What is Kawasaki disease?
Kawasaki disease which is also called mucocutaneous lymph node syndrome and infantile polyarteritis nodosa is the leading cause of acquired heart disease in children in the United States and Japan. This disease predominantly affects infants and young children. It is a self limiting disease of unknown cause which presents with fever, skin rash and lymph node enlargement. Though most of the children recover from the illness without any serious complication, in a few children the disease affects the arteries of the heart causing serious complications.
Kawasaki disease is an acute self limiting febrile illness involving arteries in infants and young children. This disease is characterized by inflammation of small and medium sized arteries throughout the body. The most significant arteries that are involved are the coronary arteries which are the arteries supplying blood to the heart muscle. Involvement of carotid arteries leads to abnormal dilatation of the arteries (aneurysm) and myocardial infarction.
Kawasaki disease is more common in children. More than three fourth of those who are affected by this disease are under 5 years of age. Boys are more affected than girls. Kawasaki disease was first described in 1967 in Japan. It has overtaken acute rheumatic fever as the leading cause of acquired heart disease in the United States and Japan. But it can affect all ethnic groups. About 3000 cases of Kawasaki disease are diagnosed in the United States every year. In the United States, Kawasaki disease is more common during the winter and early spring months.
Though Kawasaki disease is a self limiting condition it can recur in about 3% of the children. Even though it commonly affects children younger than 5 years of age, it has now been increasing diagnosed in older children and adolescents. Less than 1% of those who are affected by Kawasaki disease die due to complications.
What causes Kawasaki disease?
Kawasaki disease causes inflammation of the arteries (vasculitis). The cause of this disease is not known. The clinical features and the self limiting nature of this condition indicate that it could be due to an infection. But no specific organism has been proved yet to be causing this disease. The increased prevalence of this disease in Asian population especially the Japanese has led to the theory that Kawasaki disease could be a genetically mediated disease. Now it has been proposed that Kawasaki disease could be due to infection in genetically predisposed individuals.
Kawasaki disease symptoms in children
Kawasaki disease symptoms in children occur in three phases. The three phases of Kawasaki disease are:
- Acute phase which lasts for the first 10 days
- Sub acute phase which lasts from the 11th to 25th day
- Convalescent phase which lasts from the 25th day till the blood test including platelet count return to normal.
Kawasaki disease symptoms during acute phase:
- Abrupt onset of high fever – The temperature is usually more than 39 degree Celsius. With treatment the fever lasts for about 2 days. Without treatment it lasts for about 10 days.
- Conjunctivitis – Both the eyes are involved. But unlike other common causes of conjunctivitis, there will be no discharge from the eyes.
- Redness, dryness, fissuring, peeling, cracking, and bleeding of the lips
- Red swollen tongue ( “strawberry tongue”)
- Redness of the inner lining ( mucosa) of the oral cavity
- Redness and swelling of palms and soles
- Rashes on the trunk, extremities and genitals
- Lymph node enlargement on one side of the neck
Kawasaki disease symptoms during sub acute phase:
- Peeling of skin around nails
- Disappearance of fever, rash and enlarged lymph node
- Increased platelet count in the blood
- Weakening and bulging of the coronary arteries in about 20% of the affected patients ( aneurysm of coronary arteries)
- Collection of fluid around the heart ( pericardial effusion), heart failure and myocardial infarction
Kawasaki disease symptoms during convalescent phase:
- Platelet count and erythrocyte sedimentation rate return to normal
- Deep transverse grooves appear on the fingernails or toenails
Diagnosis of Kawasaki disease
There are a few other diseases like measles, Rocky Mountain spotted fever, juvenile rheumatoid arthritis, drug reaction and scarlet fever which may mimic Kawasaki disease. The diagnosis of Kawasaki disease can be done based on the clinical features alone. The diagnostic criteria for Kawasaki disease include the following:
- Fever lasting for 5 days or more along with at least 4 of the following 5 principal features
- Principal features
- Redness of both eyes without discharge
- Oral cavity changes which include redness and cracking of lips, redness of the oral mucosa and strawberry tongue
- Rash mainly on the trunk
- Redness and swelling of palms and soles during acute phase and peeling of skin around nails during the sub acute phase
- Enlarged lymph node of at least 1.5 cm in size on one side of the neck
If in addition to fever, less than 4 principal features are found, then Kawasaki disease can be diagnosed if abnormalities of the coronary arteries can be detected with echo or angiography tests.
Laboratory tests may reveal the following:
During acute phase
- High white blood cell count
- High C reactive protein and erythrocyte sedimentation rate
During sub-acute phase
- Increased platelet count
- High C reactive protein and erythrocyte sedimentation rate
During convalescent phase
- Platelet count returns to normal
Echo during the second week may show aneurysm of the coronary arteries. Angiogram may also show the aneurysm. Chest x-ray may show signs of heart failure. Patients affected by Kawasaki disease may suffer from myocardial infarction and electrocardiogram may be done to diagnose it. Electrocardiogram may also help to detect rhythm abnormalities of heart.
Kawasaki disease treatment in children
Since Kawasaki disease can cause serious complications, the initial treatment should be given in the hospital. Kawasaki treatment in children should be started early to prevent complications. Symptoms will disappear within 2 days if the treatment early. If Kawasaki disease treatment is started within 10 days, it will prevent the complications involving the coronary arteries. Even without treatment symptoms will disappear in about 2 weeks; but heart complications may occur later
The treatment of Kawasaki disease in children include:
- Intravenous gamma globulin reduces the risk of getting coronary artery aneurysm
- High dose aspirin for variable time to control fever, rash and joint pain followed by low dose aspirin for 6-8 weeks or even longer to prevent complications involving the heart. Aspirin should be stopped if the child develops flu or chickenpox.
If the complications involving the coronary arteries have developed, evaluation and treatment is done by pediatric cardiologist and the following treatment is given.
- Anticoagulant medications like aspirin, warfarin and heparin to prevent clotting
- Coronary artery angioplasty to open narrowed coronary arteries and allow blood to flow through it
- Stent placement to allow blood to flow through blocked coronary arteries
- Coronary artery bypass graft to replace the narrowed segment of coronary arteries with section of blood vessel taken from arm, leg or chest.