Primary immunodeficiency (PID), is a term used to cover a large number of different conditions that affect how the body’s immune system works. Sometimes these conditions are also referred to as primary immune deficiencies.
What is the immune system?
The immune system is made up of specialised cells, proteins, tissues and organs that defend people against germs, micro-organisms and some types of cancer. It works to keep people healthy and to prevent infection. When problems with the immune system occur, it can lead to illness and infection.
Why are they called primary?
They are called primary because of the basic, built-in nature of the immune deficiency. The term is used to separate PID from conditions where the immune system is affected by secondary causes, such as other diseases (e.g. HIV), drug treatment, chemotherapy, malnutrition or environmental exposure to toxins.
How do people get PID?
PIDs are mainly genetic disorders, meaning they are inherited and can be passed on from one generation to the next. They are caused by errors in the genes and proteins of the cells that make up the immune system. Most children with PID are born with the condition. In PID some of the DNA building blocks that make up the genes involved in the workings of the immune system are either not there or altered (‘mutated’). This results in either missing or faulty proteins, causing essential parts of the body’s defence against infection not to be made or work properly. For many PIDs the precise genetic mistake is now known, and understanding of these conditions is increasing all the time. Over 280 different PID conditions involving different parts of the immune system have now been identified.
What happens in PID?
Children with a PID have parts of their immune system missing or not working correctly, hence the term ‘deficiency’. This leaves them with reduced or no natural defence against germs, such as bacteria, fungi and viruses, which surround us every day.The consequences are that children with PID get infections more frequently than is usual and the infections can take longer to get better. When antibiotic treatment is required, PID patients are often prescribed longer and stronger courses. Even then sometimes the infections can come back. Susceptibility to infection is one of the most common symptoms of PID. Often PID is diagnosed early in a child’s life but signs of immunodeficiency can also occur for the first time in older children, teenagers or adults. Occasionally other medical problems can arise as complications of PIDs. These include ‘autoimmune’ and ‘inflammatory’ problems, where the immune system reacts inappropriately against the body’s own tissues, as well as a slightly increased risk of cancer in some conditions.
If your child has two or more of these signs, your child needs to be evaluated for Primary Immunodeficiency.
1 Four or more new ear infections within 1 year
2 Two or more serious sinus infections within 1 year
3 Two or more months on antibiotics with little effect
4 Two or more pneumonias within 1 year
5 Failure of an infant to gain weight or grow normally
6 Recurrent, deep skin or organ abscesses
7 Persistent thrush in mouth or fungal infection on skin
8 Need for intravenous antibiotics to clear infections
9 Two or more deep-seated infections including septicemia
10 A family history of Primary Immunodeficiency
What treatments are available?
The treatment you receive will be dependent on the type of PID you have and how it affects your immune system. A large proportion of people with a PID have immunoglobulin replacement therapy to help keep them free from infection and are given antibiotics as and when an infection occurs. Some other types of PID may involve taking antibiotic and/or antifungal medicine daily to stave off infection. More specialised treatments and potential cures for some types of PID include bone marrow transplantation, enzyme replacement therapy and gene therapy. Research is leading to a greater understanding of the causes of PID, leading to better-tailored treatments for those affected. Taking preventative measures to avoid exposure to infection also plays a key role in keeping people with a PID well.
