HIV infection rate among blood donors in Japan in 1999
(IASR 2000; 21: 140-141)

The HIV antibody positive rate in donated blood has been ceaselessly increasing in Japan, although it is continuously decreasing or remaining at a low level in Europe and North America. The HIV positive rate per 100,000 donated blood reached 1.02 in 1999, which is almost the same as the median of the rates in Western Europe in 1997 (1.05). Table 1 shows a relative index regarding the rate of HIV positive donated blood and the prevalence of HIV in general population in Western Europe and Japan. The median of the indexes of the Western Europe was 7.0 (25/75 percentile, 3.7/10.2), whereas the Japanese index was 13 times higher (90.0). Thus, the HIV positive rate in donated blood is abnormally high in Japan, considering the degree of HIV prevalence.

In 1997, approximately 60% of the positive donated blood (32/52) was collected from the whole country to measure the antibody titer. Three of those 32 samples (9.4%) were found to be the blood in the early antibody-rising phase (<18 days since appearance of the antibody), if it is defined as an "antibody titer of <1:1,000 by the particle agglutination (PA) method". Considering 22 days of the infectious window period before rise of the antibody, possible acceptance of the contaminated blood cannot be ruled out.

As a background of the accumulation of HIV positive donated blood, 1) insufficient screening by questionnaire, 2) blood donation for testing purposes, 3) donation by high risk groups (especially men who have sex with men), are important in Japan. Further investigations and research are essential for appropriate preventive intervention measures. In order to improve the sensitivity of blood screening, the Japanese Red Cross has decided to employ a nucleic acid amplification (NAT) method, which shortens the window period by half. However, such efforts may encourage high risk population to donate blood more often for the purpose of HIV testing. Anonymous HIV screening service system, which is available more conveniently in time and place, is imperative.

Reported by: Masahiro Kihara, Dept. of Global Health and Socio-epidemiology, Kyoto University School of Public Health; Mitsunobu Imai, Kanagawa Prefectural Institute of Public Health; and Masaru Shimizu, Central Clinical Laboratories, Tokyo Women's Medical University

Correspondence: Masahiro Kihara;
E-mail: poghse@pbh.med.kyoto-u.ac.jp

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