Hammondia hammondi

Hammondia hammondi is a species of obligate heteroxenous parasitic alveolates of domestic cats (final host). Intracellular cysts develop mainly in striated muscle. After the ingestion of cysts by cats, a multiplicative cycle precedes the development of gametocytes in the epithelium of the small intestine (each oocyst of the species averaging 11×13 μm). Oocyst shedding persists for 10 to 28 days followed by immunity. Cysts in skeletal muscle measure between 100 and 340 μm in length and 40 and 95 μm in width. Some of the intermediate hosts (e.g. guinea pigs, hamsters) develop low levels of antibody and some cross-immunity against Toxoplasma. H. hammondi is a protozoa that does not have a gram reaction. H. Hammondi parasites multiply asexually or sexually in the intestines of cats. Between 1–3 days after introduction to cats, bradyzoites are found in sections of the cat's small intestine. On the 4th day, daughter cells of the parasite can be found near the host cell's nucleus, in the cytoplasm. At 6 and 7 days, they are found inside the cells of the intestinal lining. Relation to Toxoplasma gondii - very similar although H. hammondi has a smaller group of hosts that it can infect. This group is cats, rats, mice, other small rodents, goats, and roe deer. Mice were used to test the differences between T. gondii and H. hammondi, telling scientists that H. hammondi infections in mice can only be caused by oocysts, because thats the stage of when it can be infectious, and mice that are immunosuppressed won't show any symptoms of the parasite. As a sporozoite, H. hammondi has a cell body that is the shape of a crystal. As a tachyzoite, the secretory organelle will interact with electrons more strongly and appear darker. Finally, bradyzoites are smaller in size. So even though the two parasites are nearly identical, there are ways to tell them apart under the microscope. As an experiment, oocysts were given to eight dogs while cysts were given to four dogs. Between the period of 16–101 days, all of the experimented dogs died and did not shed oocysts. The intestines of the dogs were given to cats which then shed oocysts after 8–10 days. The scientists found out that there were no lesions in any of the twelve dogs that were given the parasite. Lesions are a common symptom from multiplication of tachyzoites that was found in mice after tissues cysts were formed. Dogs, along with the other rodents, are intermediate hosts and cats are the final host. That means cats are don't experience the symptoms of the disease. The year 1975 was the year that scientists have discovered H. hammondi. A cat from Iowa was infected, along with a cat from Germany and three out of 1,604 cats from Hawaii. Over a thousand cats were killed by the Humane Society in Ohio and their feces were examined for intestinal issues. H. hammondi was discovered along with some other parasites. There was a wide range of the disease. In Australia, 1978, another scientist discovered feeding his laboratory-raised cats infected mice and rats. The result was the cats shedded oocysts. In Japan, scientists discovered that feeding goat muscles to cats. The cat from Germany was fed roe deer muscles and shedded oocysts. Proving that there are a lot of intermediate hosts and cats being the final host.