Domesticated rats have a longer lifespan than that of wild rats. Because domesticated rats are protected from predators and have ready access to food, water, shelter, and medical care, their average lifespan is around two to three years, in contrast to wild "R. norvegicus" which average a lifespan of less than one year. However, wild rats generally have larger brains, hearts, livers, kidneys, and adrenal glands than laboratory rats. The fancy rat and wild rat also both face a multitude of differing health concerns; the former is at risk of developing a pneumococcal infection from exposure to humans, while the latter may harbor tapeworms after coming in contact with carriers like cockroaches and fleas.