Severe infections can both result and cause it. Lack of proper rest is yet another cause. Yet another cause are nutritional deficiencies. Some natural healing specialists believe that any infectious disease may be considered an immune deficiency problem. The taking of aspirin has been linked to Reye's syndrome, asthma, low birth weight and birth defects.
Meat contains hormones, antibiotics, and bacteria which brings on disease.
Alcohol, nicotine, and a high-sugar diet weaken the immune system. Hypothyroidism can also result in immune deficiency. Marijuana, cocaine, and the morphine family are other culprits. Mercury amalgam fillings are yet another incipient cause. Eat lots of fresh fruit and vegetables.