Contagiousness
Pertussis is highly contagious. The bacteria spread from person to person through tiny drops of fluid from an infected person's nose or mouth. These may become airborne when the person sneezes, coughs, or laughs. Other people then can become infected by inhaling the drops or getting the drops on their hands and then touching their mouths or noses. Infected people are most contagious during the earliest stages of the illness up to about 2 weeks after the cough begins. Antibiotics shorten the period of contagiousness to 5 days following the start of antibiotic treatment.

Prevention
Whooping cough can be prevented with the pertussis, vaccine which is part of the DTaP (diphtheria, tetanus, acellular pertussis) immunization. DTaP immunizations are routinely given in five doses before a child's sixth birthday. To give additional protection in case immunity fades, the AAP now recommends that kids ages 11-18 get a booster shot of the new combination vaccine (called Tdap), ideally when they're 11 or 12 years old, instead of the Td booster routinely given at this age. As is the case with all immunization schedules, there are important exceptions and special circumstances. Your child's doctor will have the most current information.

Experts believe that up to 80% of nonimmunized family members will develop whooping cough if they live in the same house as someone who has the infection. For this reason, anyone who comes into close contact with a person who has pertussis should receive antibiotics to prevent spread of the disease. Young children who have not received all five doses of the vaccine may require a booster dose if exposed to an infected family member.

Incubation
The incubation period (the time between infection and the onset of symptoms) for whooping cough is usually 7 to 10 days, but can be as long as 21 days.

If your child has whooping cough, it will be treated with antibiotics, usually for 2 weeks. Many experts believe that the medication is most effective in shortening the infection when it's given in the first stage of the illness, before coughing spells begin. But even if antibiotics are started later, they're still important because they can stop the spread of the pertussis infection to others. Ask your child's doctor whether preventive antibiotics or vaccine boosters for other family members are needed.

Some children with whooping cough need to be treated in a hospital. Infants and younger children are more likely to be hospitalized because they're at greater risk for complications such as pneumonia which occurs in about one in five children under the age of 1 year who have pertussis. Up to 75% of infants younger than 6 months old with whooping cough will receive hospital treatment. Infants and younger children are more likely to require hospitalization because they're at greater risk for complications such as pneumonia, ear infections, dehydration and  seizures In infants younger than 6 months of age, whooping cough can even be life-threatening.

The disease has been recognized for several centuries, and medical historians argue over whether the name "mumps" comes from an old word for "lump" or an old word for "mumble."

Mumps was common until the mumps vaccine was licensed in 1967. Before the vaccine, more than 200,000 cases occurred each year in the United States. Since then the number of cases has dropped to fewer than 1,000 a year, and epidemics have become fairly rare. As in the prevaccine era, most cases of mumps are still in children ages 5 to 14, but the proportion of young adults who become infected has been rising slowly over the last two decades. Mumps infections are uncommon in children younger than 1 year old.

After a case of mumps it is very unusual to have a second bout because one attack of mumps almost always gives lifelong protection against another. However, other infections can also cause swelling in the salivary glands, which might lead a parent to mistakenly think a child has had mumps more than once.

Signs and Symptoms
Cases of mumps may start with a fever up to 103 degrees Fahrenheit (39.4 degrees Celsius), as well as a headache and loss of appetite. The well-known hallmark of mumps is swelling and pain in the parotid glands, making the child look like a hamster with food in its cheeks. The glands usually become increasingly swollen and painful over a period of 1 to 3 days. The pain gets worse when the child swallows, talks, chews, or drinks acidic juices (like orange juice).

Both the left and right parotid glands may be affected, with one side swelling a few days before the other, or only one side may swell. In rare cases, mumps will attack other groups of salivary glands instead of the parotids. If this happens, swelling may be noticed under the tongue, under the jaw, or all the way down to the front of the chest.

Mumps can lead to inflammation and swelling of the brain and other organs, although this is not common. Encephalitis (inflammation of the brain) and meningitis (inflammation of the lining of the brain and spinal cord) are both rare complications of mumps. Symptoms appear in the first week after the parotid glands begin to swell and may include: high fever, stiff neck, headache, nausea and vomiting, drowsiness, convulsions, and other signs of brain involvement.

Mumps in adolescent and adult males may also result in the development of orchitis, an inflammation of the testicles. Usually one testicle becomes swollen and painful about 7 to 10 days after the parotids swell. This is accompanied by a high fever, shaking chills, headache, nausea, vomiting, and abdominal pain that can sometimes be mistaken for appendicitis if the right testicle is affected. After 3 to 7 days, testicular pain and swelling subside, usually at about the same time that the fever passes. In some cases, both testicles are involved. Even with involvement of both testicles, sterility is only a rare complication of orchitis.

Additionally, mumps may affect the pancreas or, in females, the ovaries, causing pain and tenderness in parts of the abdomen.

Contagiousness
The mumps virus is contagious and spreads in tiny drops of fluid from the mouth and nose of someone who is infected. It can be passed to others through sneezing, coughing, or even laughing. The virus can also spread to other people through direct contact, such as picking up tissues or using drinking glasses that have been used by the infected person.

People who have mumps are most contagious from 2 days before symptoms begin to 6 days after they end. The virus can also spread from people who are infected but have no symptoms.

Prevention
Mumps can be prevented by vaccination. The vaccine can be given alone or as part of the measles-mumps-rubella (MMR) immunization, which is usually given to children at 12 to 15 months of age. A second dose of MMR is generally given at 4 to 6 years of age, but should be given no later than 11 to 12 years of age. As is the case with all immunization schedules, there are important exceptions and special circumstances. Your child's doctor will have the most current information.

Incubation
The incubation period for mumps can be 12 to 25 days, but the average is 16 to 18 days.

The rash begins as multiple small, red bumps that look like pimples or insect bites. They develop into thin-walled blisters filled with clear fluid, which then becomes cloudy. The blister wall breaks, leaving open sores, which finally crust over to become dry, brown scabs. One of the most characteristic features of the chickenpox rash is that all stages of the lesions can be present at the same time.

Chickenpox blisters are about a quarter to half an inch wide, have a reddish base, and appear in bouts over 2 to 4 days. Some children have only a few blisters, whereas others have several hundred. The rash may be more extensive or severe in kids who have skin disorders such as eczema.

Some children have a fever , abdominal pain, or a vague sick feeling a day or 2 before the rash appears. These symptoms may last for a few days, and fever stays in the range of 100 to 102 degrees Fahrenheit (37.7 to 38.8 degrees Celsius), although it may occasionally be higher. Younger children often have milder symptoms and fewer blisters than older children or adults.

Normally, chickenpox is a mild illness, but certain groups of people are more likely to have a more severe illness that could lead to complications. These include infants, adolescents, adults, and people with weak immune systems from either illnesses or from medications such as long-term steroid use. The most common complication of severe chickenpox illness in these groups of people is a bacterial infection that can involve many sites of the body including the skin around the blisters, bones, lungs, joints, and the blood. Other serious complications are due to the virus itself infecting the organs and include viral pneumonia , bleeding problems, and inflammation of the brain (encephalitis ).

Anyone who has had chickenpox as a child is at risk for a complication later in life called shingles. After an infection, some of the varicella-zoster virus may remain inactive in nerve cells near the spinal cord. Many years later, the virus can reactivate and resurface as shingles. When it reactivates, it affects the nerve to the skin. Symptoms, such as a tingling feeling, itching, or pain followed by a rash with red bumps and blisters appear only in the area of the skin that the nerve goes to.

Contagiousness
The contagious period for chickenpox begins about 2 days before the rash appears and lasts until all the blisters are crusted over. A child with chickenpox should be kept out of school until all of the blisters have dried, which is usually about 1 week, but you don't have to wait until all the scabs fall off to let your child get back to a normal schedule.

Pregnant women, as well as people with diseases or problems with their immune system, should not be near a person with chickenpox. If a pregnant woman who hasn't had chickenpox in the past contracts it (especially before 20 weeks), the fetus is at risk for birth defects. If she develops chickenpox 5 days before to 2 days after delivery, the newborn is at risk for life-threatening varicella (the mother has transferred the virus to the baby, but she hasn't had time to produce and transfer antibodies, which fight off infection, to the baby before it's born).

If the mother had chickenpox in the past (before the pregnancy or any time more than a week before delivery), then the fetus receives antibodies through the placenta. That means the mom's immunity gets passed on to the baby through the placenta and breast milk, so it would be unlikely for the infant to get sick. But antibodies are not fail-safe; there is no 100% guarantee that a baby won't get the infection - it's just less likely. Or, the infant might have the disease, but it won't be as severe. It's also important for pregnant women to realize that they're at increased risk of chickenpox complications if they catch it for the first time while pregnant.

People who haven't had chickenpox can also catch it from someone with shingles, but they cannot catch shingles itself. Why can't a person catch shingles from someone else? It's because shingles can only develop from a reactivation of the varicella-zoster virus in a person who has previously had chickenpox.

Prevention
Since 1995, a varicella vaccine has been given to children older than 12 months, as well as adults. The vaccine is about 70% to 85% effective at preventing mild infection, and more than 95% effective in preventing moderate or severe disease. People who do develop chickenpox after vaccination have much milder symptoms with fewer skin blisters and a fast recovery.

The vaccine is recommended to be routinely given to children at 12 to 18 months of age. Older children, adolescents, and adults who haven't had chickenpox should also be immunized. Whereas children 12 months to 12 years receive a single vaccine dose, adolescents and adults require two vaccine doses a minimum of 4 weeks apart. Considering that the vaccine could prevent illness and even deaths, not enough children are being vaccinated, according to the Centers for Disease Control and Prevention (CDC). As is the case with all immunization schedules, there are important exceptions and special circumstances. Your child's doctor will have the most current information.

There's also a second type of prevention for certain people who are at risk for severe disease and who've already been exposed to the infection. A ready-made form of immune protection called varicella-zoster immune globulin (VZIG) is given to newborns whose mothers had chickenpox at the time of delivery; high-risk patients (such as those with leukemia or immune deficiencies); and kids receiving drugs that suppress the immune system.

Healthy children who have had chickenpox do not need the vaccine - they usually have lifelong protection against the illness. However, 10% to 20% of people who've had chickenpox develop shingles later in life.

Incubation
The incubation period for chickenpox is 10 to 21 days after exposure; most cases appear in 14 to 17 days. For example, if one child in a family breaks out with chickenpox picked up at school, siblings probably will show symptoms about 2 weeks later.

Duration
Chickenpox usually lasts 7 to 10 days in children, but typically lasts longer in adults.

Once the bacteria are in the body, they produce a neurotoxin (a protein that acts as a poison to the body's nervous system) known as tetanospasmin that causes muscle spasms. The toxin first affects nerves controlling the muscles near the wound. It can also travel to other parts of the body through the bloodstream and lymph system. As it circulates more widely, the toxin interferes with the normal activity of nerves throughout the body, leading to generalized muscle spasms. Without treatment, tetanus can be fatal.

In the United States, most cases of tetanus follow a cut or deep puncture injury, such as a wound caused by stepping on a nail. Sometimes the injury is so small that it is never seen by a doctor. Injuries that involve dead skin (such as burns, frost bite, gangrene, or crush injuries) are more likely to cause tetanus. Wounds contaminated with soil, saliva, or feces - especially if not properly cleaned - and skin punctures from nonsterile needles (such as with drug use or self-performed tattooing or body piercing) are also at increased risk.

Another form of tetanus, neonatal tetanus, occurs in newborns who are delivered in unsanitary conditions, especially if the umbilical cord stump becomes contaminated. Prior to immunizations, neonatal tetanus was much more common in the United States. Now, routine immunizations for tetanus produce antibodies that mothers pass to their unborn babies. These maternal antibodies and sanitary cord-care techniques have made newborn tetanus very rare in developed countries.

In fact, tetanus in general is rare in the United States and other nations with tetanus vaccination programs - fewer than 50 cases of tetanus have been reported each year in the United States since 1995. However, many developing countries have no effective prevention and immunization programs against tetanus, so the disease is much more common there.

Signs and Symptoms
Tetanus often begins with muscle spasms in the jaw (called trismus), accompanied by difficulty swallowing and stiffness or pain in the muscles of the neck, shoulders, or back. These spasms can spread to the muscles of the abdomen, upper arms, and thighs.

Neonatal tetanus causes the same symptoms in newborns.

Contagiousness
Tetanus cannot be spread from person to person.

Prevention
There are two important components of tetanus prevention: tetanus immunization (receiving routine tetanus vaccinations) and what's known as post-exposure tetanus prophylaxis (receiving a shot after an injury occurs).

For children, tetanus immunization is part of the DTaP (ditheria, tetanus, and acellular pertussis ) vaccinations. Children typically receive a series of four doses of DTaP vaccine before 2 years of age, followed by a booster dose at 4 to 6 years of age. After that, a tetanus and diphtheria booster (Td) is recommended at 11 to 12 years of age, and then every 10 years through adulthood. As is the case with all immunization schedules, there are important exceptions and special circumstances. Your child's doctor will have the most current information.

Post-exposure tetanus prophylaxis also involves getting tetanus shots, but after an injury occurs. Which shots are given will depend on the number of years since the patient's last booster, the total number of tetanus vaccinations the patient has received, and the nature of the wound. The doctor may recommend a tetanus booster (Td or DTaP, depending on the patient's age) and/or an injection of tetanus immune globulin (TIG) to neutralize any toxin released by the bacteria.

Neonatal tetanus can be prevented by making sure that all pregnant have had their tetanus immunizations and by delivering babies in sanitary conditions. If you are pregnant, discuss your immunization record with your obstetrician well before your due date.

Incubation
The incubation period for tetanus is usually 2 to 14 days, with most symptoms beginning around the seventh day. In neonatal tetanus, symptoms start within the first 2 weeks of life.

Chickenpox, which occurs most often in the late winter and early spring, is very contagious - if exposed to an infected family member, about 80% to 90% of those in a household who haven't had chickenpox will get it. However, immunization of children with the chickenpox vaccine that's now available is expected to decrease cases of the disease dramatically over the next few years.

Although it's more common in kids under the age of 15, anyone can get chickenpox. A person usually has only one episode of chickenpox in his or her lifetime. But the virus that causes chickenpox can lie dormant within the body and can cause a different type of skin eruption later in life called shingles, also referred to as herpes-zoster.