Just like adults children are occasionally ill. Yet there are many differences between sickness in children and sickness in adults. Among other things these differences result from the fact that a child, who is still in the process of growing up, has often no idea of what is happening to him and is not able to indicate what the problem is.
Illnesses in children distinguish themselves by having a different origin, by having different symptoms and often by having different consequences to those that commonly occur in an adult.
Many illnesses are the result of an infection. There are infections that occur so frequently in children that they are called childhood disorders. These are for example measles, German measles (rubella) and chickenpox. However, it is not true that the pathogens that cause these infections have a preference for children. It is possible for adults to contract measles for example, although it happens only rarely. The reason that these illnesses occur mainly in children is that the pathogens are present nearly everywhere and as a result nearly everybody comes into contact with them very early in life. Only after having such a contagious disease does immunity develop that will usually last a lifetime. Consequently most adults have antibodies against these diseases although they may not even realize that they were exposed to, say, measles as a child. In addition to these so-called childhood disorders, children regulary experience infections of the upper respiratory tract. These include infections of the tonsils and colds, but also for instance inflammation of the middle ear (otitis media). Inflammation of the middle ear is fairly common because the Eustachian tube is still comparatively short. Symptoms of otitis media may include earache, caused by the pressure on the eardrum of accumulated fluid, and slight deafness. When the child grows older the tube becomes longer and then it is more difficult for the bacteria and viruses to end up in the ear. Another reason for the fact that respiratory infections occur so frequently between the second and the seventh year is that they are not overcome by the child’s imperfectly functioning immune system.
The development of the immune system
During its growth in the womb the baby usually does not come into contact with pathogens. Even if the mother contracts an infection, the placenta is impregnable to most micro-organisms. Consequently, when the child is born it has not developed antibodies against any infectious diseases. Yet there are some antibodies in theof the new born. They originate from the mother and protect the child against those infections experienced by the mother before she became pregnant. When the mother is breastfeeding, antibodies also enter the baby in the milk. These antibodies protect mainly the mucous membranes of the respiratory tract and the intestines. Consequently breast-fed babies are less prone to infections of the intestines and the respiratory tract. The antibodies of the mother remain in the child’s for up to two years at the most. In the meantime the child’s body has already begun to make antibodies itself, but this is not sufficient by a long way to combat all the pathogens it is exposed to. By the time the child is about three years old, the level of antibodies is at its lowest. That is why this is the time when it may suffer from recurrent respiratory infections. In normal circumstances this period of diminished resistance lasts only a few years. That is why recently an excessively aggressive treatment of infections that occur in this period has been questioned. It is possible that the beneficial effect of the surgical removal of the tonsils would have happened just as well without the operation, because this kind of surgery is usually performed at a moment when the resistance is on the increase again.