Bird diseases


Atoxoplasmosis is a disease caused by a unicellular parasite related to coccidia. Mainly songbirds such as canaries, finches, starlings, … are susceptible to this parasitic infection. This disease is also popularly referred to as ‘large liver disease’ because affected birds often have an enlarged liver which then becomes visible as a large, dark spot through the abdominal wall.

Infection route:

Atoxoplasma is a host specific disease, which means that the atoxoplamosis species found in canaries is not contagious to finches, starlings, … and vice versa. The parasite is transmitted via the faecal – oral route, and not by mites as was often claimed in the past. So infectious oocysts (eggs) are excreted with the manure, they have to mature for a while and are then absorbed by other birds, so that they become infected.

An infection with this parasite can often be fatal, especially for young birds.
The disease is caused by Atoxoplasma serini, a unicellular parasite related to coccidia. In contrast to the coccidia, which mainly cause problems in the intestines, A. serini can be found in more places in the body. It starts in the blood cells and spreads to other organs including liver, spleen and intestines.

Adult birds can be carriers of the parasite and show little or no symptoms themselves. However, the faeces contain oocysts (a kind of egg packets) through which they can infect other birds and their young.


Young birds that become infected are often fat, convex, skinny and may have watery stools. Often you can see a dark spot through the abdominal wall which is actually the enlarged liver. Often several young birds are infected and the mortality rate is very high…
The best way to find the pathogen is to look at the liver and spleen of dead birds. Under the microscope, the parasites can be seen in cells of these organs.


This is done with medication that kills the parasites, but the problem is that the birds are easily re-infected, and it is difficult to eradicate the parasite completely. Treatment is also made more difficult because the parasite also settles in places where there is little or no access to medication (such as tendons and joints). After stopping the cure, it can also come back, because the unattainable parasites start multiplying again.

The ideal product for treatment is Cocci – Clozine (Giantel) which contains the following active ingredients: sulfaclozine sodium monohydrate and sucrose.

The way of treatment that gives good results is as follows:

  • 5 consecutive days of treating the birds with Cocci – Clozine
  • Then do not treat for 3 days
  • Treat the birds again for 5 consecutive days with Cocci – Clozine
  • Do not treat again for 3 days

It is best to repeat this cycle of 5 days and 3 days of rest 4 times in a row. This is the best way to get rid of the parasite.

In addition, good hygiene in the lofts is of course very important. This prevents the birds from ingesting many oocysts and thus continuously reinfecting themselves. Despite extensive treatment, it is difficult to completely remove the parasite from an aviary.

The Dutch company Giantel has responded to the wish of many bird enthusiasts to bring a product (with exactly the same composition as the original ESB3) back onto the market.

The product Cocci – Clozine is now officially registered and available from veterinarians.

For questions and/or to make an appointment, please contact Giantel B.V.

You can also directly contact Dr. Stijn Rans