7 Remarkably Common Viral Infections Explained

A Look at the Common Cold, Influenza, Croup, and More

Millions of Americans get sick with viral infections every year. Viruses are microscopic infectious organisms that cause respiratory, gastrointestinal, neurological, or others symptoms. They can spread from insect to human (such as the West Nile virus) or person-to-person through sex (like herpes, HPV, and HIV) or casual contact, such as influenza and the common cold.

Woman coughing.
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This review of common viruses focusses on those transmitted through everyday contact. These viruses cause either respiratory and gastrointestinal symptoms and are commonly spread through schools, offices, and other public places.

The best way to protect yourself against community-spread viral infections is to wash your hands frequently, disinfect commonly touched surfaces, and stay away from people who are sick.

The Common Cold

Most adults get two to four colds a year, while children may get several more. The common cold can be caused by many different viruses. Most often, the cold is caused by an adenovirus, coronavirus, or rhinovirus.

Symptoms of the common cold are typically mild and last between a week and 10 days. Usually, self-treatment at home with comfort care and perhaps the use of over-the-counter medications to relieve symptoms is all that's necessary.

Cold viruses are spread by droplets, either when someone coughs or sneezes nearby or from touching surfaces contaminated with those droplets, stool, or respiratory secretions.

Use common prevention measures to reduce your chances of getting a cold. These include washing your hands frequently, using hand sanitizer when you don't have access to soap and water, not touching your face, and avoiding others who are sick.

Influenza (The Flu)

Influenza is the virus that causes the seasonal flu. There are numerous strains of influenza that can cause flu symptoms, and the virus mutates from year to year.

Although the flu isn't serious for everyone, hundreds of thousands of people in the U.S. are hospitalized because of it every year.

Worldwide, it is estimated that between 250,000 and half a million people die from the flu each year.

While self-treatment is appropriate for mild cases, people who are at high risk for complications (such as pneumonia) may be treated by their doctor with antiviral drugs.

The best way to prevent the flu is by getting a yearly flu vaccine. Hundreds of studies have proven that the vaccine is both safe and effective. If you aren't sure if it is right for you and your family, be sure to discuss it with your healthcare provider. Note, though, that there are few people for which it's contraindicated.

As with the common cold, influenza is spread by respiratory droplets, and the same tactics of handwashing and avoiding those who are sick are the second line of prevention.

Bronchitis

Bronchitis may be caused by a bacteria, virus, or even chemicals, but the viral type of this infection is the most common. It can cause a cough that lasts for weeks and is a common complication of both colds and the flu.

If you are concerned that you might have bronchitis, contact your healthcare provider. Treatment will depend on your symptoms and the type of bronchitis that you have.

Gastroenteritis (Stomach Flu)

Gastroenteritis, or the stomach flu, is a very common viral infection. This unpleasant illness causes symptoms such as vomiting and diarrhea, and is highly contagious.

Stomach flu (gastroenteritis) is different from influenza (seasonal flu). Gastroenteritis may be caused by viruses such as rotavirus and norovirus, among others.

The viruses that cause stomach flu are spread through feces. The virus may contaminate food or water, or may be picked up from surfaces or contact with an infected person. Handwashing and using good sanitary techniques can help prevent the spread of these viruses.

Some Ear Infections

Often, ear infections happen after you have a cold or the flu. They are far more common in children than in adults, probably due to the smaller passages to the inner ear.

It used to be that all ear infections were treated with antibiotics because it was believed that most cases were caused by bacteria. More evidence has shown that middle ear infections are also often viral and will resolve on their own without these drugs.

Treatment usually depends on how much pain the infection is causing and other symptoms a person is experiencing. If the case is mild, the doctor will usually recommend watchful waiting with a couple of days of bed rest, getting enough fluids, and taking age-appropriate pain relievers (acetaminophen for children under 6 months old, acetaminophen or ibuprofen for others).

Your doctor may still give you a prescription for antibiotics if the symptoms are severe, or a delayed prescription to fill in two to three days if symptoms haven't improved—just in case.

The Centers for Disease Control and Prevention (CDC) notes that the best prevention for ear infections in infants is breastfeeding. The advice for everyone is to not smoke, avoid secondhand smoke, get the annual flu vaccine, and practice good handwashing to prevent getting colds or the flu.

Croup

Croup can be caused by many different viruses, with human parainfluenza virus types 1 and 3 being the most common. It occurs almost exclusively in young children but can be very scary for both the child that gets it and their parent(s).

Croup is characterized by a cough that sounds like a seal barking. Some children may also experience stridor, which is a whistling sound made when the child is inhaling.

Croup can often be treated at home by breathing in steamy or cold air. About 60% of children get better within 48 hours. No medications are needed for mild cases that don't show stridor or a drawing-in of the chest wall when breathing at rest. A cough suppressant (dexamethasone) might be prescribed for those with these signs. In severe cases, treatment is given that supports breathing.

If cough or stridor is not relieved by home treatment, a visit to the doctor or emergency room (depending on severity and time of day) may be necessary.

RSV

Respiratory syncytial virus (RSV) is a viral infection that can be life-threatening for premature babies up to the age of 2 but causes typical cold symptoms in older children and adults. For most who have mild symptoms, fever reducers and preventing dehydration is appropriate care.

RSV creates a lot of mucus and it may be very difficult for very young children to breathe when this occurs. Many babies who were premature and get RSV during the first two years of life need to be hospitalized.

The virus is spread by respiratory droplets from coughs and sneezes, or contact with contaminated surfaces. While most children are contagious for three to eight days, some continue to shed the virus for four weeks. This makes it hard to avoid the virus in daycare centers or schools.

There is currently no vaccine for RSV. Synagis (palivizumab) injections contain antibodies that can help prevent RSV in premature babies who are at high risk.

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