Because guinea pigs are similar to humans in the symptoms and immune response they have to bacterial infections, they have been studied for more than 200 years. They have contributed to advances in treating diseases that affect the lungs, ears, eyes, arteries, stomach, intestines, and those that are sexually transmitted. Today, they remain important models in many research areas. One such is the evaluation of treatments for tuberculosis (TB). The disease progression of TB in guinea pigs shares many of the same characteristics as that in humans. Researchers are working with guinea pigs to develop more effective vaccines that prevent TB.