人類微小病毒B19型(human parvovirus B19, B19V)主要透過呼吸道飛沫與密切接觸傳播，常引起傳染性紅斑(erythema infectiosum)，又稱「第五種疾病」或「蘋果病」。感染者多僅有輕微感冒症狀或無症狀，但免疫不全者、造血功能異常者及孕婦可能出現嚴重併發症，如關節炎、再生不良性貧血及胎兒水腫，並與孩童心肌炎相關。<br>近年來，多國（美國、法國、義大利、以色列）報告B19V病例異常增加，特別是在COVID-19疫情後，可能與社交距離措施導致的免疫力下降有關。歐洲疾病預防與控制中心(European Centre for Disease Prevention and Control, ECDC)於2024年指出，自2023年底以來，歐洲多國孕婦及血液捐贈者中B19V感染率上升，呼籲醫師提高警覺。本研究將探討B19V的臨床表現、診斷、治療，並綜合全球流行病學報告與文獻，提出預防對策。

Human parvovirus B19 (B19V) is primarily transmitted through respiratory droplets and close contact. It commonly causes erythema infectiosum, also known as fifth disease (often called apple disease in Japan and Taiwan). Most infected individuals experience only mild cold-like symptoms or remain asymptomatic. However, immunocompromised individuals, patients with hematopoietic disorders, and pregnant women may develop severe complications such as arthritis, aplastic anemia, and hydrops fetalis. Additionally, B19V has been linked to pediatric myocarditis. <br>In the years following the COVID-19 pandemic, several countries—including the United States, France, Italy, and Israel—have reported an abnormal increase in B19V cases. This resurgence may be related to immune susceptibility resulting from prolonged social distancing measures. In 2024, the European Centre for Disease Prevention and Control reported that since late 2023, infection rates of B19V have risen among pregnant women and blood donors in several European countries, prompting healthcare professionals to heighten awareness of this virus. This study explores the clinical manifestations, diagnostic methods, and treatment options of B19V and summarizes relevant global epidemiological reports and literature to propose preventive strategies.