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Changes at Bacille Calmette-Guerin inoculation site may signal Kawasaki disease
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The appearance of redness or crust formation at the Bacille Calmette-Guerin inoculation site may be a useful diagnostic marker of Kawasaki disease in children aged 3 to 20 months, according to recently published data.
Researchers in Japan investigated epidemiologic factors of Kawasaki disease among 15,524 patients who participated in a 2007 Japanese nationwide epidemiologic survey on Kawasaki disease.
Redness or crust formation appeared at the inoculation site for 7,745 patients. More than 70% of complete cases of Kawasaki disease, or those patients presenting with five or six principal signs, presented with redness or crust formation at the vaccine inoculation site. Patients whose first day of hospital visit was within one to four days of onset were more likely to present with redness and crust formation at the site than those patients whose first hospital day was within five to nine days or 10 or more days of onset (P<.001).
To evaluate the specificity of the sign in Kawasaki disease diagnosis, the researchers also observed patients aged 2 years or younger who were diagnosed with respiratory syncytial virus or rotavirus infection through a commercial rapid test and required hospitalization.
None of these patients had redness or crust formation at their vaccine inoculation sites.
Uehara R. Pediatr Infect Dis J. 2010;29(5):430-433.
This study is from the very active Kawasaki disease epidemiology group in Japan (Yanagawa, Nakamura, Uehara et al.) that has carried out national surveys of Kawasaki disease every two years since 1970. In Japan, well over 90% of infants receive BCG immunization by age 6 months, and Japanese pediatricians have known for years that redness and crusting at the former BCG site is very common when a child develops Kawasaki disease. Dr. Uehara and colleagues used data from the 19th nationwide Kawasaki disease survey in Japan that included cases in 2005 and 2006 to define the proportion of children with Kawasaki disease at various ages who developed BCG site changes. Overall, almost exactly half of patients WITH Kawasaki disease showed redness and crusting at the former BCG site, including more than 70% of those aged 3 to 20 months old with typical Kawasaki disease. The age-specific proportion of patients with Kawasaki disease and with BCG site changes peaked at 90% for those aged 6 to 8 months old, and fell to about 75% at 15 to 17 months old, to 45% at 24 to 29 months old, to 18% at 36 to 41 months old, and to 5% to 10% at 42 months and older. There was little correlation with coronary abnormality rates and BCG reactions among patients WITH Kawasaki disease. Control groups of children with respiratory syncytial virus or rotavirus infection showed no such reaction.
The BCG reaction serves as another clue to the diagnosis of Kawasaki disease, which is sometimes very difficult to establish because of the lack of a specific diagnostic test. Personally, we have been able to diagnose Kawasaki disease in a child who had redness and crusting at a BCG site on two occasions: one patient who had moved recently from Japan to Chicago and one who was recently adopted from Central America out of 1,800 cases seen at our hospital in Chicago. However, this is a very helpful clinical feature in those countries that routinely use BCG immunization, providing one more strong diagnostic clue in the febrile child with some features suggesting Kawasaki disease and can help with diagnosis of incomplete (atypical) Kawasaki disease. The pathogenesis of BCG site reaction is not clear, but some have proposed that heat shock proteins may be involved. Unfortunately, US pediatricians only rarely will benefit from this interesting clinical feature that is so common in Japan because so few of US children have received BCG.
– Stanford T. Shulman, MD
Infectious Diseases in Children Editorial Board