Hosts

• Toxoplasma gondii can potentially infect virtually any warm-blooded animal. The primary host, however, is always a member of the cat family because it is only in these animals that it can reproduce sexually. All other infected animals are referred to as secondary hosts.
  
  

Infection

• Infection can occur in two ways. One is when raw or undercooked meat containing the parasite is eaten. At this point the parasite is in a stage of its life cycle known as sporozoite. The other one is by ingesting food contaminated with the feces of the primary host, a member of the cat family, which contains oocysts.
  
  

Asexual Reproduction

• The sporozoites cross the intestinal wall and migrate to several organs, enter their cells and start to divide asexually. Initially the sporozoites reproduce rapidly but, in healthy individuals, this evokes an immune response that slows them down. The parasite encloses itself in a tough, protective wall and becomes a bradyzoite. This form is very resistant and they can accumulate in great numbers inside so-called tissue cysts. Additionally, bradyzoites are infective and can infect an animal that consumes infected prey. Bradyzoites remain alive and able to infect for months or even years.
  
  

Sexual Reproduction

• This takes place exclusively in felines: domestic and wild cats. When a cat consumes contaminated prey, the parasites invade cells in its small intestine. It is here that sexual reproduction takes place, and the result is an egg protected by a cyst called oocyst. The oocysts leave the cat through its feces and can also infect a new host if it ingests food contaminated with them.
  
  

Toxoplasmosis

• Normally, toxoplasmosis is not a grave or dangerous in humans, but there are two notable exceptions. The first one is in individuals who have their immune system compromised such as AIDS patients or transplant recipients. They cannot control the rate of asexual reproduction, and the result is often a life-threatening infection. The other exception is that the parasite can lead to birth defects if a pregnant woman is infected, especially during the first trimester.