【要旨】水痘帯状疱疹ウイルス（varicella-zoster virus、以下 VZV）は初感染で水痘を起こし、その後脊髄後根神経節に潜伏感染し宿主の加齢、免疫抑制、ストレス等に伴い再活性化し帯状疱疹を起こす。水痘予防のためワクチンが定期接種化され水痘患者数は減少しているが（pros）、一方で患者数減少に伴うナチュラルブースター効果の減衰に伴い、既感染者の水痘特異的細胞性免疫能の減衰スピードが速くなり、帯状疱疹患者の増加、若年化が懸念されている（cons）。帯状疱疹患者の増加は、疱疹後神経痛だけでなくウイルス再活性化に伴うさまざまな神経合併症の増加にもつながる。よって、今後帯状疱疹ワクチンによる帯状疱疹予防の重要性が増すと考えられる。

A 59-year-old man with a history of diabetes mellitus had pain and swelling in the left side of the neck following dental treatment 1 week earlier. A diagnosis of neck cellulitis was suspected at a local clinic, and an antimicrobial agent was administered by intravenous drip infusion. The following day, the patient was referred to our department because of worsening symptoms. Physical findings at the initial presentation showed marked swelling around the left parotid gland, and laryngoscopy revealed edematous changes of the laryngeal surface of the epiglottis and the left arytenoid mucosa. Computed tomography on admission showed an increased density of subcutaneous adipose tissue in the area from the left cheek to the neck. The patient was admitted to the hospital due to the risk of airway obstruction. After admission, the administration of ampicillin/sulbactam was started. The following day, skin redness with blisters appeared on the face and trunk. According to the consultation with a dermatologist, the patient was admitted to a negative-pressure isolation room because of suspected varicella. Subsequently, varicella was definitively diagnosed based on increased levels of varicella-zoster virus immunoglobulin M. On hospital day 9, as crusts formed, the patient was discharged from the isolation room. On hospital day 13, treatment was discontinued due to the improvement in neck cellulitis. In the present case, as skin rash appeared after the start of treatment, other diseases such as drug eruption were initially suspected. However, the dermatologist diagnosed the patient with varicella based on the findings of skin and blood tests. The patient’s history of varicella was unknown. However, in cases of severe otolaryngological infections, as in the present case, clinicians should be aware of the possibility that adults are susceptible to contract varicella, particularly in patients who are in a somewhat immunocompromised state, such as those with concomitant diabetes.