Abortion is a worldwide problem in the livestock industry accounting for annual economic losses of billions of dollars, and N. caninum is a major cause of it. Neosporosis is a newly recognized disease of animals. Until 1988 it was misdiagnosed as toxoplasmosis. Considerable progress in understanding the biology of neosporosis has been made in the last 30 years, resulting in more than 2,000 scientific publications. The economic importance of abortion in cattle, and the availability of knowledge, reagents, and technology used to study toxoplasmosis, have contributed to the rapid progress in...