Infections stem from invasions of the body by bacteria, viruses, fungi or parasites. While individuals of all ages are prone to infections, children are more likely to come down with a bug. The immune system is made up of cells that are programmed to identify and kill invading microbes. Childhood infections include diseases as varied as the common cold, bronchiolitis, croup and ear infections. Children are far more susceptible to infections because of the immaturity of their immune system and because of their higher exposure to microbes.
Immunity
The immune system has two components: the innate system and the acquired system. The innate system is present in all people and consists of a variety of natural infection-resisting mechanisms. Some cell types attack all bacteria regardless of its type, the skin protects against bacteria, and stomach acids can kill many microbes before they reach the intestines. The acquired immune system, on the other hand, is a potent system that can fend off microbes. However, unlike the innate immune system, it takes time for the acquired immune system to "learn" and mature. As children get older, the system becomes more responsive against more microbes and can better protect against them.
Hygiene
Children are not the most scrupulous followers of hygiene practices. From eating food off the floor to eating mud, children expose themselves to far more microbes than adults. Children cough and sneeze without covering their mouths, might not wash their hands after using the bathroom, and are more likely to get cuts and bruises from outdoor games. All of these practices can leave children more susceptible to getting infections.
Anatomical Variations
Anatomical variations in children leave them predisposed to one common infection: ear infections. According to the National Institute on Deafness and Other Communication Disorders, three out of four children will have an ear infection by their third birthday. The middle is ear is drained by a canal, called the eustachian tube that opens into the upper part of the throat. In children, the eustachian tube is more level, which prevents easy drainage of middle ear fluid. The stagnant fluid allows for growth of bacteria, leading to ear infections.
Immune Deficiencies
Children are prone to a number of so-called primary immunodeficiencies. These conditions are genetically inherited. Bruton's agammaglobulinemia is a disease that affects boys because of defective antibody synthesis. Chronic granulomatous disease is a condition in which immune cells can't effectively kill bacteria. Severe combined immunodeficiency is a serious immunodeficiency in which nearly all the immune cells are defective. Children who inherit these primary immunodeficiencies have frequent and serious infections.
