This Topic of the Month Answers the Following Questions

News from the American Academy of Allergy, Asthma and Immunology

Topic of the Month - April 2007

Primary Immunodeficiency Diseases

What is primary immunodeficiency?

This Topic of the Month answers the following questions: People with immunodeficiency get the same kinds of infections that other people get-ear infections, sinusitis and pneumonia.  What is primary immunodeficiency? The difference is that their infections occur more frequently, are  What causes primary immunodeficiency? often more severe and have a greater risk of complications.  How is immunodeficiency recognized in children?  How is a diagnosis made? Patients who have immunodeficiency get infections that usually  How many infections are too many? do not go away without using antibiotics and often recur within  How is immunodeficiency treated? one to two weeks after antibiotic treatment is completed. These individuals frequently need many courses of antibiotics each year  When should someone see an allergist/immunologist? to stay healthy.

There are several forms of immunodeficiency, some of which are very severe and life-threatening. For example, patients with severe forms of immunodeficiency are more likely than other people to develop infections inside certain areas of the body, such as the bones, joints, liver, heart or brain. Other forms of immunodeficiency are milder but still important enough to cause recurrent and severe infections.

What causes primary immunodeficiency?

The most common forms of immunodeficiency are caused by defects in a person's ability to produce blood proteins called antibodies. Antibodies are proteins that attach to germs and help the body eliminate them. Simple blood tests can measure the number of antibodies a patient is producing. To fully evaluate an individual's antibodies, it may be important to measure specific antibody responses by giving them diptheria, tetanus and pneumococcal (pneumonia) vaccines and performing a blood test before immunization and three to four weeks later.

Skin tests or more specialized blood tests can diagnose other forms of immunodeficiency. Allergy skin tests are sometimes done because allergies often contribute to infection susceptibility, and many patients with immunodeficiency also suffer from allergies.

How is immunodeficiency recognized in children?

Although small children are expected to have a large number of respiratory infections, it is important to monitor children for unusually frequent or severe infections. This is because the most serious immunodeficiencies usually become apparent during the first years of life. Signs that a physician should consider examining a patient further for possible immunodeficiency include persistent fungal infection of the mouth or skin, prolonged diarrhea or persistent cough. If a primary care or family physician believes that a patient's infections exceed the normal range, the doctor should consider referring the patient to an allergy/immunology specialist.

How is a diagnosis of immunodeficiency made?

In most cases, a higher than normal frequency of infection is the most important issue, but sometimes a single infection with an unusual germ is enough to trigger the need for the doctor to perform a thorough evaluation of the patient. Allergist/immunologists often use the frequency of the use of antibiotics to mark the frequency of significant infections. Older children and adults with healthy immune systems seldom require antibiotic treatment. However, for the reasons mentioned earlier, many younger children receive several courses of antibiotic therapy each year. Therefore, the number of ear infections that may be "normal" in a child under 5 years of age is clearly abnormal in older children and adults.

How many infections are too many?

General guidelines for determining if a patient may be experiencing too many infections are:

 The need for more than four courses of antibiotic treatment per year in children or more that two times per year in adults.  The occurrence of more than four new ear infections in one year after four years of age.  The development of pneumonia twice over any time.  The occurrence of more than three episodes of bacterial sinusitis in one year or the occurrence of chronic sinusitis.  The need for preventive antibiotics to decrease the number of infections.  Any unusually severe infection or infections caused by bacteria that do not usually cause problems in most people at the patient's age.

Patients who have a family history of immunodeficiency or unexplained severe infections should also sometimes be evaluated for an immunodeficiency, even before they develop any infections. This may be done at birth in some cases. An allergist/immunologist will be able to counsel patients about the risk of other family members being carriers of or being affected by an immunodeficiency. Other patients may have immunodeficiencies that can be recognized before the development of infections because of the presence of other abnormalities, such as congenital malformations. It is important to recognize these situations since infections and their complications may be prevented by an early diagnosis and prompt institution of corrective measures.

How is immunodeficiency treated?

The key to minimizing problems with infections is to understand the basis of the immunodeficiency by using appropriate testing. Once a physician properly diagnoses a patient's immunodeficiency, he or she can provide treatments that will help them lead a more full life. Treatments are available for many immunodeficiencies. For example, the most common forms of immunodeficiency are often treated with infusions of antibodies called intravenous immunoglobulins (IVIG). IVIG essentially replaces the antibodies that your body is unable to make. An allergist/immunologist is experienced in using such treatments, which help minimize infections, speeds recovery and strengthens the immune system.

When should someone see an allergist/immunologist?

If you experience recurrent and usually severe infections, an allergist/immunologist will consider if you need to be evaluated for immunodeficiency. Very often, this evaluation may give reassuring results and even improve your immunity since immunizations may be part of the evaluation. If an immunodeficiency is detected, early treatment prevents complications of infections that then contribute to making other infections worse and more difficult to treat. Patients should consult with an allergist/immunologist for more information on recurrent infections, immunodeficiency, proper diagnosis and treatments.

The AAAAI's How the Allergist/Immunologist Can Help: Consultation and Referral Guidelines Citing the Evidence provide information to assist patients and health care professionals in determining when a patient may need consultation or ongoing specialty care by the allergist/immunologist. Patients should see an allergist/immunologist if they:

 Have chronic or recurrent infectious rhinosinusitis.  Have any of the following warning signs:  Eight or more new infections within one year.  Two or more serious sinus infections within one year.  Two or more months on antibiotic with little or no 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 year.  Need for intravenous antibiotics to clear infections.  Two or more deep seated infections.  A family history of immune deficiency.

Additional Resources

o Tips to Remember: Recurrent Infections o Fast Facts: Immunology o News Release: Treatment of Immunodeficiency Disorders o Tips to Remember: Role of the Allergist/Immunologist o Allergic Conditions: Infections

This topic was reviewed on 4/1/2007 by Stuart Friedman, MD, FAAAAI, Patients & Consumers Web Editor.