Avian Botulism outbreak

Masterton District Council is very aware of the impact the bacterium Clostridium botulinum is having on the waterfowl and fish population at Henley Lake. This is a naturally-occurring organism and the environmental conditions throughout the country this summer have seen a significant rise in local, regional and national outbreaks of Avian Botulism.

As the disease is spread through consumption of contaminated maggots, the best way to break the cycle is to act swiftly to remove dead or severely affected birds and fish before maggots appear and are eaten by other birds.

The Council has tasked its parks contractor to carry out increased surveillance and proactive removals. Warning signage has also been installed.

We appreciate witnessing the impact on wildlife can be distressing and motivates some members of the community to take action themselves, but our preferred approach is that this work is carried out by our contractors. This ensures recommended MPI disposal methods are followed, which also plays a part in breaking the cycle of infection.

Although the risk to humans is low, personal protective measures should always be taken when handling infected birds or fish.

About Avian Botulism

Avian botulism is a disease that causes paralysis in birds and often kills them. The disease is caused by Clostridium botulinum, a bacteria that's around in the environment all year round. When low water levels, low oxygen levels in ponds and waterways, poor water quality/pollution and warm temperatures combine, the bacteria can quickly reach toxic levels.

Birds contract avian botulism when they eat maggots that have fed on the bacteria. Freshwater fish and eels can also be poisoned 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
• handle dead fish or waterfowl with bare hands – always wear gloves
• harvest or eat birds, eels or fish from areas where botulism is present.

What we’re doing

When there's an outbreak, we work to contain it by:

• removing dead animals from Council-owned land, to break the maggot cycle and slow the spread
• working with other agencies and organisations including Greater Wellington and HUHA in combating the outbreak
• putting up signs in affected areas, warning about what’s happening and what you should do
• planting and other restoration techniques that help improve water quality.

What you can do

• Avoid feeding ducks – it’s better to allow them to forage naturally.
• Don't 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 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 about 70 centimetres deep.
• Always wear gloves when handling the dead animals, and wash your hands with soapy water afterwards.
• Let friends and whānau know how they can help reduce avian botulism.