Table 3.
Vertical postnatal HTLV-1 transmission data (1984–2018) separated by the infant feeding modes and duration of breast-feeding (breastfed for <6 months, >6 months, mixed-method and PIF-fed infants)
| Year (country) | Breast-feeding <6 months | Breast-feeding >6 months | Mixed feeding | PIF feeding | Study duration | References | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Incidence/total number of infants in study | % | Incidence/total number of infants in study | % | Incidence/total number of infants in study | % | Incidence/total number of infants in study | % | |||
| 1986 (Japan) | Not reported | 13/16 (BF duration not specified) | 25 | Not reported | Not reported | Birth-18 months | (49) | |||
| 1987 (Japan) | Not reported | BF (duration not specified) 11/24 | 46 | Not reported | 1/11 | Tested at 12 months | (50) | |||
| 1987 (Japan) | Not reported | 12 months 5/8 | 63 | 12 months 2/7 | 29 | Not reported | Tested at 12 months and 18 months | (51) | ||
| –18 months 5/18 |
28 | 18 months 3/29 | 10 | |||||||
| 1990 (Japan) | Not reported | 17/44 | 39 | 5/49 | 10 | 0/10 | 0 | Retrospective study of 1–13 year olds | (52) | |
| 1991 (Japan) | <6 months 4/90 | 4·4 | >7 months 20/139 | 14·4 | Not reported | 9/158 | 5·7 | Tested every 3 months for 1 year, then 6 months for 2 years | (53) | |
| 1991 (Japan) | <3 months 2/39 | 5·1 | <12 months 6/23 | 26·1 | Not reported | 2/12 | 16·7 | Tested every 6 months | (54) | |
| <6 months 5/22 | 22·7 | >12 months 5/13 | 38·5 | |||||||
| 1996 (Gabon) | <6 months not reported | >8 months 4/34 | 11·8 | Not reported | Not reported | Tested every 6 months until 2/4 years old | (55) | |||
| 1997 (Japan) | <6 months 2/51 | 3·9 | >6 months 13/64 | 20·3 | Not reported | 4/162 | 2·5 | Infant s > 30 months were tested | (56) | |
| 1997 (Jamaica) | <6 months not reported | <12 months 8/86 |
9 | Not reported | Not reported | Birth–24 months | (57) | |||
| >12 months 19/60 |
32 | |||||||||
| 1999 (French Guyana) | <3 months 1/35 | 2·9 | 7–9 months 1/13, | 7·7 | Not reported | 0/23 | 0 | Retrospective study of 0–12 year olds | (58) | |
| 4–6 months 1/17 | 5·9 | 10–12 months 7/68 | 10·3 | |||||||
| >12 months 9/70 | 12·9 | |||||||||
| 2018 (Brazil) | Not reported | <12 months 7/145 | 4·8 | Not reported | Not reported | Birth–until BF stopped | (59) | |||
| >12 months 34/143 | 23·8 | |||||||||
| Total | 15/254 | 5·9 | <12 months 88/624 | 14·1 | 10/85 | 11·8 | 16/376 | 4·3 | n/a | |
| >12 months 72/304 | 23·7 | |||||||||
*
This review records the incidence in each study of vertical HTLV-1 transmission, the total number of infants in the study and the percentage of the transmission rate (incidence/total number of infants in study (%)). It should be noted that no definitions were found for feeding modes; therefore, it is not known if breast-feeding was strictly exclusive or if other solids and/or liquids were allowed. Therefore, all HTLV-1 reports must be viewed as potentially having some PIF exposure.