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He’s always sick: ENT infections and immunodeficiency

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Otis is a three year old boy presenting to the emergency department with a fever and purulent discharge from his left ear. He otherwise looks well. However, his mother mentions this is his third ear infection since he was born, and he always seems to have a cough and a cold. She asks you if there could be a problem with his immune system.

Some children have constant ear, nose or throat infections during childhood. We know that for a small but significant minority of children, this may be the presenting feature of primary immunodeficiency. Let’s look at how these may present, when to think of it and what to do about it.

Primary immunodeficiency is rare

It’s worth stating from the outset that the majority of children with recurrent ENT infections will not have a primary immunodeficiency. There is a relatively common phenomenon called “physiological immunodeficiency of infancy”, where-by there is a natural nadir in immunoglobulin levels as maternal immunoglobulin fades, and the child’s immune system has only just become able to produce immunoglobulin for itself. This is at its lowest between 3-6 months and resolves typically by age 1. However, fully developed protection against encapsulated organisms doesn’t reach maturity until between 2-5 years, and IgA production doesn’t reach adult levels until adolescence. It can be normal for young children to suffer 4-11 respiratory infections a year (depending on exposure, e.g. siblings, nursery, etc.)

When should I suspect immunodeficiency?

When considering the characteristics of infections that should trigger suspicion for immunodeficiency, we should be thinking about the following:

More severe infections than is usual

Combined immunodeficiency disorders (affecting both cellular and humoral immunity), such as severe combined immunodeficiency (SCID), present in the first 3-6 months with severe, life-threatening infection. Unusually aggressive infections should prompt further investigation.

Infections with unusual organisms

Infections with certain pathogens can point towards specific diagnoses, including respiratory infections with Pseudomonas aeruginosa (think cystic fibrosis or primary ciliary dyskinesia), oral/oesophageal candidiasis (consider HIV or chronic granulomatous disease), upper respiratory infections with Pneumocystis carinii (think HIV or other T cell deficiencies) or recurrent otitis/sinusitis with Neisseria meningitidis (think complement deficiency).

Finally, to a lesser extent:

Frequency of infection

This is the least predictive of immunodeficiency, given the discussion above. Persistent sinopulmonary infections in younger children with encapsulated bacteria can be the presenting feature of the rare condition X-linked agammaglobulinaemia (XLA: boys who produce no immunoglobulins). In late childhood and adolescence, the same presentation in a milder form may be a sign of combined, variable immunodeficiency (CVID), a heterogeneous group of disorders of antibody production.

Other rare conditions include chronic granulomatous disease (CGD), which may present with deep abscesses of the outer ear or mastoid, or HIV presenting with recurrent otitis media (usually with other associated features)

When to refer

The Jeffrey Modell foundation has produced some general guidelines for when to consider referral for immunodeficiency workup:

  • Four of more new ear infections within 1 year
  • Two or more serious sinus infections within 1 year
  • Two or more months on antibiotics with little effect
  • Two or more pneumonias within 1 year
  • Failure of an infant to gain weight or grow properly
  • Recurrent, deep skin or organ abscesses
  • Persistent thrush in the mouth or fungal infection on skin
  • Need for intravenous antibiotics to clear infections
  • Two or more deep-seated infections including septicaemia
  • A family history of primary immunodeficiency

Although low specificity, they provide a helpful framework when thinking of children with more severe infections than usual.

Should I do some tests?

If considering referral, some basic tests are helpful to do first (if the child is severely unwell, don’t wait for tests to refer).

Full blood count

This is useful for ANY suspected immunodeficiency. Persistent lymphopaenia in a child <2yrs should prompt screening for SCID.

NB: It can be normal to have transient lymphopaenia or neutropaenia in isolation in young children following a viral illness. Incidental neutropaenia does not need repeat testing if there are no concerns about underlying immunodeficiency.

Immunoglobulins

IgG, IgM and IgA levels are helpful in investigating children with recurrent ENT/airway infections.

It is also worth considering an HIV test if symptoms are consistent, but ensure you have a discussion with parents before testing.

If both FBC and immunoglobulins are normal in recurrent infections, it is perfectly acceptable to wait for 3 -6 months to see if the condition improves before referral.

Conclusions

Primary immunodeficiencies are rare but important, and ENT infections may be the presenting feature

The severity of infection and presence of opportunistic pathogens are a much stronger predictor than the frequency of infections

Basic tests such as FBC and Immunoglobulins should be performed in children prior to/pending referral if they are not severely unwell

Consider investigation and referral for primary immunodeficiency early in children with severe infections and failure to thrive, or those with family history

Further reading: https://www.entmasterclass.com/ENT_Journal_2019_Interactive.pdf page 9

Author

  • Alasdair Munro is a Paediatric registrar in the UK, currently working as a Clinical Research Fellow in Paediatric Infectious Diseases. His interests include evidence based medicine, diagnostics and antimicrobial resistance. @apsmunro | Ally's DFTB posts

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