Tuberculosis Cows (IMAGE) Penn State Caption Tuberculosis kills 1.4 million people every year, making it the most deadly disease arising from a single infectious agent. Researchers found that the number of cases that are due to transmission from animals, as opposed to human-to-human transmission, may be much higher than previously estimated. Credit Vivek Kapur, Penn State Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.