Aims Kawasaki disease is an uncommon cause of fever in a young infant (less than 6 months) and is associated with life-threatening complications. Cytomegalovirus has been linked with atherosclerosis of coronary arteries in some adult studies. Acute Cytomegalovirus infection has been detected in a few reported cases of Kawasaki disease in infants.

Methods A retrospective case review was done of a 3 month old Asian infant, who presented to a district general hospital, with a 3 day history of fever and irritability. She was treated with intravenous antibiotics for presumed sepsis. The fever persisted after 5 days and she was transferred to a tertiary hospital for further investigations into the cause of fever.

Results Cytomegalovirus DNA was detected by polymerase chain reaction (PCR) in the infant’s blood. Cytomegalovirus IgM was not detected. ECG and echocardiogram were not performed due to lack of clinical evidence of underlying cardiac cause at the time. The fever was settling and infection markers were improving. The infant looked to be improving, according to the parents. The infant became acutely unwell, arrested and passed away on day 13 of illness.

At post-mortem, multiple thrombosed giant aneurysms (up to 17mm) of the coronary arteries were found. There were multiple saccular coronary artery aneurysms affecting the right coronary (11 × 17mm), left descending coronary artery, left diagonal artery, left circumflex and the right posterior descending artery. The pericardial cavity contained 70mls of blood. There was moderate to severe coronary artery arteritis. The cause of death was cardiac tamponade secondary to rupture of a coronary artery aneurysm, caused by Kawasaki disease. Cytomegalovirus DNA was detected in liver and lung tissue.

Conclusion Kawasaki disease is an uncommon but important differential in a young infant with fever and requires prompt treatment with immunoglobulins and Aspirin. If echocardiography is not available, an ECG may provide useful information such as ST segment changes and Q waves. The presence of Cytomegalovirus DNA on blood PCR raises the possibility of Kawasaki disease and a positive result may be helpful additional information in the diagnosis of Kawasaki disease.