The organisms multiply in the wall of the small intestine and produce oocysts, which are then excreted in great numbers in the feces for two to three weeks. Within five days the shed oocysts may sporulate, becoming infectious to other animals and to humans. Sporulated oocysts are highly resistant to environmental conditions and can survive in moist shaded soil or sand for many months. During the intraintestinal infection cycle in the cat, some Toxoplasma organisms released from the ingested cysts penetrate more deeply into the wall of the intestine and multiply as tachyzoite forms. Very soon these forms spread out from the intestine to other body sites, starting the extraintestinal infection cycle.
Most cysts probably remain dormant for the life of the host.
Most healthy exposed cats shed oocysts during acute infection with Toxoplasma, but will not shed them after the acute infection. Even in those few cats that do re-excrete oocysts after another exposure to Toxoplasma, the number of oocysts shed is smaller and may even be insufficient to transmit the parasite effectively. Ingestion of tissue cysts in infected prey or in other raw meat is probably the most common route by which cats are exposed to Toxoplasma. Most cats show no clinical signs of infection with Toxoplasma. Lethargy, depression, loss of appetite, and fever are typical early nonspecific signs.