Botulism (Limberneck, Western duck sickness)

Occurrence: Worldwide.
Species affected: All. Common in broilers, pullets and wild water fowl.
Age affected: All ages.
Causes: Soil-borne bacterium- Clostridium botulinum.
Effects: Loose feathers, sleepiness, neck, wing, eyelid and/or leg paralysis, diarrhoea and high mortality. Dead birds decompose rapidly.


Detailed causes:
Clostridium botulinum is gram-positive and spore-forming rod, anaerobic, and a soil-borne pathogen. It causes acute paralysis of the neck and frequently occurs in duck populations of the Mid Western US. All species of poultry of any age are susceptible, and it is common in broilers, pullets and wild water fowl. The organism produces a type A neurotoxin. There are 8 antigenically distinct toxigenic groupings of this type-A toxin. It is spread by cannibalism and eating insects. There is a 1-2 day incubation period.

Special note
In commercial poultry it is a filth disease caused by poor management and sanitation. Outbreaks in wild ducks in western US can cause mortality in tens of thousands of bird. Large numbers of ducks produce high volumes of organic faecal material. This material produces an anaerobic environment, which favours growth of clostridium that is washed into the area from eroded soil. Flies and maggots feeding on carcasses spread the toxin.

Clinical signs:
Signs include loose feathers, sleepiness, neck, wing, eyelid and/or leg paralysis, diarrhoea, soiled vent, and high mortality. Dead birds decompose rapidly.

Postmortem lesions
Few to no gross lesions are seen. Maggots can be seen in the upper digestive tract.

Diagnosis:
Diagnosis includes rapid central nervous system signs (paralysis) with no gross lesions. The Mouse bioassay includes inoculating mice with serum to determine if toxin is present. If the toxin is present, the mice will show clinical signs. Fluorescent antibody detection of organism. It simulates Marek’s disease (MD) and drug and chemical toxicity.

Treatment and control:

Prevention
Pick up and destroy dead birds at regular intervals (twice a day), control flies, remove litter, and disinfect house.

Treatment
None for commercial poultry. Bacitracin, streptomycin, vitamin and mineral therapy are somewhat effective for expensive birds.