TABLE 1.

HTLV-1 seroprevalence among Japanese blood donors in literature.

References	Maeda et al., 1984	Hashimoto et al., 1991	Satake et al., 2012
Year of screening	1983	1988	2006–2007
Areas screened	64 Blood centers	77 Blood centers	All 47 prefectures
Screening test method	IF	PA, IF	PA, IF
No. screened	12,800	614,879	1,196,321
No. HTLV-1-positive	241	11,586	3,787
Overall seropositive rate (%)	8.0	1.88	0.32
Seropositive rate (%) by age group	(Only Kyusyu area)	M/F	M / F
16–19 years	2.0	2.3/2.9	0.12 / 0.11
20–29 years	2.6	4.4/4.8	0.17 / 0.20
30–39 years	3.8	8.0/10.1	0.22 / 0.27
40–49 years	5.1	10.3/21.0	0.57 / 0.63
50–59 years	6.2	13.7/14.3	0.97 / 1.26
60–64 years			1.29 / 1.66
70–79 years	N.D.	N.D.	1.59 / 2.36
80–89 years	N.D.	N.D.	1.92 / 2.96
90–99 years	N.D.	N.D.	2.19 / 3.48

HTLV-1 = human T-cell leukemia virus type 1; PA = particle agglutination; IF = immunofluorescence, N.D. = not done.