Birds that feed on decomposing carcasses such as
raptors and birds that frequent landfill sites.
Clinical signs which have been described include
progressive weakness and paralysis with loss of ability
to fly. Leg paralysis with birds using wings to pull
themselves forward. Inability to hold up their heads
(limberneck), resulting in drowning. Paralysis of the
third eyelid with protrusion across the eye. Most birds
dying of botulism are usually in good condition as the
botulinum toxin is usually rapidly fatal.
As they are no characteristic gross or microscopic
lesions, diagnosis of avian botulism can be
challenging. Suspected diagnosis is usually based on
geographic location, time of year, species of avian
involved, clinical signs observed and absence of
significant pathology at post mortem. The finding of
maggots or decomposing carcass material (particularly
bone) in the digestive tract of birds suspected of dying
from botulism, is also supportive of the diagnosis.
Confirmation of the diagnosis relies on the detection
of botulism toxin within the intestinal tract of dead
birds. The biological mouse protection test has largely
been replaced with the botulism toxin ELISA and qPCR
for the various botulism toxin genes.
Monitoring and surveillance documenting geographic
locations, conditions and dates of outbreaks,
facilitates the early prediction and recognition of
future disease outbreaks.
1. Rocke, T. E., and J. K. Bollinger. 2007. Avian botu-
lism. in N. J. Thomas, D. B. Hunter, and C. T. Atkin-
son, editors. Infectious diseases of wild birds. 377-
416 Blackwell Publishing, Ames, Iowa, USA.
2. Son K et al. 2018. Minimizing an outbreak of avian botulism
(Clostridium botulinum type C) in Incheon, South Korea.
The Journal of Veterinary Medical Science. 80: 553–556.
3. The State of Victoria Department of Environ-
ment and Primary Industries Melbourne, Aus-
tralia. 2014. Avian Botulism Information kit.
4. Vidal D et al. 2011. Real-time polymerase chain reac-
tion for the detection of toxigenic Clostridium botu-
linum type C1 in waterbird and sediment samples:
comparison with other PCR techniques. Journal of
Veterinary Diagnostic Investigation 23: 942-946.
5. Wildlife Health Australia Fact Sheet. Botulism in Australian
wild birds. www.wildlifehealthaustralia.com.au. 2019:7.
Control in outbreaks.
Removal of dead birds and fish is highly effective in
removing high protein carcass and maggot sources
of toxin. Collection of carcass material with double
bagging and incineration is the most effective means
of toxin destruction. Burying of carcasses is a less
effective control mechanism.
Guidelines suggested for handling bird or fish
Once carcass collection is complete, dispose of
gloves in a bag and thoroughly wash hands.
For burial of carcasses, ensure this is done
away from the shoreline, remove them from
the garbage bag(s), and bury them at least 75
cm deep, to discourage other animals from
Burning / incineration of Avian Botulism infected
carcases is considered the safest method of
Do not compost carcasses of suspected Avian
(Courtesy of The State of Victoria Department of
Environment and Primary Industries Melbourne,
Wear protective gloves when handling suspected
Carcasses should be double bagged.