Immunology - Recurrent Infections

Question 1

How many respiratory infections do normal, healthy children have each year?

Answer 1

4-8 infections

When starting nursery or school and during winter months, children more likely to pick up recurrent infections

Question 2

What features of recurrent infection should lead to further assessment?

Answer 2

• Chronic diarrhoea, since infancy
• Failure to thrive
• Look unusually well with severe infection e.g. afebrile with large pneumonia
• More infections than expected - particularly bacterial LRTI
• Unusual or persistent infections e.g. CMV, candida and jiroveci

Question 3

What investigations are used for recurrent infections?

Answer 3

• FBC - low neutrophils (phagocytic disorder) low lymphocytes (T cell disorder)
• Immunoglobulin abnormalities (B cell disorders)
• Complement proteins
• Antibody response to vaccines
• HIV test
• CXR - scarring from previous infections
• Sweat test - CF
• CT - bronchiectasis

Question 4

What antibody responses are particularly important for identifying recurrent infections?

Answer 4

Pneumococcal and haemophilus vaccines