More than 60 million people in the US and 4.1 million Australians, probably are infected with the Toxoplasma parasite, but very few have symptoms because the immune system usually keeps the parasite from causing illness.
The parasite is common in warm-blooded animals including birds cats, rats, mice, pigs, cows, sheep, and chickens. People get toxoplasmosis from contact with faeces (stool) or from eating undercooked meat.
People don't spread the infection to other people except when a mother gets toxoplasmosis during pregnancy and passes it to her unborn baby. Toxoplasmosis is a very severe infection for unborn babies and for people with weakened immune systems. Unborn babies are at risk of severe infection that may result in mental retardation, blindness in one or both eyes, or death. In healthy children and adults, toxoplasmosis may cause no symptoms at all, or a mild illness (swollen lymph glands, fever, headache, and muscle aches) 5 to 23 days after exposure. People who have had toxoplasmosis in the past and then develop problems with their immune systems (such as AIDS) can have severe infections of the brain that can lead to death. Infections can be treated with antibiotics. Talk to your doctor if you think you have been exposed to the Toxoplasma parasite.
Toxoplasmosis is an infection caused by a single-celled parasite (protozoan organism) named Toxoplasma gondii. It is found throughout the world.
May cause rapid and fatal disease in fledgling birds.
Clinical signs of disease in fledglings are nonspecific and include diarrhoea, anorexia, ruffled feathers, ataxia, and enlargement of the liver that may be grossly visible through the living birdís skin as "black spot". Lesions may also form in the eyes causing blindness and in the brain of the Fife Canary.
Mortality rates are high and the disease can devastate an aviary. Adult birds that are spreading the disease often lack clinical signs, making elimination of the parasite from aviaries difficult. The ease of spreading the infection lasts for up to eight months due to the long life of the parasite. Toxoplasma is insidious due to its long life in persistently infected adult birds and its stability in the environment. The parasites are shed in the faeces and become infectious after 1 to 5 days.
Diagnosis has traditionally been via post-mortem examination and microscopic analysis of fledglings that die acutely or by faecal flotation on persistently infected adult birds. Diagnosis can also be made on the live bird by peripheral blood smear examination. Identification is notoriously difficult.
Effective treatments for canaries have not yet been perfected. Reduction of faecal-oral transmission can be achieved by cleaning cages frequently, using screen or wire cage bottoms to separate birds from infected droppings, and by frequently changing drinking and bathing water to minimise faecal contamination. Primaquine is reported to suppress tissue forms of the parasite, and sulfachlor has been recommended to reduce the shedding of the parasite in the droppings. Sulphonamides and amprolium, administered to adults before the breeding season and again when chicks are weaned, have also been suggested to reduce chick morbidity. However, none of these treatment protocols have been very effective. Treatment also include (trimethoprim 0.08 g/ml H2O and sulfadiazine 0.04 g/ml in water for 2 wk and followed up with a second treatment regime of 3 wks)
Box ED: Atoxoplasma associated with an isosporan oocyst in canaries. J. Protozool 17:391-396, 1970.
Levine H, et al: The genus Atoxoplasma (Protozoa, Apicomplexa). J. Parasitol 68:719-723, 1982.
Box ED: Exogenous stages of Isospora serini (Aragao) and Isospora canaria sp. in the canary (Serinus canarius linnaeus). J Protozool 22:165-169, 1975.
Greiner EC, Ritchie BW: Parasites. In Ritchie BW, Harrison GJ, Harrison LR (eds): Avian Medicine: Principles and Application. Lake Worth, FL: Wingers; 1994: 1007-1029.
Center for Veterinary Public Health.
Compiled by P Ailwood. Published 28/02/05