Suspected cases of mycoplasmosis in passerines birds in bird feeders in Quebec.

Recently, some birdwatchers from the province of Quebec sent us photographs of sick birds. The examination of these pictures leads us to believe that these birds are affected by a Mycoplasma gallisepticum infections. This suspicion is based on the presence of ocular lesions highly characteristic of this infectious condition. That being said, for now we have not been able to confirm the presence of this infection.

Mycoplasmosis, also known as house finch eye disease, is an infectious bacterial disease that affects the eyes and upper respiratory tract of birds. The house finch (Carpodacus mexicanus) is by far the most commonly affected species. This infection has also been documented in other passerines, such as the American goldfinch (Carduelis tristis), the purple finch (Carpodacus purpureus), the evening grosbeak (Coccothraustes vespertinus), and the pine grosbeak (Pinicola enucleator).

This disease mainly affects birds on the eastern part of the North America. It is usually observed in proximity of bird feeders. The first episode of avian mycoplasmosis in house finches was described in the winter of 1994. Since then, the disease has spread to all populations of house finches. Populations of house finches have been particularly affected by this disease. Since the frequency of this disease appears to have decreased considerably in recent years, scientists have suggested a certain equilibrium between this pathogen and susceptible birds. However, the occurrence of cases during the last three winters indicates a recrudescence of this disease.

In passerine birds, mycoplasmosis mainly affects the eyes. The disease is characterized by a swelling of the eyelids and redness of the conjunctiva often associated with secretions and crusting. Sneezing and breathing difficulties can also be observed. In extreme cases, the crusts and swelling may cause complete closure of the eyes. These birds have difficulty feeding due to visual impairment; they are often found on the ground, looking for seeds near bird feeders. Consequently, even if this conjunctivitis is not directly fatal, the blindness can be responsible for starvation that can lead to death. In addition, birds become an easy prey for predators.

Bird feeders are potential sites for transmission of this disease. The following recommendations can help to prevent the spread of the infection and will help to keep wild birds healthy:

• During a known outbreak of mycoplasmosis, temporarily remove bird feeders and bird baths (for one to two weeks) to reduce bird aggregation.

• Clean your feeders and bird baths regularly with a solution of 5% bleach (one volume of bleach for 19 volumes of water). Allow feeders and baths to dry before putting them back in place.

• It is usually not recommended to treat infected wild birds, as the use of antibiotics could lead to the development of a carrier state which could lead to an overall increase in the spread of the disease.

Although Mycoplasma gallisepticum does not affect people, wild birds may be affected by other diseases that can potentially spread to people and pets (for example, Salmonella, Campylobacter and E. coli). It is therefore important to take the following precautions when cleaning bird feeders:

• Brushes and equipment used to clean bird feeders and baths must not be used for other purposes. Keep them outside and away from food preparation areas.

• Wear rubber gloves when cleaning bird feeders and wash your hands and forearms thoroughly with soap and water, especially before eating and drinking. Avoid handling sick or dead birds directly with bare hands.

Report any sick or dead birds to the Canadian Wildlife Health Cooperative. Find your closest regional centre at: http://www.cwhc-rcsf.ca

Stéphane Lair

CWHC – Quebec