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MCEIRS

AVIAN INFLUENZA TRAINING

Individual Study Guide

Version: May 9, 2011 Revised January 2017

Agricultural Worker Health and the Influenza Virus

Minnesota Center of Excellence for Influenza Research and Surveillance

AGRICULTURAL WORKER HEALTH INDIVIDUAL STUDY GUIDE

Minnesota Center of Excellence for MCEIRS Avian Influenza Training Influenza Research and Surveillance General Influenza: Agricultural Worker Health

CONTENTS

Agricultural Worker Health and Influenza Virus

Introduction

Lesson 1: Influenza Virus Review

Lesson 2: Transmission of Influenza Viruses

Lesson 3: Personal Hygiene and Personal Protective Equipment

Lesson 4: Avian Influenza in Poultry Workers

Lesson 5: Preventing Avian Influenza in Poultry Workers

Lesson 6: Influenza in Swine Workers

Lesson 7: Preventing Swine Influenza in Swine Workers

Glossary

Resources

AGRICULTURAL WORKER HEALTH INDIVIDUAL STUDY GUIDE 2


INTRODUCTION

Agricultural Workers and the Influenza Virus

Agricultural workers, including poultry and swine workers, are at risk of exposure to and infection with zoonotic influenza viruses. Zoonotic influenza viruses (those passed from animals to humans) are rarely transmitted person to person. However, the interspecies transmission of influenza viruses raises concern about mutation or reassortment of viruses and the development of new strains of influenza that have the potential to become pandemic viruses. Pandemic viruses are influenza viruses that have developed the ability to pass from person to person and little or no immunity to the new virus exists in the human population. Agricultural workers may be the first to be exposed to a new pandemic strain. Education and training, personal hygiene, and the use of personal protective equipment can help to reduce exposure to zoonotic influenza viruses. Vaccination, medical surveillance, and the inclusion of agricultural workers in the pandemic planning process are other measures that can protect agricultural workers from disease.



Figure 1

Figure 2

LESSON 1: INFLUENZA VIRUS REVIEW

INFLUENZA A VIRUS

Influenza viruses belong to the Orthomyxoviridae family of segmented negative-sense RNA viruses. The genus influenza A consists of a single species: influenza A virus. Influenza A viruses are the main cause of influenza in birds, humans, and other mammalian species. (See Figure 1) Influenza B is also an important cause of influenza in humans, whereas influenza C is a relatively uncommon cause of human disease. Influenza D has recently been found in swine and cattle, but is not known at this time to cause disease in humans.

Influenza A virus subtypes are defined by two of the surface proteins that are part of the structure of the virus, as shown in Figure 2:

H – Hemagglutinin (HA) N – Neuraminidase (NA)

There are 18 different HA antigens (H1 to H18) and 11 different NA antigens (N1 to N11) for influenza A. These antigens give rise to the subtype designation. Subtypes H1 to H16 and N1 to N9 are found in birds (mostly wild birds) and some of these subtypes have been found in mammals. H17N10 and H18N11 were discovered in bats in Guatemala in 2009 and in Peru in 2013, respectively. The NA genes in these influenza subtypes are highly divergent from other known influenza NAs and researchers propose that the attachment and activation of these viruses occur by a different mechanism than other influenza viruses. As of

January 2017, these two subtypes appear to be unique

In this lesson we will cover

• Influenza A Virus • Avian Influenza • Swine Influenza • Seasonal and Pandemic Influenza



to the bat population, but have been shown to infect and replicate in other mammalian cells (such as canine cell lines).

Some viruses have been shown to be zoonotic and have passed between birds and humans. Interspecies transmission has also occurred between birds and other mammals such as swine, and between mammalian species such as humans and swine.

Influenza viruses can mutate or reassort to form new viruses. Sometimes the mutation or reassortment can result in a virus that is capable of infecting another species or can affect the virulence (severity) of the virus.

AVIAN INFLUENZA

Wild birds are considered to be the reservoir for influenza A viruses. All HA and NA subtypes of the influenza A virus (except for H17N10 and H18N11, which as of January 2017 had only been identified in bats) have been found in avian species, especially waterfowl and shore birds. Aquatic birds may not show any clinical signs of infection, but the viruses replicate in the intestinal tract of the birds and are shed into the environment.

Avian influenza viruses are classified according to the disease severity in domestic chickens, with two recognized forms: highly pathogenic avian influenza (HPAI) and low-pathogenicity avian influenza (LPAI).

• HPAI – Highly pathogenic avian influenza (previously known as fowl plague) is rare. It causes severe disease in domestic poultry and can cause mortality rates of up to 100% in affected flocks. Only certain subtypes of H5 (such as H5N1) and H7 (such as H7N7) have been associated with HPAI. These subtypes have also been associated with LPAI.

• LPAI – Low-pathogenicity avian influenza occurs more frequently than HPAI. It can cause mild upper respiratory symptoms in domestic poultry but does not typically cause death in affected flocks.

Some HPAI viruses have infected humans and have caused illnesses ranging from mild conjunctivitis to severe rapidly progressive pneumonia with death.

SWINE INFLUENZA

Swine influenza is an important respiratory pathogen in pigs. Pigs are susceptible to infection with influenza viruses of human, swine, and avian origin. Because of this, pigs also can serve as hosts in which influenza viruses from different species can undergo reassortment if a pig is infected with two or more different strains of influenza virus at the same time.



Strains of H1N1, H3N2, and H1N2 swine influenza have become endemic in swine in North America. Some strains of swine influenza have infected humans, but such strains generally have not been easily passed from person to person. One exception is the 2009-10 H1N1 pandemic, which was caused by an influenza strain that was genetically related to viruses that had been circulating in swine over recent years. Public health officials generally believe that the virus likely originated in the swine reservoir.

SEASONAL AND PANDEMIC INFLUENZA

In temperate climates, influenza in humans tends to occur during the fall and winter seasons and is therefore considered a seasonal illness. In the tropics, however, influenza occurs year round. Currently, seasonal influenza is usually caused by certain strains of H1N1 or H3N2 influenza A viruses, or by influenza B viruses. The circulating strains vary from year to year, as immunity to the viruses develops or the viruses mutate.

Pandemic influenza occurs when a new strain of influenza emerges where: (1) there is little or no immunity to the virus in the human population and (2) the virus is able to spread efficiently from person to person. A pandemic virus may cause mild to severe disease. Pandemics of the last 100 years occurred in 1918-9, 1957-8, 1968-9, and 2009-10.



LESSON 2: TRANSMISSION OF INFLUENZA VIRUSES

MODES OF TRANSMISSION FOR INFLUENZA VIRUSES

Influenza viruses potentially can be transmitted through droplet, contact, and airborne modes. Influenza virus transmission occurs at close range rather than over long distances.

DROPLET TRANSMISSION • Influenza viruses are predominantly transmitted by large droplets. • Droplets are expelled by coughing and sneezing and generally travel through the

air no more than a few feet from the infected person. • Transmission via large droplets requires close contact between the source and

recipient persons, permitting droplets, which do not remain suspended in the air, to come into direct contact with oral, nasal, or ocular mucosa.

DIRECT AND INDIRECT CONTACT TRANSMISSION • Direct contact transmission involves skin-to-skin (such as hand-to-hand) contact

between an infected person and a susceptible person. • Influenza viruses can live for up to several days on nonporous environmental

surfaces; therefore, indirect contact transmission can occur when hands that touch contaminated surfaces subsequently come into contact with mucous membranes of the eyes, nose, or mouth.

• The proportion of influenza virus transmission caused by direct or indirect contact remains unknown; however, transmission by these routes can occur.

AIRBORNE TRANSMISSION • Airborne transmission of influenza viruses can occur, at least over short

distances, via small droplets expelled by sneezing, coughing, or talking that can remain suspended in the air and have the potential to travel farther than several feet.

• Airborne transmission does not appear to play a predominant role in the spread of influenza viruses.

In this lesson we will cover:

• Modes of Transmission




• Personal Hygiene • Personal Protective Equipment

LESSON 3: PERSONAL HYGIENE AND PERSONAL PROTECTIVE EQUIPMENT

Basic personal hygiene practices can be important in preventing the transmission of influenza viruses from animals to agricultural workers. Personal protective equipment (PPE) can be used as an adjunct to personal hygiene. The amount and specific types of PPE are determined by an assessment of the risks in a particular situation.

PERSONAL HYGIENE

HAND WASHING

Hand washing is one of the most important infection control methods that can be used to prevent the spread of influenza viruses. Hand washing can help prevent the spread of influenza from animals to people and can also help prevent people from spreading influenza from infected to uninfected animals.

Hands should be washed for 15 to 20 seconds with soap and water. If hand washing facilities are not available, alcohol-based hand sanitizers also can be used. If hands are visibly soiled, this method may not be as effective and hand washing with soap and water should be performed.

Workers should wash hands:

• After contact with an infected or potentially exposed animal • After contact with animal feces, urine, or other body fluids from animals • After contact with potentially contaminated surfaces • Before breaks and before leaving the farm • After removing PPE or gloves

Frequent hand washing or use of hand sanitizers may cause skin irritation or dermatitis. This can cause breaks in the skin that could allow entry of infectious agents. Use of lotions may reduce dryness caused by frequent hand washing.



ADDITIONAL PERSONAL HYGIENE PRACTICES

Workers should not eat, drink, smoke, or apply makeup or contact lenses in animal areas. Workers should wash hands with soap and water or use an alcohol-based hand sanitizer before conducting any of the above activities.

Workers should shower and change clothes before leaving the farm. Work clothing should be left at work and should not be worn off the farm or to workers’ homes. If possible, work clothing should be laundered at the farm and not at workers’ homes.

PERSONAL PROTECTIVE EQUIPMENT (PPE)

GLOVES

Lightweight (8 to 12 mil), disposable gloves such as nitrile or vinyl, or heavy weight (18 mil or greater) rubber gloves that can be disinfected after use, can be used to protect hands from contamination. The gloves chosen will depend on dexterity and durability needs according to the tasks being performed.

If gloves are worn for extended periods, dermatitis may develop. The use of a thin cotton glove inside the work glove can help absorb moisture. Workers should take care not to touch their faces with gloved hands and to change gloves if they are punctured, torn, or otherwise damaged. Gloves should be properly disposed of before leaving the area, and workers should wash hands after removing gloves.

PROTECTIVE CLOTHING

The use of protective clothing will prevent skin contamination and the spread of influenza viruses to other areas on clothing. Disposable protective clothing or protective clothing that can be cleaned and disinfected on site is preferred. For example, coveralls or a surgical gown with long, cuffed sleeves can be used. In addition, an impermeable apron could be used, depending on the work being performed. Heavy chemical-resistant clothing can add to heat stress, so lighter permeable (breathable) clothing should be chosen when working in a warm environment.

Disposable head or hair covers and disposable shoe covers, or boots that can be disinfected (such as boots made of rubber or polyurethane), will also help to prevent the spread of contamination.

EYE PROTECTION

Influenza viruses can be transmitted through contact with mucous membranes of the eye. This primarily occurs through self-inoculation with contaminated hands or gloves. Face shields, unvented safety goggles (eyecup), or indirectly vented goggles with anti-fog coating can be used in low-risk situations. These items are not airtight and will not



protect against airborne contaminants. Directly vented goggles and safety glasses may provide limited protection and help to prevent self inoculation but are not recommended for protection against splashes and airborne particles.

The use of a full-facepiece respirator also provides eye protection.

Corrective lenses need to be incorporated into the eye protection, or the face shield should fit over the corrective lenses. The user should ensure that the fit of the eye protection does not interfere with the fit of a respirator (such as a half-facepiece respirator), and vice versa. The goggles or other eye protection should not obstruct the vision of the wearer.

RESPIRATORY PROTECTION

In the United States, if agricultural workers are required to wear a respirator, they must be enrolled in a respiratory protection program. By regulation, a written respiratory protection program must be in place and an administrator who oversees the program and who can be a resource for employees must be appointed.

Alternate methods of reducing exposure to airborne contaminants should be considered before resorting to respiratory protection. Mechanical rather than direct handling of contaminated material (i.e., the use of an enclosed tractor cab when removing carcasses from a facility); increasing ventilation; or using dust-suppression techniques can be used to reduce particles in the air.

Surgical masks function as physical barriers and may protect the wearer from splashes and prevent the worker from touching the mouth or nose. These masks may also help to stop spread of contamination originating from the wearer. However, surgical masks are not respirators; they do not fit tightly and are not intended to act as a filter. Respirators are designed to filter small particles and reduce inhalation of contaminants by fitting tightly to the wearer’s face.

As part of a respiratory protection program, workers must be trained on the use of respirators. The proper respirator is selected based on the risks in the environment, the activities performed by the worker, the duration of work, and the fit of the respirator to the worker. Respirators need to be fit-tested to ensure a proper seal for both safety and comfort. Seal checks should be performed every time the respirator is put on. In all cases, a medical evaluation is necessary before using a respirator, because some respirators may increase breathing resistance.

There are many types of respirators, including air-supplying and air-purifying respirators. An example of an air-supplying respirator is a self-contained breathing apparatus used by firefighters. Air-purifying respirators include particulate respirators



that filter out particles in the air and respirators with cartridges that filter out chemical vapors and gases. The air-purifying, particle-filtering types of respirators are the types most often used to reduce worker exposure to influenza viruses.

In the United States, respirators are tested and certified by the National Institute for Occupational Safety and Health (NIOSH). If a mask is not certified by NIOSH, it is not legally a respirator.

Types of Respirators

Disposable Filtering Facepiece Respirators

Disposable filtering facepiece respirators are not designed to be used more than once and are considered to be contaminated after use. They are capable of collecting airborne particles, including influenza viruses, but they cannot capture gases or vapors.

• There are three categories of disposable filtering facepiece respirators: N, R, and P. The “N” indicates “not resistant to oil,” “R” indicates “somewhat resistant to oil,” and “P” indicates “strongly resistant to oil.”

• The letter is followed by a number (95, 99, or 100). These numbers refer to the percentage of particles that are filtered out (i.e., >95%, >99%, or >99.97%).

• N95 disposable filtering facepiece respirators are considered to be the minimum protection for potential exposure to influenza viruses. On poultry farms, R or P respirators should be considered if oil is used as a dust suppressant.

• These respirators need to be fit-tested. Many persons with facial hair or other interfering facial structures (missing teeth, scars) may not be able to achieve an acceptable seal and will need to choose an alternate means of protection.

• Children should not wear these types of respirators.

Advantages include:

• Inexpensive • Lightweight • No maintenance involved • Does not affect mobility

Some disadvantages include:

No eye protection May be difficult to breathe while wearing May add to heat burden Inadequate seal will result in air leaks



Reusable Elastomeric Half-Facepiece or Full-Facepiece Respirator

Another type of respirator is a reusable elastomeric half-facepiece or full-facepiece respirator. These respirators can be cleaned, disinfected, and reused. The filter in the respirator is disposed of and replaced periodically. These respirators also require fit-testing and may not be able to be fitted to some wearers.

Advantages include:

• Moderately expensive • Minimal maintenance • Does not affect mobility • Full-facepiece models provide eye protection

Disadvantages include:

• No eye protection in half-facepiece models • May be difficult to breathe while wearing • May add to heat burden • Inadequate seal will result in air leaks

Powered Air Purifying Respirators (PAPRs)

Powered air purifying respirators (PAPRs) are battery-powered respirators that pull air through a filter and to the face of the wearer. The battery and filters are usually worn at the waist, and the air is supplied through a hose to the hood, helmet, or facepiece.

Advantages

• Full-facepiece models provide eye protection and allow for wearing of prescription glasses

• Low breathing resistance • Creates a cooling effect with air flow • Can be worn by those who cannot wear face-fitting models

Disadvantages

• Expensive • Requires high level of maintenance • Battery is added weight and may affect mobility



Donning and Doffing PPE

It is important to don (put on) and doff (remove) PPE in a specific order to reduce the potential for exposure to contamination.

Putting on PPE

• Put on coveralls • Put on boots or shoe covers • Put on respirator • Put on goggles • Put on head covering • Put on gloves

Removing PPE

• Leave on respirator, goggles, or other eye protection and gloves • Remove coveralls and boots • Remove head covering • Dispose of all protective clothing in proper containers or bags • Remove gloves • Wash hands • Remove goggles or other eye protection • Remover respirator • Wash hands again

Disposal/Decontamination of PPE

Disposable PPE should be treated as contaminated and disposed of in approved containers or by approved methods. The container should be:

• Closable • Leak-proof • Labeled or color coded

Workers should be aware that cleaning non-disposable clothing and equipment can pose a contact risk. Contaminated PPE should be handled with disposable gloves, and aerosolization of surface contamination should be avoided when cleaning.




• Transmission of Avian Influenza Viruses from Birds to People • HPAI in Poultry Workers • LPAI in Poultry Workers • Serological Studies in Poultry Workers • Transmission of Avian Influenza Viruses from Birds to People

LESSON 4: AVIAN INFLUENZA IN POULTRY WORKERS

TRANSMISSION OF AVIAN INFLUENZA VIRUSES FROM BIRDS TO PEOPLE Influenza viruses are shed in the feces and respiratory secretions of birds. The viruses primarily are transmitted from birds to people by:

▪ Direct handling of an infected bird ▪ Slaughtering, defeathering, butchering, or preparing diseased birds

Consuming raw or very undercooked poultry or poultry products (such as duck blood soup) has also been implicated in transmission of H5N1 avian influenza. Indirect contact with infected materials or fomites also may lead to transmission.

HPAI IN POULTRY WORKERS

HPAI avian influenza, referred to as “fowl plague,” has been recognized in poultry since the 1800s. Influenza viruses that cause HPAI have been limited to the H5 and H7 subtypes.

Transmission of HPAI from birds to humans was first recognized during an outbreak of HPAI H5N1 in poultry in Hong Kong in 1997. In 2003, H5N1 re-emerged in Asia and since that time has caused numerous outbreaks of avian influenza in poultry or wild birds in Asia, the Middle East, Europe, and Africa.

Human infections associated with HPAI viruses include the following:

• 1997 HPAI H5N1 Hong Kong: 18 cases, 6 deaths; none of these symptomatic cases were in poultry workers, but 3% of cullers and 10% of poultry workers had evidence of infection with the virus by measuring antibodies in their blood.

• 2003 HPAI H7N7 Netherlands: 89 cases of conjunctivitis in poultry workers, 1 death (a veterinarian); the highest risk of illness was in veterinarians and cullers. In addition, 50% of cullers developed antibodies to the virus.



• 2004 HPAI H7N3 Canada: 2 cases, both in poultry workers (one was a culler), both had conjunctivitis and other flu-like symptoms; 10 others developed compatible symptoms, but H7N3 virus infection was not confirmed.

• Since 2003 more than 850 people in Asia, Europe, and Africa have become ill with HPAI H5N1 avian influenza, and more than 450 have died. Many of the people affected by this virus have been poultry workers.

LPAI IN POULTRY WORKERS Before 2013, the risk of infection when workers were exposed to LPAI viruses was considered low, and human infections were rarely identified. However, during the spring of 2013, a novel H7N9 influenza virus was recognized in humans in China. Since then a seasonal pattern has emerged with the majority of cases occurring in winter months or early spring. As of January 2017, over 1000 human cases with at least 360 deaths had been reported. Around the same time that this illness was recognized, China reported the occurrence of an LPAI H7N9 virus in chickens, pigeons, and environmental samples. This LPAI virus is similar to the virus that causes disease in humans. Many of the people who became ill or died from the H7N9 virus were workers in live-bird markets.

Another example of illness associated with LPAI viruses involving poultry workers occurred in the United Kingdom in 2006 and involved an LPAI H7N3 strain. One confirmed case was identified in a poultry worker who suffered from conjunctivitis after exposure to infected poultry; other cases of conjunctivitis and respiratory symptoms occurred in workers who had used incomplete levels of PPE, but these cases were not confirmed as H7N3 influenza infections.

In 2013 H6N1 and H10N8 LPAI viruses caused respiratory disease and death in several people who had visited live-bird markets in China; however, these viruses have not yet been seen in poultry workers.

SEROLOGICAL STUDIES IN POULTRY WORKERS Serologic studies for exposure to avian influenza viruses (i.e., studies looking at the antibodies present in blood) have been performed in poultry workers. The presence of antibodies indicates past infection. It is likely that many of these infections were either asymptomatic or involved mild symptoms only.

• Hong Kong 1998: During the outbreak of HPAI H5N1, 3% of 293 government workers who were involved in culling and 10% of 1,525 other poultry workers were found to have antibodies to the H5N1 virus.



• Italy 2003: 3.8% of workers had H7 antibodies after exposure to LPAI H7N3. • China (Guangdong province) 2004: In H5N1-affected areas, persons with

occupational exposure to poultry had higher antibody titers to avian influenza H5N1 and H9N2 viruses than those who did not work with poultry.

• United States (Iowa) 2004: Veterinarians who worked with poultry had higher antibody titers for H5, H6, and H7 avian influenza viruses than control subjects.

• United States (Iowa) 2004-2006: Poultry workers had increased titers against avian influenza H5, H6, and H7 viruses.

• United States (Iowa) 2009: Antibodies to LPAI virus H4, H5, H6, H9, and H10 were found in workers on small or free-range turkey farms.

• China 2013: A serologic survey conducted in one of the Chinese provinces with a high incidence of H7N9 infections found that >6% of workers in live-bird markets had evidence of H7N9 infection, while members of the general population had no evidence of infection.



LESSON 5: PREVENTING AVIAN INFLUENZA IN POULTRY WORKERS

Preventing avian influenza in poultry workers can be accomplished by preventing disease in poultry, early recognition and control of disease in poultry, personal hygiene practices and the use of PPE, training and education of poultry workers, and health monitoring of workers.

PREVENTING DISEASE IN POULTRY

Strict biosecurity procedures should be followed to keep influenza out of flocks. This involves preventing exposure of flocks to wild bird reservoirs and infected poultry. Poultry can be exposed to avian influenza viruses from wild or domestic reservoirs through:

• Direct contact with an infected bird • Environmental contamination from:

o Manure o Respiratory secretions o Carcasses

• Fomites or vectors contaminated with manure or respiratory secretions, including:

o Footwear or clothing of employees, service persons, or visitors o Vehicles o Equipment that is shared with or has been on other farms o Eggs o Pests (e.g., rodents, wild birds, insects)

Biosecurity is the development of specific management practices and behaviors to prevent the introduction of disease though these routes.


• Preventing Disease in Poultry • Early Recognition and Control of Disease in Poultry • Personal Hygiene and PPE • Training and Educating Workers • Health Monitoring of Workers • Protecting Workers during an Outbreak of HPAI • Protecting Workers during an Outbreak of LPAI



EARLY RECOGNITION AND CONTROL OF DISEASE IN POULTRY

Many countries, states, and/or regions have enacted surveillance plans for avian influenza. Participation in these programs may allow for early recognition of avian influenza infection. Operations should also develop customized avian influenza response plans in coordination with appropriate government agencies.

Recognizing the clinical signs of HPAI and LPAI also may result in early detection of disease. Clinical signs include:

HPAI:

• Sudden death • Coughing, sneezing, nasal discharge, excessive lacrimation (increased tear

formation in the eyes) • Fever • Swelling and/or discoloration of the head, comb, wattles, and legs • Diarrhea • Depression, anorexia (lack of appetite) • Incoordination or other neurological signs

LPAI

• No visible signs • Decreased feed consumption • Decreased egg production • Ruffled feathers • Mild respiratory signs

Sick or dying birds should be reported to the proper authorities as soon as possible, and a diagnosis should be obtained early in the course of an outbreak. If avian influenza is diagnosed, the farm should be quarantined and biosecurity procedures tightened to prevent disease spread.

PERSONAL HYGIENE AND PPE

Personal hygiene practices, such as washing hands, as well as the use of PPE, such as protective clothing and eye and respiratory protection, are often part of the biosecurity procedures in a poultry operation. These practices will not only help to prevent the transmission of agents between birds but will also help to protect workers from exposure to infectious agents such as avian influenza viruses. The use of specific PPE is based on an assessment of the risks in the environment and to the individual. Personal hygiene practices and PPE are discussed in detail in Lesson 3.



TRAINING AND EDUCATING WORKERS

Training and education is important for the protection of poultry workers. Training should be conducted on biosecurity procedures, personal hygiene practices, and proper use of PPE. Education on disease recognition in both poultry and people and on the specific avian influenza response plans developed by the employer is also essential.

HEALTH MONITORING OF WORKERS

Workers should be trained to recognize the signs of avian influenza virus infection in humans. Signs can include:

• Fever • Cough • Sore throat • Difficulty breathing • Conjunctivitis (eye infection) • Muscle aches • Diarrhea

Poultry operations should enact health surveillance programs and monitor for influenza-like illness in the workplace. Workers should report influenza-like illness to the company and receive medical attention as soon as possible.

PROTECTING WORKERS DURING AN OUTBREAK OF HPAI

During an outbreak of HPAI, infection control procedures should be increased. For example, during an outbreak of HPAI H5N1, workers involved in high-risk activities such as culling should wear a higher level of PPE. Gloves, protective clothing such as coveralls, head covering and boots, air-tight eye protection (such as unvented goggles), and properly fitted respirators should be worn. PPE should be removed and disposed of safely away from areas of potential exposure.

In addition to enhanced PPE, personal hygiene practices such as washing hands are vital during an HPAI outbreak.

Workers should be alert for symptoms of influenza-like illness (fever, respiratory signs, and/or conjunctivitis) for at least 1 week after potential exposure. Workers should seek immediate medical attention if these symptoms occur, and the healthcare provider should be notified of the potential exposure to HPAI viruses.

In the United States, the Centers for Disease Control and Prevention (CDC) recommends that workers responding to an outbreak of HPAI receive prophylactic



antiviral medication during the period of potential exposure and for 1 week following. Currently, the drug most often used for influenza treatment and prevention is oseltamivir (Tamiflu).

In 2015, Eurasian HPAI H5 viruses were detected in North America for the first time. The viruses affected both wild birds and domestic poultry. In order to control the disease many producers, poultry workers, state, and federal workers were charged with depopulating poultry farms and cleanup of barns before restocking poultry. In response to this, the CDC developed “Recommendations for Worker Protection and Use of Personal Protective Equipment to Reduce Exposure to Highly Pathogenic Avian Influenza A H5 Viruses.”

Key recommendations are:

• Avoid unprotected direct physical contact with sick birds, poultry carcasses, and poultry feces or litter.

• Wear recommended PPE (properly-fitted safety goggles, disposable gloves, boots, a NIOSH-certified respirator [e.g., N95], and disposable fluid-resistant coveralls when in direct contact with birds, poultry carcasses, and poultry feces or litter, and when going into any buildings with sick or dead poultry, or carcasses, feces, or litter from potentially-infected poultry.

• Put on and take off PPE in separate clean areas.

• Reusable PPE (e.g., rubber boots, rubber apron) should be:

o Cleaned until visible dirt is removed, and then

o Disinfected with an EPA approved disinfectant that has label claims against influenza A viruses (http://www.epa.gov/oppad001/influenza-disinfectants.html) according to the manufacturer’s instructions.

• Avoid touching the eyes, mouth, and nose after touching any contaminated material while wearing PPE.

• Do not eat, drink, smoke, or use the bathroom while wearing PPE.

• Safely remove PPE in sequence:

o Remove and dispose of the apron, if worn;

o Clean and disinfect boots;

o Remove boots;



o Remove and dispose of the coverall;

o Remove and dispose of gloves;

o Wash hands with soap and water;

o Remove goggles and respirator;

o Clean and disinfect reusable goggles and respirator;

o Wash hands with soap and water again.

• Perform good hand hygiene such as hand-washing with soap and water or using an alcohol-based hand rub after removing PPE if soap and water are not immediately available.

Shower at the end of the work shift and leave all contaminated clothing and equipment at work. Never wear contaminated clothing or equipment outside

PROTECTING WORKERS DURING AN OUTBREAK OF LPAI

Although the risks involved with responding to an outbreak of LPAI may be lower, workers should be protected from exposure. An assessment of the risks, including the particular virus, the activities being performed, the length of the potential exposure, and the health status of the worker, will assist in determining the proper level of PPE to be used when responding to an outbreak of LPAI.



LESSON 6: INFLUENZA IN SWINE WORKERS

In pigs, influenza viruses are usually transmitted from the respiratory tract by large droplet spread. People also primarily acquire infection from pigs through inhalation or large droplet contamination. Direct and indirect contact transmission also can occur.

EVIDENCE OF OCCUPATIONAL EXPOSURE TO SWINE INFLUENZA VIRUSES

Swine have receptors for swine, avian, and human influenza viruses. Influenza viruses can pass from swine to humans and from humans to swine, although sustained person-to-person transmission of swine influenza viruses has been rare.

Transmission of swine influenza viruses from swine to humans historically has been uncommon; only 50 cases were identified between 1958 and 2005. Thirteen of the cases involved occupational exposure to pigs (swine workers, lived on a swine farm, etc.) Swine influenza infections in workers may go unrecognized, because the signs and symptoms of swine influenza closely resemble those of human influenza.

Several studies have shown that persons with occupational exposure to pigs (swine workers, swine veterinarians, etc) are more likely to have antibodies to swine influenza viruses than persons with no occupational exposure to pigs. Working in confinement operations and not using PPE, such as gloves, likely increases the risk of exposure.

• 2002: Wisconsin swine farm residents and employees had higher antibody titers to swine influenza viruses than non-exposed controls.

• 2002-2004: Iowan farmers and veterinarians had higher antibody titers to swine influenza viruses (H1N1 and H1N2) than meat-processing workers or controls.

• 2004-2005: Iowan swine confinement workers were found to have elevated antibody titers to H1N1 swine influenza virus if they occasionally or never wore gloves, or if they smoked.

• 2006: Iowan swine workers were found to have elevated antibodies to swine influenza viruses (H1N1 and H1N2); a triple reassortant virus was isolated from an ill farmer.

In this lesson we will cover: • Transmission of Influenza Viruses from Pigs to People • Evidence of Occupational Exposure to Swine Influenza Viruses • The H3N2v Influenza Virus



THE H3N2v INFLUENZA VIRUS

In 2011, an H3N2 swine influenza virus containing the M gene from the pH1N1 virus was detected in people and associated with exposure to pigs at agricultural fairs in the United States. In 2011 and 2012, over 320 cases of H3N2 variant virus (H3N2v) were identified in 13 states. In 2013-16, 43 additional cases of H3N2v were identified in 8 states. In December 2016, a case of H3N2v was reported from Canada. Other variant viruses have also been detected in the US since 2005, including H1N1v and H1N2v. Most cases had very close contact with swine, but human-to-human spread of the virus also has been recognized.




• Preventing and Controlling Swine Influenza in Pigs • Recognizing Swine Influenza in Pigs • Training and Educating Workers • Personal Hygiene and PPE • Health Monitoring

LESSON 7: PREVENTING SWINE INFLUENZA IN SWINE WORKERS

As with poultry workers, preventing swine influenza in swine workers can be accomplished by preventing disease in swine, early recognition and control of disease in swine, personal hygiene practices and the use of PPE, training and education of swine workers, and health monitoring in workers.

PREVENTING AND CONTROLLING SWINE INFLUENZA IN PIGS

Biosecurity practices are the major means of preventing swine influenza infection in pigs. Basic biosecurity practices in swine operations include:

• Separation of pigs and isolation from other herds, including management practices such as “all-in, all-out” and quarantine and isolation practices

• Control of the number of people, vehicles, and equipment coming onto the farm; ensuring that people have not been in contact with other pigs; ensuring that anyone or anything coming onto the farm is cleaned and disinfected

• Practice of robust sanitation and pest management procedures • Use of personal hygiene practices and PPE

The use of vaccination in pigs may reduce, but will not eliminate, the risk of transmission of swine influenza viruses to workers. RECOGNIZING SWINE INFLUENZA IN PIGS

Early recognition and diagnosis of swine influenza in pigs will help to achieve early control of the disease. Workers should be trained to recognize and report respiratory signs seen in pigs as soon as possible.

Clinical signs in pigs may include:



• Fever • Anorexia • A barking cough • Weight loss • Lethargy • Sneezing • Ocular or nasal discharge • Labored breathing • Conjunctivitis • Spontaneous abortion

Swine influenza is characterized by rapid onset and spread of disease. The incubation period in swine is usually 1 to 3 days. The mortality (death) rate is relatively low (1% to 3%), and most affected animals recover within 5 to 7 days after illness onset.

TRAINING AND EDUCATING WORKERS

Training and education is important for the protection of swine workers. Training should be conducted on biosecurity procedures, personal hygiene practices, and proper use of PPE. Education on disease recognition in both swine and people can lead to early disease containment activities.

PERSONAL HYGIENE AND PPE

Many swine facilities use shower-in and shower-out procedures as part of biosecurity plans. The use of dedicated clothing and hand washing practices are basic infection control practices that can prevent swine influenza infections in workers.

Swine workers should be provided with and trained in the use of PPE, including gloves, boots, and other protective clothing. Eye and respiratory protection also may be used in swine facilities to prevent exposure to influenza viruses. Workers should dispose of PPE properly and wash hands or shower out after removing PPE. Personal hygiene practices and PPE are discussed in detail in Lesson 3.

HEALTH MONITORING

Workers should be informed that the signs and symptoms of swine influenza are similar to those of seasonal influenza. Workers should report any influenza-like illness to their supervisors and receive medical attention when needed.

If workers are exposed to animals with confirmed influenza infection, antiviral prophylaxis may be considered. The antiviral medication should be taken during the time that the workers are exposed to the disease and for 5 to 7 days after the last



exposure. The drug most often used for influenza treatment and chemoprophylaxis is oseltamivir.



LESSON 8: PREVENTING PANDEMIC AND SEASONAL INFLUENZA IN AGRICULTURAL WORKERS

THE POTENTIAL ROLE OF AGRICULTURAL WORKERS IN PANDEMICS

Influenza pandemics are caused by the introduction of a novel influenza virus into the human population where: (1) there is little or no immunity to the virus and (2) the virus is able to spread efficiently from person to person.

• Pandemic influenza viruses can arise through the process of antigenic shift, which refers to substantial genetic changes in the HA or NA, or a shift from one subtype to another in a given population. Antigenic shift can occur due to reassortment between human and animal strains, which appears to be what caused the strains of the 1957 and 1968 pandemics to emerge in the human population; these strains involved genes from viruses of avian and human origin. The 2009 pandemic H1N1 strain was a reassortant virus that involved several different lineages of swine viruses: American H3N2 triple reassortment, classical swine H1N1 lineage, and the Eurasian avian-like swine H1N1 virus.

• Pandemic strains can also arise through the process of antigenic drift, where small mutations in the virus can result in gradual adaptation of an animal virus to the human population. For example, the 1918 H1N1 strain may have originated in the avian reservoir and then adapted gradually to the human population over time through a series of genetic mutations to become a global pandemic strain.

Although uncommon, occupational exposure to poultry or swine can result in zoonotic transmission of influenza viruses from animals to humans. In addition, influenza viruses can be transmitted from humans to animals, especially swine. It is possible that co-infection with two viruses (in either swine or in humans) could result in the development of a new pandemic influenza strain.

Workers may introduce zoonotic influenza infections to their families. Agricultural workers could serve as a bridge between an infected animal population and the public.

• In one study that looked at swine influenza infection in swine workers, spouses of the workers also had elevated antibody titers to swine influenza viruses.

• Avian influenza virus infections were also detected in household contacts of infected poultry workers.


• The Potential Role of Agricultural Workers in Pandemics • Seasonal Influenza in Agricultural Workers



Conversely, a pandemic strain in humans may be passed to swine. For example, at the height of the recent H1N1 pandemic, the H1N1 2009 virus was passed from infected humans to herds of swine in a number of countries around the globe. In one swine outbreak in Canada in April 2009, the pigs initially acquired illness from an infected human. Two workers, who reported no contact with infected humans, but who were in contact with infected pigs, then developed symptoms of 2009 H1N1. After the use of extensive PPE and the administration of antiviral medication to potentially exposed workers, no further cases of influenza were seen in the workers.

Because of their position at the human-animal interface, agricultural workers should be included in pandemic planning efforts.

SEASONAL INFLUENZA IN AGRICULTURAL WORKERS

Workers infected with seasonal influenza should stay home for 7 days or for 24 hours after fever has resolved (without the use of fever reducing medications) whichever is longer. Sick leave policies in poultry or swine operations should support this practice.

This will prevent the spread of the seasonal virus among the workers and may also prevent the introduction of human influenza viruses into swine populations. Hand hygiene and “cover your cough” practices will also help to reduce the spread of influenza viruses in animal facilities.

Workers should be offered seasonal influenza vaccination. Vaccination may reduce the risk of co-infection and development of novel viruses.



GLOSSARY

Air-purifying respirator - a respirator with an air-purifying filter, cartridge, or canister that removes specific air contaminants by passing ambient air through the air-purifying element.

Air-supplying respirator - a respirator that supplies the respirator user with breathing air from a source independent of the ambient atmosphere, and includes supplied-air respirators (SARs) and self-contained breathing apparatus (SCBA) units.

All in/All out management system - A strategy directed at the control of infectious disease, especially enzootic pneumonia of pigs and viral pneumonia of calves. The barn is emptied of all animals on a particular day, the accommodation is cleaned and disinfected and then refilled, all on the one day.

Antigenic Drift - One of two ways that influenza viruses can change (the other is antigenic shift, see below). Antigenic drift refers to small, gradual changes that occur through point mutations in the two genes that contain the genetic material to produce the main surface proteins, hemagglutinin and neuraminidase. These point mutations occur unpredictably and result in minor changes to these surface proteins. Antigenic drift produces new virus strains that may not be recognized by antibodies to earlier influenza strains. This process works as follows: a person infected with a particular influenza virus strain develops antibodies against that strain. As newer virus strains appear,

the antibodies against the older strains might not recognize the "newer" virus, and infection with a new strain can occur. This is one of the main reasons why people can become infected with influenza viruses more than one time and why global surveillance is critical in order to monitor the evolution of human influenza virus strains for selection of which strains should be included in the annual production of influenza vaccine. In most years, one or two of the three virus strains in the influenza vaccine are updated to keep up with the changes in the circulating influenza viruses. For this reason, people who want to be immunized against influenza need to be vaccinated every year.

Antigenic Shift - Antigenic shift is one of two ways that influenza viruses can change (the other is antigenic drift, see above). Antigenic shift refers to an abrupt, major change to produce a novel influenza A virus subtype in humans (i.e., one that has not circulated previously among people). Antigenic shift can occur either through direct animal (poultry)-to-human transmission or through mixing of human influenza A and animal influenza A virus genes to create a new human influenza A subtype virus through a process called genetic reassortment. Antigenic shift results in a new human influenza A subtype.

Antigens - A substance that elicits a specific (as opposed to nonspecific) immunological response. Foreign antigens typically stimulate a response from the body's adaptive immune system resulting in the production of antibodies and effector T-cells; antigens



that produce an immune response can also be called “immunogens.”

Biosecurity - Security from transmission of infectious diseases, parasites and pests.

Endemic – present in a predictable, continuous pattern in an animal community at all times; said of a disease that is clustered in space but not in time.

Epidemic - A disease occurring suddenly in humans in a community, region or country in numbers clearly in excess of normal.

Epizootic - A disease occurring suddenly in animals in a community, region or country in numbers clearly in excess of normal.

Filtering facepiece (dust mask) - a negative pressure particulate respirator with a filter as an integral part of the facepiece or with the entire facepiece composed of the filtering medium.

Fit test -the use of a protocol to qualitatively or quantitatively evaluate the fit of a respirator on an individual. (See also Qualitative fit test QLFT and Quantitative fit test QNFT.)

Fomite – Inanimate objects or materials on which disease producing agents may be conveyed.

Genetic Drift - See Antigenic Drift

Genetic Reassortment – The exchange of gene segments between viruses that have a segmented genome.

Gradual Adaptation - A process of small genetic changes in the viral

genome that allows an influenza virus to adapt over time to become an efficient pathogen in the human host; this process does not involve reassortment events. Researchers believe that the 1918 H1N1 pandemic strain was initially of avian origin and that the virus evolved into a severe pandemic strain in humans through the process of gradual adaption.

Hemagglutinin (HA) - An important surface structure protein of the influenza virus that is an essential gene for the spread of the virus throughout the respiratory tract. This protein enables the virus to attach itself to a cell in the respiratory system and penetrate it. It is used to name influenza A subtypes and is referred to as the "H" in the influenza virus subtype (e.g., H5N1).

Host - An organism on or in which a parasite lives.

HPAI (Highly Pathogenic form of Avian Influenza) - Often fatal in chickens and turkeys. HPAI spreads more rapidly than LPAI and has a high mortality rate in domestic birds.

Infection - Invasion of the body or a part of the body with a pathogenic organism, which multiplies in the host. A person or animal with an infection may or may not exhibit symptoms. An infection without symptoms is called asymptomatic.

LPAI (Low Pathogenic form of Avian Influenza) - Naturally occurs in wild birds and can spread to domestic birds. In wild birds, LPAI strains generally do not cause signs of infection. In domestic birds, the illness is not severe and mortality rates are low. LPAI H5 and H7 strains have the potential to mutate into



HPAI and are therefore closely monitored.

Morbidity - Disease; morbidity rate is the incidence or prevalence of disease in a specific population during a specified interval of time or a specific point in time.

Mortality - Death; mortality rate is a measure of the number of deaths in a population during a specified interval of time.

Mutation - Any alteration in a gene from its natural state. Specific mutations and evolution in influenza viruses cannot be predicted, making it difficult if not impossible to know if or when a virus such as H5N1 might acquire the properties needed to spread easily among humans.

Neuraminidase (NA) - An important surface structure protein of the influenza virus that is an essential enzyme for the spread of the virus throughout the respiratory tract. This protein enables the virus to escape the host cell and infect new cells. It is used to name influenza A subtypes and is referred to as the "N" in the influenza virus subtype (e.g., H5N1).

Outbreak - Presence of disease in numbers in excess of normal in a specific geographic area or population.

Pandemic - A worldwide outbreak of a disease in humans in numbers clearly in excess of normal. A global influenza pandemic may occur if these conditions are met:

• A new subtype of influenza A virus emerges for which there is little or no immunity in the human population.

• The virus can spread easily from person to person in a sustained manner.

Powered air-purifying respirator (PAPR) - means an air-purifying respirator that uses a blower to force the ambient air through air-purifying elements to the inlet covering.

Pathogenic - Causing disease or capable of doing so.

PPE – Personal protective equipment; equipment used to prevent skin and mucous membrane contact with infectious materials

Prevalence - The proportion of individuals (humans or animals) in a population having a disease or specific characteristic (such as a positive antibody test to a particular pathogen).

Prophylaxis – Prevention of or protection again disease, often involving the use of a biologic, chemical or mechanical agent to destroy or prevent entry of infectious organisms

Reservoir - A person or animal that serves as a host to a pathogenic agent, generally without visible symptoms of the disease or injury.

Respirator – an apparatus used to modify air for inspiration

Respiratory protection program - A regulatory program in the United States that requires employer to develop and implement a written respiratory protection program with required



worksite-specific procedures and elements for required respirator use. The program must be administered by a suitably trained program administrator. In addition, certain program elements may be required for voluntary use to prevent potential hazards associated with the use of the respirator.

Seal check – an action conducted by the respirator user to determine if the respirator is properly seated to the face

Seasonal Flu ("Common Flu", "Winter Flu") - Influenza caused by one of the common influenza subtypes known to be circulating in the human population; seasonal influenza peaks in the winter months in the Northern and Southern Hemispheres and tends to be year-round in tropical regions.

Strain - Influenza virus subtypes are further characterized into strains. New strains of influenza viruses replace older strains through the process of antigenic drift (i.e., small mutations in the genetic material of the virus).

Swine Flu - A respiratory disease in pigs caused by influenza A virus. Outbreaks in swine herds are common; the illness is relatively mild, and most animals recover. Domestic birds can be a source of influenza A in swine, and transmission from humans to swine and from swine to humans has occurred.

Virulence - A pathogen's ability to invade host tissues and the severity of disease produced.

Virulent - Highly lethal; causing severe illness or death.

Virus - Any of various simple submicroscopic parasites of plants, animals, and bacteria that often cause disease and that consist essentially of a core of RNA or DNA surrounded by a protein coat. Unable to replicate without a host cell, viruses are typically not considered living organisms.

Zoonoses - Diseases that transfer from animals to humans.



RESOURCES

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All definitions are found at one or more of the following sources:

http://www.osha.gov/dts/shib/shib121304.html

http://www.osha.gov/OshDoc/data_AvianFlu/avian_flu_factsheet.pdf

http://www.osha.gov/OshDoc/data_AvianFlu/avian_flu_guidance_english.pdf

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http://www.who.int/influenza/resources/documents/guidance_protection_h5n1_02_2008/en/

http://www.who.int/influenza/resources/documents/guidance_protection_h5n1_02_2008/en/

http://jid.oxfordjournals.org/content/early/2013/08/09/infdis.jit430.short



CDC: http://www.cdc.gov/flu/avianflu/

USDA http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=influenza_glossary.xml

http://www.cdc.gov/flu/avianflu/

http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=influenza_glossary.xml

http://www.usda.gov/wps/portal/usda/usdahome?contentidonly=true&contentid=influenza_glossary.xml

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