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.
If the spores of funguses are inhaled or enter the body through a break in the skin , they can take hold and cause infection. The most common fungal infection in infants is candidiasis , commonly called thrush . This infection is treated with antifungal medications that kill the fungus. Fungal infections can become serious and even life-threatening if they are not treated, as they can spread throughout the body. Congenital and genetic diseases and disorders Congenital diseases are those that are present from birth but not inherited.