Chapter 20
PREVENTION of ILLNESS from BIOLOGICAL HAZARDS

Gregg M. Stave*

Once we become aware of the potential biological hazards in a particular work setting, we can develop an effective plan to prevent occupational illness. Prevention of illness from biological hazards is accomplished by a combination of the three classic prevention strategies—primary, secondary, and tertiary prevention.

Primary prevention aims to prevent illness before the disease process begins. Strategies include vaccination and measures to limit potentially hazardous exposure to biological agents and organisms. Exposures can be limited by using engineering controls (including ventilation and containment systems), proper work practices, and personal protective equipment (such as gloves, uniforms, laboratory coats, safety glasses, and respirators). Environmental monitoring may be useful to determine if controls are effective in reducing potential exposures.

Secondary prevention entails intervention when the physiologic changes that precede illness are recognized or when subclinical illness develops. Secondary prevention is most effective when a surveillance system detects these events systematically. Medical screening must therefore focus on both the results for individuals and those for the group (epidemiologic evaluation).

Tertiary prevention is directed at limiting the consequences of clinical illness once it has occurred. It may involve medical treatment, work restrictions, and/or removal of the worker from further potential exposure. Specific preventive practices vary, depending on the work setting and the level of hazard.

OCCUPATIONS WITH POTENTIAL BIOLOGICAL HAZARDS

Occupational biological hazards are those encountered when the workplace has greater risk of exposure than the surrounding community. Thus, the common cold is not usually considered to be an occupational biological hazard even though one employee can contract a cold from another, because cold viruses are ubiquitous in the community at large.

Biological hazards may be found in diverse work settings. In some settings, such as research laboratories conducting studies on specific biological agents or organisms, the hazards are clearly identified. On farms and at zoos, specific zoonoses (animal infections that may be transmitted to humans) may be a risk. However, in most settings, the hazard is an indirect consequence of the work or a risk that arises in the work environment. Before we develop a prevention program, we need to evaluate the setting for reasonably anticipated hazards.

THE OSHA BLOODBORNE PATHOGENS STANDARD

The Occupational Safety and Health Administration (OSHA) has issued only one standard to date that addresses biological hazards. The Bloodborne Pathogens Standard (29 CFR 1910.1030) was issued in December 1991 and became effective in March 1992.1 The standard applies to all employers with one or more employees where employees may have exposure to blood-borne pathogens. Blood-borne pathogens are defined as pathogenic microorganisms that are present in human blood and can cause disease. These pathogens include, but are not limited to, hepatitis B virus (HBV) and human immunodeficiency virus (HIV). The standard applies not only to hospitals and doctors’ offices but also to many other work settings, such as clinical and research laboratories, mortuaries, emergency response teams, lifeguarding, and medical equipment maintenance.

The first requirement of the Bloodborne Pathogens Standard is the performance of an Exposure Determination. Employers must evaluate the potential for employees to be exposed to blood-borne pathogens. Occupational exposure means reasonably anticipated skin, eye, mucous membrane, or parenteral contact with potentially infectious materials on the job. Even employees who use personal protective equipment, such as gloves, are considered to be potentially exposed. If employees have the potential for occupational exposure to blood-borne pathogens, then the employer must develop a written Exposure Control Plan. Blood-borne pathogen exposure can occur from handling substances other than blood. Also, body fluids from deceased individuals can be infectious.

An employee is at risk of exposure if he or she handles these substances. Exposure risk is negligible for personnel who work in healthcare settings but who do not handle body substances—for example, telephone repair personnel. In contrast, many employers recruit work site first aid teams that include employees whose usual work does not involve contact with human body fluids. If the emergency response duties of these volunteers may lead to contact with blood or body fluids of injured coworkers, the employer should provide appropriate training and personal protective equipment and offer the hepatitis B vaccine. (OSHA issued a ruling in June 1993 that permits employers to delay the vaccination of first aid providers in specific situations. Employers considering this option should carefully review the practical implications of this policy.)

Although not specifically addressed by the OSHA standard, tissues or cell lines derived from human or primate sources are also potentially infectious. HIV does not replicate in cells outside the host, so cell lines of relatively recent origin are potentially infectious, whereas later generations will not be infectious because of a dilution effect. HBV can persist in cell lines.

When workers can become exposed to blood-borne pathogens occupationally, the employer’s written Exposure Control Plan must include certain critical elements that are described in detail in the standard. Issues to be addressed include engineering controls, personal protective equipment, and work practice controls that focus on universal precautions. Universal precautions means that all blood and body fluids should be regarded as potentially infectious; it is not sufficient to use precautions with some samples and not with others. The employer must provide training (and annual retraining) in the use of personal protective equipment, safe storage and transport of body fluids, safe disposal of potentially infectious wastes, effective decontamination of contaminated work surfaces, and prohibition of storage or consumption of food and drink in areas where there is a reasonable likelihood of exposure. Employers must provide hepatitis B vaccine promptly to employees at reasonable risk of exposure at no cost. Employees who refuse the vaccine should sign an OSHA-specified declination form. A procedure to evaluate employees who have had an exposure to determine the potential infectivity of the source and to provide appropriate medical care for the exposed worker is also required. The employer must keep records documenting training, vaccination (or declination), and postexposure evaluation.

In 2000, several states and the US Congress considered laws and regulations to encourage or require the use of newer needlestick and sharps injury prevention technology. The federal Needlestick Safety and Prevention Act was passed in November 2000 and went into effect on April 18, 2001.2 The law required OSHA to modify the Bloodborne Pathogens Standard. Legal requirements include the use of needleless systems and other engineering approaches that effectively reduce the risk of an exposure incident. The standard requires that frontline employees who are using the equipment have the opportunity for input into purchasing decisions. The needlestick log helps both employees and employers track all needlesticks to help identify problem areas or operations. When OSHA transitioned to the OSHA 300 Log for reporting occupational injuries and illnesses in 2002, it incorporated the requirement to record needlesticks and cuts from sharp objects that are contaminated with another person’s blood or other potentially infectious material as an injury. To protect the employee’s privacy, the employee’s name is not entered on the OSHA 300 Log.3 If an employee develops a blood-borne illness, such as HIV, hepatitis B, or hepatitis C, as a result of exposure, that needs to be recorded as an illness.

THE HISTORY OF OSHA GUIDELINES FOR TUBERCULOSIS

In late 1993, OSHA issued mandatory guidelines (revised February 1996) for an enforcement policy intended to protect workers from tuberculosis (TB). These guidelines were based primarily on the Centers for Disease Control and Prevention (CDC) 1990 Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Settings, with Special Focus on HIV-Related Issues.4 The guidelines pertain to employers in settings where workers are at increased risk of exposure, such as healthcare facilities, correctional institutions, homeless shelters, drug treatment centers, and long-term care facilities.

OSHA guidelines required employee training and information on the signs and symptoms of tuberculosis, hazards of transmission, medical surveillance, and site-specific controls. Employers must institute a program of early identification of suspected cases. Medical surveillance should include preplacement evaluation, periodic Mantoux testing, and management of persons with positive test results. Persons who are infectious must be treated in respiratory isolation rooms under negative pressure. A formal OSHA compliance directive was planned for after CDC completed the second edition of its guidelines. A draft of the guidelines included a requirement to create a TB infection control plan. Elements of the plan include a risk assessment, administrative controls, engineering controls, use of respiratory protection, employee education and training, and medical surveillance.

In 1997, OSHA proposed a comprehensive standard for preventing TB transmission among healthcare workers.5 It differed from the CDC guidance in the areas of risk assessment, medical surveillance, and Respiratory Protection. It also contained medical removal protection for employees. However, controversy over the standard and a precipitous drop in TB in acute care hospitals resulted in OSHA withdrawing the proposed rule at the end of 2003.6 This also resulted in OSHA withdrawing the TB-specific respirator protection standard and instead relying on the general Respiratory Protection standard. The US Congress next stepped in and restricted OSHA from enforcing provisions that require annual fit testing of respirators for occupational exposure to tuberculosis. OSHA was to take no further action until the CDC issued their revised guidelines. In December of 2005, the CDC issued Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005, which recommended periodic fit testing.7 When Congress passed the 2008 appropriations bill, it did not contain the restriction on OSHA enforcement. On January 2, 2008, OSHA resumed full enforcement of the Respiratory Protection Standard, including the requirements for fit testing of respirators when they are used for protection against TB.8

PROPOSED OSHA INFECTIOUS DISEASE STANDARD

In 2010, OSHA published a request for information (RFI) on occupational exposure to infectious agents in settings where healthcare is provided and healthcare-related settings.9 The standard could require the development of a comprehensive infection control plan. The focus would be on protecting workers from infections transmitted by contact, droplet, and aerosol routes—areas not addressed by the Bloodborne Pathogens Standard. This could include TB, influenza, MRSA, Ebola, and emerging infectious diseases.

The RFI is the first step in a process that may lead to a new OSHA standard. Since releasing the RFI, OSHA held stakeholder meetings in 2011 and initiated the Small Business Advocacy Review Panel process in 2014 as required by the Small Business Regulatory Enforcement Fairness Act of 1996. As of mid 2016, OSHA has not published a notice of proposed rulemaking for this standard.

PREVENTION OF EXPOSURE TO BIOLOGICAL AGENTS

Hazardous exposures to biological agents occur mainly through inhalation and ingestion, although skin contact (or penetration) can cause illness with some agents. These routes of exposure can be eliminated through engineering, administrative or work practice controls, and the use of personal protective equipment.

Engineering controls

The preferred preventive measure for prolonged or highly hazardous potential exposures is the use of engineering controls. Workplace controls are intended to contain biohazards at their source, reduce their airborne concentration, and limit their movement through the work site. Heating, ventilation, and air conditioning (HVAC) systems must also be appropriately designed and maintained to prevent contamination by fungi and bacteria (including Legionella pneumophila). For indoor settings, such as medical or research facilities, room ventilation can be engineered to provide directional and single-pass airflow. In hospitals, air exhausted from high-risk infectious disease isolation rooms can be further decontaminated by filtration. Use of ultraviolet light to treat exhausted air is under study. In research and clinical laboratories, handling infectious agents in a biological safety cabinet (BSC) can prevent inhalation exposures. For bioaerosol control, the correct type of unit must be used.

Class I cabinets provide personnel protection but little or no product protection. Room air flows into this open cabinet and is ducted through a high-efficiency particulate air (HEPA) filter. HEPA filters clean air supplied to the work zone, providing product protection; and the HEPA filtration of exhaust air provides environmental protection. This filtration system traps all microorganisms, including viruses, with 99.97% efficiency at the 0.3 µm particle size and essentially 100% capture of particles larger than 0.3 µm. The class I cabinet is designed for work with low- to moderate-risk biological agents. It can be used to house various aerosol-generating equipment, including blenders, centrifuges, and mixers. Since the cabinet work zone is not protected from external contamination by the inward flow of unfiltered laboratory air, the cabinet should not be used for work that requires aseptic conditions.

Class II laminar flow cabinets are the most commonly used laboratory containment devices. An air barrier at the front opening of the cabinet provides personnel protection. The air circulating in the workspace is HEPA filtered, providing protection from contamination for the biological material inside the cabinet. The exhaust is also passed through a HEPA filter and either returned to the room or ducted outside. Class II cabinets are classified as A or B, based on design, airflow, and exhaust. The class II type A cabinet is used for work with biological agents in the absence of volatile or toxic chemicals and radioisotopes, since cabinet air is recirculated within the work zone. These cabinets may be exhausted to the room or externally via ductwork. Class II type B cabinets are ducted directly to the exhaust system; the plena remain under negative pressure.

Class III cabinets are totally enclosed gastight ventilated chambers. They are used in laboratories for work with organisms that are highly infectious through the airborne route.

Clean benches are not considered BSCs. They are designed only to protect the product from contamination by providing positive pressure airflow. Using a clean bench to handle an infectious organism would cause the organism to be exhausted onto the user.

Other engineering controls include special containers for waste and sharps disposal, needleless systems, and devices such as self-resheathing needles.

Administrative controls

Administrative control focuses on maintaining good work habits to minimize exposures due to spills, accidental releases, or other causes. Hands should be washed frequently, work surfaces should be decontaminated properly, and under no circumstances should food, beverages, or tobacco products be consumed in the same work area as biohazardous agents. Access to biohazard work areas should be restricted to employees who have had appropriate safety training and who have the necessary personal protective equipment. In laboratories, mouth pipetting should be prohibited.

Personal protective equipment

The use of personal protective equipment (PPE) is indicated whenever the hazards cannot be eliminated through the use of facility design and other engineering controls. Gloves should always be worn when handling infectious agents or secretions from potentially infectious patients or animals. Protective clothing is desirable in many instances, including use of reinforced hand and arm wear (using leather or steel mesh) for certain animal handling tasks where there is a risk of bite or laceration. Eye protection is important when working with certain airborne biological hazards. Instead of ordinary safety glasses, goggles or face shields should be employed when potentially infectious particulates may arise, such as when performing dental or surgical procedures on potentially infectious patients or animals.

Protection from inhalation exposure of biologicals can be accomplished by wearing a respirator. Because even the most lightweight respirators can be somewhat uncomfortable after prolonged periods of use, engineering controls are preferred except for short-term control. Surgical masks only protect the patient, animal, or product from exposure to the worker’s exhaled organisms. The worker breathes unfiltered air that enters the airway from around the sides of the mask. To protect the worker from biological hazards in the environment, one of many varieties of certified respirators must be used, such as a HEPA filter mask or dust/mist respirator. Respirator selection should be specific for the hazard and work situation. Employees using respirators are required by OSHA regulation to obtain medical clearance and to attend a training program. Training must include a fit test for the specific type of respirator being worn. These requirements apply to all respirators, including the simple dust mask.

Waste handling

The proper handling, decontamination or containment, and disposal of biological waste are important infection control measures in all work settings. In medical facilities and laboratories, wastes that are potentially infectious must be initially segregated from other wastes and placed in identifiable biohazard storage bags, affixed with the international biohazard symbol. All sharps must be placed in hard-walled, leakproof, and secure containers. Contaminated needles should not be cut or recapped prior to disposal.

Decontamination can be accomplished by means of sterilization, disinfection, sanitization, or antisepsis. Sterilization means the eradication of all living microorganisms and spores. Disinfection means elimination of most biological organisms, although hardier organisms and spores may survive. Sanitization is the lowest level of disinfection and removes most pathogenic organisms. Antisepsis means reducing bacterial counts by applying compounds to skin or other body tissues.

Disinfectants have been classified according to chemical composition and level of activity. Commercially available disinfectants often combine one or more agents. The high-level disinfectants possess a broad spectrum of antimicrobial properties and are recommended for use in the destruction of mycobacteria and the blood-borne pathogens; they are often referred to as mycobactericidal or tuberculocidal. The low-level disinfectants are recommended for use in sanitation and other public health applications. The resistance of microorganisms to chemical disinfection, from most resistant to most sensitive, is as follows: bacterial spores, tubercle bacilli, fungal spores, hydrophilic viruses, mycelial fungi, lipophilic viruses, Gram-negative vegetative bacteria, and Gram-positive vegetative bacteria. Common disinfectants and their uses are listed in Table 20.1.

TABLE 20.1 Disinfectants and their uses.

Disinfectant Antimicrobial activity Use
Chlorine-liberating halogens Hypochlorites at 1–5% aqueous concentration possess wide spectrum of activity against microbials, including HIV and HBV A 1 : 1000 dilution of household bleach recommended for use against blood-borne pathogens. Chlorination of potable water conducted at 0.2 ppm available chlorine
Formaldehyde Bactericidal, tuberculocidal, and virucidal; hours of exposure required for destruction of bacterial spores; aqueous formaldehyde (formalin) is 37% formaldehyde with 10–15% methanol in water Usefulness limited by toxicity and odor. Formalin is used as a spray and surface disinfectant. Vapor-phase formaldehyde is used to routinely disinfect biological safety cabinets and other enclosures
Alcohols (ethanol, propanol, and isopropanol) Bactericidal, tuberculocidal, and virucidal; devoid of sporicidal activity; most effective concentration is 70% in water General disinfection of surfaces and equipment. Rapid destruction (in seconds) of vegetative bacteria, fungi, and certain viruses. Leaves little to no residue
Glutaraldehyde Broad spectrum of antimicrobial activity; hours of exposure required for destruction of bacterial spores; used as 2% alkaline glutaraldehyde Excellent high-level disinfectant for inhalation therapy equipment and other devices. Residues need to be removed with sterile water wash
Iodophors Not effective as a disinfectant Primarily used as an antiseptic
Phenolics Antimicrobial properties of phenolics vary considerably Used primarily for housekeeping and sanitizing applications (e.g., Lysol)
Quaternary ammonium compounds (e.g., benzalkonium chloride (monoalkyldimethyl benzyl ammonium salt)) Possess detergent and surfactant properties; antimicrobial properties are questionable Popular for sanitizing

Sterilization can be accomplished by several techniques. Steam autoclaving is a commonly used method to sterilize cultures and stocks of microorganisms, laboratory ware, and contaminated devices and instruments. Dry heat sterilization (i.e., 160°C for 1–2 hours) can be used to sterilize glassware and metallic instruments when corrosive effects of steam on sharps and cutting edges are undesirable. However, the penetrability and killing effects of dry heat are poorer than those of steam autoclaving or gaseous sterilization. Ethylene oxide, a commonly used gaseous sterilant with high penetrability, is found in most commercial and hospital sterile processing units. Excellent containment is required for these sterilization machines to avoid worker exposures. Ionizing radiation is gaining worldwide acceptance as a commercially feasible sterilization procedure. Attributes of radiation sterilization include penetrability, final package processing, and lack of toxic residues.

SURVEILLANCE

Surveillance for infectious organisms has become a common practice in hospital settings since Semmelweis and others began promoting hand washing and aseptic surgical technique in the nineteenth century. Hospital infection control programs were initiated in the 1950s in response to the first epidemics of antibiotic-resistant staphylococcal infection among hospitalized patients. An initial enthusiasm for routine environmental culturing has been replaced by monitoring programs that tabulate rates of nosocomial infection among patients.

Target infections are usually surgical wound infections, urinary tract infections, bacteremias, and pneumonias. Now that tuberculosis rates are rising again in the United States, some hospitals are also attempting to determine if nosocomial tuberculosis infection is occurring, especially among patients with the acquired immunodeficiency syndrome (AIDS). When rates are found to be elevated, patient care practices are reviewed to correct deficiencies in urinary catheter care, intravenous equipment care, respiratory therapy, surgical care, patient isolation, or hand washing. In agriculture, animal breeding, veterinary practices, and related settings, infected animals should be segregated and promptly diagnosed. To prevent zoonoses among workers, animals should be treated or killed and disposed of properly.

In industrial settings, occupational disease surveillance generally has a different target group. Workers themselves are monitored to detect disease caused by a work exposure, such as development of elevated blood lead levels among battery-manufacturing workers. Surveillance of only a few infectious diseases (e.g., tuberculosis) is conducted in this manner.

Tuberculosis monitoring through surveillance of workers by tuberculin skin testing has three goals. First, certain workers who convert from skin test negative to positive can be treated with antimicrobial therapy to prevent development of active TB in the worker. For workers whose previous skin test reactivity is unknown and who experience an acute exposure to tuberculosis occupationally, a skin test should be done immediately and then again in 6–12 weeks to check for tuberculin test conversion. Second, early identification of potentially infectious healthcare, food service, or other workers with extensive contact with the public can prevent the infection of patients or others. Third, skin test conversion rates provide a measure of the quality of infection control procedures in healthcare workplaces.

HBV surveillance is generally limited to workers who have been exposed to a patient’s blood or body fluids, such as from a needlestick. Surveillance of healthcare workers for antibody conversion could be used to assess the quality of infection control procedures. However, this is usually not done because of its expense, because of the sometimes difficult task of determining if a conversion is work related, and because surveillance for occupational exposures such as needlesticks is more efficient.

When an exposure occurs, a targeted postexposure follow-up and treatment protocol should be initiated for the employee. The protocol includes a baseline visit in which acute treatment is based on the source’s HBV status and the employee’s vaccination status. The employee and source should also be evaluated for HIV at baseline. During follow-up over 3–6 months, the employee is then assessed for seroconversion from either virus.

Mandatory screening of physicians, dentists, and other healthcare workers for HIV has been hotly debated. Surveillance has not been required or recommended to date, because the risk for transmitting the virus to patients is very low. However, professionals who are infected should not perform exposure-prone invasive procedures and should refrain from patient contact when they have open skin lesions. There is no justification for HIV screening of workers who do not have patient contact.

In addition to healthcare workers, laboratory workers and agricultural workers can also be at risk of contracting infectious diseases occupationally. Infections that could occur from processing human tissue specimens include HBV, HIV/tuberculosis, and the following bacterial and fungal pathogens: Brucella species, Francisella tularensis, Shigella, Salmonella, Coccidioides immitis, Blastomyces dermatitidis, and Histoplasma capsulatum.

Laboratory animals can potentially transmit infections to humans, including HBV, simian immunodeficiency virus, rabies, plague, and tuberculosis. Wild animals and farm animals or their products can potentially transmit anthrax, brucellosis, erysipeloid, leptospirosis, plague tularemia, candidiasis, coccidioidomycosis, dermatophytoses, histoplasmosis, hookworm, toxoplasmosis, ornithosis, Q fever, Rocky Mountain spotted fever, viral encephalitis, hantavirus, paramyxovirus, rabies, or parasitic infections. Safe handling procedures and vaccination are recommended for preventing these occupational infections rather than surveillance among workers. Universal precautions when handling macaque monkeys are essential, including physically and chemically restraining the monkeys and use of goggles and arm-length-reinforced leather gloves. Relying on periodic serologic testing in the colony to determine which monkeys need to be handled cautiously is hazardous, because monkeys may seroconvert between testing but may appear clinically free from infection.

VACCINATION

Vaccinations are given in occupational settings for four common indications. First, employees may be vaccinated to protect them from an infectious organism such as tetanus or hepatitis B when they are at increased risk of being exposed in the workplace. Some vaccines are given as part of a postexposure protocol. Second, healthcare workers may be vaccinated against agents such as rubella or influenza to prevent them from inadvertently passing the infection to patients. Third, some company health units, as part of a corporate wellness program, may provide vaccinations against community-acquired infections such as tetanus to employees who are not at increased occupational risk of the infection. Fourth, vaccinations against agents such as yellow fever may be provided to prepare employees for international travel.

Vaccines commonly administered in occupational settings are listed in Table 20.2. For laboratory workers who handle unusual organisms, consult the chapters on specific organisms later in this book. The Infectious Diseases sections of CDC can provide helpful information. For information on dosage, administration, and contraindications, consult the package insert for each vaccine. For further information about commonly used vaccines, including those that generally do not need to be administered for occupational indications, consult the most recent Adult Immunization Schedule-United States10 and the American College of Physicians Guide for Adult Immunization.11 Vaccines used before international travel are listed separately in Table 20.3.

TABLE 20.2 Vaccines and immunobiologicals commonly administered in occupational settings.

Vaccine or immunobiological Type Worker groups Immunocompromised employees Comments
Hepatitis A vaccine Inactivated whole virus Institutional workers (caring for developmentally challenged), child care workers, laboratory workers handling hepatitis A virus, primate handlers working with animals that may harbor HAV* OK to give
Hepatitis B vaccine Recombinant DNA vaccine Healthcare workers, other workers handling human blood or body fluids OK to give No risk of acquiring HIV from vaccine
Hepatitis B immune globulin Pooled human antiserum Postexposure, hepatitis B OK to give Also known as HBIG
Immune serum globulin Pooled human antiserum Postexposure, hepatitis A OK to give
Measles, mumps, rubella Attenuated live viruses Healthcare workers, day care workers Do not give Can test employee for rubella immunity in lieu of vaccination
Polio vaccines Oral = attenuated live virus Laboratory workers handling polio cultures Do not give the oral or live vaccine
Parenteral = killed virus
Rabies vaccine Inactivated virus Workers handling animals which may have contracted rabies in the wild Do not give
Rabies immune serum globulin Human antiserum Postexposure OK to give
Tetanus–diphtheria vaccine Killed bacteria and toxoid Animal handlers, postexposure, corporate wellness program OK to give Should have booster every 10 years
Tetanus toxoid Human antiserum Postexposure OK to give
Varicella vaccine Attenuated live virus Healthcare workers Do not give
Vaccinia vaccine Attenuated live virus Workers handling vaccinia cultures Do not give

* HAV, hepatitis A virus.

TABLE 20.3 Vaccines and immunobiologicals commonly administered for international travel.

Vaccine or immunobiological Type Required versus recommended Immunocompromised employees Comments
Yellow fever Live attenuated virus May be required Do not give
Cholera Live attenuated virus May be required; physician statement contraindicating use for specific patient may be accepted Do not give Approved in 2016 for adults age 18–64, targets Vibrio cholerae serogroup O1
Typhoid
Killed bacteria Not required but highly recommended for certain high-risk locales OK to give killed vaccine only Live attenuated vaccine under development
Polio Live attenuated virus (oral) or killed (parenteral) Recommended for certain high-risk locales Do not give live attenuated If not fully immunized previously, complete primary series
Tetanus and diphtheria Killed bacteria and toxoid Recommended OK to give
Immune serum globulin Pooled human antiserum Recommended for certain high-risk locales OK to give Do not administer at same time as some live virus vaccines; may suppress immune response to them
Hepatitis A vaccine Inactivated whole virus Recommended for certain high-risk locales OK to give May be administered concomitantly with immune globulin if needed
Hepatitis B vaccine Recombinant DNA vaccine Recommended for certain high-risk locales OK to give 6 months required for full series
Rabies vaccine Inactivated virus Recommended if high-risk animal contact is likely Do not give
Measles, mumps, rubella Attenuated live viruses Recommended for certain high-risk locales Do not give
Meningococcal vaccine Mixed polysaccharides Recommended for certain high-risk locales OK to give
Malaria Chemoprophylaxis, not a vaccine Recommended for certain high-risk locales OK to give

SPECIAL SITUATIONS

Immunocompromised workers

Many individuals remain in the workforce even after developing health problems that may lead to immune system compromise. The most highly publicized group comprises those with HIV infections, but other conditions can also confer some degree of immune dysfunction. Individuals with diabetes mellitus, splenic disorders, renal dysfunction, alcoholism, or cirrhosis do not generally require special work restrictions or special work-related immunizations, but they should be followed closely by a personal physician, who may administer vaccines against pneumococcus, influenza, or other agents. Conditions in which special occupational considerations may be warranted are listed in Table 20.4.

TABLE 20.4 Immunocompromising conditions with potential occupational significance.

Condition Occupational significance
HIV 1 infection Review work practices
Do not administer live vaccines
If employee is a healthcare provider, restrict from performing exposure-prone invasive procedures
Organ transplantation, receiving immunosuppressive drugs Review work practices
Consult transplant physician before administering vaccines to avoid nonspecific immunologic response that may trigger allograft rejection
High-dose chronic corticosteroid therapy Review work practices
Consult oncologist to determine if employee is immunosuppressed
Malignant disease, receiving immunosuppressive chemotherapy Review work practices
Consult oncologist before administering live vaccines
Congenital immunodeficiency diseases Review work practices
Consult treating physician before giving vaccines
Do not give immune globulin to persons with selective IgA deficiency

Individuals with potentially immunosuppressive conditions should receive training in techniques to prevent exposure to infectious agents in the workplace, including the proper use of personal protective equipment. The need for special vaccines or surveillance should be reviewed, bearing in mind that certain vaccines—especially live virus vaccines—may be contraindicated. Consideration should be given to restricting employees from high-risk work exposures for which protective vaccinations are contraindicated. Although some employees may request to avoid certain other infectious agents and some employers may be able to accommodate these requests, standards generally do not exist for when immunocompromised employees absolutely must be restricted from working with specific infectious agents.

Pregnant workers

Some infectious diseases acquired during pregnancy can cause direct harm to the fetus or substantial maternal morbidity with indirect consequences for the developing fetus. Common agents of concern from the occupational standpoint are rubella, human parvovirus B19, cytomegalovirus, varicella zoster, hepatitis B, coccidioidomycosis, and toxoplasmosis. Prenatal screening can determine if a pregnant woman is susceptible to contracting any of these agents during pregnancy. Prenatal infection with Lyme disease, malaria, Zika, or viral encephalitis has also been associated with adverse fetal outcomes, whereas perinatal transmission has not been demonstrated for polio, rabies, or influenza.

Standards are evolving for restricting occupational exposures among pregnant workers. Some authorities focus on educating workers about optimal work practices, because it has not been demonstrated that pregnant workers are any more likely than nonpregnant workers to contract the infections of concern, even though the health consequences of becoming infected may be serious. Other authorities recommend restricting susceptible pregnant employees from working with patients in acute aplastic crisis (human parvovirus B19), adult patients or children shedding cytomegalovirus, or persons with chickenpox or herpes zoster (varicella zoster virus).

The potential reproductive risks of uncommon infectious agents that could be encountered in occupational settings should be evaluated individually. The American College of Obstetricians and Gynecologists maintains a resource center in Washington, DC, that can provide technical bulletins on perinatal care. Although female employees are often the focus of concern about occupational reproductive issues, men are also susceptible to reproductive hazards. The best-known infectious reproductive hazard for men is mumps; mumps can cause orchitis, which may lead to sterility.

Workers concerned about contracting disease from coworkers

Serious illness in an employee can generate substantial concern among coworkers. If an employee looks sick but the diagnosis is not known, coworkers may contact company health or safety personnel. Ethical issues about the confidentiality of the employee suspected of illness must then be addressed. HIV infection is an apt example. Even if coworkers suspect that an individual has the infection, there is no reason to invade his or her privacy to confirm or allay fears of infection through casual contact. The virus is not transmitted through handshakes, work surfaces, or telephones. While the virus has been isolated in very small quantities from saliva, there has never been a documented case of salivary transmission through food or eating utensils, or even through kissing on the lips. There is no evidence that the virus will replicate in insects, let alone be transmitted to humans from insects. There is no reason to restrict HIV-infected individuals from engaging in their normal work in order to allay unrealistic fears of contagion among coworkers. Coworker concerns should instead be addressed rapidly and decisively through education.

In general, employees with common viral respiratory infections are not restricted from work, because such viruses are endemic in the community. Employees with suggestive symptoms should be evaluated to rule out tuberculosis. If tuberculosis is confirmed, the individual should be restricted from work until his or her sputum becomes free of acid-fast bacilli. The local health department should be notified, coworkers should be skin tested, and follow-up should be provided as appropriate.

Occasionally, employees may become concerned that a coworker with a rash could have an infectious condition, such as scabies. Coworker anxiety may be accompanied by itching. Although scabies transmission is unlikely in the absence of personal contact, it may be helpful for medical personnel to determine the specific diagnosis in the “index” employee, to inform the work unit if treatment of coworkers is indicated, and to provide education on the myriad causes of rash that are not contagious.

International travel

International travel has become commonplace for business purposes. To prevent unnecessary illness or injury, a preventive health review before travel is strongly advised. Information on health and safety conditions for each country to be visited can be obtained from CDC. CDC maintains an international travel hotline and travel website. It issues a publication entitled Health Information for International Travel and has a database, accessible by computer, which is updated monthly. A printout can be obtained for each country that includes advice on infectious disease hazards, required and recommended immunizations, malaria prophylaxis, and food and water safety; it also details any recent incidents of civil unrest. This list underscores the importance of taking health precautions beyond vaccinations required for visa purposes. Vaccination requirements can also be obtained from embassies, the World Health Organization (Albany, NY), and sometimes from local health departments.

Travel can be categorized as high or low risk based on the country to be visited and on the person’s itinerary during his or her stay. Travel to Westernized countries or to first-class hotels in some developing countries carries a lower risk than travel to rural areas of developing countries. Immunizations can be separated into those that may be required for visa purposes (e.g., yellow fever and cholera vaccines) and those that are recommended for personal protection (e.g., diphtheria–tetanus, hepatitis A vaccine). The more commonly used vaccines are listed in Table 20.3. For information on contraindications, dosage, and timing of vaccine administration, see the product information in the Physicians’ Desk Reference (PDR). The American College of Physicians Guide for Adult Immunization provides a good overview of major aspects of preventive health during foreign travel.

Along with vaccinations and chemoprophylactic drugs, travelers should take additional precautions to reduce the risk of vector-borne diseases. No vaccines or medications are available to prevent many mosquito-borne diseases (including dengue, chikungunya, Zika, and West Nile) and tick-borne diseases (including Lyme disease). Travelers to endemic areas should take precautions including avoiding being outdoors at times of peak exposure, wearing appropriate clothing to cover exposed skin, and using repellents.

For all international business travelers, especially persons with chronic health problems, it is also advisable to investigate health insurance coverage for foreign travel, to ensure that medications are carried in their original prescription containers, and to obtain the location and telephone numbers of the US embassies in each country to be visited.

Required reporting

Certain issues related to infectious diseases require reporting by health professionals, including infections that are diagnosed in occupational health units. Each state can provide lists of infections that must be reported to local health departments. Physicians and other healthcare providers must also maintain permanent records of immunization and report certain adverse effects of vaccination to the US Department of Health and Human Services.

Business continuity and pandemic planning

Business continuity plans are developed to ensure that business interruptions have the smallest possible impact on the ability of the business to function and can recover as quickly as possible. Business continuity planning is a formal exercise that is usually connected to emergency and disaster planning. Along with the development of roles and responsibilities, and a determination of essential personnel, organizations often conduct tabletop exercises and/or drills to practice the response to varied scenarios. These exercises also provide opportunities to identify the need to modify the plan.

Potential causes of business interruption include natural disasters, fires, and accidents. Community-based infectious diseases, such as pandemic influenza, may also cause business interruption. Business continuity plans should include a response to pandemics.

Pandemics are characterized by rapid spread that can overload the healthcare system. Approaches that may mitigate impact on workplaces include social distancing (including allowing nonessential personnel to work from home when feasible), vaccination programs, and facilitating access to medications that can reduce the duration or severity of illness. Medical facilities need additional procedures that reduce the likelihood that staff, visitors, or other patients will be exposed.

OSHA developed Guidance on Preparing Workplaces for an Influenza Pandemic in 2007.12 The guidance is advisory and does not create new obligations. However, businesses are still obligated under the General Duty Clause to provide workplaces that “are free from recognized hazards that are causing or are likely to cause death or serious physical harm.”13

The guidance recommends a risk stratification approach for employers:

  • Very high exposure risk occupations are those with high potential exposure to high concentrations of known or suspected sources of pandemic influenza during specific medical or laboratory procedures.
  • High exposure risk occupations are those with high potential for exposure to known or suspected sources of pandemic influenza virus.
  • Medium exposure risk occupations include jobs that require frequent close contact (within 6 ft) exposures to known or suspected sources of pandemic influenza virus such as coworkers, the general public, outpatients, schoolchildren, or other such individuals or groups.
  • Lower exposure risk (caution) occupations are those that do not require contact with people known to be infected with the pandemic virus, nor frequent close contact (within 6 ft) with the public. Even at lower risk levels, however, employers should be cautious and develop preparedness plans to minimize employee infections.

Based upon risk level, the guidance includes recommendations for planning, work practice controls, engineering controls, administrative controls, and personal protective equipment.

Concern about bioterrorism

Concerns about biological warfare and bioterrorism have existed for several decades and have been heightened by the horrific events of September 11, 2001, and their aftermath.

Several countries are known to have had biological warfare programs and stocks of agents are known to exist. At least 35 agents and organisms have been classified as possible bioterrorism concerns. The most widely discussed are anthrax, botulism, plague, tularemia, and smallpox (Table 20.5). An epidemic of anthrax occurred in the former Soviet Union following an accidental release from a military facility in Sverdlovsk in 1979. In 2001, there were exposures to anthrax sent through the mail in the United States, resulting in several cases of cutaneous anthrax and three fatalities due to inhalation anthrax. In 2008, the Department of Justice and FBI officials released documents and information showing that charges were about to be brought against an Army scientist at Ft. Detrick, Maryland, who committed suicide before those charges could be filed. These episodes have led to heightened fears about the possibility of further small- and also large-scale bioterrorism activities.

TABLE 20.5 Potential Biological Warfare Agents

Disease Incubation Symptoms Signs Diagnostic tests Transmission and Precautions Treatment (Adult dosage) Prophylaxis
Inhaled Anthrax 2–6 days Range: 2 days to 8 weeks Flu-like symptoms Respiratory distress Widened mediastinum on chest X-ray (from adenopathy)
Atypical pneumonia
Flu-like illness followed by abrupt onset of respiratory failure
Gram stain (“boxcar” shape)
Gram positive bacilli in blood culture
ELISA for toxin antibodies to help confirm
Aerosol inhalation
No person-to-person transmission
Standard precautions
Mechanical ventilation Antibiotic therapy Ciprofloxacin 400 mg iv
q 8–12 hours Doxycycline 200 mg iv initial, then 100 mg iv q 8–12 hours
Penicillin 2 mil units iv q 2 hours – possibly add gentamicin
Ciprofloxacin 500 mg po bid or doxycycline 100 mg po bid for ~8 weeks (shorter with anthrax vaccine)
FDA-approved vaccine: administer after exposure if available
Botulism 12–72 hours Range:
2 hours – 8 days
Difficulty swallowing or speaking (symmetrical cranial neuropathies)
Symmetric descending weakness
Respiratory dysfunction No sensory dysfunction No fever
Dilated or un-reactive pupils
Drooping eyelids (ptosis)
Double vision (diplopia)
Slurred speech (dysarthria) Descending flaccid paralysis
Intact mental state
Mouse bioassay in public health laboratories (5–7 days to conduct)
ELISA for toxin
Aerosol inhalation Food ingestion
No person-to-person transmission
Standard precautions
Mechanical ventilation Parenteral nutrition Trivalent botulinum
antitoxin available from State Health Departments and CDC
Experimental vaccine has been used in laboratory workers
Plague 1–3 days by inhalation Sudden onset of fever, chills, headache, myalgia
Pneumonic: cough, chest pain, hemoptysis
Bubonic: painful lymph nodes
Pneumonic:
Hemoptysis; radiographic pneumonia – patchy, cavities, confluent consolidation
Bubonic: typically painful, enlarged lymph nodes in groin, axilla, and neck
Gram negative coccobacilli and bacilli in sputum, blood, CSF, or bubo aspirates (bipolar, closed “safety pin” shape on Wright, Wayson’s stains) ELISA, DFA, PCR Person-to-person transmission in pneumonic forms
Droplet precautions until patient treated for at least three days
Streptomycin 30 mg = kg = day in two divided doses × 10 days
Gentamicin 1–1.75 mg = kg iv/im q 8 hours
Tetracycline 2–4 g per day
Asymptomatic contacts; or potentially exposed
Doxycycline 100 mg po q 12 hours × 7 days
Ciprofloxacin 500 mg po Tetracycline 250 mg po q 6 hours × 7 days Vaccine production discontinued
Tularemia “pneumonic’ 2–5 days Range: 1–21 days Fever, cough, chest tightness, pleuritic pain
Hemoptysis rare
Community-acquired, atypical pneumonia Radiographic: bilateral patchy pneumonia with hilar adenopathy (pleural effusions like TB)
Diffuse, varied skin rash May be rapidly fatal
Gram negative bacilli in blood culture on BYCE (Legionella) cysteine-or S-H-enhanced media
Serologic testing to confirm: ELISA, microhemagglutination
DFA for sputum or local discharge
Inhalation of agents No person-to-person transmission but laboratory personnel at risk
Standard precautions
Streptomycin 30 mg = kg = day IM divided bid for 10–14 days
Gentamicin 3–5 mg = kg = day iv in equal divided shoulders × 10–14 days
Ciprofloxacin possibly effective 400 mg iv q 12 hours (change to po after clinical improve- ment) × 10–14 days
Ciprofloxacin 500 mg po q 12 hours × 2 weeks
Doxycycline 100 mg po q 12 hours × 2 weeks Tetracycline 250 mg po q 6 hours
Experimental live vaccine
Smallpox 12–14 days
Range: 7–17 days
High fever and myalgia; itching; abdominal pain; delirium
Rash on face, extremities, hands, feet; confused with chickenpox which has less uniform rash
Maculopapular then vesicular rash – first on extremities (face, arms, palms, soles, oral mucosa)
Rash is synchronous on various segments of the body
Electron microscopy of pustule content PCR
Public health lab for confirmation
Person-to-person transmission
Airborne precautions
Negative pressure
Clothing and surface decontamination
Supportive care
Vaccinate care givers
Vaccination (vaccine available from CDC)

Courtesy of Michael Hodgson, M.D., Office of Public Health and Environmental Hazards, Veterans Health Administration, Washington, D.C.

While publicized incidents of bioterrorism led to significant fears, it should be kept in mind that the actual risk of being involved in an event is extremely small. The dissemination of large quantities of bioterrorism agents and organisms fortunately has many significant technical challenges.

A prudent response to concerns involves different actions for individuals, professionals, and organizations. In general, people should be reassured that their personal risk is very low and that they should take reasonable precautions in everyday life. This includes not handling suspicious looking mail and packages and accessing their local emergency response system as needed. The practices of hoarding antibiotics or using antibiotics without a medical diagnosis should be discouraged.

For the medical and emergency response community, there is a need to learn to recognize the signs and symptoms of bioterrorism agents and organisms (Table 20.5). This is of special concern because many of these diseases are otherwise uncommon or, as in the case of smallpox, have not been seen for decades. Significant improvements in the public health infrastructure are needed to continue to enhance readiness for bioterrorism.

The animal care community can provide an early warning, since some of the organisms involved are animal pathogens. Veterinarians, farmers, and others who work with and care for animals need to recognize potential public health implications of certain problems seen in animals.

Organizations and companies that handle mail and packages need to develop prudent handling procedures to recognize and isolate suspicious items. Medical, maintenance, safety, and security staffs and emergency response personnel should receive appropriate training.

Finally, concerns about bioterrorism should be kept in perspective in the context of the everyday risks. Most preventable morbidity and mortality are due to addictions (especially tobacco), modifiable lifestyle factors, and treatable diseases and risk factors. Individuals, healthcare personnel, and health systems should maintain and increase the focus on these more mundane issues, as they will ultimately have the greatest impact on life and health.

References

  1. 1. Occupational Safety and Health Administration. Occupational exposure to bloodborne pathogens: final rule. 29 CFR Part 1910.1030. Washington, DC: Department of Labor, 1991. https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=10051&p_table=STANDARDS (accessed June 14, 2016).
  2. 2. Needlestick Safety and Prevention Act. An act to require changes in the bloodborne pathogens standard in effect under the Occupational Safety and Health Act of 1970. Pub. L. 106-430, 114 Stat. 1901 (2000). https://history.nih.gov/research/downloads/PL106-430.pdf (accessed June 23, 2016).
  3. 3. Occupational Safety and Health Administration. Recording criteria for needlestick and sharps injuries. 29 CFR 1904.8. Washington, DC: Department of Labor, 2001. https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9639 (accessed June 14, 2016).
  4. 4. Dooley SW Jr, Castro KG, Hutton MD, et al. Guidelines for preventing the transmission of tuberculosis in health-care settings, with special focus on HIV-related issues. MMWR 1990; 39(RR-17):1–29
  5. 5. Occupational Safety and Health Administration. Occupational exposure to tuberculosis; proposed rule. Fed Regist 1997; 62:54159–308.
  6. 6. Occupational Safety and Health Administration. Occupational exposure to tuberculosis; proposed rule; termination of rulemaking respiratory protection for M. tuberculosis; final rule; revocation. 29 CFR 1910, Docket No. H-371. Washington, DC: Department of Labor, 2003. https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=FEDERAL_REGISTER&p_id=18050 (accessed June 14, 2016).
  7. 7. Jensen PA, Lambert LA, Iademarco MF, et al. Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings, 2005, MMWR 2005; 54(RR-17): 1–141.
  8. 8. Occupational Safety and Health Administration. Tuberculosis and respiratory protection enforcement. 29 CFR 1910.134; 1910.134(f)(2). Washington, DC: Department of Labor, 2008. https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=Interpretations&p_id=26013 (accessed June 14, 2016).
  9. 9. Occupational Safety and Health Administration. Infectious diseases. Request for information. Fed Regist 2010 75(87):24835–44. https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=FEDERAL_REGISTER&p_id=21497 (accessed June 23, 2016).
  10. 10. Centers for Disease Control and Prevention. Adult Immunization Schedule: United States, 2016. http://www.cdc.gov/vaccines/schedules/hcp/adult.html (accessed June 23, 2016).
  11. 11. American College of Physicians. Guide to Adult Immunization. http://immunization.acponline.org (accessed June 14, 2016).
  12. 12. OSHA. Guidance on Preparing Workplaces for an Influenza Pandemic. https://www.osha.gov/Publications/influenza_pandemic.html (accessed June 14, 2016).
  13. 13. Occupational Safety and Health Act of 1970. 29 USC 654 Sec. 5(a)1 https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_id=3359&p_table=oshact (accessed June 14, 2016).

Further Reading

  1. American College of Obstetricians and Gynecologists. Perinatal viral and parasitic infections. ACOG practice bulletin 151. Cytomegalovirus, Parvovirus B19, Varicella Zoster, and Toxoplasmosis in Pregnancy (June 2015). Obstet Gynecol 2015; 125(6):1510–25.
  2. Babcock HM, Woeltje KF. The development of infection surveillance and control programs. In: Bennett JV, Brachman PS, eds. Hospital infections, 6th edn. Philadelphia, PA: Lippincott, Williams & Wilkins, 2013:57–62.
  3. Burge HA, Feeley JC. Indoor air pollution and infectious diseases. In: Samet JM, Spengler JD, eds. Indoor air pollution: a health perspective. Baltimore, MD: The Johns Hopkins University Press, 1991:273–84.
  4. Centers for Disease Control and Prevention, National Institutes of Health. Biosafety in microbiological and biomedical laboratories, 5th edn., HHS publication no. (CDC) 21-1112. Washington, DC: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institutes of Health, 2009. http://www.cdc.gov/biosafety/publications/bmbl5/bmbl.pdf (accessed June 23, 2016).
  5. Committee on Hazardous Biologic Substances in the Laboratory, National Research Council. Biosafety in the laboratory: prudent practices for the handling and disposal of infectious materials. Washington, DC: National Academy Press, 1989.
  6. Fleming DO, Hunt DL, eds. Biological safety: principles and practices, 3rd edn. Washington, DC: American Society of Microbiology Press, 2000.
  7. Henderson DA, O’Toole T, Inglesby TV. Bioterrorism: guidelines for medical and public health management. Chicago, IL: American Medical Association, 2002.
  8. Livingston EG. Infectious agents and non-infectious biologic products. In: Frazier LM, Hage ML, eds. Reproductive hazards of the workplace. New York: John Wiley & Sons, Inc., 1998:463–505.
  9. North Carolina Department of Labor, Division of Occupational Safety and Health. Farm safety, NC-OSHA industry guide no.10. Raleigh, NC: North Carolina Department of Labor, 2008. http://www.unctv.org/content/sites/default/files/0000011508-NCDOL%20farm%20work.pdf (accessed June 23, 2016).
  10. Sears SD, James NW. International medicine: care of travelers and foreign-born patients. In: Fiebach NH, Kern DE, Barker LR, et al., eds. Principles of ambulatory medicine, 7th edn. Philadelphia, PA: Lippincott, Williams & Wilkins, 2006:609–44.
  11. Welch LS, Blodgett DW. Occupational and environmental disease and bioterrorism. In: Fiebach NH, Kern DE, Barker LR, Ziegelstein RC, Zieve PD, Thomas PA, eds. Principles of ambulatory medicine, 7th edn. Philadelphia, PA: Lippincott, Williams & Wilkins, 2006:118–36.
  12. Wilson ML, Reller LB. Clinical laboratory-acquired infections. In: Bennett JV, Brachman PS, eds. Hospital infections, 6th edn. Philadelphia, PA: Lippincott, Williams & Wilkins, 2013:320–8.

Suggested websites

  1. Centers for Disease Control and Prevention, http://www.cdc.gov (accessed June 14, 2016).
  2. National Institutes of Health, http://www.nih.gov (accessed June 14, 2016).
  3. National Institutes of Health. Biodefense and Bioterrorism, http://www.nlm.nih.gov/medlineplus/biodefenseandbioterrorism.html (accessed June 14, 2016).
  4. Occupational Safety and Health Administration, http://www.osha.gov (accessed June 14, 2016).

Bioterrorism websites

  1. CDC. Bioterrorism, http://emergency.cdc.gov/bioterrorism/ (accessed June 14, 2016).
  2. Dembek ZF, Alves DA, U.S. Army Medical Research Institute of Infectious Diseases. Medical management of biological casualties handbook, 7th edn. Fort Detrick, MD: U.S. Army Medical Research Institute of Infectious Diseases, 2011. http://www.usamriid.army.mil/education/bluebookpdf/USAMRIID%20BlueBook%207th%20Edition%20-%20Sep%202011.pdf (accessed June 23, 2016).

Pandemic planning websites

  1. OSHA. Guidance on Preparing Workplaces for an Influenza Pandemic, https://www.osha.gov/Publications/influenza_pandemic.html (accessed June 14, 2016).
  2. U.S. Department of Health & Human Services Influenza Pandemic, http://www.flu.gov/pandemic/ (accessed June 14, 2016).

Note

..................Content has been hidden....................

You can't read the all page of ebook, please click here login for view all page.
Reset
34.237.75.165