Contact us

What is HTLV-1

Transmission

Overview

HTLV-1 is thought to be almost entirely, although not exclusively, transmitted via direct contact between infected and uninfected cells. In practice this means transmission requires the transfer of cell-containing fluids such as blood, semen or breast milk.

Sexual transmission

While sexual transmission is generally thought to account for most transmission globally, there are very few studies that can distinguish sexual from other modes of transmission. In prospective studies of serodiscordant couples, transmission has been shown to be greater from men to women than the reverse. Data from cross-sectional studies is generally consistent with this, with women having higher prevalence than men. A higher proviral load has been shown to be a risk factor for transmission. There are no epidemiological data demonstrating a protective effect of condoms, but condoms are highly likely to be protective based on biological plausibility.

Exposure to blood and blood products

Several studies conducted outside of Australia have demonstrated transmission from blood products containing cellular components, and organ donations. In Australia all blood donations are tested for HTLV-1 and the risk of transmission is negligible.

Injecting drug use has been found to be associated with HTLV-1 positivity. While there is no data demonstrating this, it is highly likely that avoiding receptive needle sharing would prevent acquisition of HTLV-1.

Clusters of infection have been associated with cultural practices involving blood exposure, including one Australian study that looked at self-flagellation in non-Aboriginal people. Any form of blood exposure not involving a sterile single use sharp could potentially lead to transmission, including tattooing and traditional cutting practices.

Vertical Transmission 

The reported rate of vertical transmission to child ranges from 3.9%-27%, with a consensus estimate of 20%. The primary mode of vertical transmission is through breastfeeding. As there is a residual transmission rate of about 5% in exclusively formula fed babies it is assumed that intrauterine and intrapartum transmission can occur. Systematic reviews have found breastfeeding for less than 3-months to be equal to commercial formula feeding. Breastfeeding for more than 6 months greatly increases the risk of HTLV-1 transmission. 

Two retrospective studies have shown a significant association between maternal proviral load (PVL) and the risk of vertical transmission. In one study the transmission rate increased from 5% to 15% for a PVL greater than 0.5%. There is no known PVL threshold below which transmission does not occur.  

In mothers with a high PVL some guidelines recommend caesarean section, immediate cord clamping and anti-retroviral drugs for both the mother and child based on laboratory data, however there are currently no published clinical data demonstrating a benefit from such interventions.  

For more information refer to Prenatal and Postnatal Care for People who are Pregnant    

References

  • WHO. Human T-lymphotropic Virus Type 1: Technical Report. 2021.
  • McGregor S, Legrand N, Naruka E, Chacon GP. Review of current literature and evidence on human T-lymphotropic virus type 1 infection.: Kirby Institute; 2024.
  • Einsiedel LJ, Pham H, Woodman RJ, Pepperill C, Taylor KA. The prevalence and clinical associations of HTLV‐1 infection in a remote Indigenous community. Medical Journal of Australia. 2016;205(7):305-9.
  • Einsiedel, L., Pham, H., Talukder, M. R., Taylor, K., Wilson, K., Kaldor, J., Gessain, A., & Woodman, R. (2021). Very high prevalence of infection with the human T cell leukaemia virus type 1c in remote Australian Aboriginal communities: Results of a large cross-sectional community survey. PLoS neglected tropical diseases, 15(12), e0009915. https://doi.org/10.1371/journal.pntd.0009915
  • Einsiedel, L., Woodman, R.J., Flynn, M. et al. (2016). Human T-Lymphotropic Virus type 1 infection in an Indigenous Australian population: epidemiological insights from a hospital-based cohort study. BMC Public Health 16, 787. https://doi.org/10.1186/s12889-016-3366-5
  • Grivas, K. Freeman., & R. Baird. (2014). Human T-lymphotropic virus-1 serology in the Northern Territory: 2008–2011. Pathology, 46(7), 644-648
  • Martin F, Gilks CF, Gibb R, Jenkins A, Protani M, Francis F, et al. Human T-cell leukaemia virus type 1 and Adult T-cell leukaemia/lymphoma in Queensland, Australia: a retrospective cross-sectional study. Sexually transmitted infections. 2023;99(1):50-2.
  • Smith, S., Russell, D., Horne, P., & Hanson, J. (2019). HTLV-1 is rare in Far North Queensland despite a significant burden of classically associated diseases. Pathology, 51(1), 91–94. https://doi.org/10.1016/j.pathol.2018.10.010
  • Talukder, M. R., Woodman, R., Pham, H., Wilson, K., Gessain, A., Kaldor, J., & Einsiedel, L. (2023). High Human T-Cell Leukemia Virus Type 1c Proviral Loads Are Associated With Diabetes and Chronic Kidney Disease: Results of a Cross-Sectional Community Survey in Central Australia. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 76(3), e820–e826. https://doi.org/10.1093/cid/ciac614
  • Talukder MR, Clauss CS, Cherian S, Woodman R, Einsiedel L. Risk factors for HTLV‐1, acute kidney injury, and urinary tract infection among aboriginal adults with end stage kidney disease in central Australia. Journal of Medical Virology. 2021;93(11):6362-70.
  • Grivas R, Freeman K, Baird R. Human T-lymphotropic virus-1 serology in the Northern Territory: 2008–2011. Pathology. 2014;46(7):644-8.
  • McCallum GB, Oguoma VM, Versteegh LA, Wilson CA, Bauert P, Spain B, et al. Comparison of profiles of first nations and non-first nations children with bronchiectasis over two 5-year periods in the Northern Territory, Australia. Chest. 2021;160(4):1200-10.
  • European Centre for Disease Prevention Control. Geographical distribution of areas with a high prevalence of HTLV-1 infection. ECDC: Stockholm;. 2015:10.
  • Brazil Ministry of Health. Clinical Management Guide for HTLV Infection / Ministry of Health, Health Surveillance Secretariat, Department of Chronic Diseases and Sexually Transmitted Infections. In: Transmitted DoCDaS, Infections, editors. 2021.
  • Government of Chile Ministry of Health. HTLV-1 Patient Care Protocol. Santiago2018.
  • Health LaWSRG. HTLV-1 Mother-to-Child Transmission Prevention and Control Manual. Tokyo: The University of Tokyo; 2022.
  • Styles CE, Hoad VC, Denham-Ricks P, Brown D, Seed CR. Self-flagellation as possible route of human T-cell lymphotropic virus type 1 transmission. Emerging Infectious Diseases. 2019;25(10):1996-7.
  • Rosadas C, Taylor GP. Current interventions to prevent HTLV-1 mother-to-child transmission and their effectiveness: a systematic review and meta-analysis. Microorganisms. 2022;10(11):2227.
  • Itabashi K, Miyazawa T. Mother-to-child transmission of human T-cell leukemia virus type 1: mechanisms and nutritional strategies for prevention. Cancers. 2021;13(16):4100.
  • Boostani R, Sadeghi R, Sabouri A, Ghabeli-Juibary A. Human T-lymphotropic virus type I and breastfeeding; systematic review and meta-analysis of the literature. Iranian journal of neurology. 2018;17(4):174.
  • Ureta‐Vidal A, Angelin‐Duclos C, Tortevoye P, Murphy E, Lepère JF, Buigues RP, et al. Mother‐to‐child transmission of human T‐cell‐leukemia/lymphoma virus type I: implication of high antiviral antibody titer and high proviral load in carrier mothers. International journal of cancer. 1999;82(6):832-6.
  • van Tienen C, McConkey SJ, de Silva TI, Cotten M, Kaye S, Sarge-Njie R, et al. Maternal proviral load and vertical transmission of Human T cell Lymphotropic Virus type 1 in Guinea-Bissau. Retrovirology. 2011;8:1-.
  • Imperial College Healthcare. Brief Clinical Guidelines for the Management of HTLV-1/2 Infection. London: National Centre for Human Retrovirology (NCHR); 2024.
  • Cheng, A., Khawar, L., Hoad, V., Styles, C., & McGregor S. Transfusiontransmissible infections in Australia: 2023 Surveillance Report. Kirby Institute, UNSW Sydney, and Australian Red Cross Lifeblood; 2023
  • May JT, Stent G, Schnagl RD. Antibody to human T-cell lymphotropic virus type I in Australian aborigines. Med J Aust. 1988 Jul 18;149(2):104. doi: 10.5694/j.1326-5377.1988.tb120516.x. PMID: 2839756.
View more...

Back to top

Acknowledgement of Country

NACCHO, acknowledges the Traditional Owners of this land which continues to be under their ongoing custodianship. We pay our respect to Elders past, present and emerging.

Developed by:

The National Aboriginal Community Controlled Health Organisation (NACCHO) ABN 89 078 949 710 and ASHM Health ABN 48 264 545 457 | CFN 17788

Funded by:

The Australian Government Department of Health and Aged Care

Disclaimer:

Whilst the Australian Department of Health and Aged Care provides financial assistance to NACCHO, the material contained in this resource produced by NACCHO and ASHM should not be taken to represent the views of the Australian Department of Health and Aged Care. The content of this resource is the responsibility of NACCHO and ASHM. www.naccho.org.au - www.ashm.org.au

NACCHO © 1992 - 2024

Funded by the Australian Government

Members of the Coalition of Peaks