Tehran University of Medical Sciences Current Journal of Neurology 2717-011X 17 4 2018 11 29 174 179 EN Reza Boostani Department of Neurology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran Ramin Sadeghi Nuclear Medicine Research Center, Mashhad University of Medical Sciences, Mashhad, Iran Amir Sabouri Department of Neurology, School of Medicine, Washington University, Saint Louis, Missouri, USA Ali Ghabeli Marvdasht Shahid Motahhari Hospital, Department of Neurology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran 2018 07 20 2018 11 29 Background: The human T-cell lymphotropic virus type-I (HTLV-I) is the first identified pathogenic human retrovirus. Breastfeeding has been reported to be the predominant route of vertical transmission of HTLV-I. The objective of this systematic review was to pool and evaluate the data on the transmission of HTLV-I with different infant-feeding practices on children born to HTLV-I-positive mothers. We conducted a systematic review of comparison of HTLV-I transmission risk to breastfed and bottle-fed babies. Methods: We searched the following databases: MEDLINE, SID, Magiran, and Cochrane Library. The search strategy was limited to articles in English. Initial screening identified 254 citations; of these, 96 potentially relevant articles were identified. After reviewing the 96 full-text articles in detail, 7 reports met the inclusion criteria for this review. Results: Pooled odds ratio (OR) and risk difference (RD) of HTLV-I transmission in the breastfed group compared to the bottle-fed infants were [OR = 3.48, 95% confidence interval (CI): 1.58-7.64, P = 0.0020, Cochran’s Q = 27.7, P = 0.0010, and I2 = 67.5%] and (RD = 17.1%, 95% CI: 7.5%-26.7%, P < 0.0001, Cochran’s Q = 106, P < 0.0001, and I2 = 91.5%). So, we have evidence to support that exclusive breast feeding more than 6 months in comparison to bottle feeding highly increases transmission rate of HTLV-I infection. We have also enough evidence to support that exclusive breast feeding up to 6 months compared to bottle feeding does not increase transmission rate of HTLV-I infection (pooled OR = 0.912, CI: 0.45-1.80; OR: 3.83, CI: 1.80-8.10, respectively). Conclusion: The current meta-analysis showed that short period (less than 6 months) of breastfeeding did not increase risk of HTLV-I infection transmission from mother to child among breastfeeders and more than 6 months of breastfeeding significantly increased the risk of HTLV-I infection. However, our meta-analysis shows that refraining from breastfeeding can decrease the risk of vertical HTLV-I transmission. https://ijnl.tums.ac.ir/index.php/ijnl/article/view/1614