In the United States, the percentage of pigs harboring viable parasites has been measured (via bioassay in mice or cats) to be as high as 92.7% and as low as 0%, depending on the farm or herd. Surveys of seroprevalence ("T. gondii" antibodies in blood) are more common, and such measurements are indicative of the high relative seroprevalence in pigs across the world. Along with pigs, sheep and goats are among the most commonly infected livestock of epidemiological significance for human infection. Prevalence of viable "T. gondii" in sheep tissue has been measured (via bioassay) to be as high as 78% in the United States, and a 2011 survey of goats intended for consumption in the United States found a seroprevalence of 53.4%.