It is normal for a healthy child to have 6-8 respiratory infections per year. Frequent infections are common when starting nursery or school and during the winter months. Most children with recurrent infections have a normal immune system. \
Causes
The most common cause is increased exposure to infections (e.g., at nursery, school, and with siblings).
Key pathological causes of recurrent infections in children include:
- Primary immunodeficiency disorders (e.g., selective IgA deficiency or severe combined immunodeficiency)
- Secondary immunodeficiency (e.g., HIV infection, malnutrition or immunosuppressants)
- Respiratory conditions (e.g., asthma, cystic fibrosis, primary ciliary dyskinesia or bronchiectasis)
- Anatomical abnormalities (e.g., urinary tract, adenoidal hypertrophy or heart defects)
- Neurological disorders causing swallowing difficulties and aspiration (e.g., cerebral palsy)
- Haematological disorders (e.g., sickle cell disease or leukaemia)
Features
Unusual features associated with recurrent infections may suggest underlying immunodeficiency or other pathology, for example:
- Chronic diarrhoea since infancy
- Poor growth or failure to thrive
- Recurrent severe infections (e.g., requiring IV antibiotics)
- Persistent oral thrush after infancy
- Unusual organisms (e.g., Pneumocystis jirovecii)
- Recurrent infections across multiple sites
- Family history of immunodeficiency
Investigations
A specialist referral is indicated when a pathological cause of recurrent infections is suspected. A full history and examination will guide the choice of investigations, which may include:
- Full blood count: Low lymphocytes suggest a possible T-cell disorder
- Immunoglobulins: Abnormalities suggest a B-cell disorder
- Complement testing: Abnormalities suggest a complement disorder
- Antibody responses to vaccines (e.g., tetanus, pneumococcal and Haemophilus influenzae type b)
- HIV test
- Chest x-ray for chronic infections and structural abnormalities
- Sweat test for cystic fibrosis
Last updated April 2026
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