What to know about airborne diseases

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According to the Centers for Disease Control and Prevention (CDC), airborne diseases can spread through a direct or an indirect form of transmission, depending on the germ involved.

The pathogens may enter the air in wet droplets, for example, when someone breathes or sneezes. There, they will be suspended in the air, and some droplets dry out, leaving microscopic particles. While suspended in the air, these particles can attach to or enter the body systems of people nearby.

Some particles, such as the fungus Aspergillus, are widely present in the environment. It occurs in soil, plants, including decomposing plant matter, household dust, and building materials, as well as food and water. During building renovations, breathing in dust that contains the fungus may cause disease in some people.

Anthrax, too, is present in the soil in many places around the world. When dust forms from that soil, a person can become sick if they breathe in anthrax spores.

Here are some characteristics that droplet residuals may have, according to the CDC:

• They contain microorganisms that could be active.
• They may have a protective coat of dry secretions, such as mucus or saliva.
• They may stay in the air indefinitely.
• They may carry over long distances.

Air currents can disperse the microorganisms, but how far they travel depends partly on the environment. The further the droplets travel from the source, the lower the risk of infection, due to environmental factors.

Depending on the pathogens, factors that affect how long they remain active include:

• air temperature
• humidity
• exposure to sunlight or other forms of radiation
• the weight of the particles, which can affect how long they take to settle
• the structure and stability of the pathogen

It is not always possible to prevent the spread of airborne diseases, but individuals and authorities can take measures to reduce the risk by recommending or ensuring adequate ventilation and the use of protective equipment.

Depending on the type of organism, the degree of exposure, and individual factors, airborne particles may cause illness to develop if exposure occurs.

Many diseases can arise after exposure to airborne particles, including:

• the common cold, which can develop from a rhinovirus
• chickenpox, caused by the Varicella zoster virus
• mumps, caused by a paramyxovirus
• measles, caused by another paramyxovirus
• whooping cough, a bacterial infection caused by Bordetella pertussis
• COVID-19, caused by the SARS-CoV-2 virus
• aspergillosis, caused by the Aspergillus fungus
• tuberculosis (TB), caused by the bacterium Mycobacterium tuberculosis
• anthrax, a bacterial infection resulting from contact with Bacillus anthracis spores
• diphtheria, a bacterial infection caused by Corynebacterium diphtheriae
• meningitis, which can result from exposure to certain bacterial, viral, or fungal particles

Some experts believe influenza transmits through the air, but not all scientists agree.

Measures taken by hospitals and individuals can help prevent the spread of airborne infectious diseases.

Tips for individuals include:

• staying away from other people when symptoms are present or after receiving a diagnosis of an infectious disease
• wearing a face mask in public places
• keeping rooms properly ventilated
• regularly cleaning and servicing ventilation systems
• covering the mouth and nose when coughing or sneezing

Hospitals and other healthcare centers follow strict guidelines regarding ventilation methods and other measures to protect people from particles that cause airborne diseases and other health problems.

Experts believe that some diseases can spread through more than one route. For example, if microorganisms enter the environment when a person coughs, they may stay in the air or land on surfaces. These surfaces become fomites, which is a term for an object likely to carry an infection. If another person touches a fomite and then touches their mouth, they may then develop symptoms of the disease. Influenza is one example where this might happen, research suggests.

During the COVID-19 pandemic, people should follow local guidelines about testing, isolation, and wearing face coverings. Here, learn more about how to help stop the spread of COVID-19.

The symptoms of an airborne disease will vary widely, depending on the type of disease. Here are some examples of the main symptoms and treatment approaches for some of these diseases:

The outlook will vary widely depending on a person’s diagnosis. Some airborne diseases, such as the common cold, produce minor symptoms in most people and usually resolve within a few days. Others, such as COVID-19, can be life-threatening or involve long-term complications.

Antibiotics can help manage a bacterial infection, and antifungal medications may help resolve infections due to fungi. Antivirals can help slow the activity of a virus in some cases, but there is currently no cure for a virus. However, vaccines can prevent many viruses from causing severe illness.

While antibiotics have improved the outlook for many bacterial infections, some diseases, such as TB, are becoming resistant to antibiotic treatment, making them harder to treat.

The best approach is to take measures to prevent and avoid infection.

Airborne diseases can pass from one person to another when particles that contain pathogens enter into the air, and some then remain suspended there. A range of fungi, viruses, and bacteria can all transmit in this way.

To avoid infection or passing a disease on to another person, people should take care to cover their mouth and nose when sneezing and stay away from other people if they are unwell. Hospitals should follow guidelines to ensure adequate ventilation.

During the COVID-19 pandemic, people can help prevent the spread of disease by using face coverings in public places and isolating according to their current local guidelines.