Infectious Respiratory Disease

Research Content

Children and disease transmission in schools

There are countless contact points in a Kindergarten classroom. From the moment students enter, they share a closet, use the same toilet, pass around school supplies and toys, and sit closely together on the carpet. A study found that 80% of microbes on school desks came from humans, not from the environment, and were brought in and left behind by the people using the space.²

Young children also tend to be physically affectionate, frequently hugging or holding hands for comfort. Transmission can happen in many ways, including the airborne route, and the Leung et al study concisely organizes direct contact into three categories. The three contact modes are physical non-skin contact, such as tagging or grabbing sleeves; verbal non-physical contact, like face-to-face conversation within one meter; and direct skin-to-skin contact.³

Adding to the germ load is the state of classroom environments. For many urban, school-aged children, primary school (Kindergarten) is their first time in a crowded group setting, which increases the risk of respiratory virus transmission. Children average five to seven respiratory infections per year.⁴ In a high-occupancy space that students are required by law to attend, schools have a duty to reduce infection risks. In one study, 20% of desk surfaces tested during the cold season (late September to early October) carried one of these illnesses.⁵ The most common respiratory viruses found in schools are adenovirus, rhinovirus, and coronavirus.

Most Common Respiratory Viruses in Schools

Adenovirus

Wallace Rowe and his team first discovered human adenovirus (HAdV) in 1953. The team took cells from adenoids (small pads of tissue located behind the nose, at the back of the throat that help trap germs that enter your body through your nose) and isolated them.⁶ Adenoviridae appear hexagonal with spikes protruding from vertices. On average they measure 70-90 nanometers in diameter. In lab animals they are known to cause tumors, but there are no cases in humans. The human symptoms include common cold or flu-like symptoms, fever, sore throat, acute bronchitis, pneumonia, pink eye, and acute gastroenteritis. Transmission occurs through close personal contact from infected person to susceptible person. Close personal contact is when a susceptible person encounters an adenovirus droplet, such as but not limited to, touching, shaking hands, touching an infected surface, or through an infected person’s stool. Although uncomfortable, most adenovirus infections can be managed with over-the-counter medications.⁷

Rhinovirus

Discovered in the 1950’s and responsible for most cold-like illnesses are the human rhinoviruses (HRVs). Known as the common cold, science is still searching for a “cure”. The search for a vaccine or cure is difficult as there are more than 160 human rhinovirus serotypes, all with high levels of variability.⁸ Rhinovirus can be spread by droplets and other forms of direct contact- or through airborne transmission. Symptoms can be nonexistent, but most of the time include runny nose or nasal congestion, a cough, sneezing, sore throat, headache, mild body aches, or fever. Infections can trigger asthma attacks, or lead to secondary bacterial ear infections, sinus infections, bronchitis, or pneumonia.⁹ Treatment for rhinovirus focus on the relief of symptoms. Over the counter medication, rest, and fluids are suggested.¹⁰

Coronavirus

Coronaviruses (HCoV) were first discovered in humans in the 1960’s. Coronavirus is an umbrella term used to describe a family of viruses. This family includes seven species that infect humans that scientists know of. Coronavirus is also known to infect other mammals. The virus has surface spikes, thus its name “corona” or crown in Latin. Transmission of coronaviruses may occur through airborne exposure, such as but not limited to breathing the air where someone who is carrying the virus has sneezed or coughed, making direct contact with an infected individual, and touching exposed surfaces or it may be transmitted through close contact droplet exposure, where large particles of the disease are expelled during coughing, sneezing, talking, or breathing heavily on a susceptible person’s mucous membranes. Similarly to adenovirus and rhinovirus, there is no one-size-fits-all treatment for coronaviruses. Symptoms can be helped through over the counter medication, rest, and liquids.¹¹

Although there are seven types of human coronaviruses, three coronaviruses have especially led to serious symptoms and death in humans. The first of those is SARS-CoV-1, which resulted in over 8,000 confirmed cases and 774 deaths globally.¹² In the United States, there were 29 reported cases and no deaths. SARS-CoV-1 was first found in Foshan, China in November 2002. An emergency travel advisory was issued by the World Health Organization, who called the virus a "global threat”. By July 2003 WHO announced that SARS-CoV-1 had been contained.  Although there continued to be a few cases, the last reported outbreak, in China was contained in May 2004 and there have been zero cases since. SARS-CoV-1 symptoms were flu-like: fever, cough chills, fatigue, shortness of breath, headache, and diarrhea.  Age was a strong factor in the severity of the illness; the risk of fatality increased to about half of all infected individuals over the age of 60.  

The second notable coronavirus is the Middle Eastern Respiratory Syndrome, knowns widely as MERS was reported in Saudia Arabia in 2012. A total of 2,627 cases of MERS are confirmed, 947 of those resulting in death. (Of the 2,627 total cases, 2,218 of them were from Saudi Arabia causing 866 deaths).¹³ Only two people in the United States were diagnosed. The MERS outbreak was mostly in the Middle East, more specifically Saudi Arabia, and is primarily accepted as transmitted through droplets, although airborne transmission may occur. Infected camels first spread the virus to humans.¹⁴ Symptoms included especially high fever, persistent cough, shortness of breath, and gastrointestinal symptoms.

The third, and probably the most well-known coronavirus is SARS-CoV-2, or COVID-19. In Wuhan, China, late 2019, patients began experiencing symptoms of a pneumonia-like illness that was not responding to standard treatments. By the end of March 2020, COVID-19 spread to much of the world and quarantine and isolation procedures were implemented by many countries.¹⁵ In the US people quarantined in their homes, and mask wearing in public began to lower the risk from the disease. At one point, 77% of all public schools were forced to close and quickly switched to a virtual learning format.¹⁶

As of April 2024, there were 704,752,890 COVID-19 cases worldwide and 7,010,681 deaths. 111,820,082 of those cases were in the United States and 1,219,487 of the deaths.¹⁷ It is now widely accepted that COVID-19 largely transmitted by an airborne route. The virus spreads from an infected person’s mouth or nose expelling infectious particles through coughing, sneezing, singing, or breathing. These diseased particles can range in size from larger respiratory droplets of 50-100 microns to small aerosols less than five microns in aerodynamic diameter.¹⁸

Another factor of transmission was that cases ranged in symptoms, including many asymptomatic cases, and resulting in spread of the virus from people that were not aware they were carriers. Others experienced severe respiratory illness. The range of symptoms included fever or chills, cough, shortness of breath, sore throat, new loss of taste or smell, fatigue, headache, and gastrointestinal issues.

Treatment for COVID-19, like the symptoms of the disease, vary with severity. For less severe cases, treatment may include rest, drinking plenty of fluids, and over the counter medication. For more serious cases, the FDA has approved antiviral medications, especially for those who are more susceptible to the disease. These medications are known as Paxlovid, remdesivir, and Lagevrio.¹⁹ Paxlovid and Lagrevio may be taken orally at home, while remdesivir infusions are given intravenously at a healthcare facility for three consecutive days. The most powerful treatment is prevention, and vaccines are available for COVID-19. The are extremely effective at preventing severe illness and hospitalizations.²⁰

Other Health Risks in Schools

Asthma

Asthma is a chronic respiratory disease of the lungs categorized by symptoms of coughing, wheezing, tightness of the chest, and shortness of breath. Symptoms and severity of asthma vary by case, as well as by possible triggers (allergens, exercise, weather changes, stress, etc.).²¹ Asthma is characteristically hard to diagnose, and many healthcare providers practice a “wait-and-see” approach when it comes to their young patients. Diagnosis does not usually occur until age seven. Something that adds to the difficulty of diagnosis is due to the causes not being fully understood. Some factors may include genetic tendency to develop allergies, airway infections at a very young age, and exposure to environmental factors (cigarette smoke or other air pollution).²² Young students’ lungs are still developing and are at higher risk of breathing in airborne contaminants and hazardous air pollutants. Children also have a higher breathing rate (breaths per time) compared to adults; because of this, students are being exposed to pollutants at a higher risk than teachers. When a child with asthma’s airways become irritated by pollutants, they become inflamed, making it hard for them to breathe fully and properly. Common symptoms of childhood asthma are wheezing while breathing, shortness of breath, and frequent coughing in the presence triggers.²³

One in ten school aged children in the United States are diagnosed with asthma.²⁴Richmond also ranks eighth in the United States for worst places to live for people with allergies and asthma. Many of my students live in areas with poor air quality and live with asthma.²⁵

Mold

Mold area form of multicellular fungi that exist anywhere sufficient moisture is present. Mold is dispersed by tiny reproductive cells, or mold spores, that may become aerosolized and when they land on damp spots indoors, they begin growing and metabolizing whatever they are growing on to survive. Mold spores are not visible with the naked eye; they range from 2-10 micrometers. If sufficient moisture or dampness are present (typically at a water activity above 0.8), mold will grow on building materials, often appearing in schools on roof materials, around windows, near water fountains, back side of dry wall, bathroom tiles, in duct work, and in books and carpets.²⁶

Many species of mold found in buildings common allergens and exposure may result in may result in negative health effects, including respiratory issues for students and staff. Many older school buildings suffer from poor infrastructure including leaky roofs, pipes, windows, foundations that encourage mold growth. When regular maintenance is ignored or under budgeted for, the building becomes more vulnerable to mold growth.²⁷ The instance of mold has been confirmed by professional tests in every classroom at my school and we have had both visible mold and the characteristic musty smell.

Health effects from instances of mold include irritation of the eyes, skin, nose, and throat. Respiratory issues are common and are often exacerbated by spore inhalation. These health impacts are especially risky in children, due to their immature immune system.²⁸

Dust Mites

Microscopic arachnids feeding off dead skin cells shed by people are known as dust mites. Dust mites exist in any fabric materials, bedding, sofas, carpets, and stuffed animals and proliferate in buildings where relative humidity levels are consistently above 50%. Dust mites are allergens and can trigger respiratory issues, including asthma, in children.²⁹ Dust mites can be restricted by keeping a dry, low humidity classroom, regular dustings with wet rags (as to not spread them around), vacuuming floors, regularly cleaning carpets, and minimizing stuffed animals in the classroom.

Environmental Factors of Disease and Transmission

Although the air around us can seem uncontrollable, airborne transmission of disease can in fact be minimized in a few ways. Seeking control and building according to structure purpose (building used for school, for health settings, etc.) and modifying systems will curate cleaner environments. Two environmental factors to focus on when discussing indoor transmission of airborne disease are relative humidity and ventilation. Children spend most of their time indoors and the concentrations or pathogens and allergens is highest indoors.

Following the flow of the traditional infection control pyramid, that was adapted from the US Centers for Disease Control, the factors of controlling infectious respiratory disease are as follows from most to least effective.

1. Elimination- to physically remove the pathogen
2. Engineering Controls- to separate the people and pathogen
3. Administrative Controls- to instruct people what to do
4. Personal Protective Equipment- to use masks, gloves, gowns, etc.³⁰

Experts note that “The benefits of an effective ventilation system, possibly enhanced by particle filtration and air disinfection, for contributing to an overall reduction in the indoor airborne infection risk, can be an effective approach to elimination.³¹

Ventilation

The process of providing outdoor air to a space or building by natural or mechanical means in referred to as ventilation.³² Ventilation refers to how quickly the air in a certain space (classroom, restaurant, hospital, etc.) is removed and then replaced with a mix of recycled and filtered indoor air and new outdoor air. Filtration moves air through filters and lowers the overall concentration of viruses in the air. The likelihood of a person catching an infectious respiratory disease is linked to ventilation rates in a space. Public schools of course have a range of ventilation systems, from purpose-designed mechanical systems to simple opening of windows.³³ The Centers for Disease Control Recommends that rooms be ventilated at a minimum of five air changes per hour to control viral respiratory disease.

Humidity

Humidity refers to the amount of water vapor present in the air. Relative humidity describes how much water vapor is in the air compared to how much water vapor air could hold at the given temperature. Optimal ranges of relative humidity usually land between 40-60% and when spaces are out of that range, there may be significant impacts on health. The lower the humidity in a space, the higher the risk of irritation of the mucous membrane of eyes and airways (dryness) and increases the survival of many airborne viruses. It also allows for the water component of a pathogen-containing droplets to evaporate and then become suspended in the air for longer amounts of time.³⁴ Higher amounts of humidity create a damp environment and can offer a space for mold and dust mites to proliferate.³⁵

Hygiene Techniques and History

Soap was invented by the Babylonians in 2800 BC. Egyptians bathed regularly in “soap” made from oil and salts. Years later, soap making would emerge in Europe, especially in Italy, Spain, and France and eventually made its way to the settlers of Jamestown in 1600. Native Americans used plants and saps to create soaps of their own as well as rinsing themselves regularly in bodies of water.³⁶ This begs the question, why did handwashing and proper hygiene techniques for medicinal purposes not begin until much later?

In the 1840’s there was a maternity ward in Vienna General Hospital so large it was split into two, one teaching wing for doctors, and one for midwives. The two wards operated nearly identically but there was a troubling difference between the two, maternal mortality rate. The Midwives experienced 36.2 deaths per 1,000 births, while the doctors’ experienced 98.4 for every 1,000 births. This caused chaos and finger pointing, labeling the doctors as agents of death or suggesting that the priests were inciting psychological terror by ringing bells on the unit. A Hungarian doctor by the name of Ignaz Semmelweis was deeply troubled by the deaths of mothers and began working to find the cause of the inconsistency between wards. Later named the “Savior of Mothers”, Semmelweis discovered that doctors were going straight from autopsies to births, carrying cadaver material with them. He theorized that because of this; the women may be dying due to cadaveric material from the doctors’ hands entering their bodies during childbirth. Even though this theory was incorrect, it did prompt doctors to begin washing their hands after autopsies with chlorinated lime. After adopting handwashing. Maternal death dropped to match that of the midwife’s ward.

Though this was a big win for modern medicine, Semmelweis was not well received by colleagues for a few reasons. Many others had to continue to push for handwashing, including doctors such as Oliver Wendell Holmes and Joseph Lister who respectively said doctors with dirty hands, or surgeons who failed to sterilize instruments, were risking and causing unnecessary mortality. Florence Nightingale, widely known as the founder of modern nursing, once wrote “Every nurse ought to be careful to wash her hands very frequently”.³⁷

It was not until the 1980’s that the first national hand hygiene guidelines were published in the United States, followed by other countries. Hand washing was and is recommended every time before and after handling food, going to the restroom, and after being in public places. Proper handwashing steps are as follows:

1. Stand in front of a sink and take care not to touch the sink and its surfaces with your hand.
2. Turn on the warm water. Wet your hands and wrists. Take care to keep your hands and forearms lower than your elbow, to prevent drippage.
3. Use approximately 5mL of antiseptic soap and lather to ensure all surfaces of your hands and forearms are covered in soap.
4. Use friction and rubbing of the hands for no less than 15-30 seconds to ensure germ removal. (Finger interlacing, palm to palm, and backs of fingers to opposing palm are all general techniques)
5. When rinsing soap and water off, remember to keep hands down, elbows up.
6. Use a disposable towel to dry hands off and do not immediately re contaminate by touching sink or doorknobs.³⁸

Microbial Exposure Hypothesis

Thanks to the microbial exposure hypothesis, formerly known as the hygiene hypothesis, we now know that reduced exposure to a variety of microbes, typically in the first year of life, may lead to improper development of the immune system. However, the idea that being “too clean” can make us sick, is far too broad to be true.³⁹ Exposure to a variety of microbes in early life has shown to lessen allergies and risk of autoimmune disease. Even during neonatal life, the immune system can be broadly stimulated by exposure, especially in the gastrointestinal tract and the lungs.⁴⁰ The goal is not to sterilize the classroom, but to keep it clean enough to be safe and functional, while encouraging interaction with nature, allowing for microbial exposure that strengthens immunity.