The association between HTLV-1 infection and clinical outcomes

Project overview 

This review will examine the association between HTLV-1 infection and adverse health outcomes including all-cause mortality, cause-specific mortality linked to defined clinical conditions, cause-specific mortality linked to asymptomatic HTLV-1 infection, and morbidity (in relation to defined clinical conditions). It complements the development of a mathematical model comparing targeted antenatal screening with no screening, considering both health outcomes and costs over the lifetimes of mothers and children.

Status: ongoing 

Contact: kerry.dwan@york.ac.uk 

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What is the problem?

Human T-lymphotropic virus type 1 (HTLV-1) is a virus that infects certain white blood cells and is transmitted through infected bodily fluids, including through breastfeeding, sexual contact, blood transfusions, organ transplants, or sharing needles. There is no cure or vaccine, and infection with HTLV-1 is lifelong. Most people infected with HTLV-1 remain symptom-free, but a small proportion become seriously ill with a rare type of cancer (called adult T-cell leukaemia/lymphoma) or an illness resulting in weakening and stiffness of the muscles in the legs which gets worse as time goes on (known as HTLV-1-associated myelopathy/tropical spastic paraparesis). In the UK, HTLV-1 is not common (affecting only around 5 in 10,000 pregnant women, mostly from regions such as the Caribbean, South America, Japan, and parts of Africa), but the health outcomes of HTLV infection are not fully understood.

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What are we doing?

We sought to find out whether having HTLV 1 is linked to worse health outcomes, such as a higher risk of death (overall and from specific diseases), death among people who have HTLV 1 but no symptoms, and illness related to known HTLV 1 associated conditions.

We identified and reviewed all the published evidence on the health consequences of being infected with HTLV-1 and compared people who had confirmed HTLV-1 infection to those without the virus. We examined and summarised the evidence on a range of health consequences for people with HTLV-1, including the number of people who developed an illness and the number of people who died. This project was informed by an advisory group that included clinical experts and people with lived experience of HTLV-1infection.