https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5810111/

Immigrant and refugee populations bring public health challenges to host nations. In the current global refugee crisis, children are the most vulnerable subpopulation. Diseases that were considered rare in the host nation may be highly prevalent among immigrant children. The prevalence of nutritional rickets is increasing in high-income countries, largely driven by an influx of immigrant populations.

Thacher TD, Pludowski P, Shaw NJ, Mughal MZ, Munns CF, Högler W. Public Health Rev. 2016 Jul 22;37:3. doi: 10.1186/s40985-016-0018-3. eCollection 2016. PMID: 29450045