These often occur on a background of tiredness and lethargy:
Recurrent bacterial infections affecting the nose, sinuses and lungs cause green/yellow pus as a nasal discharge or sputum and can require repeated courses of antibiotics. If repeated courses of antibiotics are being prescribed, investigations may be indicated.
Specialised white blood cells (neutrophils) combine with antibodies (immunoglobulins) to fight bacterial infections and both can be easily measured. If total immunoglobulins are in the normal range, then more subtle defects of the antibody aspect of the immune system can be detected by the measurement of specific antibodies to the two main pathogens that affect the nose and lungs. Fortunately these latter defects can often be remedied by appropriate immunisations.
Recurrent skin infections can result from non-symptomatic staphylococcus aureus carriage in the nose (not MRSA) and again this can be usefully treated locally, once condition has been confirmed by bacterial cultures.
Recurrent viral upper respiratory tract infections (URTIs) are not uncommon especially when there are young children in the house! However if they become a clinical problem further tests can be considered.
Viruses are typically cleared by antibodies and certain white blood cells called lymphocytes. Both of these can be investigated.
Recurrent attacks of shingles (herpes zoster) and cold sores (herpes simplex) need appropriate investigation.