Chapter 18 Lesson 3 Textbook PDF

The Common Cold MAIN IDEA​ ​Just about everyone has a cold once in a while​. Have you ever had a cold? You probably have. Most people have at least one cold each year. The cold is the most common communicable disease. Colds are responsible for more school absences than any other illness. Cold sympt...

The Common Cold MAIN IDEA​ ​Just about everyone has a cold once in a while​. Have you ever had a cold? You probably have. Most people have at least one cold each year. The cold is the most common communicable disease. Colds are responsible for more school absences than any other illness. Cold symptoms include runny nose, headache, sore throat, coughing, sneezing, and mild fever. You might be wondering, if colds are so common, why they can’t come up with a vaccine to guard against colds. Well, there are hundreds of different viruses that are responsible for the common cold. Because there are so many, scientists can’t develop vaccines for all of them. Besides, scientists believe there are probably twice as many viruses that cause the cold than they already know about. The common cold is here to stay. So, what can you do if you have a cold? The first thing you should do is protect others. When you sneeze, cover your nose and mouth to prevent the infection from spreading. When you sneeze, thousands of infected droplets containing the cold virus are released into the air. They can be spread through direct or indirect contact to others. To recover from a cold, rest in bed. During the first 24 hours your cold is contagious. So, it is best if you stay at home and don’t infect others. Your parents might also give you over-the-counter medicines to help relieve your cold symptoms. You should also drink plenty of fluids when you have a cold. If your cold symptoms get worse, or your sore throat lasts for several days, you should see a doctor. READING CHECK Explain​ Why should you stay home for 24 hours after your cold symptoms appear? The Flu MAIN IDEA​ ​The flu is a common communicable disease​. Your joints and muscles ache. You have fever, chills, fatigue, and a headache. You have the flu. Influenza (in floo EN zuh), or the flu, is another communicable disease. You’ll notice the symptoms of the flu are different from the common cold. Flu symptoms usually affect you more quickly and more seriously than cold symptoms do. Like a cold, though, flu can be spread through both direct and indirect contact. Resting and drinking lots of fluids can help you recover faster from the flu. Some types of flu are serious and require a doctor’s care. December through March is considered to be “the flu season.” This is because most cases of the flu are reported during these months. Flu viruses are not the same as the viruses that cause colds. Every year, certain strains of the flu virus are stronger and spread faster than the year before. Scientists meet every year to determine which strains will spread fastest during the next flu season. Then they develop vaccines for those strains of flu. Some types of flu can be dangerous. Just after World War I, a flu outbreak killed about 20 million people around the world. Over 600,000 of those people were in the United States. Today scientists are doing their best to keep that kind of flu outbreak from happening again. READING CHECK Compare​ How are the flu and the common cold similar? Other Communicable Diseases MAIN IDEA​ ​All communicable diseases have a contagious period​. Communicable diseases have a contagious period​.​ Often, the contagious period begins before the person starts to show symptoms. The contagious periods for several communicable diseases are listed in the Lesson Resources panel. Chicken pox, measles, and mumps all have specific contagious periods. Chicken pox is contagious for about a week before symptoms appear. Typical symptoms for chicken pox include an itchy, bumpy rash, fever, and aching muscles. The itchy bumps will blister and then dry up. When they are dry, chicken pox are no longer contagious. A vaccine for chicken pox became available in 1995. Since then, the disease is much less common. Measles has symptoms that include a rash, fever, and head and body aches. Measles are contagious a few days before symptoms appear. The contagious period lasts about five days after the symptoms appear. Measles is a dangerous disease. Around the world, over 1 million children die each year from measles. Vaccines are available in the United States and some other countries. Because of the vaccine, measles is less common than it once was. Mumps causes a fever, headache, and swollen salivary glands. Mumps are contagious about a week before symptoms appear and for about nine days after that. More than 90 percent of the children in the United States are vaccinated against mumps. Fewer people get the disease now. READING CHECK Explain​ How have the vaccinations for chicken pox, measles, and mumps affected people? Mononucleosis Mononucleosis (MAH noh nook klee OH sis), or mono, is often called the “kissing disease.” It’s called the kissing disease because the people most likely to catch it are teens and young adults. People in these age groups tend do more dating and more kissing. This makes them more vulnerable to the disease. It is spread through contact with the saliva of an infected person. It can also be spread by contaminated drinking glasses and eating utensils. Symptoms can vary but generally include a sore throat and swollen lymph glands in the neck and throat area. Fatigue, loss of appetite, fever, and headache are also symptoms. Severe cases may include an enlarged spleen and an infected liver. People diagnosed with mono are advised to take it easy. Rest is the best treatment for mono. The good news is that once a person is fully recovered from mono, they cannot get it again. Hepatitis Hepatitis (hep uh TY tis) has several symptoms. Yellowing of the skin and whites of the eyes and inflammation of the liver are common symptoms. Other symptoms include fatigue, weakness, loss of appetite, fever, headaches, and sore throat. There are three common strains of hepatitis: A, B, and C. A different virus causes each strain. Hepatitis A is commonly found in areas that have poor sanitation. It spreads when infected human wastes contaminate the food and water sources. If someone consumes contaminated water or food, they can become infected. An open wound that is cleaned with contaminated water can also cause the infection to spread. There is no treatment for hepatitis A. However, it will usually clear up in a few months. Rest and healthful food choices help in the recovery from hepatitis A. Hepatitis B and C can be more dangerous. These strains can cause permanent damage to the liver. They can lead to cirrhosis and liver cancer. These types of hepatitis are usually spread through contact with infected blood or other body fluids. They can spread when drug users share needles. They can also spread through sexual contact. There are vaccinations for hepatitis A and B. There are medications that can help treat hepatitis B and C. Tuberculosis Symptoms of tuberculosis (TB) (too ber kyuh LOH sis) include cough, fatigue, night sweats, fever, and weight loss. It is spread through the air when an infected person coughs or sneezes. The cough or sneeze carries tiny droplets that are then inhaled by another person. A person can have tuberculosis, or TB, and not even know it. He or she may not show any symptoms. They may not be sick, but they can still spread the disease. Doctors and other health care providers often test people to be sure they do not carry TB. Tuberculosis can be treated with medications. However, the treatment period is longer than for most other bacterial infections. Treatment for TB can take up to nine months. Your age, overall health, and type of medication used determine how long it might take. If TB is not treated properly, it can be fatal. Until 1985, TB was rare in developed countries. The spread of HIV, the virus that causes AIDS, has contributed to the increase in TB. People with HIV have a weakened immune system. This keeps them from fighting off bacterial infections such as TB. In countries where TB is a problem, babies are given a vaccination for TB. The vaccination is not 100 percent effective. So, scientists are working to develop a better vaccine. Pneumonia Pneumonia is usually caused by bacteria or viruses. Bacteria or viruses live in your sinuses, nose, mouth, and the environment. When these spread to your lungs, pneumonia can occur. Symptoms include fever, cough, chills, and nausea. Pneumonia can also cause vomiting, chest pains, and difficulty breathing. Pneumonia is spread through direct or indirect contact with an infected person. You can catch it from people whether or not they show symptoms of illness. Pneumonia caused by bacteria can be treated with antibiotics. Pneumonia caused by viruses can be treated with antivirals. People with pneumonia need to rest and drink plenty of fluids. People who have other illnesses such as diabetes or HIV/AIDS are at greater risk to catch pneumonia. There are ways to lower your risk for getting pneumonia. First, pneumonia can be prevented with vaccines. Next, practicing good hygiene can reduce your risk for pneumonia. Wash your hands often and thoroughly. Keep hard surfaces such as counters and desks that you touch often clean. Cough or sneeze into a tissue or into your elbow or sleeve. Reduce your exposure to cigarette smoke. All of these can help reduce your risk for pneumonia. Strep Throat Have you ever had a sore throat? Sore throats can be very painful and uncomfortable. Most sore throats are caused by a virus. Strep throat is caused by bacteria. So it can be treated with antibiotics. Strep throat is spread through direct or indirect contact. When someone infected with strep throat breathes or coughs, they release droplets into the air. If you happen to breathe in some of those droplets, you will likely get strep throat. How do you know if you have strep throat? If you have a red and painful throat, fever, and swollen lymph nodes in your neck, you may have strep throat. Your symptoms might also include headache, nausea, and vomiting. If you have these symptoms, get medical help. If strep throat is left untreated, it can lead to more serious illnesses. It can lead to rheumatic fever, which can damage the heart. It can also lead to nephritis, which can damage the liver. Treatment with antibiotics can prevent these illnesses. READING CHECK Compare​ How are the symptoms for pneumonia and strep throat similar?