Both domestic and wild animals may act as reservoirs for parasites, and some can transmit infections to humans. A disease caught by a human from an animal is called a zoonosis. Examples of zoonotic diseases include hydatid disease or Toxomplasma gondii . Toxoplasma gondii is normally a parasite of cats and rodents. It can be transmitted to humans, and it is known to cause birth defects.
Parasitic infections cause damage by physical trauma.
They also cause damage by destroying cells , tissues , or organs by mechanical or chemical means. Parasites also divert the host's nutritive substances. Some parasites also produce toxins that further damage the host. This site focuses primarily on those parasites of interest to humans, either directly or because of economic importance to livestock. The information is divided into these catagories.