Until November 2001, eight vaccinations had been offered to Japanese children on a routine basis; namely, diphtheria-tetanus-pertussis, polio, measles, rubella, Japanese encephalitis, and BCG. The 2001 amendment of the Immunization Law introduced an influenza vaccine for the elderly population. This paper reviews the progress of the immunization program in the broader context of infectious disease control in Japan. There are two recent major policy changes in the field of infectious disease control in Japan. One is the strengthening and revitalization of the infectious disease control program, particularly surveillance, by the enactment of new 1999 legislation entitled “Law concerning the Prevention of Infectious Diseases and Patients with Infectious Diseases”. The other major policy change is a review of existing immunization programs and the amendment of the Immunization Law in 2001. In this article, the present routine vaccination program, as well as the recent amendments to the law, are described. Current policy issues are then discussed, including polio vaccination after the WHO “Zero Polio” announcement in the Western Pacific Region in 2000; strategies for changes in measles, rubella, tuberculosis, and influenza control; as well as adverse reaction monitoring/surveillance and feedback for improving vaccine safety. Finally, the future prospects of intended/planned changes in the vaccination policy are considered.

The success of global smallpox eradication in 1980 led all the nations of the world to discontinue smallpox vaccination. To date, however, the threat of deliberate release of smallpox virus has led health authorities to reconsider smallpox vaccination and at the same time, to urge to evaluate duration of the immunity of the population vaccinated before 1980. Although available data is scarce and incomplete, the study suggests that protective immunity lasts longer in a good percentage of vaccinees, although the real percentage and duration are not known. Accordingly, how to establish a national vaccination policy for preparedness in Japan and elsewhere was discussed. The study is intended to cause interest and debate among the medical and public health community.

Hepatitis B e antigen-positive human serum was treated with 50-90% ethanol at room temperature for 1-60 min, then the antigenicity of S antigen (hepatitis B surface antigen, in a narrow sense) was determined by radioimmunoassay and the antigenicities of pre-S1 and pre-S2 antigens were measured by enzyme immunoassay. In addition, hepatitis B virus (HBV) DNA in the treated serum was detected by polymerase chain reaction. All antigenicities markedly decreased within 60 min at an ethanol concentration of 70-80%, and the decrease was faster in pre-S1 and pre-S2 antigens than in S antigen. Although HBV DNA remained in all ethanol-treated serum samples, no HBV DNA was detected after treatment with 1% sodium hypochlorite for 1 min. Based on the results, we speculate that one mechanism of loss of HBV infectivity by ethanol is the inhibition of virus binding to hepatocytes.

Methods of rapidly extracting chromosomal DNA from human pathogenic yeasts were used in mitochondrial DNA (mtDNA) studies. This paper is concerned with rapid and reliable methods of extracting mtDNA for sequence analysis for species or strain identification, and epidemiological study of medically important fungi and fungal infections. To determine the optimal method of mtDNA extraction without isolating mitochondria, we examined three commonly used methods: 1) boiling, 2) glass bead disruption, and 3) a commercially available kit. We assessed the amount and quality of DNAs using a spectrophotometer and specific polymerase chain reaction (PCR). The DNA yield depended on the extraction method used and the yeast species. An adequate amount of mtDNA was obtained with both glass beads and a commercially available kit to amplify the mitochondrial gene using PCR without isolating the mitochondria. These techniques are convenient for extracting DNA from a variety of small-scale samples.

We explored the degree of Japan’s contribution to research in the field of infectious disease in the last decade. Articles published from 1991-2000 in highly reputed journals on infectious disease were accessed through the MEDLINE database. The number of articles having an affiliation with a Japanese institution was counted in total and for the respective journals. The proportions of randomized controlled trials (RCTs), case-control/cohort studies, and case reports among the articles affiliated with Japan were also calculated, and were compared with the overall proportions of these types of articles for all articles published in these journals. Japan’s contribution to research on infectious disease was 3.4% of the total articles and ranked sixth among all countries. The recent trend in contribution was negative, although not statistically significant (P = 0.19). RCTs in total articles published in these journals were 3.9%, which proportion has been increasing significantly over time. On the other hand, only one RCT (0.2%) was reported from Japan in the last decade. In addition, the proportion of case-control/cohort studies (2.2%) was smaller for articles from Japan than those from other countries. Compared with those of other developed countries, Japan’s contribution to research on infectious disease has been unsatisfactory in the last decade. An explanation for this phenomenon should be determined and remedial measures should be taken forthwith.