Trend of adenovirus type 7 infection, an emerging disease in Japan

The program of the National Epidemiological Surveillance of Infectious Dise ases under the auspices of the Ministry of Health and Welfare started in 19 81 apprehended in 1995 emergence of adenovirus type 7 in Japan. We analyzed the reported data of type 7 comparing with those of type 3, both belonging to the same subgenus B, and the following results were obtained: After 1981, the main serotypes in the reports of adenovirus isolation/detec tion were types 3, 2, and 1 in this order. The reports of isolation of aden ovirus type 7 used to be extremely few, however, suddenly increased in 1995 . In 1997, reports of isolation of adenovirus type 3 decreased and those of type 7 acquired the third place after those of types 2 and 3. Type 7 infec tion occur almost every month, but most frequently during May-September. Th e ages of cases from which type 7 was isolated were 0-4 years accounting fo r 55%, 5-9 years 35%, teens 6.3% and adults 4.0%, being similar proportions to those yielding type 3. Clinical diagnoses of cases yielding adenovirus type 7 were pharyngoconjunc tival fever (PCF) and influenza-like illness, these two accounting for half . The symptoms were severe, being characterized by higher maximum body temp erature during the feverish period and severe pneumonia. Encephalitis and a rthro-muscular pain were seen in only type 7-infected cases, although such cases were few.