What aspect of viruses cause disease in humans and other organisms?

Viruses cause disease in humans and other organisms by disrupting the normal functions of cells. Viruses are obligate intracellular parasites, meaning they require a living host cell to reproduce. Once inside a host cell, a virus will use the cell's machinery to make copies of itself. This process can damage the cell and interfere with its normal functions.

Some of the specific ways that viruses can cause disease include:

* Direct cell damage: Viruses can directly damage cells by disrupting their membranes, destroying their organelles, or altering their genetic material. This damage can lead to cell death or impaired cell function.

* Immune response: The body's immune response to a virus can also cause damage to cells. When the immune system mounts an attack against a virus, it can release chemicals that can damage healthy cells in the process. This is why some viral infections can cause symptoms such as fever, inflammation, and tissue destruction.

* Secondary infections: Viruses can also make people more susceptible to secondary infections by bacteria or other microorganisms. This is because viruses can damage the body's natural defenses, such as the skin and mucous membranes, making it easier for other pathogens to enter the body.

The severity of a viral infection can vary depending on the type of virus, the health of the host, and the route of infection. Some viral infections are mild and cause only minor symptoms, while others can be life-threatening.