tropical pulmonary eosinophilia, loiasis, and onchocerciasis; and 3) flukes, i.e. schistosomiasis, fascioliasis, clonorchiasis, paragonimiasis, and fasciolopsiasis. Other infections associated with increased eosinophil blood counts include: protozoan infections, i.e. Isospora belli and Dientamoeba fragilis) and sarcocystis); fungal infections (i.e. disseminated histoplasmosis, cryptococcosis [especially in cases with central nervous system involvement]), and coccidioides); and viral infections, i.e. Human T-lymphotropic virus 1 and HIV. Autoimmune diseases
Hypereosiophilia or eosinophilia may be associated with the following autoimmune diseases: systemic lupus erythematosus eosinophilic fasciitis, eosinophilic granulomatosis with polyangiitis, dermatomyositis, severe rheumatoid arthritis, progressive systemic sclerosis, Sjögren syndrome, thromboangiitis obliterans, Behçets disease, IgG4-related disease, inflammatory bowel diseases, sarcoidosis, bullous pemphigoid, and dermatitis herpetiformis. Allergic diseases
Eosinophilia and comparatively fewer cases of hypereosinophilia are associated with the following known diseases that are known or thought to have an allergic basis: allergic rhinitis, asthma, atopic dermatitis, eosinophilic esophagitis, chronic sinusitis, aspirin-induced asthma, allergic bronchopulmonary aspergillosis, chronic eosinophilic pneumonia, and Kimuras disease.Certain types of food allergy disorders may also be associated with eosinophilia or, less commonly, hypereosinophilia. Allergic eosinophilic esophagitis and the Food protein-induced enterocolitis syndrome are commonly associated with increased blood eosinophil levels. Drugs
A wide range of drugs are known to cause hypereosinophilia or eosinophilia accompanied by an array of allergic symptoms. Rarely, these reactions are severe causing, for example, the drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. Drug- induced hepatitis marked by immunoallergic pathology, which has much bidirectional crossover with DRESS syndrome, is typically accompanied by some severity of eosinophilia.
Eosinophilia is a condition in which the eosinophil count in the peripheral blood exceeds 5×108/L (500/μL). Hypereosinophilia is an elevation in an individuals circulating blood eosinophil count above 1.5 x 109/L  (i.e. 1,500/μL). The hypereosinophilic syndrome is a sustained elevation in this count above 1.5 x 109/L (i.e. 1,500/μL) that is also associated with evidence of eosinophil-based tissue injury. Eosinophils usually account for less than 7% of the circulating leukocytes. A marked increase in non-blood tissue eosinophil count noticed upon histopathologic examination is diagnostic for tissue eosinophilia. Several causes are known, with the most common being some form of allergic reaction or parasitic infection. Diagnosis of eosinophilia is via a complete blood count (CBC), but diagnostic procedures directed at the underlying cause vary depending on the suspected condition(s). An absolute eosinophil count is not generally needed if the CBC shows marked eosinophilia. The location of the causal factor can be used to classify eosinophilia into two general types: extrinsic, in which the factor lies outside the eosinophil cell lineage; and intrinsic eosinophilia, which denotes etiologies within the eosiniphil cell line. Specific treatments are dictated by the causative condition, though in idiopathic eosinophilia, the disease may be controlled with corticosteroids. Eosinophilia is not a disorder (rather, only a sign) unless it is idiopathic.Informally, blood eosinophil levels are often regarded as mildly elevated at counts of 500–1,500/μL, moderately elevated between 1,500 and 5,000/μL, and severely elevated when greater than 5,000/μL.