• Eosinophils >450 (Eos/ul)

• Useful in the assessment of travellers/migrants

• Helminth infections

• May be the only sign, commonly no symptoms

• May be less prominent in people from endemic countries

Causes

• Allergies, autoimmune

• Infections

  • Helminths: lung passage, tissue invasion (not in the early stage of infection): nematodes (whipworm, hookworm, strongyloides, trichinella), trematodes (schistosomiasis), cestodes (echinococcus)

  • Ectoparasites (scabies, myiasis)

  • Protozoa e.g. sarcocystis, cystoisospora belli

  • Resolving bacterial/viral infections "eosinophilic dawn"

  • Fungal e.g. coccidioidomycosis, paracoccidioidomycosis

  • HIV?

• Neoplasm

• Drugs

• Rare eosinophilic disorders

• Other

Assessment

• Travel, timing

• Exposures (freshwater, food, walking barefoot)

• Extent of eosinophilia

  • Stage of infection: early vs. late

  • Tissue invasion

  • Duration of infection

  • Immune response

• Other symptoms

  • Diarrhoea, abdominal discomfort

  • Skin: urticaria, migratory swellings, tracks

  • Jaundice

  • Neuro: headache, seizures

Investigations

• Stool OCP: for helminths (cannot always see strongyloides)

• Serology: (but issues with cross-reaction)

  • Schistosomiasis: (EIA, IFAT)

  • Strongyloides:

• Nucleic acid detection: strongyloides (but not sensitive)