Prevalence of human T‐lymphotropic virus type 1 carriers among pregnant women in Hokkaido, Japan

Abstract

As there is a risk of MTCT of HTLV-1, the HSGP HTLV-1 MTCT was organized in 2011. To determine how many pregnant women are infected with HTLV-1 in Hokkaido, which is the northernmost and the second largest island in Japan with a population of 5 467 000 and 39 392 newborns in 2011, the HSGP HTLV-1 MTCT asked all facilities that may care for pregnant women in Hokkaido in July 2013 to provide information on the number of pregnant women who underwent screening for anti-HTLV-1 antibody using particle agglutination or chemiluminescent enzyme immunoassay, and the numbers of those with positive, equivocal, and negative test results in the screening and confirmation tests using western blotting or PCR methods in 2012, respectively. A total of 111 facilities participated in this study and provided information on 33 617 pregnant women who underwent screening in 2012, corresponding to approximately 85% of all pregnant women who gave birth in Hokkaido in 2012. Of 81 candidates for a confirmation test because of positive (n ¼ 77) or equivocal (n ¼ 4) results on screening, 63 (78%) underwent the confirmation test and, finally, 34 (0.1%) and 33 563 (99.8%) women were judged to be HTLV-1 carriers and non-carriers, respectively. It was concluded that the prevalence rate of HTLV-1 carriers was low, one per 1000 pregnant women in Hokkaido. Approximately 40 infants are born yearly to mothers infected with HTLV-1 in Hokkaido.

Risk factors associated with HTLV-1 vertical transmission in Brazil: longer breastfeeding, higher maternal proviral load and previous HTLV-1-infected offspring

“…HTLV-1 transmission primarily occurs through the following routes: 1) vertically (from mother to child), including a long time of breastfeeding (8); 2) sexual contact, primarily from men to women; and 3) parenterally through the transfusion of contaminated blood and blood components or through contaminated needles 7 . Concerning mother-to-child-transmission (MTCT) transmission, a review 8 pointed out that in infants breastfed, the MTCT occurs at rates varying from 7.4% 9 to 32% 10 , compared with a rate of less than 5% among bottle-fed children, some of them tested during adulthood 9 , 11 – 14 . Although prolonged breastfeeding seems to play a central role in the spread and maintenance of endemicity 9 , 12 , 14 , the relative importance of HTLV-1 main routes of transmission in Brazil is still a matter of discussion 15 , 16 .…”

HTLV-1 is predominantly sexually transmitted in Salvador, the city with the highest HTLV-1 prevalence in Brazil

“…Transmission occurs through contaminated blood or tissue, from mother-to-child, predominantly through breast-feeding, as well as through sexual contact [ 1 , 14 ]. Since the establishment of blood screening for HTLV-1, the transmission of this virus in endemic areas primarily occurs from mother-to-child and/or through sexual intercourse [ 15 , 16 ]. The risk of transmission of HTLV-1 per coital act, particularly between new sexual partners, is unknown.…”

Intrauterine infection with bovine leukemia virus in pregnant dam with high viral load

“…In HTLV-1 infection, breast milk intake is considered the main route of vertical transmission in human. Although a few reports indicate that HTLV-1 is transmitted within the uterus [ 3 , 14 , 16 ], the risk of intrauterine infection is low in humans, unlike BLV transmission in cattle. This difference might be explained by the viral load during pregnancy.…”