Post-arrival infection screening — branching viva

Opening question

Examiner: The registrar asks what screen this child needs. What is your frame, and what governs it? [9]

Candidate: My frame is that this child needs a single comprehensive post-arrival infection screen targeting the silent infections she looks well with — the must-not-miss five of tuberculosis, HIV, hepatitis B, hepatitis C, and parasitic and intestinal disease — plus a vaccination review, a nutritional assessment, and a developmental and mental-health screen. The single principle that governs it is re-verification: the overseas folder is a starting point, never a substitute, and I repeat every serology that matters in my own laboratory before I act on the paper. I deliver it in a trauma-informed frame with a trained interpreter, because this is the entry to the medical home, not a surveillance exercise. [9] [8]

Examiner: Why the must-not-miss five in particular? [7]

Candidate: Because these are the silent, chronic or latent infections that the child looks well with and that will harm her years from now if I do not find them today — and because every one of them is treatable. Latent tuberculosis reactivates years later and is prevented by a short-course regimen. Chronic hepatitis C is cured with direct-acting antivirals. HIV is transformed by antiretrovirals into a chronic controlled condition. Strongyloides can persist for decades and cause fatal hyperinfection at the first immunosuppression, and it is cured with ivermectin. The point of screening is that the well-looking child is the one carrying these conditions. [7] [10]

Branch 1 — the tuberculosis test

Examiner: How will you screen this four-year-old for tuberculosis, and why that test? [11]

Candidate: I will use an interferon-gamma release assay — an IGRA — because she is four and likely BCG-vaccinated, and the IGRA is preferred over the tuberculin skin test in children two years and over as it is unaffected by prior BCG and requires only a single visit. If the IGRA is positive, I follow it with a chest radiograph and a symptom screen to distinguish latent from active disease. The tuberculin skin test remains useful in young infants or where IGRA is unavailable, but it is harder to interpret in a BCG-vaccinated child. [11] [9]

Examiner: The IGRA comes back positive, the chest radiograph is normal, and she has no cough, fever or weight loss. What is the diagnosis and your management? [11]

Candidate: That is latent tuberculosis infection — a positive cell-mediated immune response with no radiographic or symptomatic evidence of active disease. I treat her to prevent future reactivation with an age-appropriate short-course regimen, for example three months of rifampicin plus isoniazid or four months of rifampicin per the national guideline, after excluding active disease. I involve paediatric infectious diseases and complete the public-health notification required by the local jurisdiction. [11] [9]

Branch 2 — the parasitic screen

Examiner: A colleague tells you that stool microscopy for ova, cysts and parasites is enough for the parasite screen. Do you agree? [10]

Candidate: No. Stool microscopy is part of the screen, but it has a low sensitivity for chronic Strongyloides and Schistosoma carriage, and a single negative stool does not exclude these infections. I send three stool samples plus serology for Strongyloides stercoralis and, given her region of origin, Schistosoma species. Serology is the standard in the Australasian and United Kingdom screening programmes, because these parasites persist silently for decades and carry the risk of fatal hyperinfection during later immunosuppression — and both are treatable today, ivermectin for Strongyloides and praziquantel for schistosomiasis. [10] [9]

Examiner: Her Strongyloides serology comes back positive. What do you do? [10]

Candidate: I treat her presumptively with ivermectin, because a positive serology reflects infection and the chronic carriage carries the future-hyperinfection risk. I do not wait for stool confirmation, because stool microscopy is the less sensitive test in chronic carriage. I also screen the household if they share the exposure, and I document the result so that she is never given corticosteroids or immunosuppression in future without this on the record. [10] [8]

Branch 3 — the blood-borne viruses

Examiner: Her hepatitis C antibody comes back positive. Walk me through your confirmation. [8]

Candidate: A positive hepatitis C antibody reflects exposure, not necessarily chronic infection, so I confirm it with a hepatitis C RNA nucleic-acid test. Only a viraemic child has chronic hepatitis C, and chronic hepatitis C in a child of treatment age is curable with direct-acting antivirals. If the RNA is negative, she has cleared the infection; if it is positive, I refer her for curative therapy and assess her for co-infection with hepatitis B and HIV, because co-infection changes the management. [8] [4]

Examiner: And if the child had been a four-month-old infant with a reactive HIV serology rather than a four-year-old? [8]

Candidate: That is a different algorithm, because maternal antibody persists for up to eighteen months, so a reactive HIV serology in an infant reflects exposure rather than infection. The diagnostic test in a child under eighteen months is an HIV DNA or RNA PCR, not serology. I would not treat a serology-positive infant as infected without PCR confirmation, and I would not dismiss the result either — the PCR resolves the ambiguity and the infant with confirmed infection starts antiretrovirals immediately. [8] [9]

Branch 4 — catch-up immunisation

Examiner: The overseas record lists a string of vaccines. How do you handle her immunisation? [4]

Candidate: I do not trust the record — I build the catch-up schedule on serological evidence. I test for antibodies to the vaccine-preventable diseases where serology is reliable — hepatitis B, measles, rubella, varicella, and where appropriate mumps and tetanus — and I vaccinate the child without immunity on an accelerated catch-up schedule that respects minimum ages and intervals. The child with evidence of immunity is not over-vaccinated. I prioritise measles-containing vaccine because the under-immunised migrant child is a recognised source of outbreaks, and I check hepatitis B vaccine status alongside the household-contact assessment, because a hepatitis B surface-antigen-positive child places her unvaccinated contacts at risk. [4] [8]

Branch 5 — equity and the medical home

Examiner: These families sometimes do not come back. How do you make the screen count? [9]

Candidate: By converting the screen into a relationship, not a checklist. I use a trained interpreter — never a child — because the consent, the history and the trust all depend on accurate communication. I give the family a clear, interpreter-mediated summary, a named clinician and a dated follow-up plan that delivers the treatment, the catch-up immunisation, the growth and developmental monitoring, the mental-health support, and the dental, vision and hearing care. The screen succeeds when it becomes the entry to the medical home, and the family returns because the relationship is there. [9] [7]

Wrap

Examiner: Summarise the post-arrival infection screen in one sentence. [9]

Candidate: Screen every migrant child for the must-not-miss five — tuberculosis, HIV, hepatitis B, hepatitis C, and parasitic disease — with a core panel built on the principle of re-verification, treat every positive because almost everything found is curable today, build catch-up immunisation on serological evidence, and convert the screen into a trauma-informed, interpreter-mediated medical home that owns the follow-up. [9] [10]