Environmental conditions (daycare, school) – An infant or toddler at home may get 5-6 upper respiratory infections a year. The same child in daycare may get 10-12 a year. Over time, the immune system builds up and infections become less frequent.
Allergies (allergic rhinitis) – Allergic inflammation in the nose often blocks the sinuses and Eustachian tubes, resulting in frequent sinus and ear infections.
Immune deficiencies – The body’s immune system may not have all the usual “weapons” to fight off infections, thus making one susceptible to frequent infections. There are a number of deficiencies, some mild and others severe, which can lead to recurring infections.
Structural abnormalities (nasal polyps, enlarged adenoids) – A structural abnormality can lead to recurring infections in one particular area, such as a nasal polyp which blocks the opening to one of the sinuses and leads to frequent infections of that sinus.