Reducing Transmission of Pathogens Between Athletes

Samuel Hume

Daniel J. Sexton

Introduction

Multiple athletes in close quarters is a key risk factor for transmission of pathogens. Simply put, more close interactions with other athletes lead to more movement of pathogens such as bacteria and viruses. These pathogens can be transmitted directly from one player to another in close quarters such as a locker room or training facility. However, transmission through direct contact is not the only way that pathogens can spread (Table 5.1). Pathogens can move from player to player through a contaminated environment, droplets in the air after a cough or sneeze, contaminated food, or, rarely, through exposure to blood.

Various interventions to decrease the risk of transmission and the risk of infection are outlined throughout this book. In this chapter, we first outline key concepts on pathogen transmission among athletes. We then summarize general principles to prevent transmission. Some of these principles should sound familiar by this point. As this chapter focuses specifically on reducing transmission of pathogens between athletes, we emphasize the importance of vaccination strategies and outbreak mitigation.

Concepts of Microbial Spread

Microbes may be transmitted in numerous ways that are particular to the type of organism (Figure 5.1). Each method of transmission requires different prevention strategies.

Direct and Indirect Contact

Common bacteria such as staphylococci (including methicillin-resistant Staphylococcus aureus [MRSA]) and respiratory viruses such as influenza primarily are transmitted between persons through either direct contact such as when shaking hands, grappling, or tackling or indirectly through contamination of environmental surfaces and objects such as shared gym equipment. In order for pathogens to spread via environmental surfaces,

they must survive long enough to remain viable when the next person touches the surface. Unfortunately, most pathogens summarized in Table 5.1 can live for hours or longer on environmental surfaces.

Table 5.1 Transmission of Pathogens Between Athletes

Mode of Transmission	Pathogens	Examples of Transmission	Methods of Prevention
Contact—direct	Staphylococcus aureus (including MRSA) Group A streptococci Influenza Respiratory viruses and the “common cold” Herpes simplex Tinea (Tinea capitis, T. corporis, T. pedis) Pubic lice (pediculosis pubis) Norovirus Molluscum contagiosum Warts (human papillomavirus) Scabies (Sarcoptes scabiei)	Hand shaking Direct player contact on field	Hand hygiene Showering after practice
Contact—indirect (via fomites/environment)	S. aureus (including MRSA) Norovirus Influenza	Sharing towels Gym equipment Shared razors	Minimize shared items Disinfect equipment between users
Droplet	Influenza Mumps Respiratory viruses and the “common cold” Whooping cough (pertussis) Neisseria meningitis Group A streptococci	Sitting next to a symptomatic player on a team bus or flight	Vaccination Masks Exclusion of symptomatic and exposed players
Airborne droplet nuclei	Measles Tuberculosis Chicken pox (varicella)	Shared bus, hotel, or meeting room with the infected player	Vaccination Masks Exclusion of symptomatic and exposed players
Foodborne/enteric	Norovirus Salmonella Campylobacter Hepatitis A Giardia Cryptosporidiosis Bacillus cereus Leptospirosis	Eating a contaminated packed meal while travelling Exposure to fecally contaminated equipment	Exclusion of symptomatic players Avoiding undercooked or contaminated meat/surfaces
Bloodborne	Hepatitis B Hepatitis C HIV	Failure to use safe injection practices (eg, using contaminated multidose vial for joint injection)	Safe injection practices: Single-use vials Sharps container Self-retracting needles
Note: some pathogens in bold can be transmitted through multiple modes.

Figure 5.1 Methods for microbe transmission between athletes.

Respiratory Droplet Spread

Other organisms, such as the mumps virus, spread via droplets of saliva or respiratory tract secretions induced by sneezing, coughing, or speaking. Droplets can travel up to 3 feet (1 m) from the source to people or to environmental surfaces.

Airborne Droplet Nuclei Spread

Smaller infective particles called droplet nuclei that result from coughing can remain airborne for prolonged periods. Thus, these particles may lead to infection in individuals who are well beyond the 3 feet (1 m) that droplets travel. Essentially, these droplet nuclei can permeate an entire room and often remain suspended in the air for hours. These particles can even lead to transmission and infection of people who enter the vicinity hours later. Examples include the measles virus and tuberculosis.

Enteric Spread (Fecal-to-Oral Spread)

Certain bacteria such as Salmonella and viral pathogens such as norovirus and hepatitis A virus can be transmitted via contaminated food or water. For example, Salmonella may be transmitted by contaminated raw or undercooked chicken or eggs. Hepatitis A is transmitted through the ingestion of fecally contaminated food or water. Norovirus can be spread
through contact with fecally contaminated food or through contact with fecally contaminated surfaces. Unfortunately, exposure to fecal contamination occurs more often than one might think. As an old infectious disease adage goes, “if stool were fluorescent, the world would glow.”

Bloodborne Spread

Direct contact with blood may result in transmission of bloodborne viruses such as hepatitis B, hepatitis C, and human immunodeficiency virus (HIV). Direct contact with blood with intact skin poses no risk, but contact in the setting of breaches in skin or mucous membranes can lead to risk of transmission.

Multiple Routes

Numerous organisms are transmitted via multiple routes. For example, influenza virus may be transmitted via droplet spread to people nearby when an infected individual sneezes, via direct contact with hands contaminated with respiratory secretions, or indirectly via touching contaminated surfaces such as door handles.

General Principles—Strategies for Minimizing Microbial Spread Between Athletes

Colonization, Subclinical Infection, and Infection (Table 5.2)

As described in Chapter 4, athletes can be either colonized or infected with certain microbes. Colonization implies the host does not have any symptoms or ill effects attributable to the organism. Infection means that the host is suffering ill effects from the organism, and the patient is symptomatic. During the early phases of infection, a pathogen may be present and starting to grow or incubate but is not yet causing symptoms. This phenomenon is labeled as a “subclinical infection.” In general, this label implies that the process is about to lead to symptoms of infection. The term “subclinical infection” is also used to describe an infection that leads to mild symptoms.

Bacterial and viral pathogens can be transmitted to others regardless if causing colonization, subclinical infection, or infection. As an example, hepatitis A virus can be transmitted in the latter half of the incubation period prior to the onset of symptoms. Similarly, athletes whose skin is colonized with MRSA can transmit the bacteria to others. In fact, people colonized with MRSA may lead to more environmental contamination than people undergoing treatment for an MRSA infection.¹

Table 5.2 Organisms Don’t Always Cause Symptoms

	Organism Present?	Organism Increasing in Number?	Organism Causing Symptoms?	Transmission of Organism Possible?
Colonization	Yes	No	No	Yes
Subclinical infection	Yes	Yes	No	Yes
Infection	Yes	Yes	Yes	Yes

On one hand, people with infection must follow infection prevention cornerstone concept #1: people with infection should be isolated from uninfected people. Don’t come to work if you’re sick or you will infect your coworkers. For athletes, don’t participate in team activities if you’re sick or you will infect teammates and team staff. On the other hand, people without symptoms of infection can transmit pathogens when they are colonized or during a subclinical phase of infection. This fact leads to infection prevention cornerstone concepts for the prevention of transmission between athletes #2—standard precautions, #3—hygiene, and #4—vaccination.

Standard Precautions

Standard precautions, also known as “universal precautions,” are used in healthcare facilities in all situations in which healthcare workers come into contact with patients. As we’ve noted throughout this book, athletic training facilities are healthcare facilities; thus, standard precautions should be used at all times. While healthcare providers are routinely trained in the use of standard precautions, we believe it is equally important for athletes to use standard precautions to the greatest extent possible.

The elements of standard precautions include hand hygiene; the use of gloves, gowns, and eyewear where contact with bodily fluid can be reasonably expected; cough etiquette; and safe injection and needle disposal practices. The importance of hand hygiene and safe injection practices is discussed in detail in Chapter 4. Cough or respiratory etiquette involves covering the mouth and nose during coughing, promptly disposing of facial tissues contaminated with respiratory secretions, and performing hand hygiene after contact with respiratory secretions. These precautions are central to the reduction of transmission of infections within healthcare settings and contained environments where people come into close contact such as within sporting facilities, military barracks, and cruise ships. In general terms, standard precautions for athletes include cough etiquette; frequent use of hand hygiene before and after training sessions and at times when the group comes together for team meetings and to eat and travel; and segregation of personal care products such as soap, razors, towels, and drink bottles.

Both formal and informal team policies can endorse a culture of safety and reinforce each individual’s contribution to both personal and team health. Below are a series of practical and (where possible) evidence-based recommendations that enhance infection prevention between athletes and within teams.

HYGIENE

Strategies to promote and improve hand and body hygiene are core components of infection prevention. Improving hygiene reduces risk of infection for the individual and for others. Hygienic practices such as hand hygiene, postpractice showering, and source control are discussed in detail in Chapter 4.

Hygienic practices such as hand hygiene, postpractice showering, and source control are discussed in detail in Chapter 4.

VACCINATION

Vaccination is a cornerstone of infection prevention efforts. Several highly transmissible and potentially serious infections can be reliably prevented among athletes and players using safe and effective vaccines. Vaccination provides temporary or lifelong immunity against specific infections and is a mainstay of infection prevention practices. Immunity is effective and long-lasting for some infections such as hepatitis A and B, while it provides incomplete or short protection for other infections such as influenza. Vaccination prevents infections through two mechanisms. First, vaccinated individuals have increased protection. Second, community or herd immunity reduces transmission risk when a high enough proportion of a population has been immunized. Thus, vaccination in the population setting actually protects unimmunized individuals.

While standard childhood vaccination schedules provide protection into adolescence and early adulthood, some persons may have inadvertently or deliberately missed critical vaccinations, or immunity may have waned with time leaving individuals at risk for infection. Reviewing vaccination history, testing for protective antibodies, and then undertaking catch up or revaccination is a reasonable strategy to prevent infections within teams—both for the individual athlete and for the entire team. While standard childhood and adult catch-up immunization schedules are subject to both national and local variability, vaccination should be considered against the pathogens listed in Table 5.3.

Valuable methods for minimizing the impact of vaccine-preventable illnesses on athlete health include (1) developing a reliable system to assess the vaccination status of athletes and support staff and (2) implementing strategies to ensure both standard and selected additional vaccinations have been provided.

Best Practice Develop a written policy for vaccine-preventable infectious diseases among players and team personnel.

Recommendation 1 Develop a policy about immunizations for vaccine-preventable diseases (influenza, pertussis, meningococcus, measles, mumps, and chicken pox) in players and team personnel.

Rationale: Several highly transmissible and potentially serious infections can be easily prevented among athletes using safe vaccines: influenza, Bordetella pertussis (pertussis or “whooping cough”), meningococcal meningitis, measles, mumps, and chicken pox. An example of a policy for vaccine-preventable diseases is included in Appendix 1D. Vaccine Information Sheets (VISs) for influenza vaccine, tetanus-diphtheria-acellular pertussis (Tdap) vaccine, meningococcal vaccine, measles-mumps-rubella (MMR) vaccine, and chicken pox vaccine are provided by the Advisory Committee on Immunization Practices (ACIP) and should be reviewed prior to vaccine administration (www.cdc.gov/vaccines/acip/index.html).

Table 5.3 Catch-up Vaccinations Recommended on a Population Level

Measles

Mumps

Rubella

Diphtheria

Tetanus

Pertussis

Hepatitis A and B

Meningococcus ACWY, B

Polio

Human papillomavirus

Influenza

Varicella

Vaccines are highly effective and safe.

Influenza

Best Practice Provide influenza vaccination to prevent influenza (the “flu”).

Recommendation 1 Provide influenza vaccination to all players and staff annually.

Recommendation 2 Track compliance with influenza vaccination among players and staff.

Rationale: Influenza is a common and partially preventable respiratory infection that is readily transmitted from person to person. Influenza infection significantly reduces respiratory capacity and athletic performance even in players with relatively mild infections. A small but important percentage of young and otherwise healthy individuals who acquire influenza may develop severe infections that require hospitalization and, occasionally, intensive care.

Vaccination is the most effective method to prevent flu. Influenza vaccines have proven benefits that are important for athletes and teams. Most importantly, players who receive influenza vaccines are less likely to have fever or influenza-like illness, are less likely to miss practice and games, and are less likely to spread influenza to teammates.²^,³^,⁴ It is important to recognize, however, that numerous viruses can cause “influenza-like illness”; thus, vaccination will not prevent all episodes of influenza-like illness. This fact should be emphasized when players or skeptics complain “I received influenza vaccine, and I got the flu anyway.” We are including specific educational materials regarding facts and myths about the benefits and safety of influenza vaccination in Appendix 1E.

Vaccination is the most effective method to prevent flu.

From a team perspective, vaccinated players who are exposed to influenza are less likely to spread the virus and are, thus, less likely to cause a locker room-wide outbreak that could potentially devastate a team. Thus, immunization has benefits for individual players and the team.

We continue to believe the best and most effective approach is to require that all players receive influenza vaccination. This approach is now widely used in most hospitals in the United States. We acknowledge, however, that this approach may not be feasible in some settings without union, parent, and/or player approvals. Compliance among athletes is typically low, between 20% and 30%. However, some programs have achieved much higher rates of compliance (even up to 90%) through highly visible and active campaigns.

Strategies for Improving Uptake of Influenza Vaccination Among Athletes

Use influenza vaccination “blitzes,” in which vaccination is provided by practitioners at the team facilities on specific days and times, so that influenza vaccination can be immediately provided onsite to whomever consents. However, don’t limit access to these blitzes. Make sure it is clear the vaccination is available any time.
Use influenza vaccination mobile “stations” that move frequently between strategic, high-traffic locations (eg, cafeteria, training room, outside locker room) so that individuals can be immunized during the course of their normal activities without an appointment or clinic visit.
Provide educational materials to players at the beginning of influenza season describing the benefits of the vaccination and debunking the myths about the vaccine (see Appendix 1E).
Recruit player champions to promote the use of the vaccination. Champions are ideally team leaders who can “show the way” for younger players. If someone in your facility has been impacted by influenza (the player or family member), have that player share his or her story and help advocate for the vaccination.
Focus on players with families, pregnant partners, and young children. Vaccination of the player provides protection against importing influenza into the team from his family as well as protecting his family against importation of the virus from the team. These players should have the biggest motivation for vaccination.
Demonstrate receipt of the vaccination by team leaders and coaches (ie, lead by example).
Post signs promoting influenza vaccination (see the ebook version of this book for example signs).

Vaccination can be given intranasally or via intramuscular (IM) injection. In 2017, the ACIP recommended against the use of the intranasal formulation (a live attenuated vaccine) due to lack of efficacy against the common H1N1 influenza strain. However, the intranasal vaccine was reintroduced and approved by the ACIP for the 2018 season (and beyond) following a change in the H1N1 component.⁵ We welcome the reintroduction of the intranasal vaccine, as it provides a method for overcoming one of the key excuses for not receiving a vaccine—the injection or “shot.” Similarly, egg allergies are no longer sufficient to prevent receipt of the vaccine, as egg-free formulations now exist. Injections can be given using either trivalent (covers three types of flu) or quadrivalent (covers four types of flu) vaccine.

Recommendation 4 Mandate that all athletic trainers and team medical staff receive annual influenza vaccination.

Rationale: Most US healthcare institutions now require that all healthcare workers receive annual influenza vaccination.⁶ Requiring that team healthcare providers, including athletic trainers and team physicians, receive annual influenza vaccination leads to two benefits. First, it helps improve the “culture of safety” by providing an outward and visible demonstration of the importance of influenza prevention. Second, as athletic trainers have regular close contact with players, immunized athletic trainers are unlikely to spread influenza from one player to another during their routine work and activities.

Hepatitis A and Hepatitis B

Best Practice Provide vaccine to prevent hepatitis A and hepatitis B infections.

Recommendation 1 Ensure athletes have been vaccinated against hepatitis A and B.

Rationale: Hepatitis A and hepatitis B are viral infections that can cause serious liver damage. Hepatitis A is an acute illness acquired by ingestion of contaminated food. Hepatitis B can be an acute and/or chronic disease that is acquired from exposure to contaminated blood (eg, a needle stick).

Hepatitis A vaccine became available in the United States in 1996 but was not widely used prior to 2006 when it became part of the standard vaccines administered to American children. However, many young adults did not receive this vaccination in childhood and thus remain vulnerable to acquiring hepatitis A.

In light of the above, it is not surprising that outbreaks of hepatitis A continue to occur even though the overall incidence of hepatitis A has declined. A large and persistent outbreak of hepatitis A began in San Diego in 2015 and continued into 2017.⁷ Cases linked to this outbreak have occurred in multiple states including Arizona, Indiana, Michigan, Colorado, and Tennessee. The average age of 3421 cases reported in 2017 was 40 years; two-thirds of the affected individuals were men. Over 25,000 cases were reported between November 2016 and September 2019, contributing to 15,500 hospitalizations and 259 deaths.⁸

Due to these outbreaks, the United States Centers for Disease Control and Prevention (CDC) supports the use of hepatitis A vaccine after known or possible exposure to a single case of hepatitis A. Some experts have recommended vaccination in athletes involved in close-contact sports “because this disease typically leads to months of reduced physical performance and [because] hepatitis A can be easily transferred to teammates and opponents.”⁹ Another aspect of hepatitis A risk is international travel. For example, the CDC recommends that travelers to most Central American, South American, and Southeast Asian destinations receive vaccination against hepatitis A, as the virus can be acquired via contaminated food or water regardless of where you are eating or staying. Specific recommendations for specific destinations can be found at wwwnc.cdc.gov/travel/destinations/list.

Hepatitis B vaccine became part of routine childhood immunizations in the United States in 1991. Outbreaks are more likely to occur in locations where health care is provided. More specifically, these outbreaks occur because of poor, unsafe, and sometimes illegal activities during invasive medical procedures (eg, hemodialysis, surgical centers, injections) (www.cdc.gov/hepatitis/outbreaks/healthcarehepoutbreaktable.htm). The CDC reported 23 outbreaks of hepatitis B related to health care from 2008 through 2017; 18 occurred in long-term care facilities and 5 occurred in medical settings such as dental clinics, outpatient oncology clinic, surgical center, and two pain clinics. See Chapter 4 for additional information about safe injection practices to prevent the risk of hepatitis B transmission.

Hepatitis B is more contagious than hepatitis C or HIV. Transmission has occurred in contact sports, such as among members of a Japanese sumo wrestling club,¹⁰ during American football,¹¹ and among cross-country runners in Sweden.¹²

Recommendation 2 Vaccinate all athletic trainers and team medical personnel against hepatitis B.

Recommendation 3 Document that all athletic trainers and team medical personnel have been vaccinated against hepatitis B.

Rationale: The risk of transmission due to high-risk exposures to blood infected with hepatitis B is approximately 33% (one in three). Vaccination is highly effective in reducing this risk to near zero, is long-lasting, and is safe.¹³ In fact, healthcare facilities that do not offer the hepatitis B vaccine to employees have been sued for negligence.¹⁴ Therefore, most medical facilities require hepatitis B vaccination as a requirement for employment.

Based on previous discussions with athletic trainers, we believe the vast majority of athletic trainers and team physicians are already vaccinated against hepatitis B. In the event that
athletic trainers or team physicians have not been vaccinated against hepatitis B, we recommend they receive the vaccination series. We also recommend documenting the vaccination status for each athletic trainer and physician. This requirement is especially important for new staff members.

Pertussis

Best Practice Provide vaccine to prevent pertussis infection (“whooping cough”).

Recommendation 1 Ensure all athletes have completed recommended DTaP series.

Rationale: Pertussis is widely and erroneously believed to be a rare disease of infants and children. In fact, pertussis is common. An estimated 2 million Americans acquire pertussis each year. Pertussis causes an illness that typically manifests as cough (often prolonged) with or without fever. During the second phase of illness, cough due to pertussis can be so severe that it leads to vomiting (ie, paroxysms of cough leading to posttussive vomiting). Among children, the illness often causes a characteristic “whooping” sound or “whooping cough.”

Vaccination is the key strategy to prevent infection with pertussis. The ACIP currently recommends that children in the United States receive five doses of the diphtheria-tetanus-pertussis (DTaP) vaccine: 2 months, 4 months, 6 months, 15 to 18 months, and 4 to 6 years old.¹⁵

Recommendation 2 Ensure athletes have received at least one dose of Tdap.

Recommendation 3 Provide the Tdap vaccine in place of standard tetanus when indicated.

Rationale: The ACIP recommends that children in the United States receive one dose of Tdap vaccine at age 11 or 12 years.¹⁶ “Acellular” refers to the fact that the immune response is triggered by immunogenic proteins, toxins, and other cellular components and is not due to an intact bacterium. As such, pertussis vaccine cannot and does not cause pertussis. As this recommendation is relatively recent, most adult athletes will not have received a dose. As a result, adult athletes should receive a dose of Tdap. If the athlete is unsure if he or she has received Tdap, the CDC recommends providing a booster. Furthermore, if a player requires a tetanus booster due to an injury that requires sutures, the Tdap can be given instead of the standard tetanus booster.

The fact that immunization for pertussis in childhood does not produce durable immunity in adults is widely underappreciated. While infants have more severe infections, adolescents and adults actually account for >60% of cases in the vaccination era.¹⁷

Because immunity induced by pertussis vaccine characteristically declines with time, adults who were vaccinated during childhood can and do become infected with B. pertussis. For example, 40% of previously immunized adults contract pertussis after exposure to infected children.¹⁸ Though unlikely to cause death, adults with pertussis often have prolonged, significant illnesses. Pertussis infection regularly results in unnecessary doctor visits, unnecessary use of antibiotics, and most importantly from a team perspective, increased absenteeism from work.¹⁹ Several studies have demonstrated that the majority of adults with pertussis missed between 7 to 10 days of work²⁰; 10% to 16% of adults with pertussis missed more than a month of work.²¹^,²²^,²³^,²⁴

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