Childhood Diseases

Diseases that are more common among children than among adults are referred to as childhood diseases. That is not to say that adults cannot or will not contract these illnesses; but usually children contract these diseases and form the immunity against them that will protect them as adults. In fact, some of these diseases may be quite uncomplicated in children, but may be life-threatening when contracted by an adult who never had the disease as a child. Vaccines provide immunization against some of these diseases; others, however, can neither be prevented nor cured.

Although the first vaccination for any disease was administered in the late eighteenth century, the development of immunology proceeded slowly for the next hundred years. Dr. Edward Jenner, an English physician, noticed that milkmaids who developed cowpox from contact with cows were immune to the plague (smallpox). He correctly hypothesized that exposure to the cowpox somehow conferred protection on the milkmaids. Jenner withdrew some of the material from the skin pustules of the milkmaids and injected it under the skin of his own children, and they never developed smallpox. His methodology, however, was not accepted by the mainstream medical world of the time. Also, the means to develop, test, and produce vaccines were unknown. Physicians had not yet connected disease to the existence of microscopic organisms (bacteria).

Some childhood diseases are brought on by a bacterium or virus (chickenpox or measles, for example), others are inherited (Tay-Sachs disease or sickle cell anemia), and still others are caused by heavy use of alcohol or drugs by the mother while she is pregnant.

Many of these diseases are contagious—that is, can be passed on from one person to another by transmission of the bacterium or virus. Children are brought together in school buses and classrooms, and these close quarters are ideal for the transmission of the etiologic agents that cause diseases. When one child contracts measles, usually several in the same bus or class will also get the disease before steps can be taken to slow the rate of transmission, because such infections are often most contagious before any outward symptoms appear. A child with mumps can infect a number of other children before he actually shows signs of being ill. This is particularly true of the common cold. The virus that causes the cold is especially numerous in the early stages of the cold, before the patient actually starts to sneeze and develop a fever.

Much research is directed toward developing vaccines and remedies for diseases which are presently incurable (e.g., the common cold or AIDS), but virus-borne diseases are much more difficult to cure or prevent than the bacterial diseases. A virus cannot be seen under the normal light microscope used in laboratories. A special electron microscope must be used to see a virus. Viruses can also change or mutate to fend off any natural immunity that may develop against them. Some diseases, such as the common cold, are caused by more than one virus. A cold can be brought on by any one of some 200 viruses. A vaccine, if developed, would be effective against only one virus; many scientists feel such a vaccine would hardly be worth the trouble to develop. Even diseases that are caused by a single virus (such as AIDS) can defy the development of an effective vaccine.

The etiologic agents of contagious diseases can be passed from one person to another in any number of ways. They are present in droplets of saliva and mucus sprayed by sneezing and coughing. They can be conveyed by passing an object from the infected person to someone else. With the close proximity of children in classrooms, the agent can be passed quickly through the class.

Chickenpox

Chickenpox is one of the most easily transmitted childhood diseases; it is second only to measles. It is caused by the varicella-zoster virus, which may reactivate to cause shingles in individuals who have already had chickenpox. After exposure to the virus, a 7-21 day period of incubation occurs before any symptoms appear. Chickenpox begins with a low fever and general feeling of tiredness. Soon a rash develops on the abdomen and chest, which may or may not spread to the extremities, but usually affects the scalp. The rash appears in successive stages; as a result, some of the bumps are mature while others are just appearing. The rash progresses from the initial red bumps through a vesicle stage, in which they are filled with liquid, to a mature, crusty stage. Itching is intense, but scratching can cause localized infection of the broken vesicles and may require antibiotics. Within a week after the appearance of the rash, the patient is no longer infectious.

There is no treatment for chickenpox, but the Food and Drug Administration approved a varicella-zoster vaccine in March 1995. The live-virus vaccine, developed from a strain of the virus isolated in Japan in 1981, is recommended for children between the ages of 12-18 months. A person also develops immunity to the virus if he has experienced an outbreak of chickenpox. The outbreak is usually harmless to children and passes within a week without any noticeable permanent effect. In adults the disease is much more serious; it can cause damage to the eyes and, in males, the testes. An adult with chickenpox also requires a longer period of recuperation than does a child. Pregnant women who contract chickenpox may pass the infection on to their unborn child, with serious consequences. Varicella-zoster immunoglobulin may be given to such pregnant women, in an effort to decrease the complications to the fetus. Children who have weakened immune systems (due to chemotherapy treatments for cancer, for example) may have severe, life-threatening complications from chickenpox. Anti-viral medications (such as acyclovir) may be given in an attempt to decrease the severity and shorten the duration of the illness.

Even when the infection has disappeared, however, the virus remains in the person's body and can cause shingles later in life. The chickenpox virus lies dormant in some nerve cells and can become active in an individual after the age of 50 years. In this case, the nerve root becomes inflamed, and the area of the body served by that nerve is affected. Again an eruption occurs, but in this case it is very painful. A rash may appear on the abdomen or any area of the arms or legs. The outbreak lasts for five to six days, unless the patient has an underlying cancer, in which case the rash may persist for two weeks or longer.

It is not possible to predict who will have shingles after they have had chickenpox as a child. There is no treatment for shingles, but usually an individual will have it only once and then be immune to any further outbreaks. If the virus infects certain facial nerves, care must be taken to prevent damage to the eyes. Unlike chickenpox, shingles is not contagious. The virus is confined to the nerve fiber and is not released into the air.

Measles

Measles generally refers to nine-day measles, also called rubeola, a highly contagious disease spread by a virus. A person who has the measles virus can pass it to others before he shows signs of the disease. Once exposed to the virus, it will be 7-18 days before the typical measles rash develops. The patient is infectious, however, for the two to four days immediately before the rash appears; thus he spreads the disease unknowingly. Present in mucus and saliva droplets from the nose and mouth, the virus is spread by coughing or sneezing.

The initial symptoms of measles include headaches, a low fever, tiredness, and itchy eyes. Spots appearing on the roof of the mouth look like white grains of sand surrounded by an inflamed area. These are called Koplik's spots. A sore throat may also develop. The rash appears three to five days later: a bright red outbreak usually begins on the side of the head in front of the ears and spreads over the body within the next day or two. The temperature may climb to 104°F (40°C). Inflammation of the eyes may cause painful sensitivity to light.

The disease is short lived; the rash fades within three to five days and the body temperature returns to normal. The disease, while active, renders the patient much more susceptible to bacterial infections and may worsen diseases such as tuberculosis, if present. Pneumonia and ear infections are common complications of measles, especially in infants and very young children. Also, the virus can penetrate the central nervous system and cause encephalitis (inflammation of the brain tissue), which can lead to convulsions, coma, and even death. A person with measles should have bed rest during the active stage of the disease and be protected from exposure to any bacterial infections.

Fortunately, a vaccine has been developed against measles. The vaccine is a suspension of a live, attenuated (weakened) virus which is given to children at the age of approximately 15 months. The vaccine causes the formation of antibodies against the measles virus that will protect the child from future infections.

Another form of measles, known as three-day measles, German measles, or rubella, is also caused by a virus. Contagion is high because the infected person can transmit the virus to others for a week before showing any symptoms, and remains infectious for up to a week after the measles rash disappears.

Rubella is less infectious than the nine-day measles, and some infections may be so mild that the patient's case of rubella goes undetected. After exposure to the virus, an incubation period of 14-21 days passes before any symptoms appear. Usually the symptoms afflict only young children; teenagers and adults will not develop the typical rash.

The rubella rash is similar to that of nine-day measles but is less extensive; it appears on the face and neck and may spread to other areas. The rash lasts about three days before fading. No other symptoms, such as a sore throat, accompany the rash.

The most serious complication of three-day measles is its effect on a woman in the early stages of pregnancy. The virus can cause loss of the fetus or stillbirth, or it may result in congenital (birth) defects. These birth defects can include heart defects, eye defects (including glaucoma and cataracts), deafness, bleeding problems, mental retardation, and an increased risk of diabetes mellitus, thyroid problems, and future encephalitis (brain inflammation). A woman in the first three months of pregnancy should be protected from exposure to individuals who have measles. This form of measles can also be prevented by vaccination.

Mumps

Mumps, also called epidemic parotitis, is a viral infection of the salivary glands, especially the parotid glands. The mumps virus is spread in droplets of saliva sprayed during sneezing or coughing, and can be passed along on any object that has the infected saliva on it. The virus is present in the saliva of the infected person for up to six days before symptoms appear. Late winter and early spring are the peak periods of mumps epidemics, and children aged 5-15 years are most commonly infected. The disease is not as infectious as chickenpox or measles, and it is rare in children under two years of age.

The first symptom of mumps is pain during chewing or swallowing. The pain is worsened by acidic foods such as vinegar or lemon juice. The parotid gland, located in the area at the angle of the jaw, becomes sensitive to pressure. Body temperature increases to 103–104°F (40°C) once the inflammation of the parotid gland begins. The infected parotid gland becomes inflamed and swollen; the swelling may extend beyond the gland to the ear and the lower area of the jaw. The swelling reaches its maximum within two days and then recedes.

The mumps virus can also penetrate the central nervous system and cause abnormally high numbers of cells to accumulate in the spinal fluid. Usually this form of encephalitis has no residual effects, although rarely some facial paralysis or deafness due to auditory nerve damage may result. Mumps afflicting an adult male can cause atrophy of the testes and, in some cases, subsequent sterility. Patients should remain in bed until the fever accompanying the disease has subsided.

There is no treatment for mumps. Usually it is benign and will leave no residual effects other than a natural immunity against catching it again. During the illness, patients may take aspirin to ease the pain in the jaw and lower the fever. Eating soft food also helps to ease jaw pain. Anyone who has been in contact with a mumps patient should be watched closely for up to four weeks to see whether he or she will also develop the disease. A live-virus mumps vaccine is available for administration to children who are 15 months of age.

Sickle cell anemia

Sickle cell anemia is named for the shape assumed by some of the red blood cells in persons who have this disease. It primarily affects people of African descent, but it can also be present in people of Mediterranean descent, such as Arabs and Greeks.

Some people carry the gene for sickle cell anemia without having any active symptoms. For those in whom the disease is active, however, a "sickle cell crisis" can be a painful and debilitating experience.

When the red blood cell undergoes changes that alter its shape from a disk to a sickle, the cells can no longer pass easily through the tiniest blood vessels, the capillaries. The sickle cells stick in these vessels and prevent the passage of normal cells; as a result, the organ or muscle dependent on blood flow through the affected capillaries is no longer getting oxygen. This causes a very painful crisis that may require the hospitalization of the patient.

No treatment exists for sickle cell anemia, so the person who has the active disease must avoid infections and maintain a healthy lifestyle. Any activity that is strenuous enough to cause shortness of breath can also bring on a crisis.

Tay-Sachs disease

Tay-Sachs disease is an inherited, invariably fatal condition in which a missing enzyme allows certain toxic substances to accumulate in the brain. Under ordinary circumstances the enzyme, hexosaminidase A, breaks down these toxins, but without its presence the toxins accumulate.

The condition causes the development of red spots in the eye, retarded development, blindness, and paralysis. The child usually dies by the age of three or four. Tay-Sachs disease primarily affects Jews from eastern Europe.

Parents who carry the gene for Tay-Sachs can be counseled about having children. Statistically for parents who are both carriers of the gene, one in four children will have the active disease, two of the four will be unaffected carriers of the gene, and one of four will have neither the gene nor the disease.