You've probably heard of viruses like `HIV`. But you may not have heard much about the virus `HTLV-1`. This is also a type of virus that can enter our body's cells and cause disease. But don't worry, for most people this won't be a big problem. But it's good to know, right? So let's see what `HTLV-1` is, how it develops, and what can be done about it.
What is `HTLV-1`? Let's understand it simply!
`HTLV-1` stands for `Human T-lymphotropic Virus type-1` . This belongs to a group of viruses called `Retrovirus`. Do you remember that we talked about `HIV` (HIV) virus being a `Retrovirus`? One of the special features of these `Retrovirus` is that when they enter our cells, their genetic information, that is, their `genetic material`, is inserted into the `DNA` (DNA) of our cells. Imagine it as if a virus had entered a computer.
Both the `HIV` virus and the `HTLV-1` virus attack the `T cells` in our immune system. But the way they work is very different. `HIV` destroys `T cells` and weakens the immune system. But `HTLV-1` does not destroy such `T cells`. In fact, many people infected with `HTLV-1` do not show any symptoms. They live just like healthy people.
However, a very small percentage of infected people develop two conditions many years later, perhaps 30 to 60 years later. One is a type of blood cancer called Adult T-cell Leukemia/Lymphoma (ATL or ATLL). The other is a disease of the nervous system called HTLV-1- associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP).
Are there other types of `HTLV`?
Yes, there are several types of `HTLV` viruses that infect humans. For example, there are `HTLV-1`, `HTLV-2`, `HTLV-3` and `HTLV-4`. All of these cause lifelong infection. However, so far, only `HTLV-1` causes specific diseases.
How common is this `HTLV-1`? Is it present in Sri Lanka?
The `HTLV` virus is found in many parts of the world. Experts estimate that between 5 and 20 million people worldwide are infected with `HTLV-1`. However, the infection rate varies greatly between countries and regions.
For example, in North America, less than 1% of the population has it. However, in parts of Japan, Africa, South America, Australia, Iran, and some parts of the Caribbean, more than a third of the population is reported to have this infection. It is difficult to find clear data about the situation in Sri Lanka, but it is important to be aware of such viruses.
What are the symptoms of this? Does it happen to everyone?
As mentioned earlier, the majority of people infected with `HTLV-1` do not show any symptoms. They do not even know that they have this virus in their bodies. Symptoms only appear many years after infection, when the previously mentioned `ATL` or `HAM/TSP` conditions develop.
Symptoms of `ATL` (Adult T-cell Leukemia/Lymphoma) may include:
- Feeling tired all the time (`Fatigue`)
- Skin rashes, eczema-like conditions
- Swollen lymph nodes – such as in the neck, armpits, and groin
- Constipation
- Memory loss, confusion
- Bone pain
Symptoms of `HAM/TSP` (HTLV-1-associated myopathy/tropical spastic paraparesis) may include:
- Weakness or stiffness that gradually increases in one or both legs
- Back pain
- Urinary incontinence
- Numbness in the limbs, tingling sensation (Peripheral neuropathy)
What other diseases can be caused by `HTLV-1`?
About one in 20 people (about 5%) infected with the HTLV-1 virus develop conditions called ATL (cancer) or HAM/TSP (neurological disease).
- `ATL` is a type of cancer that develops in the blood . It also has several subtypes (such as `acute`, `lymphoma`, `smoldering`, `chronic`). The treatment and prognosis of each type may vary slightly.
- `HAM/TSP` is a disease that affects the nervous system. It has some similarities to the disease `Multiple Sclerosis` (`MS`). It causes muscle weakness and progressive problems with the nervous system.
In addition to these two main diseases, researchers have found that HTLV-1 can also cause some inflammatory and autoimmune diseases . However, the exact relationship between them is still unclear. Some of these diseases include:
- Dermatitis
- Arthritis
- Inflammation of the inner parts of the eye (`Uveitis`)
- Sjögren's syndrome
How do HTLV-1-related diseases develop? Why doesn't everyone get them?
When the `HTLV-1` virus enters our bodies, it goes straight to the `CD4` cells (also known as `helper T-cells`) in our immune system. These `CD4` cells are like our body's police officers, a type of cell that helps protect us from disease.
Now, retroviruses like HTLV-1 carry their genetic information in a molecule called RNA. When they enter our cells, the virus cleverly converts its RNA into something similar to the DNA that contains our cells' information. Then, the piece of DNA (called a provirus) that it has made inserts itself into our cells' own DNA. In other words, the virus inserts a piece of itself into the software that controls our cells.
Now our cells, thinking that piece of the virus's `DNA` is part of themselves, start to make more copies of the virus. These newly produced `HTLV` virus copies go and infect many more `CD4` cells. Even though the virus spreads in the body in this way, it usually doesn't cause any symptoms.
However, in some people, after many years, this infection causes their body to produce too many `T cells`. That is when a condition called `ATL` leukemia occurs. In other cases, this virus can infect the nervous system and cause a condition called `HAM/TSP`. Why this only happens to some people is still being researched.
How is this `HTLV-1` virus transmitted from one person to another?
There are several main ways in which the `HTLV-1` virus can be transmitted. It is very important to be aware of these:
- Through sexual intercourse: unprotected vaginal, anal or oral sex.
- From mother to child through breastfeeding: When an infected mother breastfeeds her child.
- By sharing needles: Especially among people who inject drugs.
- Rarely: Through blood transfusions or organ transplants. However, in many countries, blood and organ donations are now screened for the virus, so transmission through these methods is rare.
Who is at higher risk of developing `HTLV-1`?
There are several factors that increase the risk of HTLV-1 infection:
- Injecting drugs without a prescription.
- Being born or living in an area where the `HTLV` virus is prevalent.
Some areas with high rates of HTLV-1 infection include:
- Southwest Japan
- African countries south of the Sahara Desert (`Sub-Saharan Africa`)
- Some parts of South America
- Caribbean Islands
- Northern Iran
- Central Australia
Important: Even within the same country, the infection rate is not the same in all areas. Some small areas may have a high infection rate, even if the overall rate is low.
What are the possible complications of HTLV-1 infection?
The `HTLV-1` virus alone does not weaken the immune system. However, if `ATL` (cancer) or `HAM/TSP` (neurological disease) develops, the immune system can be weakened. Then, `opportunistic infections` that do not normally occur in healthy people easily develop. Some of these infections can be life-threatening.
How do you accurately identify an `HTLV-1` infection?
Doctors diagnose HTLV-1 infection with a blood test. This test looks for antibodies (antibodies) that have been produced in the body against the HTLV virus, or for the presence of the virus's genetic material (RNA).
However, this is not a routine test for everyone. A doctor may refer you for this test in the following cases:
- If you have a medical condition (e.g., symptoms of ATL or HAM/TSP) that you think may be related to HTLV-1 infection.
- If you live in an area where HTLV infection is common and you are planning to breastfeed.
- If you are hoping to become a blood donor or an organ donor (this is now a mandatory test in many places).
Is there a treatment for `HTLV-1`? Can it be cured?
To be honest, there is no cure yet for the `HTLV-1` virus. That is, the virus cannot be completely eliminated from the body. However, there are treatments for the diseases `ATL` and `HAM/TSP` caused by `HTLV-1`.
These are used as treatments for `ATL` (cancer):
- Medications used for other types of lymphoma, for example chemotherapy .
- Antiviral medications, such as zidovudine (Retrovir®) and interferon alfa. However, not all types of ATL respond to these antiviral medications.
- Stem cell transplant . This is not possible for everyone with ATL. But if successful, it can significantly extend life expectancy.
For people with `HAM/TSP` (neurological disease), the following treatments are used to control symptoms and provide relief:
- `Interferon alfa`.
- Reduce inflammation with `Corticosteroids`.
- Interferon beta. This may help reduce inflammation and prevent nerve damage.
- Reduce muscle spasticity and stiffness with Baclofen (Lioresal ®) or tizanidine.
- Oxybutynin for urinary incontinence.
What happens if I have `HTLV-1`? Should I be worried?
This is the most important thing. Not everyone who has the HTLV-1 virus will develop either ATL or HAM/TSP. In fact, the majority of those infected can live normal lives without developing these serious diseases.
However, if you develop these conditions, the outlook depends on the type you have. People with the smoldering or chronic types of ATL may have a better outcome than those with other types. Although HAM/TSP tends to get worse over time, you can live for decades after diagnosis.
How can I protect myself from this `HTLV-1` virus? Are there any ways to prevent it?
Yes, there are things we can do to prevent the spread of the `HTLV-1` virus.
- Testing donated blood and organs for HTLV-1 can help prevent the spread of the virus.
- You can do these things to reduce your personal risk:
- Avoid injecting drugs without a prescription.
- Avoid reusing the same injection needles or sharing them with others.
- Avoid unprotected sex. Always use a latex condom during any type of sexual intercourse (vaginal, anal, or oral).
- If you have been tested positive for HTLV-1, avoid breastfeeding and donating blood. If you have HTLV-1 and want to breastfeed, seek advice from a doctor experienced in HTLV-1. Expressing breast milk and freezing it, then thawing it, may reduce the risk of transmitting the virus to your baby, but it is important to seek medical advice before doing so.
What does `HTLV` positive mean?
Being `HTLV` positive means that you have `HTLV-1` or another type of `HTLV` in your body. It does not mean that you will definitely develop `ATL` or `HAM/TSP`. If you are `HTLV-1` positive, there are precautions you can take to avoid spreading the virus to others (such as not breastfeeding, avoiding unprotected sex).
How dangerous is this `HTLV`?
The `HTLV` virus, when taken alone, is usually not dangerous and does not cause symptoms. However, it is important to be aware of it, as `HTLV-1` can sometimes cause cancer, neurological diseases, or inflammatory conditions.
When should I see a doctor?
If you have questions about getting tested for HTLV-1, or if you are HTLV-1 positive and want to know what precautions you should take, be sure to talk to a doctor. It is especially important to be aware of this if you live in an area where HTLV-1 is common.
Finally, things to remember
Okay, so we've talked a lot about `HTLV-1,' haven't we? Remember, although this is a virus that is found all over the world, it is not common in many places. Only a very small percentage of those infected develop serious illness.
The most important thing is not to panic if you test positive for HTLV-1. Most people can live a healthy life without any symptoms. However, being aware of this virus, how it is transmitted, and how to prevent it can help protect yourself and those around you.
If you have any further questions about this, don't hesitate to ask your family doctor or a doctor who is knowledgeable about this. Stay healthy!
` HTLV-1, Retrovirus, ATL, HAM/TSP, Cancer, Neurological disease, Viral infection
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