No definite cause for Kawasaki disease

Some pediatric diseases are obvious from day one, while others take a while to declare themselves. My little patient came to the office with a history of two days of high fever, thick yellow-green nasal drainage and a cough. He was alert, and during the exam I found a left serous otitis (fluid behind one ear drum) and decreased breath sounds on the right side without any respiratory distress.

I placed the child on oral antibiotics for his clinical pneumonia, and as always, instructed the parents to call if the child wasn't improving or if they had any concerns. Three days later the trio was back in the office, and while the parents reported that the boy had improved as far as the nasal congestion and cough were concerned, his high fevers persisted.

The child had unusually dry lips, red, swollen fingers and a rash that had started on the torso and was now spreading to the extremities. An enlarged neck node was big enough to cause a noticeable head tilt, and while the whites of the toddler's eyes were red, they lacked the thick gooey discharge that typically accompanies a case of pink eye.

The boy's prolonged fever and evolving collection of physical features pointed to a new diagnosis. After contacting the emergency room at the city children's hospital, I sent the child in for further evaluation and treatment by the pediatric infectious disease service.

The boy was suffering from Kawasaki disease, a vasculitis or inflammation of the blood vessels. KD is well-studied and treatable, but though researchers feel an infectious agent is the likely culprit, Kawasaki disease still lacks a defined cause.

Unlike common pediatric infectious diseases, KD is not diagnosed by a throat swab or a positive blood culture, but by putting together classic historical, physical and laboratory findings.

Kawasaki disease is diagnosed when a child has a fever for at least five days, and presents with at least four of five other physical findings: redness of the whites of both eyes without drainage; red throat, strawberry tongue or cracked lips; swelling, redness or peeling of the hands and feet; swollen glands in the neck; and body rash. No single laboratory test defines KD, but markedly elevated inflammatory markers are commonly seen in children with the disease.

In an article in The Permanente Journal, physicians Janelle Cox and Robert Sallis report that each year Kawasaki disease affects about 18 out of 100,000 American children. Ninety percent of KD patients are younger than 5 with the disease affecting boys more often than girls. Kawasaki cases tend to occur most often in winter and spring, and the disease incidence is found to be highest among children of Asian descent, hinting at a genetic component.

As a vasculitis, KD can cause inflammation of medium-sized blood vessels such as the coronary arteries. Some children develop coronary aneurysms, and Cox and Sallis note that Kawasaki disease is the No. 1 cause of acquired childhood heart disease in the United States. The authors caution that accurate diagnosis and prompt treatment are important since up to 25 percent of untreated children develop cardiac complications. That number drops to a relatively low 4 percent in treated patients.

Treatment of Kawasaki disease includes the use of anti-inflammatory intravenous immunoglobulin and high-dose aspirin. Pediatric patients also undergo echocardiograms soon after diagnosis and periodically after treatment to evaluate for any cardiac complications.

• Dr. Helen Minciotti is a mother of five and a pediatrician with a practice in Schaumburg. She formerly chaired the Department of Pediatrics at Northwest Community Hospital in Arlington Heights.