Bacteria cause disease. Most of these bacteria, like those listed below make their presence felt immediately and may or may not result in death. Some people though, can be infected with a bacterium that normally causes a disease and not show any harmful effects at all, people like this are called carriers.he pathogenicity of invasive bacteria, or their ability to cause disease is generally the result of toxins. Substances produced by the bacterial cell, sometimes simply as a by-produce of its normal metabolism, which interact negatively with our body, by interfering with the normal functioning.