What are frequent infections?
We live in a sea of germs, and everyone gets an infection at least once in a while. However, some people get recurring infections that need to be treated with antibiotics more frequently than advisable. For instance, a child, age two, who has had eight ear infections in one year is more than normally seen in healthy children. An adult or adolescent who needs antibiotics six to eight times every year to treat sinusitis and bronchitis is possibly suffering from a weak immune system. Other people with immune problems tend to have not only frequent infections, but infections that last longer and are more severe than the infections that most people get. An allergy and immunology specialist who is treating patients with infection problems will be trying to understand the number, type and reasons for those infections. Uncovering these answers will help in establishing a prevention strategy and early treatment if an immune abnormality exists.
Infection occurs when a disease-causing germ such as a bacteria, virus or fungus invades the body. To become infected, you must catch the germ (exposure) and have the ability to become infected (susceptibility). Exposure is something that your grandmother warned you about when she told you to stay away from Johnny because he was sick. Those in positions with a lot of people contact, such as elementary school teachers or salespersons, are more likely to be exposed to increased numbers of germs.
Susceptibility is more complicated than exposure. We are all susceptible to infection by thousands of different germs. The purpose of the immune system is to prevent infection by recognizing germs and eliminating or disabling them before they can cause infection. Remarkably, the immune system has the unique ability to learn the “face” of a germ and remember it forever. Some germ families have faces that are so similar that when your immune system learns the face of one member of the family, it protects you from infection by any member of that family. Other germ families are so different that the immune system must learn each face individually. Once your healthy immune system has learned the face of a particular germ and successfully battled it, you are no longer susceptible to infection caused by that germ.
The first line of defense against infection is located where the body has contact with the rest of the world; the skin, as well as the mucus membranes that line the respiratory system and the digestive system. Clearly, a cut on the hand is more likely to get infected than unbroken skin. Similarly, any irritation, swelling, injury or overwhelming viral or bacterial exposure to the mucus membranes lining the nose, sinuses and lungs may promote infection from disease-causing germs. If you have heavy exposure to infections such as school teachers, or if you have year-round allergies to dust mites, pollen and mold, you may be more susceptible to infection but still have a normal immune system. For some, however, frequent, prolonged, or unusually complicated infections represent a weakened immune system and a need for more specific diagnosis and treatment.
We must understand first what a normal pattern of infection is in order to understand what is abnormal. The most common infections are viral respiratory tract infections, commonly referred to as colds. The average young child between one and three years of age may get up to 12 colds a year. Typically, cold symptoms last five to 10 days. If a child gets 12 colds a year, each lasting less than 10 days and usually improving without needing treatment with antibiotics, it may seem like they are sick most of the time, because they are. These infections, however, are not a cause for concern. Colds are the result of the close contact of young children with other infected children and the fact that their immune systems are relatively immature. Once a child’s immune system learns the faces of many of the germs that cause such colds, the child will get infected less frequently.
Another infection, strep throat, is also a disease that children and adults catch because they are in close contact with infected individuals. Although we don’t completely understand why some people get strep throat frequently, we know that recurrent strep throat is rarely an indicator of immunodeficiency.
Many people confuse allergic rhinosinusitis, commonly referred to as hay fever (which causes stuffiness, nasal itch and a runny nose that lasts for weeks, but is not an infection) with a cold or sinus infection. Your allergy and immunology specialist can help you differentiate allergies from infection, or know when both are present at the same time. Once the possibility of allergy is eliminated, your allergy and immunology specialist will consider which infections reflect a high exposure to other people with infection, and which infections are warning signals of an immune system problem called immunodeficiency. There are many forms of immunodeficiency and while some are very severe and life-threatening, many are milder but still important enough to cause recurrent or unusual infections.
People with immunodeficiency get the same kinds of infections that other people get, such as ear infections, sinusitis and pneumonia. The difference is that their infections occur more frequently, are often more severe, and have a greater risk of complications. Furthermore, the infections rarely go away without using antibiotics and they often reoccur within one to two weeks after the antibiotic treatment is completed. These patients frequently need many courses of antibiotics each year to stay healthy. Patients with some forms of immunodeficiency are more likely than other people to develop infections inside the body, for example, in the bones, joints, liver, heart or brain.
In most cases, the frequency of infection is the most important issue, but sometimes a single infection with an unusual germ is enough to trigger the need for a physician to perform a thorough immunologic evaluation of the patient.
So, how many infections are too many? Allergy and immunology specialists often use the frequency of antibiotic use to mark the occurrence of frequent infections. Older children and adults with healthy immune systems seldom require antibiotic treatment. However, for the reasons mentioned above, 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 five years of age is clearly abnormal in older children and adults.
General guidelines for determining if a patient is 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 3 to 5 years of age
- The development of pneumonia twice over any time period
- The occurrence of more than three episodes of bacterial sinusitis in one year or 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
If a patient has any of the conditions noted above, the need for an immunodeficiency evaluation may be indicated. Very often, this evaluation may give reassuring results and even improve the patient’s immunity since immunizations may be part of the evaluation. If an immunodeficiency is detected, early treatment prevents complications from infections that then contribute to making other infections worse and more difficult to treat.
Although infants are more likely to contract respiratory tract infections than older patients, monitoring infection in infants and small children is especially important because the most serious immunodeficiencies usually become apparent during the first years of life. Persistent fungal infection of the mouth or skin, prolonged diarrhea or persistent cough are all signs that suggest a physician should examine the patient further. If a primary care or family physician believes that a patient’s infections exceed the normal range, the patient should be referred to an allergy and immunology specialist.
How are frequent infections diagnosed?
The most common forms of immunodeficiency are caused by defects in the patient’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 more fully evaluate your antibody health, it may be important to measure a specific antibody response by giving you diptheria, tetanus and pneumococcal (pneumonia) vaccines and performing a blood test before immunization and three to four weeks afterward. Skin tests or more specialized blood tests can diagnose other forms of immunodeficiency. Allergy skin tests are commonly done because allergies often contribute to infection susceptibility, and many patients with immunodeficiency also suffer from allergies.
How are frequent infections treated?
Understanding the basis of a patient’s susceptibility to infections is the key to minimizing infection problems. Once your allergy and immunology specialist properly diagnoses your susceptibility, treatments can be provided that help you lead a more full life.
Treatments are available for many immunodeficiencies. For example, the most common forms of immunodeficiency are treated with infusions of antibodies called intravenous immunoglobulins (IVIG). Your allergy and immunology specialist is experienced in using such treatments, which help minimize infection, speed your recovery, and strengthen your immune system.
How are frequent infections avoided?
Patients who have a family history of immunodeficiency or unexplained severe infections should be evaluated for an immunodeficiency even before they develop any infections. This may be done at birth in some cases. An allergy and immunology specialist will be able to counsel patients about the risk of other family members being carriers or about 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. Recognition of these situations is very important since infections and their complications may be prevented by an early diagnosis and prompt institution of corrective measures.
Since most immune deficiencies are genetically based, there is no cure at the present time. However, proper evaluation and diagnosis will eventually open the door to cures as medical science progresses.
- American Academy of Allergy, Asthma & Immunology http://www.aaaai.org/patients.stm