Human T-Lymphotropic Virus 1,Breastfeeding,and Antiretroviral Therapy

Editor: Human T-lymphotropic virus 1 (HTLV-1), the first human retrovirus described, is the causative agent of a neglected disease affecting 5–10 million people worldwide with uneven geographic distribution and high prevalence in some areas of Japan, Brazil, the Caribbean Islands, the Andean States, and Central and Southern Africa. ¹ While HTLV-1 is often considered a lifelong asymptomatic infection, the cumulative risk of developing adult T cell leukemia (ATL) is calculated as 1–5%. For HTLV-1-associated diseases in general, including ATL, HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), uveitis, polymyositis, and arthropathy, the lifetime risk may be close to 10%. ²

The mode of transmission for this retrovirus is through blood or sexual contact, and mother-to-child-transmission (MTCT) occurs in approximately 20% of infants breastfed for 6 months or more ³ . However, the advantages of breastfeeding over formula feeding to prevent overall child morbidity and mortality have been well established, especially in developing countries. This creates a paradox, whereby refrainment of breastfeeding to prevent HTLV-1 transmission has been effective in a developed country such as Japan, ³ but is inappropriate for developing countries with higher infant morbidity and mortality.

In HIV-1 infection, maternal and infant antiretroviral therapy (ART) is one of the most important measures to prevent HIV-1 MTCT. ⁴ If ART was used to prevent postpartum HTLV-1 infection of neonates through breast milk feeding, HTLV-1 transmission could be halted. However, prevention of vertical HTLV-1 infection is not part of routine health care practice. Interestingly, studies demonstrate the capacity of zidovudine (AZT) to significantly inhibit HTLV-1 infection of lymphocytes in vitro and in vivo. ^{5, 6}

We suggest that in areas of high prevalence of HTLV-1 infection, formal guidelines be adopted to screen pregnant women for HTLV-1 and a trial performed to assess the therapeutic benefit of ART for women during delivery, and for the infant for the duration of breastfeeding, to prevent HTLV-1 transmission. A healthy and vigorous ethical debate should be initiated to discuss such challenges. A way to stop HTLV-1 vertical transmission should be pursued and offered to mothers and children in areas of high HTLV-1 prevalence around the globe.