The incubation period is about 7-10 days (ranges from 4 to 14+ days) after wound contamination, since it takes time for the organism to germinate and produce sufficient toxin to produce symptoms.
General symptoms:
(1) dizziness
(2) fatigue
(3) fever may be present if the wound is contaminated with other bacteria, but the wound may appear innocuous
Ocular signs and symptoms:
(1) blurred vision
(2) diplopia
(3) ptosis
(4) extraocular muscle weakness
(5) pupils fixed or dilated
(6) nystagmus
Oropharyngeal symptoms:
(1) dysphagia
(2) dry mouth
(3) dysarthria and dysphonia
(4) sore throat
(5) facial nerve dysfunction
(6) hypoactive gag reflex
(7) tongue weakness
Neurologic symptoms:
(1) extremity weakness that is symmetric
(2) weakness progresses from proximal to distal and in a descending pattern (cranial nerves to cervical, thoracic, lumbar and finally sacral nerves)
(3) hypoactive deep tendon reflexes
(4) dyspnea
(5) respiratory arrest
The paralysis is prolonged. A person with severe intoxication may require mechanical ventilation for weeks or months before recovering.
Laboratory testing:
(1) Serum assay for toxin may be negative in mild cases.
(2) Stool assay for toxin will be negative.
(3) An anaerobic stool culture for Clostridium botulinum will be negative.
(4) An anaerobic wound culture will demonstrate Clostridium botulinum.
The toxin assay is based demonstrating its effect after injection into mice. Mixing the serum with specific antitoxin antibodies will neutralize the effect.
