HTLV-1 Testing and Diagnosis

Overview

Discussions about testing for HTLV-1 should emphasise informed shared decision making, and understanding the implications of a positive or negative test result. There are no currently available treatments for HTLV-1, and a diagnosis may carry stigma, shame and adverse mental health impacts. 

Informed Consent and Shared Decision Making

The decision to test for HTLV-1 must be made by the person to be tested following a process of informed shared decision making, preferably using a culturally appropriate decision-aid. Where the clinician has insufficient knowledge to adequately explain the risks and benefits of testing, they should refer the person to another clinician or obtain sufficient support to gain informed consent. 

Shared decision making is more than informed consent. Shared decision making is a consultation process where a clinician and patient jointly participate in making a health decision, having discussed the options and their benefits and harms, and having considered the patient’s values, preferences and circumstances. Shared decision making is especially valuable when there is uncertainty as to which option is superior, when each option has different inherent benefits and harms, or when the decision is likely to be strongly influenced by patients’ preferences and values.  

Documentation of shared decision making is also important so that other services do not repeat the process, particularly for people who access care at several clinics, or who attend specialist antenatal clinics throughout pregnancy. 

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

Pregnant People

All Aboriginal pregnant people, and other people whose baby will be identified as Aboriginal, who are living in or were born in high prevalence communities for HTLV-1 should be offered information about HTLV-1. This should include the availability of testing and the implications of a positive and negative test for their own and their baby’s health. This discussion should occur with a clinician with knowledge of HTLV-1 as soon as safely possible in pregnancy.  

HTLV-1 testing should never be included in a predefined antenatal care test set. 

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

People Requesting Testing, Including Partners and Sexual Contacts of People Living with HTLV-1

The potential benefits and harms of testing for all Aboriginal people, including partners of Aboriginal people, who are living in, or were born in, high prevalence communities should be discussed with people who request testing. This includes people who have had sexual contact with a person living with HTLV-1.

Children Birthed or Breastfed by a Person Living with HTLV-1

Do not routinely test children who may have been exposed to HTLV-1 during pregnancy, birth or breast feeding. There is currently no proven health benefit to diagnosing a child with HTLV-1 and testing may lead to harms, including stigma, shame and adverse mental health impacts. In the absence of a specific clinical indication, testing should be deferred until the child can understand the implications for themselves and make an informed shared decision about testing.  

Children with Symptoms Consistent with HTLV-1

Testing of children presenting with symptoms consistent with HTLV-1 associated health conditions should be carefully considered as to the immediate clinical benefit of ascertaining HTLV-1 status versus the potential harms associated with diagnosis of an untreatable chronic infection. Testing should only be performed where the result will alter clinical management and the decision to test is made as a shared decision with the child’s carers. 

People Presenting with Symptoms Consistent with HTLV-1-Associated Disease

Recommend testing for HTLV-1 in all Aboriginal people who are living in, or were born in, high prevalence communities with clinical findings suggestive of ATLL, HAM/TSP, infective dermatitis or HTLV-associated uveitis.  

Consider testing for HTLV-1 in patients with diseases possibly associated with HTLV-1, including crusted scabies, bronchiectasis and tuberculosis, where knowing HTLV-1 status may alter management, or where the person wishes to know their status to prevent transmission. 

How to Test for HTLV-1

Testing is performed by requesting HTLV-1 serology on a serum sample. Local laboratories will perform an initial HTLV-1 screening antibody test, which is then sent to a reference laboratory for confirmation. Confirmation is usually performed with Western Blot. Ideally a PCR test is also used to aid confirmation, however this is as of March 2025 not funded by the Medicare Benefits Schedule. 

The result will be reported as positive, negative or indeterminant. Indeterminant results can usually be resolved with repeat testing after a 1-month interval.  

Interpreting HTLV-1 Test Results

• Positive – person is HTLV-1 infected.  
• Negative – person is not HTLV-1 infected. False negative results can occur so where the clinical suspicion is high repeat the test and seek expert advice.  
• Indeterminant – requires additional testing with either a repeat serological test and/or proviral load assay to determine infection status. Seek expert advice.  

Positive Results

Persons found to be positive for HTLV-1 should be informed that they are infected with HTLV-1 and that HTLV-1 is a lifelong infection. People with HTLV-1 should be given information regarding modes and efficiency of transmission, and the probability of developing HTLV-1 associated conditions.

All people found to be positive for HTLV-1 should be provided with information regarding modes and efficiency of transmission, and how to minimise the risk of transmission by: 

• Not sharing needles or syringes or other injecting equipment  

• Using condoms to prevent sexual transmission 

• Not donating blood, semen, body organs, or other tissues 

• If undergoing cultural rituals where blood is involved, ensuring all equipment is single use and no blood to bloodstream contact occurs 

• Engaging in pre-conception counselling if they are planning to become pregnant  

People found to be positive for HTLV-1 should also be provided with advice about general health, such as smoking cessation, diet and exercise. Referral to a mental health worker or psychologist should also be considered.

For more information refer to Management and Care

It is not currently recommended to perform pro-viral load testing for patients living with HTLV-1 who are not pregnant, planning pregnancy or considering breastfeeding.