Use of an immunotherapeutic vaccine to treat a life-threatening human arteritic infection caused by Pythium insidiosum

Abstract

A 14-year-old Thai boy presented because of a history of headache, mandibular swelling, and facial nerve palsy. A microorganism identified as Pythium insidiosum was cultured from the mandibular abscesses. Despite treatment with amphotericin B, iodides, ketoconazole, and surgery, the infection progressed. Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) of the neck revealed an aneurysm in the external carotid artery. The aneurysm was removed. MRA performed later showed stenosis of the internal carotid artery. Immunotherapy was recommended as a last resort. One hundred microliters of the P. insidiosum vaccine was subcutaneously injected into the patient's left shoulder, and 14 days later a similar dose was administered. Four weeks following the first vaccination, the patient's headache had disappeared, the facial swellings had dramatically diminished, the cervical lymph node had shrunk, and the proximal left internal carotid artery stenosis had significantly improved. One year after the vaccinations, the boy was considered clinically cured.