We rely on our immune system to defend against infectious diseases. If the immune system is compromised, all sorts of germs – viruses, bacteria, fungi, parasites, etc, may invade our bodies without too much resistance. We call this condition immunodeficiency.
This happens when the major components of the immune system, the white blood cells, have defects either in quantity and / or quality. Secondary or acquired immunodeficiencies are relatively common, as they can be induced by environmental factors such as drugs (particularly those used in treating cancers and after organ transplantation, and corticosteroids), HIV virus, malnutrition, etc. Primary immunodeficiency diseases (PIDD), on the other side, are a rare entity. The defects are hereditary or genetic. So far more than 185 different PIDD have been identified, and the list is still growing.
Immunodeficiency may be suspected if you have recurrent or frequent infections (pneumonia, bronchitis, sinusitis, ear infections, skin abscesses, etc), the infections are hard to control requiring multiple courses or intravenous antibiotics, or the causative organisms are uncommon. Some other signs may also occur with PIDD such as poor growth or loss of weight, swollen lymph nodes or an enlarged spleen, autoimmune diseases (anemia, decreased platelet count, etc).
If your immunologist has a high suspicion for immunodeficiency, he / she will likely order blood work to evaluate immune cell numbers and functions.
For more information, go to http://primaryimmune.org/