Infant Botulism

A rare form of botulism, a rare acquired neuromuscular junction disease with descending flaccid paralysis caused by botulinum neurotoxins (BoNTs). It is due to intestinal colonization by Clostridium botulinum leading to toxin-mediated infection with toxemia.

Epidemiology

Prevalence is unknown. So far, at least 3,350 cases of infant botulism have been reported worldwide, except in Africa, and it is the most frequently occurring form of botulism in the USA and Argentina.

Clinical description

The disease affects infants between one and 52 weeks of age. Incubation is estimated between three and 30 days from the time of exposure to spores, although a case presenting after 38 hours has been reported. Clinical manifestations are similar to other forms of botulism (symmetrical cranial nerve palsy, followed by symmetrical descending flaccid motor paralysis), but infant botulism presentation is characterized by hypotonia, constipation, inability to suck and swallow, weak cry, ptosis, and poor head control. Fever is absent. The onset is subacute to acute and the disease may progress to generalized hypotonia (``floppy babies'') and respiratory failure. Cases of sudden infant death syndrome (SIDS) have been related to infant botulism. An initial presentation mimicking acute abdomen has also been reported.

Etiology

The disease is due to temporary intestinal colonization by spores of C. botulinum type A, B, E, or very rarely by neurotoxigenic strains of C. baratii type F and C. butyricum type E, and in situ toxin production. The spores can reach the intestinal tract by inhalation, or via food. Environmental dust and honey have been identified as the vehicle of spores. Intestinal colonization by Clostridia is believed to occur because normal competitive microflora has not been fully established. After spore germination and toxinogenesis, the BoNT is absorbed into the blood stream and distributed throughout the body, causing the typical manifestations of botulism.

Diagnostic methods

Diagnosis is based on clinical presentation; the electromyography (EMG) pattern is characterized by brief, small, abundant motor-unit action potentials (BSAPs). Diagnosis is confirmed by detection of BoNTs in stools or serum or, more frequently, by isolation of BoNT-producing Clostridia in stools.

Differential diagnosis

Differential diagnosis includes sepsis, dehydration, electrolyte imbalance, intoxication and encephalitis; it also includes metabolic disorders, myopathies, Guillain-Barré syndrome (Miller-Fisher syndrome), infantile spinal muscular atrophy (SMA1), congenital myasthenic syndromes and poliomyelitis (see these terms).

Management and treatment

Management consists mostly of supportive care, such as respiratory and nutritional support, in an intensive care unit (ICU). Antitoxin therapy with a human-derived Botulinum Immune Globulin (BIG-IV, anti A, B) is available for infants. Antibiotics are not effective and not recommended as they may lead to lysis of vegetative cells of BoNT-producing Clostridia, increasing the amount of free toxin. Complications include respiratory arrest with resultant hypoxic encephalopathy and irreversible brain damage or death, cardiac arrest, inappropriate antidiuretic hormone secretion syndrome with hyponatremia, serum hyposmolality and urinary hyperosmolality, and acute otitis media related to Eustachian tube dysfunction.

Prognosis

Prognosis is good in the absence of complications and, with appropriate intensive care, the survival rate is nearly 100% with or without antitoxin therapy.