Hypereosinophilic syndrome (HES) is a group of conditions in which there is an abnormal increase in eosinophil levels (eosinophilia) in the blood and tissues of the body. Eosinophils are a type of white blood cell that is part of the body’s immune system. In HES, the large number of eosinophils infiltrate tissues and cause inflammation and damage to organs. HES can affect any organ system, with the heart, skin, central nervous system and respiratory tract being the most common. Symptoms vary between individuals and depend on the organ system that are affected. HES can affect all ages, but particularly young to middle-aged adults.

Below on this page is some information about this condition as well as links to useful resources for Australians living with a rare disease.

Synonyms:  Eosinophilic leukocytosis; hes; hes – hypereosinophilic syndrome; hypereosinophilic disease; hypereosinophilic disorder

Universal rare disease classifications provide a common language for recording, reporting and monitoring diseases. Please visit the Rare Disease Classifications page for more information about these internationally recognised classifications.

ORPHA:168956 Hypereosinophilic syndrome

Hypereosinophilic syndrome is listed as a matching term for the following ICD:11 classifications:

• BC43.20 Nonfamilial restrictive cardiomyopathy
• XH51D2 Chronic eosinophilic leukaemia
• 4B03.Z Eosinophilia, unspecified (idiopathic hypereosinophilic syndrome)

Rare diseases typically display a high level of symptom complexity. There is often a wide range of symptoms and the symptoms may vary between individuals in terms of its presentation, severity, duration and impact.

Please speak to your medical team to learn more about the symptoms of this condition.

Rare diseases are often serious and progressive, exhibiting a high degree of symptom complexity, leading to significant disability. Majority of the estimated two million Australians living with a rare disease meet the Australian Government’s definition for disability (in accordance to the Australian Public Service Commission and Australian Bureau of Statistics), and many experience severe and permanent disability impacts. If you or someone you care for is experiencing disability-related impacts from a rare condition, please speak with a health or disability professional for advice. Information about relevant disability support can be found at the RARE Portal’s Disability Support Information page.

HES can occur due to the following:

• when there are certain genetic changes in myeloid cells causing them to grow uncontrollably, leading to abnormal eosinophil production and levels. This type of HES is known as primary/neoplastic HES.
• when there is an underlying condition, such as an infection, inflammatory or autoimmune condition. Examples include helminth infections, episodic angioedema, eosinophilic granulomatosis with polyangiitis (EGPA), and others. This type of HES is known as secondary/reactive HES.

In most cases, the cause of HES is unknown (idiopathic). In some families, a history of HES may be observed but the cause of their HES is still not known.

A timely diagnosis is critical for better patient outcomes, the provision of the best possible care and treatment options, access to services and support, increased reproductive confidence and the ability to participate in clinical trials.

Please speak to your medical team to learn more about the available diagnostic pathways for this condition.

Please speak to your medical team to learn more about the possible treatment or management options for your condition. Treatment will depend on an individual’s specific condition and symptoms. It is also important to stay connected to your medical team so that you can be made aware of any upcoming clinical trial opportunities.

Healthcare professionals involved in the clinical care of individuals with HES may include general practitioners (GP), immunologists, cardiologists and others. The need for different healthcare professionals may change over a person’s lifetime and extend beyond those listed here.  

Clinical care for rare diseases often involves a multidisciplinary team of medical, care and support professionals. Please note that the information provided here is as a guide and that RVA does not necessarily monitor or endorse specific clinics or health experts.

For many rare diseases, palliative care services may be relevant and useful. Palliative care services are available for people (adults, children and their families) living with a life-limiting illness. Palliative care services provide assistance, support, resources and tools to help people manage their illness and the symptoms, ease pain, and improve comfort and quality of life. Palliative care is not only for end-of-life care. It can also help at any stage of illness from diagnosis onwards, and will look different for different people. For more information about palliative care and how it can help you, please visit:

• Australian Institute of Health and Welfare: Palliative care Overview
• Australian Government Department of Health, Disability and Ageing: Palliative care
• Palliative Care Australia

If you know of any relevant clinical care guidelines, please let us know via the  Contribute page.

Individuals living with rare diseases may have complex medical issues and disabilities, which are not always visible. It is often useful to refer to their medical history as well as personal information such as a medical card, doctor’s letter, or if available, a rare disease passport, for relevant information.

If you know of any relevant emergency management guidelines or information relevant to emergency care, please let us know via the  Contribute page.

ausEE Inc.: Research has information about research on eosinophilic diseases in Australia.

There are specific considerations around participating in rare disease research, including clinical trials. It is important to be mindful of issues such as data privacy, research ethics, consent and differences in research regulations between Australia and other countries.

If you are interested in finding clinical trials for your condition, please visit the following websites; however, there may not be any clinical trials available:

• Australian Clinical Trials
• ClinicalTrials.gov

It is best to discuss your interest in any clinical trials with your medical team to determine suitability and eligibility.

Australian Organisation:

ausEE Inc.
Website: https://ausee.org

ausEE Inc. is Australia’s peak national support and patient advocacy organisation representing Australians living with an eosinophilic disease, including HES. ausEE’s mission is to improve the lives of those affected by eosinophilic diseases through providing support, evidence-based information, resources, advocacy and by campaigning to raise awareness and funds for research in Australia.

Please note that RVA does not monitor or endorse each group/organisation’s operational governance and activities. When engaging with a group, please consider the information on the RARE Portal’s Finding Helpful Peer and Community Supports page.

HES varies between individuals, and each person’s experience is unique.

If you would like to share your personal story with RVA, please visit the Rare Voices Australia: Share Your Story page. RVA will consider your story for publishing on our website and inclusion on the RARE Portal.

ausEE Inc. offers support programs, including for peer support.

For information on available government and social services that provide support for individuals with a rare disease, please visit the National and State Services pages.

People living with a rare disease, including families and carers, often face unique challenges such as diagnostic delays, misdiagnoses, limited treatment options, and limited access to rare disease specialists and support. These challenges may impact people’s emotional wellbeing and quality of life. Many people find it helpful to seek mental health and wellbeing support to cope with ongoing stress and uncertainty. Connecting with people who have shared experiences through a support group may also be helpful. Information about relevant mental health and wellbeing support can be found at:

• Mental Health and Wellbeing Support for Australians Living with a Rare Disease
• The National and State Services pages underneath the ‘Mental Health’ sections listed

Further information on HES can be found at:

• Genetic and Rare Diseases (GARD) Information Center: Hypereosinophilic syndrome
• National Organization for Rare Disorders: hypereosinophilic syndrome
• American Partnership for Eosinophilic Disorders (APFED): Hypereosinophilic Syndromes

StatPearls: Hypereosinophilic Syndrome

Orphanet: Hypereosinophilic syndrome

This page has been developed by Rare Voices Australia (RVA)’s RARE Portal team. If you would like to see more information added to this page, please reach out via the Contact form. If you would like to share relevant resources for this condition, please visit the Contribute page.

If you are aware of any additional information that may benefit stakeholders with an interest in this page, or if you notice any broken links or inaccurate information, please let us know via the Contribute page.