Churg-Strauss syndrome is the older name for eosinophilic granulomatosis with polyangiitis (EGPA). EGPA is a rare, immune-mediated disease that can cause inflammation of small- to medium-sized blood vessels (vasculitis). When blood vessels become inflamed, tissues may not receive normal blood flow, which can lead to symptoms in different parts of the body. EGPA most often affects the airways and lungs, but it can also involve the sinuses, skin, nerves, digestive tract, kidneys, and heart.A hallmark feature of EGPA is eosinophilia- higher-than-normal levels of eosinophils, a type of white blood cell linked to allergic inflammation and immune responses. In EGPA, eosinophils can build up in blood and tissues and contribute to inflammation and tissue injury. Many people with EGPA have a history of asthma and chronic sinus symptoms, often for years before vasculitis is recognized.You may see both names-"Churg-Strauss" and "EGPA"-used in clinics, online resources, and medical records. Knowing both is helpful when reading about the condition or discussing it with specialists.Why understanding EGPA matters (for patients and caregivers)Being diagnosed with a rare condition can feel overwhelming. EGPA is uncommon enough that people may struggle to find clear information, connect with experienced clinicians, or locate support networks. Having a practical understanding of EGPA can make the process less intimidating and improve day-to-day decision-making.Understanding the basics helps you: Recognize possible flare signals and report changes earlyTrack symptoms in a way that's useful to your care teamPrepare better questions for appointmentsAnticipate and manage common treatment side effects (especially from systemic corticosteroids and other immune-modulating medicines)