Is it a summer flu…or something else?

You felt fine yesterday, but today you woke up with a fever, sore throat, and body aches. Your first thought might be COVID-19, but these are similar symptoms of seasonal influenza. The only problem is that it’s the middle of June—not exactly prime flu season. Can it still be the flu, or is it more likely to be something else?

Depressing newsflash: Even though it’s unlikely, you can get the flu in the summer months. Here’s what you need to know about catching influenza during the off-season, what other illnesses could be to blame for your summertime sniffles, and how to tell the difference between warm-weather ailments.

Can you get the flu in the summer?

In the northern hemisphere, a typical flu season begins in October and lasts through May, peaking between December and February. But the flu strains that circulate every year don’t disappear between June and September, says Andres Romero, MD, infectious disease specialist at Providence Saint John’s Health Center.

“It’s less common [to get the flu in summer] because influenza is a cyclical virus, but it doesn’t go away completely,” Dr. Romero explains. 

Traditionally,  less people get sick with the flu in the warmer months, so the influenza virus doesn’t have the same opportunity to spread as it does in the fall and winter. That’s because as people start spending more time indoors, respiratory viruses more easily spread from person to person. Additionally, it’s believed the influenza virus thrives in cold, dry environments. 

In summer of 2019, about 1,700 people tested positive for influenza A and B in the United States between May 19 and September 28, according to the Centers for Disease Control and Prevention (CDC). In the 2020-2021 flu season, instances of the flu were low, possibly due to COVID-19 mitigation measures like wearing masks, staying home, and social distancing. But recently, the seasonality of many common viruses, including influenza, has become less reliable. Flu cases are higher than normal in early fall 2022, with experts predicting a rough flu season ahead.

Flu-like illnesses

Although a random flu strain could be to blame for your misery, it’s much more likely that your flu-like symptoms are the result of another kind of virus. Some common viruses that circulate in the summer are:

• Enterovirus: Rhinovirus is more rampant in the winter months, but its common cold counterpart, enterovirus, loves the hot weather—meaning you’re more likely to catch it on a beach vacation than on Christmas break.
• Parainfluenza: Even though this sounds like traditional influenza, it’s generally a milder respiratory illness that likes to spread from spring through fall. Sometimes it leads to secondary illnesses like croup (in young children) and pneumonia.
• Coronavirus: What would a list of summertime illnesses be without the dreaded coronavirus? But, to be clear: There are many different kinds of coronaviruses, and prior to the recent COVID-19 pandemic, it was totally normal to catch one and experience typical cold symptoms. This year, COVID-19 is still in circulation, so if you have been exposed to someone and/or have symptoms, call your healthcare provider for next steps.
• Adenovirus: If you’re hacking away with a chest cold in the summer, it might be adenovirus. It increases its spread in the spring and winter and causes a myriad of common cold symptoms, especially ones that irritate your airways.
• Insect-borne illnesses: Lyme disease and West Nile virus are two common illnesses carried by insects. Since you usually spend more time outside during the summer hanging around ticks and mosquitos, your exposure risk increases.
• Strep throat: Although strep throat is more common in the winter and spring, it can occur at any time of the year. Sore throats are common with many viruses, but strep is a bacterial infection that must be treated with antibiotics.
• Gastroenteritis: Also known as the stomach flu or stomach bug, gastroenteritis can be caused by parasites, viruses, or bacteria. Most commonly, norovirus or rotavirus are the cause of the stomach bug, which can occur year-round–although it’s most common between the months of November and April.
• Food poisoning: Many different bacteria can cause food poisoning. Depending on the type, it can set in anywhere from 30 minutes (staphylococcus aureus) to 2 weeks (listeria) after ingesting the microbe. Food poisoning can occur year-round.   
• Mononucleosis: Also called the kissing disease, mononucleosis is usually caused by the Epstein-Barr virus and causes fatigue and weakness that can last for weeks to months. Unlike the flu, mono is not seasonal and circulates year-round.

Summer flu symptoms vs. COVID-19 and other illnesses

Wondering which virus has got your immune system down? Check this chart for the most common symptoms associated with each summer illness.

Summer flu causes and diagnosis

Even though it’s pretty atypical to catch the flu during the summer, it’s still possible. That’s because influenza viruses circulate year-round–the virus doesn’t disappear. People who have a high risk of contracting the summer flu include:

• Anyone who has traveled internationally in recent weeks, especially to the tropics, where flu activity is always ongoing, or to the southern hemisphere, where the flu season happens from April to September
• Immunocompromised people, like those undergoing cancer treatment and babies, the elderly, and pregnant women
• Anyone who works regularly with vulnerable populations, like healthcare professionals
• Anyone who didn’t receive a flu vaccine the previous year (flu shots begin to lose effectiveness after about six months, but not getting one at all leaves you more vulnerable than folks who did get a shot in the fall)

Influenza viruses can usually be detected with a nasal or throat swab. These aren’t 100% accurate and some variations are more reliable than others, but it’s a good place to start if you suspect you have the flu. Otherwise, it can be hard to figure out what’s ailing you, says Natasha Bhuyan, MD, a family physician in Arizona.

“Based on symptoms alone, these respiratory illnesses are difficult to distinguish,” Dr. Bhuyan admits. “The flu tends to be associated with more body aches and fatigue than a cold, and symptoms of the common cold include fevers, coughing, sneezing, fatigue, and congestion, [but those are also] all symptoms that overlap with COVID-19.”

There are diagnostic tests for enterovirus and adenovirus; however, they’re not commonly used. Parainfluenza can be diagnosed with a blood test or nasal swab (or a combination of the two). Blood work can identify the presence of antibodies for West Nile virus and Lyme disease, although correctly diagnosing Lyme disease can, in some cases, be tricky.

There are also nasal swabs designed to test for coronaviruses, including COVID-19, so contact your doctor for medical advice if you think you should be tested for it.

Treatment for summer illnesses

In most cases, mild to moderate respiratory infections, like colds or the flu, can be treated safely at home with plenty of rest and fluids. OTC medications such as acetaminophen, pseudoephedrine, or dextromethorphan may be needed to reduce your fever, relieve your achy muscles, or keep other symptoms at bay.

A standard case of Lyme disease can be cleared up with a course of oral or intravenous antibiotics. Since West Nile virus is a viral infection, not a bacterial one, there is no easy way to treat an infected person. Many people will experience no symptoms or mild ones that resolve on their own, while others experience complications, like meningitis, requiring hospitalization and supportive care.

Doctors are still figuring out what treatments work best for COVID-19, but if your infection is mild, it can be treated the same as a common cold or the flu. Know the warning signs of a more severe COVID-19 infection and don’t hesitate to seek emergency care, if needed.

Prevention of summer illnesses 

There’s no guarantee that you won’t get sick this summer, but preventing illness in June, July, and August is no more complicated than it is in December, January, or February! The same basic rules apply year-round. Keep yourself in good health, practice good hygiene, and regularly clean and disinfect commonly-used surfaces.

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Of course, this year, you also have to contend with the spread of COVID-19, so you should incorporate wearing a mask in public as well as social distancing as much as possible to your daily sickness-prevention routine.

For general illness prevention in the summer, here are 6 doctor-approved things you can do:

1. Get plenty of sleep and exercise. Dr. Romero says that sleeping eight hours every night is vital to your overall health and immune function, as is exercising—both will make you less likely to get sick and more able to fight off a virus if you do catch one.
2. Eat a healthy diet. Fruits, veggies, whole grains, and lean protein are packed with vitamins, minerals, and antioxidants that prime your body for battle with viruses.
3. Move your gatherings outside. You may have heard that COVID-19 doesn’t spread as easily outdoors as it does indoors, and this also holds true for most other viruses. Dr. Bhuyan suggests that you keep your summer barbeque guest list small and host outdoors, where infected respiratory droplets can’t spread as easily.
4. Keep your hands clean. Hand hygiene is hugely important in curbing the spread of illness. Avoid touching your face when you are in public, wash your hands frequently, and carry hand sanitizer for times when soap and water isn’t available. While you’re at it, disinfect your everyday items—like your cell phone and car keys—regularly to limit the transfer of germs to clean hands.
5. Protect yourself outdoors. To reduce your chances of contracting an insect-borne illness, cover as much of your body in light clothing as possible when spending time outdoors. Use insect repellent containing DEET or another EPA-approved ingredient. Avoid tall, grassy areas or areas with standing water and, if you can, limit your outdoor activity when insects are very active, i.e., dawn and dusk.
6. When in doubt, stay home. Dr. Bhuyan says it’s important to still shelter in place as much as possible, and that certain vulnerable populations (like elderly people, people with asthma or COPD, and people with immunocompromising health conditions) should seriously consider the risks involved with socializing when a virus is circulating…even in the summer.

When in doubt, ask your doctor or pharmacist. They can provide tips to help you stay healthy year-round.