Science Center Objects

Toxoplasmosis is caused by a microscopic parasites called a protozoan. The specific name of the protozoan that causes toxoplasmosis is Toxoplasma gondiiT. gondii reproduces in the gut of cats (all members of the Felidae are susceptible). Cats shed the parasite in their feces, and the parasite is ingested by other animals (intermediate hosts) causing disease. Cats can acquire the parasite from eating intermediate hosts.

What does it do?  In cats, T. gondii doesn’t do much other than replicate. Infected cats do not show clinical signs. In the intermediate host that ingests cat feces, the parasite can replicate in internal organs and cause severe illness and, occasionally, death. In humans, toxoplasmosis is particularly hazardous for pregnant females, and in such cases, the parasite can cause abnormalities in the new born.

What does it affect? In Hawaii, where feral cats are widespread, toxoplasmosis typically affects native and non native wild birds; however, it can infect any warm blooded organism (bird or mammal). The parasite has killed nene geese on Maui, red footed boobies on Oahu, and was partially responsible for the removal of native Hawaiian crows from their last remaining refuge in Kona on the Big Island.

What are the field signs? In wild birds, the field signs are few, and presence of the disease is usually indicated by mortality. At necropsy, gross lesion can include enlarged spleen, wet heavy lungs, and mottling of the heart muscle.

Where and when does it occur? Toxoplasmosis occurs anywhere where cats are present in the habitat. Studies in pacific islands have shown that where cats are absent, so is the parasite. In Hawaii, toxoplasmosis has killed wild birds on Oahu, Maui, and the Big Island.

How do you detect it?  Determining whether toxoplasmosis is the cause of death requires a necropsy and microscopic examination of tissues (typically heart, brain, lung, or spleen) for the parasite in the laboratory. Attempts can also be made to grow the parasite from tissue samples in the laboratory. For microscopic examination, tissues must be preserved in 10% neutral buffered formalin. For culture of the parasite, tissues must be submitted fresh to the laboratory.

How do you manage it?  In Hawaii and other Pacific islands, eliminate cats from the habitat, and you eliminate toxoplasmosis.