The Human T-cell lymphotropic virus type-1 (HTLV-1) retrovirus infects an estimated 5 to 10 million people worldwide. Infection results in carriage of the virus but about 90% of carriers don’t go on to develop symptoms of disease (asymptomatic).
Diseases found in HTLV-1 infected people
Among the other 10% of carriers, HTLV-1 associated diseases include:
- HTLV-1–associated myelopathy / tropical spastic paraparesis (HAM/TSP)
Spinal cord damage (myelopathy) with sensory involvement, bladder disturbances and progressive weakness and stiffness of the legs
- Infective dermatitis associated to HTLV-1 (IDH)
A recurring chronic eczema that affects HTLV-1 vertically infected (when a pathogen is transferred from mother to baby) children
Disease can move quickly if the onset is early
A new study followed 25 children diagnosed at around 8.5-years of age (yoa) with HAM/TSP in Bahia, Brazil. Most children (20 of 25) also had IDH and most (20 of 25) were female.
The patients diagnosed with both IDH and HAM/TSP developed neurologic issues earlier; 9yoa for those with both compared to 17yoa for those with a HAM/TSP diagnosis alone.
In the laboratory, 21/22 patients who had cerebrospinal fluid collected and tested, had HTLV-1 antibodies and were HTLV-1 DNA positive using a PCR targeting the tax gene. The PCR was useful to confirm infection in one patient who had no detectable antibodies in the CSF.
This report is the largest to describe such early disease progression associated with IDH.
In one case, myelopathy began at 3yoa with disease emerging in half of the patients by 10yoa. The authors suggest there might be a relationship between IDH whereby it predisposes to HAM/TSP; both share an underlying inflammatory process driven by over-production of cytokines that create an inflammatory state.
The authors concluded that transmission was probably most often vertical and highlighted that disease results in considerable burden which is worse when it starts early in life. Rapid disease progression has also been seen among cases related to blood transfusion.
Can anything be done to prevent disease?
There are no licensed drugs to treat infection nor vaccines to specifically orevent HTLV-1 disease. The study concludes that avoiding vertical transmission is an important consideration. How that can be achieved among communities where breastfeeding is an essential form of neonatal nutrition is not something the authors tried to address.
As early HAM/TSP is due to vertical transmission through breastfeeding, it is very important to avoid this pathway of infection through the detection of HTLV-1 positive mothers in prenatal care so as to advise them to refrain from breastfeeding.
- Early Juvenile Human T-cell Lymphotropic Virus Type-1–Associated Myelopathy/Tropical Spastic Paraparesis: Study of 25 Patients
- The mechanics of the polymerase chain reaction (PCR)…a primer
- Human T-Lymphotropic Virus type 1 (HTLV-1): a primer
- HTLV-I associated myelopathy (HAM): review and recent studies.