The Immunocompromised Host: The Patient with Recurrent Infection

Absract

In childhood the immune system is less effective as it is encountering antigens for the first time, learning how to make adequate responses, and acquiring memory. Young children often mix with other children in their family or nursery and so are exposed to many pathogens. As a result recurrent infection is not uncommon, sometimes raising concern that immune function is abnormal. Most children with recurrent infection have a normal immune system but a pattern of recurrent or persistent infection is also a cardinal manifestation of primary immune deficiency (PID). How do we recognize the child with an underlying PID and investigate and treat appropriately? This is an important question as normal children should not be over-investigated yet prompt recognition and early diagnosis of immunodeficiency should ensure treatment before end organ damage has occurred. For example, early institution of replacement intravenous immunoglobulin therapy for antibody deficient patients will prevent bronchiectasis or halt further damage; early diagnosis of Severe Combined Immune Deficiency (SCID) means bone marrow transplantation is more likely to succeed as it can be performed before life threatening infective damage has occurred. Early and accurate diagnosis also helps predict prognosis and facilitates genetic counselling and an accurate prediction of risk to future siblings.