Host:

All plants and animals have an immune system to protect themselves against infection. But if a child often has fever, cough and runny nose, and gets infected again and again, it is likely that he or she has primary immunodeficiency diseases.

Today we've invited Hong Kong Children's Hospital, Department of Paediatrics and Adolescent Medicine, Honorary Consultant Professor Lau Yu-lung to explain this to us.

Hello, Professor Lau, can you please share with us, what kind of disease is it actually?

Prof. Lau Yu-lung:

As the name suggests, it is a congenital disease. The genes have gone wrong. It's an immune deficiency. There's a problem with the defense system.

Then what are genes? In fact, our body carries about 20,000 genes. You can think of genes as…each gene is an instruction manual. This instruction manual tells our body what protein you need to make, how is it structured. Try to imagine in that manual, on page 12 or page 7, paragraph 8, line 5, there's an error. The product will be defective. It's all caused by genetic defects and causes resistance or the immune system to have some flaws. It's congenital immunodeficiency.

Host:

You mentioned the immune system. In fact, what does the immune system mainly consist of? How important it is in our bodies?

Prof. Lau Yu-lung:

To use an analogy, we have the Great Wall of China. If bacteria are to invade, they must break down this Great Wall. Our skin and mucous membranes is our Great Wall. Because bacteria and viruses have to penetrate our mucous membranes and skin to infect us. Of course there are many soldiers in the Great Wall. These soldiers are our immune cells and immune proteins. There are a few of the most important immune cells. There are T cells and B cells. There is also a type called phagocytes, specially for swallowing viruses and germs. T cells are the most important of all kinds of cells. It is the general and commander in this army.

Host:

If you have a compromised immune system, what problems will it cause?

Prof. Lau Yu-lung:

If the child has primary immunodeficiency, there are three aspects to think about.

The first is that there is a big problem with infection because he has no resistance. Once he or she gets some viruses or bacteria, it will be difficult to clear. Others can recover on the fifth and seventh day. He or she cannot. It may be a few weeks, or even a few months and still not recovered. And when the condition gets better, actually, it's still not 100% recovered. There are some prognostic symptoms, such as cough or phlegm. Some have light fever.

Another thing is like those with rheumatism, they have fever…fever for no reason. But it's not infection. Some have a rash, joint pain, bone pain. This is the second one. Those are the characteristics.

The third one is, everyone knows there are more and more allergies. It turns out that some people have serious allergies, such as asthma, which is very difficult to treat. Or your eczema is hard to treat, or urticaria. For no reason they have urticaria that lasts a long time. These are all possible disorders from immunodeficiency.

Host:

What is the most worrying thing about repeated infections? Will it be very dangerous?

Prof. Lau Yu-lung:

It depends on where your infection is. If it really penetrates our Great Wall, through our skin and mucous membranes into our blood stream, then the body will be poisoned. Blood circulates throughout the body, and if it reaches the brain, it will cause meningitis, or pneumonia in the lungs, arthritis in joints, osteitis if it reaches the bone. It's a serious infection. Of course, the skin and mucous membranes can be infected. But there is still the Great Wall on the outside. There's no need to be too nervous.

Host:

Children always feel uncomfortable, especially those just entering kindergarten. Maybe when a classmate is infected, then children will be infected. Maybe they are always sick. Parents will be very worried that, is there immunodeficiency disorder in the system?

Prof. Lau Yu-lung:

Let's say, babies are born like a blank sheet of paper. The immune system is the same. When I was born, I had no resistance. How do we get resistance? In fact, in the first five years, you keep encountering viruses and bacteria. Of course, a mother would be worried. There's fever and cough. But most importantly the illness will not last more than five days. They will be fine in six or seven days. We mean 100% recovered. That is, before the child gets infected next time, the child is completely normal, jumping up and down happily, can eat and play, can grow their weight and height. No need to worry. Because every normal child gets infections 8 to 10 times each year, a few dozen times in five years. So, at five years old, a child probably has gone through 40 or 50 lessons.

Host:

For immunodeficiency, is it possible to check for it? Can newborn screening which is now often done find out?

Prof. Lau Yu-lung:

Supposed so. It's not too late for Hong Kong. Because the United States or Western countries have been doing it for eight, ten years or so. Hong Kong started some two or three years ago. The SAR government has undertaken to provide funding to establish one that, when a baby is born, it screens for T-cell deficiency.

The audience just learned that T cells are our most important so-called commander-in-chief. So, it is aimed at checking this T cell, for whether there is any defect. Because of T-cell deficiency will lead to severe immunodeficiency which would require transplant to cure it.

Host:

Why is early screening important? Doctor, do you have any cases to share?

Prof. Lau Yu-lung:

I do have. Because this screening started in the last two or three years. Ten years ago, there was a kid. At that time, I was in the Immunology Department of Queen Mary Hospital. That was the most serious diagnosis of an immunodeficiency case which required a transplant. But there was no screening at that time. So this case, it wasn't until almost four or five months of age, the child was diagnosed.

At that time, BCG was a vaccine. Children in Hong Kong are vaccinated as soon as they are born. Because it is a live vaccine, because you have no resistance, the vaccine doesn't usually have any effect on a normal baby, but caused serious blood infections in this child. It had spread all over his skin, bones, liver and viscera. The transplant was quite difficult. It took many months to heal.

The past six months, because the mother, after ten years, has the courage to give birth again, so the boy has a sibling to play with and communicate with. She said, "Dr. Lau, we trust you. I don't want to be screened for this disease. Just give birth and see a doctor later. The result is both fortunate and unfortunate. The process went well. She gave birth about a month ago in Queen Mary Hospital. Because we already knew his brother has this disease, so we knew in less than a day, there was this serious defect. We went to the Children's Hospital on the same day, carried out a very successful bone marrow transplant, with the mother as the donor of stem cells. Before coming here, I saw the mother at the Children's Hospital. She knows that I'm there, so she called me right away, and said "Dr. Lau, let's take a photo". I am very happy.

Host:

Great. Thank you, Professor Lau, for sharing with us. Let's wrap it up here. Goodbye.