Veterinary researcher answers five questions about botulism

During warm summers, the news media regularly reports on deaths among waterfowl and fish due to botulism. Miriam Koene of Wageningen Bioveterinary Research (WBVR) is conducting research into this bacterial disease. She answers five frequently asked questions about botulism.

1. Why do many (water) birds and fish die from botulism in the summer?

The bacterium that causes botulism occurs naturally in water, especially in sludge. In carcasses, which provide the ideal conditions for the growth of the bacteria, it produces toxins. These toxins find their way into the larvae that feed on the carrion. The larvae are a tasty snack for birds, which ingest large amounts of the poison and often die as a result. The dead birds in turn form a new source of infection. If the outside temperature rises above 25 degrees Celsius, a snowball effect can quickly arise. Both the bacteria and the larvae thrive at high temperatures.

2. What can I do if I suspect that water contains botulism?

If you find dead birds or fish, please report your findings to the owner of the pond or lake. This will usually be the municipality or the water boards. An official will then inspect the location. If there is reason to believe that botulism is present, action will be taken. Carcasses are removed to prevent further spread and warning signs are posted.

3. What should I do if I find a dead or sick animal near water?

Never touch a dead or sick animal with your bare hands as it can be infected with a number of diseases such as bird flu. Contact the Bird Rescue Society or Animal Ambulance in the area and have them collect, treat, or remove the animal.

How do you know if an animal has botulism? Paralysis is the most obvious symptom. Affected birds have difficulty taking off and landing. The bird may also have difficulty standing and walking. At a later stage, the neck and neck and the respiratory muscles become paralyzed, preventing the animal from lifting its head and causing drowning or suffocation. The sooner an animal with botulism is treated, the greater the chance of recovery.

Dead animals must be removed without delay as they pose a potential risk of infection to other animals and humans. In the Netherlands, occasionally dead animals are removed by organizations like the Dutch Wildlife Health Center (DWHC) or the Dutch Food and Consumer Product Safety Authority (NVWA) for cause of death investigations.

4. Can my dog ​​and I still swim in natural water?

The chances that you⁠—or your dog⁠—will become infected with botulism are slim. However, there is a risk that humans and animals will become ill from a number of possible other pathogens found in cadavers. Look closely at the water you want to swim in. Does the water look clean, free of dead animals and are there no warning signs?

5. Is botulism a threat to me or my pets?

Botulism is uncommon in humans and pets such as dogs and cats. There are different types of toxins and people and pets are not as sensitive to the toxins found in dead birds. However, on rare occasions a dog may show signs of botulism, especially if he has ingested a large number of toxins, such as from eating an infected cadaver. Contact your vet immediately if you suspect a botulism infection.

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