Diphtheria remains a re-emerging infectious disease in areas with suboptimal immunization coverage. The diphtheria toxin disseminates from the respiratory tract to the circulation, which may potentially lead to severe systemic complications. We report a case of a 10-year-old Filipino male with no previous diphtheria immunization who presented with a two-week history of fever, sore throat, and dysphagia, with development of a tonsillar pseudomembrane and bull neck. He was initially managed at a referral center with diphtheria antitoxin and intravenous antibiotics but developed progressive respiratory distress requiring intubation and mechanical ventilation. Throat culture revealed Corynebacterium diphtheriae sensitive to erythromycin. Subsequent complications included acute kidney injury (AKI) necessitating hemodialysis, ventilator-associated pneumonia, and hemodynamic instability. Despite partial clinical improvement, the patient experienced recurrent respiratory failure attributed to bilateral diaphragm paresis, likely secondary to diphtheritic neuropathy, as supported by a phrenic nerve conduction study showing severely prolonged motor latencies suggestive of a demyelinating process. Prolonged ventilatory dependence led to tracheostomy. The patient also developed hypoxic-ischemic encephalopathy and subsequent focal seizures requiring anticonvulsant therapy. After a prolonged hospital course involving multidisciplinary care, the patient was sent home clinically improved and off ventilatory support, with resolution of AKI and infections, and with stable neurologic status. This case highlights the severe, multisystem complications of diphtheria in unvaccinated children, emphasizing the critical importance of early antitoxin administration, appropriate antimicrobial therapy, and comprehensive supportive care. It also underscores the need for strengthened immunization programs to prevent morbidity and mortality associated with this vaccine-preventable disease. 

Frederick Evidor is a Filipino pediatrician who finished his pediatric residency training at the Philippine Children’s Medical Center, a national tertiary referral hospital. He earned his medical degree magna cum laude at the University of Santo Tomas Faculty of Medicine and Surgery.