What is Kawasaki disease?
Kawasaki disease, also known as mucocutaneous lymph node syndrome, is an illness (usually in children) which causes fever, rash, swelling of the hands and feet, eye redness, swollen lymph glands in the neck and cracked red lips. It is an inflammatory illness involving almost the whole body with the exact cause still unknown.
The initial symptoms described above resolve over time – usually 10 to 14 days. However, in 15-20 percent of untreated patients, there is inflammation of the heart and especially, the coronary arteries. This develops a bit later, from 1-6 weeks after the initial symptoms. The inflammation of the heart muscles, valves and lining outside the heart usually resolve, but the coronary artery inflammation may worsen. When inflammation of the coronary arteries occurs in this disease, the coronary arteries enlarge or swell and form what is called an aneurysm (blowing up like a balloon). Very rarely, the coronary artery aneurysms can rupture which is fatal. More commonly, the aneurysms do not rupture but may worsen over weeks. Then, over months to years, the aneurysms become smaller or disappear, stay the same, or form blood clots which obstruct the flow of blood in the coronary arteries causing a heart attack. Small aneurysms which resolve may not cause any problems, though it is unclear if problems will occur later in life. Larger aneurysms, even if they resolve, may still result in an abnormal coronary artery. Therefore, most patients with the diagnosis of Kawasaki disease are followed by a pediatric cardiologist indefinitely, even if not frequently.
Who gets Kawasaki disease?
Kawasaki disease usually occurs in children under 5 years old, with an average age of 2. It is more common in Japan and in Asian-Americans, but can occur in any racial or ethnic group. It is not contagious as far as we know, but because it can occur in outbreaks (usually in the late winter or spring), some sort of infectious agent or germ (such as a virus or bacteria) is still suspected to somehow cause this disease. It is rare for more than one child in a family to get the disease and it is very rare for a child to get the disease again.
What are the signs and symptoms of Kawasaki disease?
Fever and irritability are usually the first signs of the disease. The fever is usually high (up to 104 degrees). The glands in the neck may become swollen. A rash usually appears on the back, chest and abdomen early in the disease and may occur in the diaper area or groin in infants and young children. The rash is usually red and may look different from one patient to another. The eyes are red (bloodshot) with no pus draining from them. The tongue may be coated and swollen with the surface resembling a strawberry (strawberry tongue). The lips may become red, dry and cracked. The palms of the hands and soles of the feet may become red and the fingers and toes may become swollen. Sometimes a stiff neck, abdominal pain or joint pain may develop. These findings are all the early signs and symptoms of Kawasaki disease, but are very similar to other diseases such as Measles, Scarlet fever, Staphylococcal infections, allergic reactions and others. Therefore, it is important that a doctor see a child with these symptoms.
The initial symptoms such as fever, rash, and gland swelling subside after 10-14 days, and peeling of the skin around the toenails and fingernails may occur. This is painless, and usually occurs during the second or third week of the illness. The peeling may spread to the hand and feet and the skin may come off in large pieces. This is not harmful. The joint swelling and abdominal pain resolve as well. During this stage of the illness, the coronary artery aneurysms occur. Over the next weeks (up to about six weeks), the illness continues to resolve.
How is the diagnosis made?
The diagnosis of Kawasaki disease is made by a doctor taking a history and performing a physical examination which shows the signs and symptoms mentioned above. Other diseases mentioned are considered when making the diagnosis. Although there are a few lab tests (like blood and urine samples) to help make the diagnosis, there is no one test to absolutely make the diagnosis. Special tests of the heart – an ultrasound or echocardiogram – are used to make pictures of the heart and see if there is any evidence to suggest inflammation. In addition, the coronary arteries are examined to see if they are enlarged. Frequently, the echocardiogram is normal in the early part of the disease so that it cannot be used to help make the diagnosis.
Is treatment available?
Once the diagnosis is established or reasonably certain, the standard of care is to give an intravenous medication called gammglobulin (IVIG). This is a bunch of special proteins (antibodies) obtained from blood which have been separated out, cleaned and purified to minimize the risk of infection. If given early in the disease, it has been shown to greatly reduce the risk of developing coronary artery aneurysms (from 15% without treatment, to less than 2% with IVIG). In addition, aspirin (an anti-inflammatory) is also given. In the past, steroids (anti-inflammatory drugs) have also been used.
Is there any way to prevent it?
We still do not know the cause, so we do not know how to prevent it.
What is the long-term outlook?
In patients who have had no coronary artery abnormalities, the outlook is excellent. Most of these children recover completely and lead normal lives with no restrictions. They may not even require any follow-up with a pediatric cardiologist. Children who have developed coronary artery abnormalities require ongoing follow-up with a pediatric cardiologist although there may not necessarily be a restriction in life styles. This is individualized and varies depending on the type of and severity of cardiac involvement of the disease. Ongoing tests such as echocardiograms, stress tests, and cardiac catheterization may be required. Some children do indeed have serious abnormalities of their coronary arteries and may need to be restricted from certain types of activity. Your pediatric cardiologist will be able to provide this information for you.
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