The immune system is a network of cells, tissues, organs, and proteins that work together to defend the body against microbes considered “foreign invaders.” Although very complex, it can be thought of as a well-trained army with elaborate communication and different soldiers trained for specific jobs.
Cells are defined by their jobs. “Helper cells” communicate information to the rest of the army. “Killer cells” directly destroy bacteria, viruses, and cancer cells. “Factory cells” churn out protein “flags” or “uniforms” to identify which microbes are bad. “Memory cells” are able to recognize previous invaders quickly. “Suppressor cells” call off the battle when the illness is over.
This army is a vigilant and powerful force. However, if one part is either absent or not functioning properly, a weak spot forms in the defenses. This is called an immunodeficiency. Individuals with an immunodeficiency experience infections more frequently, more severely, and for longer periods of time.
Some immunodeficiency disorders affect just a single protein in the immune system’s “army.” Other disorders affect multiple parts of the immune system. Therefore, the severity of the symptoms can vary tremendously. Immune disorders are as complex as the immune system itself.
Approximately two hundred different types of immunodeficiencies have been identified, only one of which is known to be caused by the well-known HIV virus. Immunodeficiency disorders can be inherited (genetic), acquired by infection, or be a temporary side effect of specific medical therapies. Immunodeficiencies with a genetic cause are called primary immunodeficiencies. One hundred and eighty-five of the known types of immunodeficiencies are genetic and fall into the category of primary immunodeficiency.
Some types of immunodeficiencies become apparent in infancy, while others may not be diagnosed until adulthood. Immunodeficiency disorders can go undetected because they do not produce unique symptoms. Rather, they appear as “ordinary” infections, such as sinus, lower respiratory, or gastrointestinal infections.
So, how does one know when an infection is a sign of a more serious problem? Immunodeficiencies should be considered to be the case if an infection is severe, unusual, difficult to treat, or recurrent. Immunodeficiency is also more likely in individuals with autoimmune disease or with a family history of immunodeficiency.
Examples of concerning infections include those that are very slow to improve, caused by unusual organisms, continue to recur, or require hospitalization and IV antibiotics.