Common Viral Infections: Types, Symptoms & Treatment

Instructor: Amanda Robb

Amanda holds a Masters in Science from Tufts Medical School in Cellular and Molecular Physiology. She has taught high school Biology and Physics for 8 years.

In this lesson we'll look at some examples of common viruses. For each one we'll describe characteristics of the virus, what the symptoms are and how the infection is treated.

What Are Viruses?

Imagine being part of a covert operation in the military. During the operation, you gain access to an elegant party hosted by one of the world's most deadly drug cartel leaders. You can't walk in guns blazing as a soldier, so you dress your best and show your invitation at the door. After you and your team have gained entry, you can grab the host and start your war from the inside out.

Although unseen, a similar situation occurs inside our bodies every time we catch a virus. Viruses are non-living infectious particles. When they strike, they slip through our bodies' defenses and hide inside our own cells. They hijack our cells into making more and more viruses. Eventually the viruses explode out of our cells, killing them, which allows the virus to spread to other cells in the body, and eventually other hosts, like your friends at work. Today, we'll be looking in detail at three common viruses: influenza, human immunodeficiency virus, and the rhinovirus.

Influenza Virus

At the beginning of every school year doctors start to advertise flu shots. These medications are designed to keep your body free of a common virus called influenza, or the common flu. People with the flu have fever, yet often feel chilled. Patients also may experience a runny nose, sore throat, cough and general exhaustion. The flu tends to feel more intense than a cold, and often comes with a fever. People with the flu are usually sick for a week or two, whereas a cold might resolve in a few days.

Diagram of the influenza virus, which is the microscopic particle responsible for the flu.
influenza virus

People can recover fully with just rest and extra fluids, but elderly patients, pregnant women, patients that have a week immune system, and children are at risk for complications. Some people can get so sick that they need to be hospitalized, and can even die. If the situation gets that serious, doctors might administer antiviral drugs, which specifically kill viruses.

In fact, more people died in the influenza pandemic of 1918 than in World War I. Up to 40 million people died during only one year of the outbreak. More recently in 2009, the swine flu, or H1N1 as scientists refer to it, caused so many people to get sick that doctors called it a global pandemic. Scientists hypothesized that up to 89 million people in 74 countries contracted H1N1 between 2009 and 2010. However, unlike the 1918 flu, only between 8,300 and 18,300 people died. This is mostly due to technology we now have to create vaccines, which primes the person's immune system to fight the virus, helping the body easily recognize the virus. The flu shot is the vaccine we get every year for the flu.

Soldiers being treated for the 1918 flu.
influenza of 1918

Human Immunodeficiency Virus (HIV)

Human Immunodeficiency Virus (HIV) was first discovered in the 1980s in America when gay men started getting rare fungal infections that are normally easily eradicated by the immune system. Scientists found that HIV infects and kills T-cells, an immune cell that attacks pathogens. Without working T-cells patients quickly become infected with other diseases, such as the flu and pneumonia.

Patients may not experience symptoms for up to ten years, which is why it is so important to get tested regularly to start treatment right away. Other people might start to feel flu-like symptoms about two to four weeks after infection, including a fever, chills, muscle aches, fatigue or a sore throat. If left untreated, HIV develops into acquired immunodeficiency disease, or AIDS. In this case, the immune system completely crashes. Other infections accumulate and the person becomes extremely tired, loses weight, and can even develop dementia and other neurological symptoms.

Symptoms of HIV
symptoms of HIV

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