Cases of avian botulism have been found in the Kapiti Coast's Waimanu Lagoons -- and an outbreak is expected to grow

The district council has confirmed a number of ducks have died with the suspected disease.

It's likely the outbreak of the fatal toxin will spread to the Waikanae Estuary Reserve, due to its proximity to the other site.

Avian botulism doesn't pose a major threat to people - but can make dogs and cats sick, if they eat the infected birds.

The lagoons are being inspected daily.