between the chest and legs and in the genital or groin area
- Swelling and redness in hands and bottoms of feet
- Red eyes
- Swollen glands, especially in the neck
- Irritated throat, mouth, and lips
- Swollen, bright red “strawberry tongue”
Phase 2: Sub-acute (Weeks 2 to 4)
During the sub-acute phase, your child’s symptoms will become less severe, but may last a while. The fever should subside, but your child may still be irritable and in considerable pain.
In the second phase, symptoms include:
- Joint pain
- Belly pain
- Stomach trouble, such as diarrhea and vomiting
- Peeling skin on hands and feet
Phase 3: Convalescent phase (weeks 4 to 6)
Your child will begin to recover during the third phase of Kawasaki disease, which is known as the convalescent phase.
Your child’s symptoms should begin to improve and all signs of the illness should eventually disappear.
But your child may still have a lack of energy and become easily tired during this time.
Kawasaki Disease Diagnosis
Kawasaki disease can be diagnosed only clinically. No specific laboratory test exists for this condition. Establishing the diagnosis is difficult, especially early in the course of the illness, and frequently children are not diagnosed until they have seen several health-care providers. Many other serious illnesses can cause similar symptoms, and must be considered in the differential diagnosis, including scarlet fever, toxic shock syndrome, juvenile idiopathic arthritis, and childhood mercury poisoning (infantile acrodynia).
Classically, five days of fever plus four of five diagnostic criteria must be met to establish the diagnosis. The criteria are:
- Erythema of the lips or oral cavity or cracking of the lips
- Rash on the trunk
- Swelling or erythema of the hands or feet
- Red eyes (conjunctival injection)
- Swollen lymph node in the neck of at least 15 mm
Many children, especially infants, eventually diagnosed with Kawasaki disease, do not exhibit all of the above criteria. In fact, many experts now recommend treating for Kawasaki disease even if only three days of fever have passed and at least three diagnostic criteria are present, especially if other tests reveal abnormalities consistent with Kawasaki disease. In addition, the diagnosis can be made purely by the detection of coronary artery aneurysms in the proper clinical setting.
Kawasaki Disease Treatment
To reduce the risk of complications treatment for Kawasaki disease should be done as early as possible, preferably while the child still has a fever. The goals of initial treatment are to lower fever and inflammation and prevent heart damage.
Treatment for Kawasaki disease may include:
Gamma globulin: Infusion of an immune protein (gamma globulin) through a vein (intravenously) can lower the risk of coronary artery problems.
Aspirin: High doses of aspirin may help treat inflammation. Aspirin can also decrease pain and joint inflammation, as well as reduce the fever.
Because of the risk of serious complications, initial treatment for Kawasaki disease usually is given in a hospital.
Once the fever goes down, the child may need to take low-dose aspirin for at least six weeks and longer if he or she develops a coronary artery aneurysm. Aspirin helps prevent clotting.
However, if the child develops flu or chickenpox during treatment, he or she may need to stop taking aspirin.
With treatment, the child may start to improve soon after the first gamma globulin treatment. Without treatment, Kawasaki disease lasts an average of 12 days and heart complications may be longer lasting.
Complications of Kawasaki disease
Kawasaki disease causes the blood vessels to become inflamed and swollen, which can lead to complications in the blood vessels that supply blood to the heart (coronary arteries).
Around 25% of children with Kawasaki disease experience complications with their heart.
If the condition goes untreated, complications can be fatal in about 2 to 3% of cases.
Because of this, the condition has become the leading cause of acquired heart disease (Heart disease that develops after birth) in the UK.
However, with effective treatment, only a few children have lasting damage.
Heart complications include:
- Inflammation of blood vessels, usually the coronary arteries, that supply blood to the heart
- Inflammation of the heart muscle
- Heart valve problems
Any of these complications can damage the child’s heart. Inflammation of the coronary arteries can lead to weakening and bulging of the artery wall (aneurysm). Aneurysms increase the risk of blood clots, which could lead to a heart attack or cause life-threatening internal bleeding.
For a very small percentage of children who develop coronary artery problems, Kawasaki disease can cause death, even with treatment.