In general, bacterial infections are treated with antibiotics. Viruses are not normally found within the body without causing an infection. Viruses, many times smaller than bacteria, are not alive until they take over normal, healthy, living cells. Once inside cells, viruses can produce disease symptoms. Some viral diseases can be treated with medicines known as antiviral agents, but viruses are completely unresponsive to antibiotics.
Viruses are the primary cause of respiratory infections in infants.
Such infections are treated mainly to make the infant more comfortable, but the infant's immune system alone has to kill off the viruses. Like bacteria, viruses enter the body by droplets, ingestion, blood , or breaks in the skin . Funguses, plantlike organisms that include mushrooms, yeasts, and molds, are also a cause of disease in infants. There are about a hundred types of funguses that live and grow naturally in and on the human body, but only ten or so of those types are disease-producing in humans. Funguses reproduce by tiny spores that are carried in air or water.