Post-arrival infection screening — formative SAQs

SAQ 1 (10 marks)

A four-year-old girl has just arrived from an orphanage in a resource-limited country to join her adoptive family. She looks well, but the pre-adoption records are sparse, in a language the family does not read, and list a hepatitis B surface antigen result and an incomplete vaccination record. The family asks what tests their daughter needs. ^[1]

Question: Outline the comprehensive post-arrival infection screen you will perform, the principle that governs it, and your plan for catch-up immunisation. (10 marks) ^[4]

Model answer

The governing principle — re-verification (2 marks). The single behaviour that defines a competent screen is that a documented pre-adoption, overseas or pre-departure record is a starting point, never a substitute. I repeat every serology that matters in my own laboratory before acting on the paper, and I check vaccine immunity serologically rather than trusting the record, because records may be incomplete, untranslated, fabricated, or record doses that did not take. ^{[1] [4]}

The core infection panel (4 marks). I send the must-not-miss five. For tuberculosis I use an interferon-gamma release assay (IGRA) in a child of four, because it is unaffected by prior BCG vaccination and requires a single visit; a positive result is followed by a chest radiograph and symptom screen to distinguish latent from active disease. I send a fourth-generation HIV antigen-antibody assay, a hepatitis B surface antigen with surface antibody and core antibody, a hepatitis C antibody, and syphilis serology, and I confirm every positive — for example, a positive hepatitis C antibody is confirmed with a hepatitis C RNA nucleic-acid test, because only a viraemic child has chronic infection amenable to cure with direct-acting antivirals. ^{[8] [5]}

The parasitic and nutritional screen (2 marks). I send stool for ova, cysts and parasites (ideally three samples) together with Strongyloides stercoralis serology and, given her region of origin, Schistosoma serology, because stool microscopy alone has a low sensitivity for chronic tissue-dwelling parasites and serology is the standard. I add a full blood count with eosinophil count, iron studies, and a blood-lead level. The reason serology matters is that Strongyloides can persist for decades and cause fatal hyperinfection during later immunosuppression, and it is curable today with ivermectin — so finding and treating it now is the point of the screen. ^{[10] [9]}

Catch-up immunisation and the medical home (2 marks). After serology I build the catch-up schedule on the evidence: the child without documented and serologically confirmed immunity to a vaccine-preventable disease is vaccinated on an accelerated catch-up schedule respecting minimum ages and intervals, and the child with evidence of immunity is not over-vaccinated. I assess growth, development and mental health in parallel, give the family a clear interpreter-mediated summary and a named clinician, and arrange dental, vision and hearing care, because the screen is the entry to the medical home rather than a checklist. ^{[4] [8]}