Maternal Proviral Load and Vertical Transmission of Human T Cell Lymphotropic Virus Type 1 in Guinea-Bissau

Abstract

The relative importance of routes of transmission of human T cell lymphotropic virus type 1 (HTLV-1) in Guinea-Bissau is largely unknown; vertical transmission is thought to be important, but there are very few existing data. We aimed to examine factors associated with transmission in mothers and children in Guinea-Bissau, where HTLV-1 is endemic (prevalence of 5% in the adult population). A cross-sectional survey was performed among mothers and their children (aged <15 years) in a rural community in Guinea-Bissau. A questionnaire to identify risk factors for infection and a blood sample were obtained. HTLV-1 proviral load in peripheral blood was determined and PCR was performed to compare long terminal repeat (LTR) sequences in mother-child pairs. Fourteen out of 55 children (25%) of 31 HTLV-1-infected mothers were infected versus none of 70 children of 30 uninfected mothers. The only factor significantly associated with HTLV-1 infection in the child was the proviral load of the mother; the risk of infection increased significantly with the log(10) proviral load in the mother's peripheral blood (OR 5.5, 95% CI 2.1-14.6, per quartile), adjusted for weaning age and maternal income. HTLV-1 sequences of the LTR region obtained from mother-child pairs were identical within pairs but differed between the pairs. Vertical transmission plays an important role in HTLV-1 transmission in this community in Guinea-Bissau. The risk of transmission increases with the mother's proviral load in the peripheral blood. Identical sequences in mother-child pairs give additional support to the maternal source of the children's infection.

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

“…In fact, several studies reported that indicators of lower socioeconomic status, such as lower educational level and low income, are associated with HTLV-1 transmission 2 and to MTCT 2 , 34 , 35 . Transmission occurred regardless of the sex of the child, but this data is controversial, since some studies have associated a higher risk of transmission to males 23 or females 22 exposed children, whereas others found a similar transmission risk for boys and girls 24 , 27 , 28 , 30 , 36 , 37 . However, the small sample size is a limitation to influence the child infection from other factors, such as history of blood transfusion, cesarean delivery or maternal coinfection with HIV, HTLV-2, HBV or an association of HIV/HCV.…”

Molecular Epidemiology of Endemic Human T-Lymphotropic Virus Type 1 in a Rural Community in Guinea-Bissau

“…This cohort was established in 1991, and subjects were examined in 1996, 2003, and 2006. In addition, in 2004 a cross-sectional study was performed to examine mother-to-child transmission of HTLV-1 [19]. HTLV-1 prevalence has been stable at around 5% in Caio throughout this period [15].…”

“…All complete LTR sequences obtained from mother-child pairs from the vertical transmission study in 2004 were also used in the current analysis (accession numbers JN655856 to JN655872). [19]. Samples for p24 sequencing were randomly selected in 2009 from stored DNA samples for an as yet unpublished immunological study.…”

Transfusion‐transmitted human T‐lymphotropic virus Type I infection in a United States military emergency whole blood transfusion recipient in Afghanistan, 2010

“…8 While the genetic variability of the HTLV-I proviral sequence is relatively low when compared to other viruses such as human immunodeficiency virus (HIV) and hepatitis C virus (HCV), epidemiologically linked infections have been identified. [10][11][12] In HTLV-I-endemic areas such as southwestern Japan, the Caribbean, sub-Saharan Africa, South America, and parts of Iran, seroprevalence rates range from less than 5% to 10%. 13 Infection is lifelong with transmission of the virus primarily through breast milk, sexual contact, blood transfusion, or from sharing needles in intravenous drug use.…”