Mrs Riani comes with her daughter Shahilya to your practice for the first time. She is aged 16 months, and has extensive impetigo not responding to treatment with "herbal medication". You discover Shahilya has not been immunised. She has pustular and crusty, widespread lesions each surrounded by inflammation, mostly around the nostrils where it all began.

Mrs Riani tells you that she has four other children, none of whom are immunised, and none of them have contracted any of the diseases. She believes this is because they live a healthy and religious lifestyle and therefore have high "natural immunity".

Mrs Riani has some difficulties understanding English and has brought her cousin along to translate.