Background
: The causes of eosinophilia are allergies, parasite infections, medications, skin diseases, and others. But, the etiologies of eosinophilia and variables associated with eosinophilia are not well known in Korea.

Methods : This study included patients in a health check up at a general hospital from May 21, 1995 until February 14, 2004. Through self-report, serology, and stool exam, variables associated with eosinophilia were tested.

Results : In the eosinophilic group, 5% were helminth infected, and more of C. sinensis infection were found the eosinophilic group with 3.9% compared to the non- eosinophilic group with 1.2% (P＜0.05) Associated variables with eosinophilia were old age, high BMI, drinking, smoking, the season of testing helminth infections, and Clonorchiasis infection. But allergy was not associated with eosinophilia. The odds ratios for eosinophilia after adjustment were 2.280 (1.694∼3.068) in helminth infections and 2.391 (1.716∼3.331) in Clonorchiasis infection.

Conclusion : In the eosinophilic group, 5% were helminth infected, and more C. sinensis infection was found. Associated variables with eosinophilia were old age, high BMI, drinking, smoking, the season of testing, helminth infections, and Clonorchiasis infection. But allergy was not associated with eosinophilia.

Hypereosinophilic syndrome is a rare disease characterized by marked peripheral eosinophilia and eosinophilic infiltration of many organs such as heart, lung, central nervous system, liver and spleen. This disease is defined by following criteria. First, sustained blood eosinophilia is greater than 1,500/mm³ longer than 6 months. Second, other apparent etiologies for eosinophilia must be absent, including parasitic infestation and allergic disease. Third, patients must have signs and symptoms of organ involvement. In Korea, some cases that eosinophil infiltrated lung, liver, gastrointestinal tract or skin were reported. In this report, we found a case showing myalgia, fatigue and eosinophilia in periodic health examination, and diagnosed hypereosinophilic syndrome.

Background
: Eosinophilia is associated with distinctive disease processes that include helminthic parasitic infections, allergic diseases and a diversity of disease of ill defined etiology. But the rate of persistent eosinophilia is not known in incidental eosinophilia without definite disease such as parasite of allergic disease.

Methods : This study included 242 middle aged men who found eosinophilia incidentally in health check up at a general hospital and followed-up after 2 years. The man who didn't know eosinophilia and never treated nor worked up for eosinophilia included. We study the persistent rate of eosinophilia after a follow-up of 2 years.

Results : In 78% of incidental eosinophilia, the number of eosinophilia was less than 1000/㎕. The rate of persistent eosinophilia which incidentally founded after a follow-up 2 years is 29.8%. Higher numbers of eosinophilia, hither rate of persistent eosinophilia. Eosinophil number less than 1000/㎕ showed 23.8% persistent eosinophilia, 1000-1499/㎕ 46.3%, 1500-1999/㎕ 57.1%, more than 2000/㎕ 80% persistent eosinophilia respectively(P<0.05).

Conclusion : Incidental eosinophilia less than 1000/㎕ usually mormalized without intervention, so simple observation is recommended.