Back To CourseMicrobiology: Help and Review
20 chapters | 336 lessons
As a member, you'll also get unlimited access to over 75,000 lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed.Try it risk-free
Like a battlefield with masses of living soldiers fighting for their freedom, your body is filled with living cells. Your cells have many different jobs, but the job of cells in the immune system is to fight off pathogens, like bacteria and viruses. Bacteria are like enemy soldiers, harmful cells entering your country.
However, like some militia groups use bombs, which are non-living but designed to do harm, viruses can also invade your body. Viruses are non-living infectious particles. They can't reproduce without a host and need a warm, living body to continue making more of themselves. There are two types of viral infections: chronic, or long lasting infections, and acute infections, which are the topic of this lesson.
Acute viral infections are viral infections that occur suddenly and either resolve quickly or result in death. In contrast, a chronic infection, like HIV, lasts for a person's entire life. Don't be fooled by the fact that the acute infections start quickly; many acute viral infections are life threatening, and some end in a quick death instead of resolving. Today, we'll look at three examples of acute viral infections: influenza, yellow fever, and Ebola.
Out of all our examples, you are probably most familiar with influenza, or the flu. The average incubation period, or how long it takes from being infected to feeling symptoms, is one to four days. For most people, after two days they start to feel achy and have a sore throat. A fever is also present. Soon, their nose might run with mucus, a sign of the body trying to expel the virus. Headaches, extreme tiredness, and a light cough also persist during this illness.
Luckily, for most people the flu resolves on its own in one to two weeks. Doctors prescribe rest and fluids. Patients also take over-the-counter medications, like Tylenol for pain, or cough syrup, to relieve symptoms. Although this does not speed up the process of recovery, it does make life more manageable. Unfortunately, the trend of taking large doses of vitamin C to prevent or recover from the flu are not supported by science. The extra vitamin C is not needed by the body and is released in the urine.
Some patients, however, like the elderly, children, and pregnant women, are at risk of serious complications from the flu. If the flu persists or symptoms continue to get worse, doctors might provide antiviral medications, which specifically kill off viruses. These medications are saved for the worst cases however, since viruses quickly change to avoid the medication after several rounds of replication.
Yellow fever is a tropical disease caused by infected mosquitoes. When the mosquitoes bite humans, the virus is transferred to their blood stream. Although most cases resolve, in some patients the disease can be quite serious.
Shortly after the incubation period, these patients experience extreme headaches, fever, chills, vomiting, pain, and weakness. The infection may feel resolved, but within hours to days, severe symptoms set in. Liver failure causes a condition called jaundice, which turns the skin and eyes yellow, hence the name yellow fever. The body shortly goes into shock, and the patient can die from organ failure.
No antivirals work on yellow fever, so doctors mainly try to control symptoms while the immune system fights it off. Fluids are given, and any lost blood can be replaced with a blood transfusion. If the kidneys start to fail, dialysis can be used to filter the blood until they heal. Avoiding further mosquito bites is also important to stop transmission of the disease and to avoid reinfection.
Ebola has been a virus in the news lately for its sensational outbreaks and lack of treatment. Outbreaks are found mostly in Africa, but in 2014, cases in other countries were documented due to global travel. The average fatality rate of the disease has been estimated at around 50%, however, some outbreaks have had an estimated 90% fatality rate.
Ebola symptoms can appear two days after infection, but the average is eight to ten days. People with Ebola first experience a headache, followed by chills, muscle aches, and weakness. As the infection progresses, patients start vomiting and having diarrhea.
The virus targets immune cells, liver cells, and cells lining our blood vessels. When the virus reproduces, it breaks these cells apart, killing them. If the blood vessels break apart, hemorrhaging occurs, which causes the characteristic red eyes of patients. Internal bleeding causes the patient's insides to liquefy. Bruises appear on the skin from ruptured blood vessels. Vomit and diarrhea are filled with blood. As the virus infects the liver, the organ begins to fail. The immune system becomes impaired and as the disease progresses, the patient has less of a chance of fighting it off.
Treatments for Ebola are limited and most patients survive because of their immune system. There are no antiviral drugs or vaccines for Ebola. Patients can be given fluids through an IV and blood transfusions to counteract the bleeding. Doctors can stabilize blood pressure and administer oxygen as the lungs fail, but there is no cure to stop the disease.
Viruses are non-living infectious particles that need a host to reproduce. Acute viral infections occur suddenly and can resolve or patients may die quickly. This is in contrast to chronic viral infections, which can last a patient's entire life.
Influenza is the flu, which is characterized by fever, headaches, a sore throat, and a cough. It usually resolves on its own; however, antiviral treatment can be used for extreme cases. Some people get a vaccine and avoid the flu all together.
Yellow fever is a tropical disease that induces liver failure and jaundice. Although most cases resolve, some patients go into shock with multiple organ failure. Although antivirals do not work, doctors can treat symptoms with fluids, blood transfusions, and dialysis.
Ebola is a virus that causes a hemorrhagic fever, which causes severe internal bleeding, vomiting, diarrhea, and, eventually, organ failure. There is no cure or treatment, and only 50% of patients recover on average.
To unlock this lesson you must be a Study.com Member.
Create your account
Already a member? Log InBack
Did you know… We have over 160 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.
To learn more, visit our Earning Credit Page
Not sure what college you want to attend yet? Study.com has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.
Back To CourseMicrobiology: Help and Review
20 chapters | 336 lessons
Next LessonWhat is Phage Therapy?