BACKGROUND: Though rare, every case of botulism is considered a public health emergency because of its severity and outbreak potential. CDC’s National Botulism Consultation Service consults on suspected botulism cases, releases heptavalent botulism antitoxin (BAT), and conducts national surveillance. The investigational new drug (IND) period for BAT before licensure was a period of enhanced surveillance during which CDC and Cangene, the manufacturer of BAT, both actively collected clinical outcome information for suspected cases of botulism treated with BAT. To assess collection of outcome information, we investigated completeness of follow-up data during and after the IND period and summarize these data.
METHODS: A suspected case of botulism is a nationally notifiable condition, most frequently reported to CDC during clinical consultations. Using standardized questionnaires, CDC collects information about demographic information and clinical features (Form 1) and outcome information (Form 2). Form 2, which is completed by clinicians upon discharge or death, collects information about hospital course, final diagnosis, death, and sequelae. We compared reporting characteristics and results during the IND (2010–2013) and the post-IND (2013–2016) periods.
RESULTS: For cases that had botulism consultation during the IND period and post-IND period, annual Form 2 return was 46%–96% and 19%–46%, respectively. Based on Form 2 data, the most frequent final diagnoses were botulism (n=78; 70%), Guillain-Barré syndrome (GBS) (n=19; 17%), and myasthenia gravis (n=4; 3.5%). The average ICU duration for cases diagnosed with botulism was 14 days (range: 1–57), compared with 34 days (range: 6–84) for GBS and 17 days (14–20) for myasthenia gravis. The fatality rate was 5% for persons diagnosed with botulism and 2% for those with other diagnoses. Barriers to reporting follow-up data include low awareness of Form 2, time and personnel constraints, difficulty reaching the clinician when Form 2 is not submitted, and duplicated reporting to Cangene for post-IND review.
CONCLUSIONS: Information about the outcome of suspected botulism cases is valuable to improve consultation for BAT release and to inform preparedness planning for large outbreaks or bioterrorism events. However, this information has been obtained for few cases in the post-IND period compared with the IND period. Improved communication and collection plans between CDC, state health departments, and treating clinicians are needed to improve follow-up data collection. Implementing a protocol for the CDC consultation service to follow up with clinicians could improve data collection and completeness without placing additional reporting burden on state partners.