Pneumonia is a contagious condition just like a cold or flu when infectious microbes are the cause of it. However, pneumonia can also result from poisoning, such as breathing in chemical fumes. Although pneumonia isn’t contagious in those cases, pneumonia can become dangerous and even deadly if not treated properly.
Types of Pneumonia
The several different types of contagious pneumonia include:
Viral infections
Viral forms of pneumonia include:
- Adenovirus.
- COVID-19.
- Human metapneumovirus.
- Human parainfluenza virus.
- Influenza (the flu).
- Measles.
- Respiratory syncytial virus (RSV).
- Rhinovirus (the common cold).
- Varicella (chickenpox).
Bacterial infections
Bacterial forms of pneumonia include:
- Chlamydia pneumoniae.
- Haemophilus influenzae.
- Legionella pneumophila.
- Bordetella pertussis (causes whooping cough).
- Chlamydia psittaci (causes of psittacosis).
Fungal and parasitic infections
Fungi inhaled from the soil or bird droppings as well as parasites can also cause pneumonia. However, these cases are rare and usually only occur in people with already weakened immune systems, which makes them more susceptive to infections of all kinds. These types indicate the type of pathogen that initially infected the lung and caused the disease.
Other types of pneumonia
Some people also describe pneumonia in terms of where a person acquired it, such as hospital-acquired pneumonia or community-acquired pneumonia.
A common term for mild cases of pneumonia in which the affected person still feels well enough to function is walking pneumonia. Despite its mildness in this respect, it’s still very contagious.
When and How Is Pneumonia Contagious?
A person with pneumonia can spread the germs when they cough, laugh, or sing, which expels the bacterial or viral infections that cause the disease. Tiny virus- or bacteria-containing droplets can land on common surfaces, such as tables, phones, or computers. You can also breathe in the droplets and bring them into your own respiratory tract.
How long a person is contagious varies depending on the type of pneumonia and how they acquired it. Additionally, some types of pneumonia are much more contagious than others. Two examples of highly contagious strains of this illness are mycoplasma and mycobacterium.
When a person who has pneumonia starts on antibiotics, they only remain contagious for the following 24 to 48 hours. This period can last longer for certain types of organisms, including those that cause tuberculosis (TB). In the case of TB, someone can remain contagious for up to two weeks after starting on antibiotics.
When someone has viral pneumonia, the contagious period starts to subside when their symptoms do. This is particularly true for fevers. Keep in mind that someone who had pneumonia may still cough occasionally for several weeks, even after they’re no longer contagious.
Though some forms of pneumonia are contagious, the disease doesn’t spread as easily as a cold or the flu. Transmission to another person generally requires more exposure to the infectious microbes of a person who has pneumonia.
That’s why pneumonia is more common among people who have been in the same area as others with pneumonia (for example, a hospital) for an extended period of time.
Incubation Period and Symptoms of Pneumonia
The incubation period is the time from when you pick up the pneumonia virus in your body to when you actively display symptoms. Many variables affect this timing, including the type of pneumonia, your general health, and your age.
When you first come down with pneumonia, you might think you have a cold or the flu because the early symptoms are quite similar. However, with pneumonia, symptoms last longer and become more severe with time instead of less.
Because the symptoms of pneumonia worsen with time, seeing your health care provider if you suspect you’ve contracted it is crucial. Left untreated, your lungs can fill with fluid and increase your risk of contracting it again.
Contact your doctor if you’re experiencing pneumonia symptoms, such as:
- Aches and pains in the chest when you cough or draw in a breath.
- Chills and fever.
- Cough that produces phlegm.
- Diarrhea.
- Fatigue.
- Nausea and vomiting.
- Shortness of breath.
These symptoms typically appear within three days to one week of when you first start feeling ill.
Some Cases of Pneumonia Are Fatal
When you get pneumonia, it can infect only one lung or both lungs or spread from one lung to the other. Pneumonia causes the air sacs in your lungs, called alveoli, to become inflamed. This inflammation is what makes breathing difficult.
Pneumonia is serious. It’s the leading cause of infectious disease death in children under age 5 across the world. As with the flu, pneumonia can also prove fatal for elderly people.
Smokers and people with asthma have a greater likelihood of catching pneumonia. However, bacterial infection is the most common cause of pneumonia among adults in the United States.
When to Seek Medical Care for Pneumonia
At UPMC, we recommend that you see your primary care provider as soon as possible or visit a UPMC urgent care center if you:
- Have a cough producing sputum that appears brown, green, or yellow in color.
- Have had a cough and a fever after experiencing flu-like symptoms.
Go to the emergency department immediately if you:
- Experience shortness of breath, high fever, confusion, or pain after a pneumonia diagnosis.
- Have a depressed immune system or a chronic condition like HIV or diabetes.
Pneumonia Treatment
The best things you can do when you have pneumonia are to:
- Drink lots of fluids.
- Get plenty of rest.
- Follow your doctor’s treatment plan.
Doctors at UPMC use the most recent treatment guidelines for pneumonia. The goal of treatment is to cure the infection or to treat the symptoms until the infection goes away on its own.
Treatment often depends on the cause.
Antibiotics can treat pneumonia caused by bacteria but won’t help pneumonia caused by a virus. If a viral or fungal infection is the cause, some antiviral medications or treatments may help.
You may also receive medicines to reduce fever or treat other symptoms, such as coughing.
How to Prevent Pneumonia
Pneumonia can result from exposure to someone else with the condition or extreme environmental exposure, like getting wet when it’s very cold.
The best way to prevent pneumonia is to avoid people who have it and manage your own health. Keep yourself healthy by staying up to date with your flu and COVID-19 vaccinations because these illnesses can lead to pneumonia.
If you have a chronic condition that might weaken your immune system and make you vulnerable to illnesses like pneumonia, monitor your health and check in with your doctor regularly.
You can further reduce your risk of developing pneumonia by not smoking or drinking in excess.
Editor's Note: This article was originally published on , and was last reviewed on .