What is Primary Immunodeficiency?
Primary Immunodeficiency (PID) is an inborn problem with the body’s immune system. The role of the immune system is to keep the body safe from viruses, bacteria, and other infections. Any problem with the immune system can result in frequent and severe infections. There are over 200 types of PID, some more severe than others.
When should you suspect PID?
Infections, especially viral ones, are very common throughout childhood and into adulthood. Young children in daycare are very susceptible to recurrent infections, particularly ear and sinus infections as well as the common cold. It is often difficult, then, to determine when a child may have a PID. In general, young children will have 8-1O upper respiratory infections per year. Older kids and adults can also expect to have at least a few mild infections yearly, especially during the winter.
In PID, people will often have recurrent infections that are slow to respond to antibiotics. They also have more severe infections, such as bone, joint, lung and blood infections that often require intravenous antibiotics and possible hospitalization. Specific criteria for when a doctor or parent should suspect a PID were developed by the Jeffrey Modell Foundation. Patients with two or more of these criteria should be evaluated for a PID.
- Four or more new ear infections within 1 year.
- Two or more serious sinus infections within 1 year.
- Two or more months on antibiotics with little effect.
- Two or more pneumonias within 1 year.
- Failure of an infant to gain weight or grow normally.
- Recurrent, deep skin or organ abscesses.
- Persistent thrush in mouth or elsewhere on skin, after age 1.
- Need for intravenous antibiotics to clear infections.
- Two or more deep-seated infections.
- A family history of Primary Immunodeficiency Disease.
How do we diagnose PID?
The diagnostic work-up of PID must be thorough and accurate. The doctor will perform a full history and physical exam. If warranted, the doctor will order appropriate lab tests evaluating the immune system. These tests will include a complete blood count to confirm that all of the immune cells are present in normal numbers. The doctor may also check immunoglobulin levels (lgG, IgA, etc). Immunoglobulins are proteins in the blood that help fight bacterial infections. If they are not present or do not work right, the patient is susceptible to recurrent and severe infections. The doctor may also check vaccine titers. This is to see if the patient responded to the vaccinations they received during childhood, such as tetanus. It is a great way to see if the immune system is working right. If the vaccine responses are low, the doctor may re-vaccinate the patient and re-check the vaccine response in 4 weeks. Again, if the vaccine does not promote the appropriate immune response, this indicates a problem with the immune system.
How do we treat PID?
If it is determined that a patient may have a PID, there are several treatment options. Some immune defects, such as IgA deficiency, only need close monitoring and occasional antibiotic therapy. More severe defects may require intravenous immunoglobulin (IVIG). IVIG replaces immunoglobulin that the patient is lacking. IVIG is taken from the blood of healthy individuals, appropriately processed and then stored. It is then given intravenously to immune deficient patients on a monthly basis. The infusion takes 3-4 hours and usually has no major side effects, although some patients get mild headaches and chills during or shortly after infusions. An alternative to intravenous replacement is to give the immunoglobulin subcutaneously. This route also has few side effects, but is self-administered and has the advantage of being done in the home. In addition, it may be better tolerated than IVIG. Both subcutaneous lg and IVIG will protect patients from recurrent infections and lessen their need for antibiotics. Most PID patients need these treatments for the rest of their lives.
If you believe that you or your child may have a problem with the immune system, Please notify your physician. The doctor will then determine if a full immunologic evaluation is warranted.