International Institute of Infection and Immunity

A: The immune system is your body's defense against disease and infection. This includes specialized cells, such as T-cells or neutrophils, specialized tissues such as the Thymus and physical barriers such as skin. Your immune system is made up of 2 divisions: a division you are born with called innate immunity and a division you develop as you age called adaptive immunity.

A: Most experts consider viruses to be a non-living microscopic particle that infects living cells. Viruses are composed of genetic material inside a protein coat (capsid). Once infection has occurred and the virus is inside a living cell, it uses that cell’s own machinery for viral replication and to send out the virus to infect other living cells.

A: A bacterial infection is caused by living bacteria inside a multicellular organism whereas a viral infection is caused by a non-living particle within a single cell or within many cells.

It is important to differentiate bacterial infections from viral infections because bacterial infections can often be treated with an antibiotic where viral infections cannot. Bacterial infections often only affect a certain part of the body such as the ears, throat or lungs and are cleared within days or weeks of taking antibiotics.

Viral infections are cleared by the body’s own defenses, the immune system. This usually takes 1-2 weeks. In some cases such as with the virus HIV our immune system does not know how to clear the virus from the body because the virus is secretly hidden within our cells. This type of viral infection is never cleared and continues to damage the body.

A: An antibiotic is a drug that kills bacteria or stops the growth of bacteria.

A: Viruses can spread from animals to animals, animals to humans, or humans to humans. When a virus spreads from animals to humans it is called zoonosis. Viruses can be transmitted through the air by an infected individual coughing or breathing or through physical contact usually through bodily fluid from an infected individual to an opening of an uninfected individual.