(NewsNation) — Mild sicknesses tend to spike during the winter months, but this season, public health experts are warning of a “quad-demic.”
The unofficial term “quad-demic” encompasses four infectious diseases: influenza, COVID-19, RSV and norovirus coexist in high numbers.
Add in whooping cough, walking pneumonia and bird flu, people are getting sick and may not know how to distinguish among overlapping symptoms.
Here’s what to know.
Flu
Cases of influenza, or the flu, reached 40 million between 2023-2024, according to the Centers for Disease Control.
Most people recover from the flu within days to a couple of weeks, but some cases can become severe. 28,000 people died last flu season.
Symptoms include:
- Fever (some, not all) or feeling feverish/chills
- Cough
- Sore throat
- Runny or stuffy nose
- Muscle or body aches
- Headaches
- Fatigue (tiredness)
COVID-19
COVID-19 has become a part of life just as the flu did. Cases are nowhere near as high as they were when the virus was first introduced, but the U.S. is still seeing positive tests, hospitalizations and deaths.
Between Oct. 1, 2024, and Dec. 14, 2024, the CDC estimates there were between 2.7 to nearly 5 million illnesses.
Symptoms include:
- Fever or chills
- Cough
- Shortness of breath or difficulty breathing
- Sore throat
- Congestion or runny nose
- New loss of taste or smell
- Fatigue
- Muscle or body aches
- Headache
- Nausea or vomiting
- Diarrhea
COVID-19 and flu symptoms are similar, but they are caused by different viruses.
“You cannot tell the difference between flu and COVID-19 by symptoms alone because some of the symptoms are the same,” according to the CDC.
Anyone experiencing symptoms should take a COVID-19 test, either at a testing site, doctor’s office or over-the-counter sold at pharmacies.
RSV
RSV, or respiratory syncytial virus, is a respiratory illness that affects the nose, throat and lungs, usually peaking in December and January.
The symptoms are similar to the common cold and other respiratory infections like the flu and COVID-19.
Infants and older adults are most susceptible.
RSV can cause other illnesses like bronchiolitis, which is inflammation of the lungs’ small airways, and pneumonia.
Symptoms include:
- Runny nose
- Congestion
- Decrease in appetite
- Coughing
- Sneezing
- Fever
- Wheezing
The CDC warns that not all symptoms will appear at once and may come in stages. Infants may experience only irritability, decreased activity and breathing difficulties without the other symptoms.
Norovirus
The stomach bug is striking again. Norovirus is highly contagious spread through contact and causes inflammation of the stomach and intestines.
The CDC reports about 19 to 21 million annual cases.
People of all ages can get norovirus, but more severe infections occur in children younger than five years old, older adults and people with weakened immune systems.
Symptoms typically develop within 12-48 hours of exposure. They include:
- Diarrhea
- Vomiting
- Nausea
- Stomach pain
- Fever
- Headache
- Body aches
- Dehydration
Other illnesses to watch this winter
Bird flu, walking pneumonia and whooping cough are also on doctors’ radars.
Bird flu: An outbreak of bird flu, or H51N avian influenza, popped up in poultry and dairy cows. The disease is common in wild birds worldwide, but it was recently diagnosed in humans.
The CDC confirmed 66 reported cases in the U.S. since last April, detecting the first severe human case in Louisiana on Dec. 13.
Infected people may not experience any symptoms, but if they do, symptoms can include an eye infection on the mild side to pneumonia and death in more severe instances.
No person-to-person spread has occurred, according to the CDC.
Walking pneumonia: Atypical, or walking, pneumonia is a mild lung infection that can develop from bacteria, viruses or mold. Its name comes from the idea that people often don’t know they have it and can carry on with daily activities despite the symptoms. People typically are not hospitalized, unlike with severe cases of pneumonia.
The CDC reports about two million infections each year, with cases increasing in the later months of last year.
Symptoms, similar to those in a bad common cold or the flu, include:
- Sore throat
- Fatigue
- Chest pain or discomfort
- Low-grade fever (less than 101 degrees Fahrenheit or 38 degrees Celsius)
- Mild chills
- Cough
- Sneezing
- Headache
Whooping cough: Lastly, whooping cough, also known as pertussis, is especially concerning for children who are too young to have completed vaccinations.
The highly contagious respiratory tract infection causes a severe hacking cough, following by a “whoop” sound with an intake of breath, according to the Mayo Clinic.
More than 10,000 cases are reported annually, according to the CDC.
Symptoms, which begin about five to 10 days after exposure and occur in stages, include:
- Runny or stuffed-up nose
- Low-grade fever (less than 100.4°F)
- Mild occasional cough
- Vomiting during or after coughing fits
- Fatigue in between coughs
- Difficulty sleeping
- Struggle to breathe
