About PID

Primary immunodeficiencies (PIDs) are a group of more than 400 potentially serious disorders, that can lead to frequent or severe infections, swellings and autoimmune problems. PID symptoms often appear in childhood, but some can first occur in adults.

PIDs can be caused by defects in the genes that control the immune system, and may be inherited. PIDs are different to AIDS (acquired immunodeficiency syndrome), that is due to human immunodeficiency virus (HIV).

PIDs occur when the immune system does not work normally. The most important role of the body's immune system is to defend against infections and other invaders (such as cancer cells), whilst protecting the body’s own cells. Everyone gets infections, however in people with PIDs these can be:

  • Unusually persistent, recurrent or resistant to treatment.
  • Due to unusual germs (bacteria, viruses, fungi and parasites).
  • Unexpectedly severe.

Some PIDs may increase the chance of autoimmunity or cancer. Autoimmunity occurs when the body doesn’t recognise its own cells and attacks them.

Early diagnosis of PIDs is important, since delayed treatment can result in complications, that may be life threatening. If someone has two or more of the following warning signs, they should discuss the possibility of having a PID with their doctor.



Four or more ear infections within one year

Two or more ear infections within one year

Two or more serious sinus infections within one year

Two or more sinus infections in one year in the absence of allergies

Two or more pneumonias within one year

One pneumonia per year for more than one year

Recurrent, deep skin or organ abscesses

Recurrent, deep skin or organ abscesses

Two or more deep seated infections such as sepsis, meningitis or cellulitis

Infection with normally harmless tuberculosis-like bacteria

Persistent thrush in the mouth, skin or elsewhere after age one

Persistent thrush or fungal infection on skin or elsewhere

Two or more months on antibiotics with little effect

Repeat viral infections (colds, herpes, warts, condyloma)

Need for intravenous antibiotics to clear infections

Need for intravenous antibiotics to clear infections

Failure to gain weight, grow normally, or chronic diarrhoea

Chronic diarrhoea with weight loss

Family history of PID

Family history of PID

This table is adapted from the 10 warning signs developed by the Jeffrey Modell Foundation www.info4pi.org

For more information go to www.immunodeficiencies.org.au 

Content created March 2019

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