Avian botulism
Avian Botulism is an avian disease which is on the rise in New Zealand. In 2023 there have been outbreaks of the disease here in Kāpiti, as well as the Horowhenua, Auckland and Waikato regions.
With rising temperatures and more sporadic rainfall we are likely to see more outbreaks of the disease in the future.
About
Avian botulism is a disease that causes paralysis in birds and often kills them. The disease is caused by Clostridium botulinum, a bacteria that is present year round in the environment. When environmental factors such as low water levels, low oxygen levels in ponds/ waterways, poor water quality/pollution and warm temperatures combine, the bacteria can multiply quickly to toxic levels.
Birds contract avian botulism when they eat maggots which have fed on the bacteria. Freshwater fish and eels are also susceptible to poisoning when the bacteria reach toxic levels.
A severe outbreak of avian botulism can kill hundreds of birds, eels and fish. The outbreak usually declines once cooler weather and rainfall arrives.
How it spreads
Avian botulism is spread through maggots which contain the pathogen. Birds don’t spread the disease to one another while they are alive, but if they die with the infection, other birds can contract botulism through maggots from the dead birds. Waterfowl are particularly susceptible, because the bacteria is often found around ponds and waterways. This is often where an outbreak begins.
Risks
There seems to be a low risk to human health from avian botulism, but it can make dogs and cats, as well as other domestic pets, very sick:
- Don’t let your pets eat dead fish, eels or birds.
- Don’t handle dead fish or waterfowl with bare hands – always wear gloves.
- Don’t harvest or eat birds, eels or fish from areas where botulism is present.
What we’re doing
When an outbreak occurs, Council does a number of things aimed at containing the outbreak:
- removal of carcasses from Council-owned land, to break the maggot cycle and slow the spread
- work with other agencies and organisations including Regional Council and HUHA in combating the outbreak
- put up signs at affected areas, warning people about what’s happening and what they should do
- planting and other restoration techniques which help improve water quality.
What you can do
- Avoid feeding ducks – it’s better to allow them to forage naturally.
- Do not feed them bread – when it rots in the ponds it promotes the growth of botulism bacteria.
- Pick up your pet’s waste and dispose of it properly
In the event of an outbreak, you can help us contain the spread:
- If you have wetlands on your property and you find dead birds or other animals on or around the water, remove the carcasses and bury them approx. 0.7m deep.
- Always wear gloves when handling the dead animals and wash hands with soapy water afterwards
- Let friends and whanau know how they can help reduce avian botulism.