Instruction of feeding methods to Japanese pregnant women who cannot be confirmed as HTLV-1 carrier by western blot test

Japan has been reported to be one of the areas of highest prevalence of human T-cell leukemia virus type 1 (HTLV-1) in the world [1,2]. For example, our earlier study indicated that about 1620 of HTLV-1 carriers have births per year in Japan [3]. To prevent mother-to-child infection of HTLV-1, Japanese obstetricians have to instruct these women about the methods as alternatives to breast-feeding [1,4]. Since September 2010, in Japan diagnosis of HTLV-1 carrier can be usually performed after the confirmation test (western blot test – WB test) following serological screening test performed for all Japanese women during pregnancy [4]. According to the Guidelines for obstetrical practice in Japan (2011), the following methods are instructed to the pregnant HTLV-1 carriers as alternatives to breast-feeding for the prevention of HTLV-1 vertical transmission: (1) formula milk feeding, (2) frozen-thawed breast milk or (3) short-term breast-feeding within the first 3 months after birth [4,5]. These alternatives have been reported to decrease the incidence of HTLV-1 vertical transmission to one-sixth in Japan [4,5]. However, there has been reported to be about 11% cases of indeterminate of WB test [3]. In these uncertain serological constellations, polymerase chain reaction (PCR) tests are available to further refine the diagnosis. However, PCR test has been thought to be a non-absolute method to provide the definite diagnosis of infection with requiring a high co-payment (about 200 US dollars) [4]. Therefore, strategies for the patients of indeterminate of WB test have not been well determined in Japan. In this study, to examine the actual strategies for pregnant women who cannot be confirmed as HTLV-1 carrier by WB test, we compared the instructed methods of feeding for the patients of indeterminate of WB test in the endemic area (Kyushu area: n1⁄4 56) with those in the non-endemic area (except Kyushu area: n1⁄4 170). This is an additional research of our previous study in 2012 concerning the current status of HTLV-1 carriers in Japan [3]. We requested the same obstetrical facilities that are members of Japan Association of Obstetricians and Gynecologists (JAOG) to provide information of instructions of feeding methods to pregnant women of indeterminate of WB test in Japan. A total of 1883 (71.3%) of them responded. As the strategy to instruct each patient of indeterminate of WB test, in this study the Japanese obstetricians selected one of the following three methods: (1) recommendation of PCR test, (2) recommendation of alternatives to breast-feeding as HTLV-1 carrier, or (3) recommendation of breast-feeding as non-HTLV-1 carrier. Table 1 shows the summary of the instructed methods of feeding for the patients of indeterminate of WB test in Kyushu and the other areas. In Kyushu area, the rate of recommendation for PCR test was significantly higher than that in the other areas (55% versus 30%, p50.01 by x test). While, the rate of instruction of breast-feeding in Kyushu area was significantly lower than that in the other areas (8.9% versus 44%, p50.01 by x test). Based on the current results, the strategies for the indeterminate cases of WB test seemed to be different between the endemic (Kyushu area) and non-endemic areas. In our previous study, the positive rate of PCR test in cases of indeterminate of WB test was observed to be 26% even in the