Airborne illness and disease

Definition

Airborne diseases are transmitted by contaminated droplets in the air. Common types of airborne disease include COVID-19, upper respiratory infection (URI), influenza, varicella or chickenpox, and tuberculosis. Other airborne illnesses, such as pertussis and measles, are less common in the United States because of high levels of vaccination among the population.

Exposure

COVID-19. This airborne, infectious disease is caused by the SARS-CoV-2 virus residing in respiratory fluids. This disease is spread by airborne particles and droplets. Common forms of transmission include exhaling, breathing, coughing, and sneezing. This can occur from distances of approximately six feet. The risks of infection are greater while a person is indoors in a space with insufficient ventilation. Other risk factors include congregating in crowded spaces and prolonging the time a person spends in such conditions. Older adults and people with pre-existing medical conditions are thought to be most at risk.

Upper Respiratory Infection and influenza. Both URI and influenza are highly contagious. They can be spread from person to person when an infected person coughs or sneezes. People can also catch a URI or the flu by touching a contaminated object (a fomite) that contains the live virus and by then touching their eyes, nose, or their mouth. Other methods of transmission include kissing and sharing food or drinks.

Certain risk factors may cause a person to be more susceptible to a URI or influenza. Those risk factors include age as young children and adults aged sixty-five years and older are more susceptible. Other factors are a compromised immune system caused by illness or treatment of an illness such as by chemotherapy. Others at risk are those that live living in a residential care facility or work in healthcare.

Varicella or Chickenpox. Chickenpox is highly contagious and can be spread from person to person when an infected person coughs or sneezes. One of the main symptoms of chickenpox is a rash that eventually leads to blisters. Touching an open blister that is leaking fluid can also lead to the spread of the disease.

As with a URI or influenza, certain risk factors make a person more susceptible to chickenpox. These include having no previous exposure, no previous vaccination, and exposure to children.

Tuberculosis. Although tuberculosis is a contagious disease, it does not spread as easily as URI, influenza, or chickenpox. It can still be transmittable when an infected person coughs or sneezes. Nonetheless, it is most commonly spread when people are in close quarters such as the home or office. Tuberculosis cannot be spread by handshaking, kissing, or sharing food or drinks.

Other risk factors for contracting tuberculosis include: having a compromised immune system, a locale where there are high rates of tuberculosis, being sixty-five years of age or older, long-term drug or alcohol use, living in a residential care facility, and working in healthcare.

People who are at high risk for contracting tuberculosis should be tested. These include healthcare workers, those with HIV or other immune system disorders, people in areas with high rates of infection, those in residential care facilities, persons who have symptoms of active tuberculosis, people who live or work in correctional facilities, injection-drug users, and persons who have has been exposed to others with active cases of tuberculosis.

Prevention

COVID-19. Vaccines offer an effective method of prevention of severe symptoms for this coronavirus. Other preventative measures include wearing a mask, maintaining physical distances, and avoiding crowded areas.

Upper Respiratory Infection. There is currently no vaccination for the prevention of URIs. Frequently handwashing is the best method of preventing the common cold, particularly before eating or preparing food.

Another way to help prevent the spread of URI is to periodically clean shared surfaces with antibacterial wipes. Examples are computer keyboards, refrigerator handles, doorknobs, and toys. Children should be encouraged to drink from their own drinking glass rather than sharing. Last, close contact should be avoided with people who have a cold or other respiratory tract infections.

Influenza. The best way to prevent influenza is to receive an influenza vaccination. In the fall of 2010, the influenza vaccine began protecting against the most common types of these viruses, including seasonal influenza and the H1N1 virus or swine flu. The Centers for Disease Control and Prevention (CDC) recommends that all persons ages six months and older be vaccinated, although with exceptions. The following people should not get a flu vaccine without consulting a physician: persons who are allergic to eggs, who have had a previous allergic reaction to the flu vaccine, who have Guillain-Barré syndrome, or who are already sick and who have a fever. Vaccination is recommended after the illness.

In addition to vaccination, there are other steps to help prevent the spread of influenza, including frequent handwashing, using a tissue to cover the nose or mouth when coughing or sneezing, periodically cleaning shared surfaces, avoiding close contact with people who have symptoms of a cold or flu, not sharing drinking glasses, and not going to work when sick.

Varicella or Chickenpox. The best method for preventing chickenpox is the varicella or chickenpox vaccine. The CDC recommends that all children and adults who do not have evidence of immunity to varicella be vaccinated. Evidence of immunity, according to the CDC, includes documentation of either of the following: two doses of varicella vaccine, blood tests that show immunity, laboratory confirmation of prior varicella disease, a diagnosis of chickenpox or verification of a history of chickenpox from a qualified health care provider, or a diagnosis of herpes zoster or shingles) or verification of a history of herpes zoster from a qualified healthcare provider.

Some people are given the chickenpox vaccine after exposure to help prevent them from contracting the disease. According to the CDC, the chickenpox vaccine is not recommended for the following people: those allergic to gelatin, those who have a moderate or serious illness, pregnant women, persons with compromised immune systems because of illness or treatment of illness, persons who have received blood or blood products three to eleven months before considering vaccination, and persons with a family history of immune deficiency.

Tuberculosis. Although a vaccine has been developed for the prevention of tuberculosis, that vaccine is not commonly used in the United States. The tuberculosis vaccine, which is known as the Bacille Calmette-Guérin vaccine, does not always protect against tuberculosis and could cause a false-positive result in people who are later tested for tuberculosis.

Preventing the spread of tuberculosis is still possible without the vaccine. For example, persons who are infected with tuberculosis can be treated before their disease becomes active. This involves regular testing of people who may be at risk. For persons who test positive for tuberculosis infection, medications that can be prescribed by doctors to help prevent active disease. Other methods of preventing the spread of tuberculosis include covering the nose and mouth with a tissue when coughing or sneezing, opening windows to ventilate rooms if the weather permits, avoiding the workplace when sick, wearing a mask around others, and avoiding close contact with family members for the first few weeks of treatment.

Symptoms

COVID-19. This disease produces a wide array of symptoms and can produce an illness ranging in severity. Symptoms typically occur two to four days after exposure. These may include fever or chills, shortness of breath, body or muscle aches, headaches, loss of taste and smell, and congestion. New variants of COVID-19 continue to materialize.

Upper Respiratory Infection. Symptoms of the common cold begin from one and three days after exposure, and may include runny or stuffy nose, coughing, sneezing, congestion, sore throat, fatigue, and a general feeling of being unwell.

Influenza. Flu symptoms are much like symptoms of the common cold, but are more severe. In addition to cold symptoms, persons who have the flu will also experience fever and chills, headache or body aches; other persons, particularly children, also may experience nausea and vomiting. There are potential complications that are related to the common cold or flu. Complications may include ear infection (particularly in small children), sinus infections, bronchitis, and pneumonia.

Varicella or Chickenpox. The main symptom of chickenpox is a skin rash, mostly on the face, scalp, chest, and back. The rash eventually blisters, then dries up and crusts over. Some people may also experience fever, headache, sore throat, and a general feeling of being unwell.

As with URIs and influenza, some people do experience complications that are related to chickenpox. Complications may include pneumonia, skin infection, and, in rare cases, encephalitis, which is an infection of the brain. Another complication of chickenpox may occur many years after a person has the disease. This complication is shingles, an infection that is characterized by a painful rash. It is usually seen in older adults and is caused by the same virus that causes chickenpox.

Tuberculosis. Many people who contract tuberculosis have no symptoms. Persons who are asymptomatic have latent TB (tuberculosis) infection and cannot spread the disease to others unless their disease becomes active.

When tuberculosis bacteria begin actively multiplying in the body, the person who is infected is said to have active TB disease. Symptoms of active TB include a persistent cough which can result in a coughing up of blood. Other symptoms include chest pain when breathing or coughing, fever, chills, night sweats, fatigue, loss of appetite, and weight loss. People with active TB are contagious and can spread the disease to others.

Complications from tuberculosis can be serious or even fatal. Tuberculosis complications may include lung damage, joint damage, damage to other organs, meningitis, and death.

Treatment

COVID-19. A number of treatments have become available for COVID-19. Most are intended for use by adults, although children typically older than twelve can also be deemed eligible. These include antiviral drugs such as Paxlovid, Remdesivir, and Molnupiravir.

Upper Respiratory Infection. There is no cure for URI. “Treatments” are designed not to cure the cold but to relieve symptoms. Over-the-counter (OTC) drugs that can help to relieve cold symptoms include nasal sprays, decongestants, and cough medicines. These medications are not recommended for children under the age of two unless approved by a physician. People who have URI should rest and drink plenty of fluids.

Influenza. As with the common URI the remedy for influenza is rest, liquids, and symptom relief. OTC decongestants and cough syrups can be used to relieve nasal congestion and cough. OTC pain relievers, such as Tylenol or Advil, can help to relieve headaches, body aches, and sore throats.

Some fever can be beneficial because it helps the body fight the virus, so many doctors recommend that fever not be treated unless it is above 102° Fahrenheit, although an exception can be made if the fever is causing a great deal of discomfort. Fever in infants under three months of age can be a sign of a serious infection, so one should seek immediate medical attention.

In some cases, a physician may prescribe antiviral medications, which are also used for symptom reduction rather than as a cure for the flu. Antiviral medications are generally only given to people who are at increased risk of flu complications, such as young children, the elderly, pregnant women, people who are in the hospital, and people who suffer from certain chronic medical conditions.

Antibiotics will not cure the common cold or the flu. They also will not relieve cold or flu symptoms because antibiotics are used to treat bacterial infections, and both the common cold and the flu are viruses.

Varicella or Chickenpox. Most healthy people do not require medical treatment for chickenpox, but some doctors may prescribe an antihistamine to help relieve itching. Oatmeal baths or calamine lotion can also help to prevent itching.

People who have other health problems or who may be considered at high risk for complications of chickenpox, may be given antiviral medications or immunoglobulin treatment. These treatments are intended to lessen the severity of the disease and, therefore, to prevent complications. OTC pain medications, such as Tylenol or Advil, can be given to reduce fever, but people with chickenpox should not be given aspirin because aspirin can cause a serious medical condition called Reye’s syndrome.

Tuberculosis. Prescribed medication can prevent TB from becoming active. It can also help cure active TB.

Impact

In the first four years since its detection, by 2025 the United States had suffered more than 1.2 million fatalities due to the COVID-19 coronavirus. Over 100 million Americans are believed to have been infected.

According to the National Institutes of Health, the United States experiences more than 1 billion cases of the common cold each year. The World Health Organization (WHO) estimates that there are between 3 million and 5 million cases of severe influenza illness each year during seasonal epidemics, resulting in between 250,000 and 500,000 deaths. CDC statistics show that during an average flu season, 5 percent to 20 percent of the US population will get the flu and more than 200,000 will be hospitalized because of complications of the flu. Since the last decades of the twentieth century, deaths from influenza in the United States have ranged from a low of 3,000 to a high of 49,000 persons.

According to the CDC, before the varicella vaccine was developed in 1995, around 4 million cases of chickenpox were reported each year in the United States. By 2023, there were fewer than 150,000 reported cases. In the same timeframe, hospitalizations had dropped from 10,000 to fewer than 1,400. Fewer than 30 fatalities were reported, down from the previous 150 that annually occurred.

WHO estimates that one-third of the world’s population is infected with tuberculosis at any given time, and that 5 to 10 percent of those who are infected will develop active TB. In 2009, about 1.7 million people died from tuberculosis.

Bibliography

"About Tuberculosis." Centers for Disease Control and Prevention, www.cdc.gov/tb/about/?CDC‗AAref‗Val=https://www.cdc.gov/tb/topic/basics/. Accessed 9 Jan. 2025.

“Chickenpox.” Mayo Foundation for Medical Education and Research, www.mayoclinic.com/health/chickenpox/DS00053. Accessed 9 Jan. 2025.

“Common Cold.” Mayo Foundation for Medical Education and Research, www.mayoclinic.com/health/common-cold/DS00056. Accessed 9 Jan. 2025.

“Coronavirus Disease (COVID-19).” The World Health Organization, 2023, www.who.int/health-topics/coronavirus#tab=tab‗1. Accessed 9 Jan. 2025.

“Indoor Air and Coronavirus (COVID-19).”United States Environmental Protection Agency, 27 Jan. 2023, www.epa.gov/coronavirus/indoor-air-and-coronavirus-covid-19#: Accessed 9 Jan. 2025.

“Preventing the Spread of the Coronavirus.”Harvard Health Publishing, 5 Aug. 2024, www.health.harvard.edu/diseases-and-conditions/preventing-the-spread-of-the-coronavirus. Accessed 9 Jan. 2025.

Mason, Robert J., et al., eds. Murray and Nadel’s Textbook of Respiratory Medicine. 5th ed. Philadelphia: Saunders/Elsevier, 2010.

“Tuberculosis.” Mayo Clinic, www.mayoclinic.com/health/tuberculosis/DS00372. Accessed 9 Jan. 2025.

“What Are Airborne Diseases?” Healthline, www.healthline.com/health/airborne-diseases. Accessed 9 Jan. 2025.