| Kawasaki disease is an uncommon (only about 3000 cases are diagnosed in the United States each year) inflammatory condition that usually (80% of the time) afflicts children younger than 5 years of age, and most commonly presents between the ages of one and two years. Its cause at this time is unknown, but it is presumed to be due to the body's response to a type of infection. The diagnosis is based on the presence of six clinical findings discussed below and at times can be very difficult to make, unless most or all of these findings are present.
The importance of making an early diagnosis (between 5-10 days from onset of fever) is to prevent later complications that may involve the arteries of the heart. Heart disease is the most serious sequelum of Kawasaki disease and causes aneurysms (bulging) in the small arteries around the heart, usually several weeks after the onset of fever. Untreated, it is one of the most common causes of heart attacks in children. Proper treatment (described below) reduces the risk of developing aneurysms to only 2-4% of children with Kawasakis.
Symptoms always include the presence of daily fever for at least 5 days or more, often up to 104F (40C). The fever may last from 10 to 25 days. The child may also have red eyes with minimal amount of discharge noted in the first few days of illness. In about 70% of cases, there will be swelling over the neck, representing enlargement of lymph nodes. A rash is usually (in about 80% of patients) present over the chest and abdomen and at times over the arms and legs. It is usually red, but no blistering should be present. Peeling of the skin may be noted around the diaper area. Similar peeling of the skin starting at the nail margins of the fingers and toes may be seen after the second week of illness. In 90% of cases, the lips will appear red, swollen and cracking in the first few days of illness. The tongue and throat may also appear more red. In the initial days, one may also notice swelling of the hands or feet followed by the peeling of the skin weeks later. These symptoms represent the acute phase, which is the first stage and lasts for the first few weeks of illness.
Other findings that may also be present, but are less specific, include extreme irritability (sometimes necessitating your physician to do a spinal tap to make sure your child does not have meningitis), hydrops of the gallbladder, sterile pyuria (white blood cells in the urine without an infection), aseptic meningitis, cough, watery diarrhea (up to 25% of patients), arthritis with joint pain and/or swelling (seen after the first week of illness), ear pain, myocarditis (inflammation of the heart), and pericarditis.
Blood tests done early in the course of disease will usually show signs of inflammation, represented by an increased ESR (erythrocyte sedimentation rate) or CRP (C Reactive protein) and white blood cell count. Other tests may find a mild anemia and platelet counts are usually very high by the second to third week of illness. EKG (electrocardiogram) is useful initially to rule out abnormalities of the heart.
Other disorders that may be difficult to distinguish from Kawasaki include: Steven Johnson Syndrome (an allergic type reaction), Scarlet Fever, and Toxic Shock syndrome.
Diagnosis of Kawasaki disease requires the presence of five of the six clinical findings discussed above, (fever, red eyes, red lips/throat, rash, swelling of hands/feet, lymph node enlargement in the neck) and blood tests that confirm the presence of inflammation. However, in many instances your child may not have all the symptoms required to make the diagnosis and may still have an atypical case of Kawasaki disease. Your physician may opt to wait several days with close supervision to see if other symptoms develop. Your child may also need more extensive tests done by a specialist, including evaluation by a Cardiologist, Pediatric Rheumatologist, Ophthalmologist or Infectious Disease specialist. It is important to try to diagnose with some certainty within ten days and start treatment to decrease the incidence of complications involving the heart.
Treatment is initiated as soon as the diagnosis is made. Your child will most likely be hospitalized and have an IV (intravenous line) placed. Intravenous Immunoglobulin (IVIG) is the treatment of choice and has been shown to dramatically decrease the incidence of heart problems (aneurysms) if given within ten days. IVIG is a blood product and thus its administration does have a risk of transmitting blood borne diseases (HIV, Hepatitis B/C virus). However, the risk is much smaller than the risk involved in acquiring these viruses form blood transfusions and the benefits of administering IVIG usually far outweigh the risk of infection transmitted by the product if the diagnosis is made with some certainty. In most cases, fever and other symptoms resolve within 24 hrs initiating IVIG. Your child may develop symptoms due to IVIG like headaches, decreased blood pressure, but these are usually transient. Some children will require more than one dose if symptoms persist.
Your child should be seen by a Cardiologist who will evaluate the condition of the heart with echocardiograms (ultrasound of the heart) on repeated occasions for several weeks to months depending on the severity of illness.
The next phase is the convalescent stage, in which symptoms have gone away. It continues until the ESR has returned to normal, usually about 6-8 weeks after the illness began. In addition to IVIG, your child will probably also be started on aspirin to decrease the inflammation in the body. The initial doses will be high for the first few weeks, and then decreased to a lower level , until the end of the convalescent stage. In children with coronary abnormalities (especially aneurysms), the dose will be continued for several months to years to prevent formation of clots in the damaged blood vessels. It is important that you discuss with your physician before stopping the aspirin, even if it has been several months and your child is doing well. You should also discuss with your physician what to do if your child develops a viral illness due to the risk of Reye Syndrome, and he should receive the influenza vaccine each year.
Most patients, if they do not develop the heart complications, recover completely without any long term effects. Children with heart aneurysms may also recover fully, depending on their severity. Overall, about 50% of aneurysms resolve in one to two years.
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