Potential Bioterrorism Agent: Category A
Also known as: Clostridium botulinum, C. botulinum, intestinal botulism, infant botulism
Hospital: Report immediately by phone
Lab: Report immediately by phone
Physician: Report immediately by phone
Local Public Health Agency (LPHA): Report immediately by phone; begin Active Surveillance for additional cases and interview case or family members for possible source.
Iowa Department of Public Health
Disease Reporting Hotline: (800) 362-2736
Secure Fax: (515) 281-5698
Botulism is caused by exposure to a neurotoxin produced by Clostridium botulinum. C. botulinum is an anaerobic, spore-forming bacterium. The toxin is produced as the bacteria multiply. The bacteria multiply under anaerobic conditions and in an acidic environment (generally pH>4). There are 7 types of botulinum toxin (A-G), but human botulism is caused only by types A, B, E, and F.
B. Clinical Description
General information: C. botulinum toxin is one of the most potent lethal substances known. In humans, botulism manifests itself in one of 4 clinical forms: foodborne botulism, wound botulism, infant (intestinal) botulism and, rarely, adult infectious (intestinal) botulism. The site of toxin production is different in each form, but flaccid paralysis is common to all.
Foodborne botulism is a severe poisoning caused by the ingestion of preformed C. botulinum toxin.
Symptoms: The clinical syndrome is dominated by neurologic signs and symptoms, including blurred or double vision, dysphagia, dry mouth, and peripheral muscle weakness. Symmetric descending flaccid paralysis is classic diagnostic for botulism. Paralysis begins with the cranial nerves, then affects the upper extremities, respiratory muscles, and finally the lower extremities.
Complications: Patients usually require ventilatory support, which is commonly for 2 - 8 weeks. Clinical manifestations are similar regardless of toxin type, but type A has been associated with a higher case-fatality rate than Type B or Type E. In general, the case-fatality rate for foodborne botulism is 5% - 10%. Recovery may take months.
Wound botulism usually presents with the same clinical picture as foodborne botulism. In wound botulism, the organism multiplies and produces its toxin in the wound. The toxin is absorbed into the bloodstream.
Infant (intestinal) botulism has a distinctly different clinical presentation than wound and foodborne botulism. In infant botulism, the C. botulinum spores are ingested, and the toxin is formed in the intestines in the absence of mature gastrointestinal flora. This disease is usually confined exclusively to infants less than one year of age.
Symptoms: The earliest clinical sign of infant botulism is constipation, followed by poor feeding, decreased sucking, lethargy, listlessness, ptosis (drooping eyelids), difficulty swallowing, a weak cry, and lack of muscle tone--giving rise to the term “floppy baby syndrome.”
Complications: Respiratory failure may occur in some cases. Infant botulism presents with a wide range of severity, from mild illness to sudden death. Some studies suggest that infant botulism may be responsible for up to 5% of cases of sudden infant death syndrome (SIDS). Among hospitalized cases in the United States, the case-fatality rate is less than 1%.
Adult infectious (intestinal) botulism occurs as a result of toxin production in the intestines in a manner similar to infant botulism. Most people with adult infectious botulism are found to have suffered from a disruption of their natural intestinal flora due to abdominal surgery, antibiotic treatment, or gastrointestinal tract abnormalities.
C. botulinum spores are ubiquitous in soils worldwide. The spores can survive indefinitely in soil under almost any environmental condition. Spores are also found in marine sediment.
D. Modes of Transmission
Foodborne botulism usually results from ingesting toxin in food that has been inadequately processed or prepared before being eaten. The most frequent source is home-canned foods, but outbreaks have also been attributed to potatoes baked in foil, minced garlic in oil, and sautéed onions held under a layer of butter. Tomato products, once considered low-risk foods because of their low ph, can no longer be dismissed as a potential vehicle. Boiling for ten minutes destroys the toxin.
Wound botulism occurs when wounds are contaminated with dirt or gravel containing botulism spores. Wound botulism has also been reported among chronic drug abusers.
Infant (intestinal) botulism, which is the most common form of botulism in the United States, results from ingestion of bacterial spores, which germinate and produce toxin in the intestines. Botulism can result ingestion of food, soil or dust contaminated with botulinum spores. Honey often contains C. botulinum spores. Some cases of infant botulism have occurred in children living in areas of construction and earth disruption.
Adult infectious (intestinal) botulism occurs in a manner similar to infant botulism.
Inhalational botulism can result from inhalation of aerosolized botulism neurotoxin.
Iatrogenic botulism can result from accidental injection of botulism neurotoxin into the systemic circulation instead of the intended therapeutic location.
E. Incubation Period
The incubation period is variable.
Foodborne botulism: neurologic symptoms appear within 12 - 36 hours (range: 6 hours to 8 days) after eating contaminated food.
Wound botulism: Median incubation period 7 days, with a range of 4 - 14 days. In general, the shorter the incubation period, the more severe the disease.
Infant botulism: Incubation period is unknown since the date of spore ingestion is usually not known.
Inhalation botulism: Ranges from 12-80 hours after exposure.
F. Period of Communicability or Infectious Period
Person-to-person transmission has not been documented.
Botulism occurs worldwide, as sporadic cases and as family and general outbreaks. In the United States an average of 145 cases of botulism are reported each year. Of these, approximately 15% are foodborne, 65% are infant botulism, and the rest are wound botulism.
A total of 152 laboratory-confirmed cases of botulism were reported to CDC in 2013. Foodborne botulism accounted for 2 (1%), infant botulism for 134 (88%), wound botulism for 14 (9%), and botulism of unknown or other etiology for 2 (1%) cases.
H. Bioterrorism Potential
Category A: C. botulinum toxins are considered a potential bioterrorism agent. If acquired and properly disseminated, botulinum toxin could cause a serious public health challenge in terms of ability to limit the numbers of casualties and control other repercussions from such an attack.
I. Additional Information
The Council of State and Territorial Epidemiologists (CSTE) surveillance case definitions for anthrax can be found at: wwwn.cdc.gov/NNDSS/script/casedefDefault.aspx
CSTE case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain uniform standards for national reporting.)
American Academy of Pediatrics. 2000 Red Book: Report of the Committee on Infectious Diseases, 25th Edition. Illinois, American Academy of Pediatrics, 2000.
Heymann, D.., ed., Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015.
CDC. Anthrax website: emergency.cdc.gov/agent/anthrax/index.asp#