Abstract
Purpose An outbreak of adult measles occurring in the eastern part of Ehime prefecture in Japan was analyzed, and the future directions of measures against infectious diseases in public health centers was studied.
Method An outbreak of adult measles (in individuals more than 18 years old) occurred in the eastern part of Ehime prefecture between October 2002 and July 2003. During this outbreak, provisional surveillance of adult measles as well as pediatric measles (less than 18 years old) was performed by all clinics and hospitals in addition to that by The Ehime Epidemiological Surveillance of Infectious Diseases (sentinel surveillance). Furthermore, identification of viral genes was performed from pediatric and adult measles patient samples.
Results 112 cases of measles in adults and 200 cases in children were reported in Ehime between October 2002 and July 2003, and the rates for the eastern part of the prefecture accounted for 89.7% and 94.1% respectively. The relation between the pediatric measles and adult measles could be followed by change in the outbreak number of patients week by week. The genotype of the measles viruses isolated was type H1, which is prevalent in China and Korea. The results of an epidemiological survey showed that 59.3% of adult and 84.1% of pediatric cases had not been vaccinated. The measles vaccination rates for adult and pediatric cases were 21.9% and 11.4%, respectively. While the number of measles cases detected by sentinel pediatric surveillance comprised 32.0% of the measles cases reported by all pediatricians, the figure for adult measles cases was only 11.6% of those reported by all clinics and hospitals.
Conclusions It was suggested that improvement in the vaccination rates and revaccination rates mainly among school children or young people is necessary to prevent measles outbreaks. The surveillance system must be strengthened to increase the number of sentinel hospitals because an outbreak may not be detected with the current approach, especially for measles among adults. Positive information exchange between public health centers and medical institutions also appear to be particularly important.
