Sniffling, sneezing, coughing: What infectious disease do you have?

By Katia Hetter, CNN

(CNN) — Welcome to winter virus season.

Cases of acute respiratory illness, Covid-19 and seasonal flu are increasing in most parts of the United States, according to the US Centers for Disease Control and Prevention.

Emergency department visits for flu and the respiratory syncytial virus, or RSV, are very high. While Covid-19 cases leading to emergency department visits are still low, they are increasing, with wastewater testing already revealing high coronavirus levels.

How can you know which infectious disease you have? Does it depend on the illness, the symptoms or the characteristics of the person who is ill? And how can people find out what to do — should they go to their primary care provider, urgent care or the hospital’s emergency department?

Against this backdrop, norovirus cases causing gastrointestinal upset also have been surging. Several other infectious illnesses are making the rounds, too, including the viruses that cause the common cold and bacteria that lead to strep throat.

To help us with these questions, I spoke with CNN wellness expert Dr. Leana Wen. Wen is an emergency physician and clinical associate professor at the George Washington University. She previously served as Baltimore’s health commissioner.

CNN: How should people who are sick decide when they need testing to figure out what illness they have?

Dr. Leana Wen: I would approach this question by thinking about whether what you would do for yourself or your sick loved one would change if you knew the specific pathogen. Your actions would depend on the pathogen in question and the person’s age, underlying medical conditions and type of symptoms.

Let’s begin with respiratory illnesses. Most healthy people who have mild symptoms like runny nose, congestion and fatigue do not need to seek medical care. More than 200 viruses cause the common cold, which is more than likely the cause of these symptoms.

Even if these healthy individuals with mild symptoms have Covid-19 or influenza, they probably wouldn’t be eligible for antiviral treatment. They could choose to take home tests for Covid-19, influenza or both if they want to know if they have these two viruses, but this knowledge wouldn’t really change their clinical management. The recommendation would be symptomatic treatment, meaning rest, lots of fluids and over-the-counter medicines like acetaminophen and ibuprofen to relieve symptoms of fever and body aches.

Testing remains important for some people though. Individuals at higher risk for developing severe disease from Covid-19 and influenza should get tested as soon as their symptoms start so that they can begin prompt antiviral treatment. People at higher risk for severe disease from Covid-19 include older individuals and those with chronic underlying medical problems. These are also individuals at higher risk of serious outcomes due to influenza. For instance, pregnant women are considered especially vulnerable to complications of the flu.

Severity of illness also plays a role for two reasons. In the case of flu, antiviral treatment is recommended for those people who are very sick with influenza, even if they don’t have risk factors for severe illness. In addition, if someone is very ill, they could have another disease. Perhaps what they have isn’t a simple cold but rather a bacterial pneumonia requiring antibiotics. Or maybe they started with a cold, but then they developed pneumonia.

Someone who has worsening cough, persistent high fevers and other concerning symptoms like chest pain, abdominal pain and trouble catching their breath needs to seek medical care to treat these symptoms and to seek the underlying cause. If symptoms are not improving after five to seven days, it would also be reasonable to contact your health care provider.

CNN: What about people with other symptoms, such as stomach upset? Do they need testing?

Wen: The majority of people with diarrhea, vomiting and stomach cramps have viral gastroenteritis caused by the very contagious norovirus. This illness comes on abruptly and is very uncomfortable, but the vast majority recover fully within a few days. No specific treatment exists, and generally testing is not recommended to confirm the diagnosis.

There are exceptions. If someone has persistent symptoms of diarrhea and vomiting, if they develop fevers, if they have severe abdominal pain, the concern is that what they have isn’t run-of-the-mill norovirus. Maybe they have a bacterial infection and need antibiotics. Maybe what they have isn’t an infection at all and could be appendicitis. They should consult with a doctor to see if additional evaluation and testing is needed.

Severity of illness, especially in vulnerable individuals, is another red flag. Babies and other young children, as well as the elderly and people with chronic kidney and heart problems, need to visit the doctor sooner rather than later to make sure they are keeping hydrated.

CNN: What other symptoms should people look out for when it comes to whether they need testing?

Wen: If your kid has a sore throat and fever, seek care to see if they have strep throat. They will need antibiotics to prevent complications that come with the group A streptococcal bacteria that causes strep throat. Many cases of sore throat are due to viruses and do not need specific treatment, so it’s important to distinguish between viral and bacterial causes of sore throat. Clinicians can sometimes also distinguish between them based on symptoms, though sometimes a strep test is done.

CNN: How should people think about when they go to which setting — primary care provider versus urgent care versus the emergency department?

Wen: I would think about three factors here.

First, if you have a primary care provider, what access do you have? Some people can reach their physician or another clinician in the same practice 24/7. That’s terrific, and in most circumstances, it’s worth calling that person to seek their counsel on next steps. Perhaps they could even do a same-day appointment in person or virtually. When possible, it’s always best to see the provider who knows you and your medical history.

If you cannot easily reach your provider or don’t have one, you will have to set a lower bar for going to an urgent care or emergency department setting. I encourage everyone to have a plan before getting ill. Know what your insurance covers and how crowded the settings may be. It’s possible that an urgent care visit is significantly cheaper than the emergency department, and the wait is likely shorter.

Second, how severe is the illness? If someone is experiencing very concerning symptoms, like chest pain, trouble breathing, numbness or weakness in an arm or leg, they should go to the emergency department right away. On the other hand, someone who isn’t feeling well but their symptoms have been going on for some time can call their primary care office for next steps. If they cannot easily reach the provider and don’t want to wait, they can go to an urgent care facility.

Third, are you in a group of individuals considered to be especially vulnerable? Babies, pregnant women, older individuals and those with underlying medical conditions face additional risks of severe illness. Patients and families should have a plan. For instance, pregnant women should know if their first call is to their obstetrician and where they can access care.

Parents of newborns and young babies should also know how to reach their pediatrician. In an emergency, they need to know which specific place they should go to, since not all urgent care or emergency departments have specialists trained to treat babies. And individuals with specific conditions, such as cancer patients on chemotherapy or people who have received an organ transplant, need to be especially on guard and know where they can access medical assistance tailored to them.

CNN: What are some preventive measures that people can take to reduce their risk of catching and transmitting infectious diseases?

Wen: It’s not easy to avoid infections during winter virus season, but people can take steps. Everyone should wash their hands regularly with soap and water, and, if soap and water are not available, use hand sanitizer. People who are especially vulnerable to severe illness should consider limiting their interactions with others. They should consider wearing a high-quality mask in indoor, crowded settings, and they should ask family members and friends who have symptoms to stay away until symptoms resolve.

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