14 DAY TRIAL // You may have heard that pregnant women should not have contact with cats.
That's because of a common parasite, Toxoplasma gondii (photo) that provokes the disease called toxoplasmosis.
Toxoplasmosis is gaining new attention because of the AIDS epidemic and bioterrorism. Severe toxoplasmosis causes AIDS patients to go into a deep dementia and become unconscious of their surroundings. "It's one of the worst syndromes an AIDS patient can die from," said Jay Radke, a Montana State University researcher. Symptoms usually appear only in people with weakened immune systems, but on rare occasions, healthy people suffer serious eye and central nervous system problems from toxoplasmosis.
Pregnant women can experience miscarriage or give birth to babies with defects. Toxoplasmosis may also cause schizophrenia and bipolar disease (dementia). It may provoke epidemics among livestocks and has ruined efforts to restore sea otters near Monterey, California. "People usually acquire toxoplasmosis by eating commercial meat or drinking water that's contaminated with Toxoplasma gondii," said Michael White, a MSU professor of veterinary molecular biology. Or by touching soil or anything that has come in contact with cat feces. "It's a complex cell just likes ours in terms of metabolism and biochemistry, which makes it a tough nut to crack," White said.
"The recently-published studies show that molecular interactions between the parasite and host directly regulate the disease's severity," White said.
Toxoplasmosis is an infection for life and genes from the parasite disrupt signals in the host's immune system. "Genetic crosses produced at MSU were critical in the study that discovered that the parasite dumps a protein into the host to dramatically regulate its immune response," White said.
But the research team discovered the role of a second pathogen protein that makes one strain of Toxoplasma especially dangerous. "Type I strains are extremely important to human medicine as they are disproportionately responsible for inflammation of the brain in AIDS patients and for severe congenital disease that is passed from mother to baby," White said. "The studies give other scientists a model for studying toxoplasmosis or related diseases like malaria and Eimeria, which causes coccidiosis," White added.
Eimeria parasites kill chickens, rabbits, sheep, goats and cattle. Researchers will try to find more effective treatments against toxoplasmosis by blocking ROP18, the gene largely responsible for making toxoplasmosis so dangerous to humans.