see also:

• allergy and hypersensitivity reactions
• urticaria
• eosinophilic meningitis - eosinophils predominate the CSF
• full blood examination (FBE)

• allergy and hypersensitivity reactions
• drug reactions:
  • asymptomatic eosinophilia:
    • olanzapine
  • drug reactions with eosinophilia and systemic symptoms (DRESS):
    • aromatic anticonvulsants and other antiepileptics, sulphonamides, allopurinol, non-steroidal anti-inflammatory drugs (NSAIDs), and certain antibiotics
  • eosinophilia-myalgia syndrome:
    • an incurable and sometimes fatal flu-like neurological condition that is believed to have been caused by ingestion of poorly produced L-tryptophan supplements¹⁾
• helminth infections (see below for eosinophilia in the returned traveller)
• eosinophilic enteropathy
• Hodgkin's lymphoma and some forms of non-Hodgkin's lymphoma
• leukaemia
• most other cancers can cause it, but more common in ovarian cancer
• systemic lupus erythematosus (SLE)
• cholesterol embolism (transiently)
• some vasculitides such as Churg-Strauss syndrome
• coccidioidomycosis - Arizona, southern California, New Mexico, western Texas
• interstitial nephropathy

• this rare chronic vasculitis can be diagnosed on basis of having 4 of the following 6 conditions with 99% specificity²⁾
  • asthma
  • blood eosinophilia > 10%
  • paranasal sinus abnormality
  • mononeuropathy or polyneuropathy
  • non fixed pulmonary infiltrates
  • histological evidence of extravascular eosinophils
• 1st and 2nd stages of allergies, sinus problems and asthma may precede stage 3 by many years
• stage 3 includes multi-organ involvement such as severe nerve pain in their legs, arms and hands, renal impairment, etc.
• associated with elevations of p-ANCA (whereas Wegener's granulomatosis is associated with c-ANCA)

• incidence in returned travellers from the tropics is ~5%
• it is suggestive of parasite infection such as a helminth infection although the absence of eosinophilia does not exclude helminth infection as less than half have eosinophilia

• strongyloidiasis - may also cause urticarial rash around waist and buttocks
• filariasis
• hookworm
• schistosomiasis
• cutaneous larva migrans
• ascariasis

• three stool examinations for ova, cysts and parasites to detect the more common gastrointestinal helminths, whose eggs may be excreted intermittently
• any macroscopically visible worms (likely to be ascarids or tapeworm) should be sent for laboratory identification
• specific serological testing is available for schistosomiasis, strongyloidiasis, filariasis, echinococcosis, toxocariasis and angio-strongyliasis

• start Rx after stool collections
• options include mebendazole, pyrantel and albendazole although of these, only albendazole is useful for strongyloidiasis, tapeworm infection or schistosomiasis.