Guidance for Protecting Workers Against Avian Flu
BACKGROUND ON THE CURRENT OUTBREAK
An outbreak of influenza A (H5N1), also know as "avian flu"
or "bird flu," has been reported in several countries
throughout Asia. Cases of avian influenza A (H5N1) in birds have
been confirmed in Cambodia, China, Hong Kong, Indonesia, Japan,
Laos, Pakistan, South Korea, Thailand, and Vietnam. Human cases
of avian influenza have been reported in Thailand and Vietnam. During
this outbreak investigation, it has not been determined that avian
flu is spread from person to person. This strain of avian influenza
A (H5N1) currently affecting Asia has not been found in the United
States. The current outbreak of avian influenza has prompted the
killing of more than 25 million birds in Asia.
In February 2004, different strains of avian flu were detected among several flocks of birds in the U.S. and state officials ordered the destruction of hundreds of thousands of birds. The avian influenza strain found in Delaware was (H7N2), in Pennsylvania the strain was (H2N2), and the (H5N2) strain was found in Texas. The strain found in Texas has been determined to be "highly pathogenic" to birds. However, the strain of avian influenza in Texas is not the same as the strain that is affecting Asia.1 There does not appear to be any connection between the illness in the flocks on the East Coast and the flock in Texas. Wild birds are the natural hosts for the virus. Avian flu viruses circulate among birds worldwide and are highly contagious among birds. It is also important to note that the United States annually imports an estimated 20,000 birds from countries with current avian influenza outbreaks, according to the U.S. Fish and Wildlife Service.
BACKGROUND ON INFLUENZA AND AVIAN FLU
Influenza is a category of viruses associated with acute (short),
usually self-limited infections, whose symptoms are most commonly
fever, muscle pain or aches, and cough. However, illness can be
more severe based upon the properties of the virus, the patient's
age, pre-existing immunity status, or pre-existing medical conditions.
The influenza virus is described by a three part naming system that includes the virus type, subtype, and strain. There are three major types (A, B, C) and a number of subtypes which are classified based upon the surface coatings of the virus. These surface coatings determine whether the virus will affect humans, pigs, horses or birds, or more than one type of animal.2 Within a specific type and subtype of influenza, there are also important differences in the particular strain of virus. For example, the strain of influenza A (H5N1) that has affected birds and humans in much of Asia is not the same strain that is affecting birds in the U.S. or Pakistan.
Influenza viruses also change or mutate over time. "Scientists know that the avian and human influenza viruses can exchange genes when a person is simultaneously infected with viruses from both the common human influenza virus and the avian type. This process of gene swapping inside the human body can give rise to a completely new subtype of the influenza virus to which few, if any, humans would have any natural immunity…If the new virus contains sufficient human flu virus genes, transmission directly from one person to another (instead of from birds to humans only) can occur."3 Some previous outbreak investigations documented limited human-to-human transmission of avian influenza. It is believed that most cases of avian influenza in humans have resulted from contact with infected poultry or contaminated surfaces.
In particular, influenza A (H5N1) has a documented tendency to acquire genes from viruses infecting other animals.4 There is particular cause for concern because this strain of influenza A (H5N1) is now spreading from birds (e.g., chickens, ducks, turkeys) to humans, and scientists are trying to determine if the virus is also spreading from human to human.5 Since this strain of influenza virus does not commonly infect humans, the general population may not have natural immunity to the virus. The current strain of influenza A (H5N1) that is transmitted from birds to humans is considered to be "highly pathogenic."
ROUTES OF EXPOSURE TO AVIAN FLU
Most human influenza infections are spread by virus-laden respiratory
droplets that are expelled during coughing and sneezing. Influenza
viruses range in size from 0.08 to 0.12 micrometers.6 They are carried
in respiratory secretions as small-particle aerosols (less than
10 micrometers in diameter).7
In an agricultural setting, animal manure containing influenza virus can contaminate dust and soil, causing infection when the contaminated dust is inhaled. Contaminated farm equipment, feed, cages, or shoes can carry the virus from farm to farm. The virus can also be carried on the bodies and feet of animals, such as rodents. "The virus can survive, at cool temperatures, in contaminated manure for at least three months. In water, the virus can survive for up to four days at 72º F and more than 30 days at 32º F. For the highly pathogenic form (of influenza A), studies have shown that a single gram of contaminated manure can contain enough virus to infect 1 million birds."8
In a food handling/preparation setting, there is also some concern that avian influenza could be transmitted from uncooked birds or bird products. The World Health Organization has also reported a study that found avian influenza A (H5N1) in imported frozen duck meat. Eggs from infected poultry could also be contaminated with the virus.
ADDITIONAL SOURCES OF INFORMATION
There are other federal agencies and international organizations
that have further resources on avian flu.
The U.S. Centers for Disease Control and Prevention (CDC) has established
avian flu public hotlines: Public 888-246-2675; Spanish 888-246-2857;
and for Clinicians 877-246-4625. The CDC has additional online resources
at http://www.cdc.gov/flu/avian/index.htm.
The World Health Organization has information on avian flu online
at http://www.who.int/csr/disease/avian_influenza/en/.
Physicians, employers and employees should contact their state or
local health department (http://www.cdc.gov/mmwr/international/relres.html)
to notify them of any symptomatic employees or suspected exposure
incidents.
BAN ON IMPORTATION OF POTENTIALLY INFECTED ANIMALS
The U.S. government has issued an order for an immediate ban on
the import of all birds (Class: Aves) from the following Asian countries:
Cambodia; Indonesia; Japan; Laos; People's Republic of China, including
Hong Kong, SAR; South Korea; Thailand; and Vietnam. The ban applies
to all birds, whether dead or alive, and all bird products, such
as eggs. This step was taken because birds from these affected countries
potentially can infect humans with influenza A (H5N1). This order
is enforced by the U.S. Department of Agriculture (USDA), the CDC
and other federal agencies, such as the Animal Plant Health Inspection
Service of the U.S. Department of Agriculture, Bureau of Customs
and Border Protection of the Department of Homeland Security, and
the U.S. Fish and Wildlife Service of the Department of Interior.
(See http://www.aphis.usda.gov/lpa/issues/ai_us/ai_trade_ban_status.html)
GUIDANCE FOR FARM WORKERS / ANIMAL HANDLERS
Avian influenza is a highly contagious disease of birds which is
currently epidemic amongst poultry in Asia. Despite the uncertainties,
poultry experts agree that immediate culling of infected and exposed
birds is the first line of defense for both the protection of human
health and the reduction of further losses in the agricultural sector.
However, culling must be carried out in a way that protects workers
from exposures to avian influenza virus and therefore reduces the
likelihood of illness or gene swapping or mutation.
Exposure to infected poultry and their feces or dust contaminated with feces has been associated with human infection; however this is a rare occurrence. The following summarizes the recommendations that have been developed by the CDC and the World Health Organization (WHO) because human infections have occurred in Asia during the current poultry epidemic. They will be updated as more information becomes available.4
All persons who have been in close contact with the infected animals,
contact with contaminated surfaces, or after removing gloves, should
wash their hands frequently. Hand hygiene should consist of washing
with soap and water for 15-20 seconds or the use of other standard
hand-disinfection procedures as specified by state government, industry,
or USDA outbreak-response guidelines.
All workers involved in the culling, transport, or disposal of avian
influenza-infected poultry should be provided with appropriate personal
protective equipment:
Protective clothing capable of being disinfected or disposed, preferably
coveralls plus an impermeable apron or surgical gowns with long
cuffed sleeves plus an impermeable apron;
Gloves capable of being disinfected or disposed; gloves should be
carefully removed and discarded or disinfected and hands should
be cleaned;
Respirators: the minimum recommendation is a disposable particulate
respirator (e.g. N95, N99 or N100) used as part of a comprehensive
respiratory protection program. The elements of such a program are
described in 29 CFR 1910.134. Workers should be fit tested for the
model and size respirator they wear and be trained to fit-check
for facepiece to face seal;
Goggles;
Boots or protective foot covers that can be disinfected or disposed.
Environmental clean up should be carried out in areas of culling,
using the same protective measures as above.
Unvaccinated workers should receive the current season's influenza
vaccine to reduce the possibility of dual infection with avian and
human influenza viruses.
Workers should receive an influenza antiviral drug daily for the
duration of time during which direct contact with infected poultry
or contaminated surfaces occurs. The choice of antiviral drug should
be based on sensitivity testing when possible. In the absence of
sensitivity testing, a neuramindase inhibitor (oseltamavir) is the
first choice since the likelihood is smaller that the virus will
be resistant to this class of antiviral drugs than to amantadine
or rimantadine.
Potentially exposed workers should monitor their health for the
development of fever, respiratory symptoms, and/or conjunctivitis
(i.e., eye infections) for 1 week after last exposure to avian influenza-infected
or exposed birds or to potentially avian influenza-contaminated
environmental surfaces. Individuals who become ill should seek medical
care and, prior to arrival, notify their health care provider that
they may have been exposed to avian influenza.
GUIDANCE FOR LABORATORY WORKERS
Highly pathogenic avian influenza A (H5N1) is classified as a select
agent and must be worked with under Biosafety Level (BSL) 3+ laboratory
conditions. This includes controlled access double door entry with
change room and shower, use of respirators, decontamination of all
wastes, and showering out of all personnel. Laboratories working
on these viruses must be certified by the U.S. Department of Agriculture.
The same BSL 3+ laboratory guidelines are recommended for conducting
virus isolation for SARS-associated coronavirus. CDC recommends
that virus isolation studies on respiratory specimens from patients
who meet the above criteria not be conducted unless stringent BSL
3+ conditions can be met. Therefore, respiratory virus cultures
should not be performed in most clinical laboratories and such cultures
should not be ordered for patients suspected of having H5N1 infection.
Clinical specimens from suspect influenza A (H5N1) cases may be tested by polymerase chain reaction (PCR) assays using standard BSL 2 work practices in a Class II biological safety cabinet. In addition, commercial antigen detection testing can be conducted under BSL 2 levels to test for influenza.
Furthermore, all employers processing biologic specimens suspected of being infected with influenza A (H5N1) must ensure that their employees comply with all provisions of 29 CFR 1910.1030 for employee protection against bloodborne pathogens.
GUIDANCE FOR MEDICAL WORKERS THAT TRANSPORT/TREAT AVIAN FLU PATIENTS
All patients who present to a health-care setting with fever and
respiratory symptoms should be managed according to the CDC's recommendations
for respiratory hygiene and cough etiquette and questioned regarding
their recent travel history (see http://www.cdc.gov/flu/professionals/infectioncontrol/resphygiene.htm).
It has not yet been determined that avian flu can be spread from
person to person. However, due to the potential risks of human to
human infection, isolation precautions identical to those recommended
for SARS should be implemented for all hospitalized patients diagnosed
with or under evaluation for influenza A (H5N1) as follows:
Standard Precautions
Pay careful attention to hand hygiene before and after all patient
contact.
Contact Precautions
Use gloves and gown for all patient contact.
Eye protection
Wear when within 3 feet of the patient.
Airborne Precautions
Place the patient in an airborne isolation room (i.e., monitored
negative air pressure in relation to the surrounding areas with
6 to 12 air changes per hour).
The CDC has recommended that, the minimum requirement is a disposable
particulate respirator (e.g. N95, N99 or N100) used in accordance
with 29 CFR 1910.134 for respiratory protection programs. Workers
must be fit tested for -the model and size respirator they wear
and must be trained to fit-check for facepiece to face seal, when
entering the room.
If transport or movement is necessary, ensure that the patient wears
a surgical mask. If a mask cannot be tolerated, apply the most practical
measures to contain respiratory secretions.
For additional information regarding these and other health-care isolation precautions, see the CDC's Guidelines for Isolation Precautions in Hospitals. These precautions should be continued for 14 days after onset of symptoms until an alternative diagnosis is established or until diagnostic test results indicate that the patient is not infected with influenza A virus (see Laboratory Testing Procedures below). Patients managed as outpatients or hospitalized patients discharged before 14 days should be isolated in the home setting on the basis of principles outlined for the home isolation of SARS patients (see http://www.cdc.gov/ncidod/sars/guidance/i/pdf/i.pdf).
GUIDANCE FOR FOOD HANDLERS
In general, good hygiene practices during handling of raw poultry
meat and usual recommended cooking practices for poultry products
would lower any potential risk to insignificant levels. Eggs from
infected poultry could also be contaminated with the virus and therefore
care should be taken in handling shell eggs or raw egg products.
Some, more limited, knowledge is available about the effect of food
handling and treatment on the influenza virus. While freezing and
refrigeration would not substantially reduce the concentration or
virulence of viruses on contaminated meat, proper cooking kills
such viruses. In general, chicken should be cooked to reach an internal
temperature of 180ºF. Employers should continuously emphasize
the importance of good hygiene practices during handling including
hand washing, prevention of cross-contamination and thorough cooking
of poultry products.
GUIDANCE FOR AIRLINE FLIGHT CREWS
This guidance is intended to assist airline flight crews in establishing
appropriate precautions in the event they must interact with a person
suspected of having avian influenza. Personnel should be aware of
the symptoms of avian influenza. Although experience with human
infection is limited, persons infected with avian influenza would
likely have fever and respiratory symptoms (cough, sore throat,
shortness of breath).
Wash hands frequently with soap and water or use an alcohol-based
hand rub if hands are not visibly soiled.
Personnel should wear disposable gloves for direct contact with
blood or body fluids of any passenger. However, gloves are not intended
to replace proper hand hygiene. Immediately after activities involving
contact with body fluids, gloves should be carefully removed and
discarded and hands should be cleaned. Gloves must never be washed
or reused.
The CDC has developed specific guidance on the handling of sick
passengers. (See http://www.cdc.gov/travel/other/avian_flu_ig_airlines_021804.htm)
The CDC has stated that, the captain of an airliner bound for the
United States is required by law to report the illness to the nearest
U. S. Quarantine Station prior to arrival or as soon as illness
is noted. Quarantine officials will arrange for appropriate medical
assistance to be available when the airplane lands and will notify
state and local health departments and the appropriate CDC Headquarters'
officials.
GUIDANCE FOR TRAVELERS
The CDC has issued precautions for travel to countries that are
reporting outbreaks of avian influenza A (H5N1) in humans and animals.
Currently, CDC does not recommend that the general public avoid
travel to any of the countries affected by avian influenza A (H5N1).
CDC has issued the following recommendations for travel to countries
reporting human or animal cases of avian influenza A (H5N1):
Before you leave:
Assemble a travel health kit containing basic first aid and medical
supplies. Be sure to include a thermometer and alcohol-based hand
rub for hand hygiene.
Educate yourself and others who may be traveling with you about
influenza. Information about influenza is provided on CDC's influenza
website: (http://www.cdc.gov/flu/).
Be sure you are up to date with all your shots, and see your health-care
provider at least 4–6 weeks before travel to get any additional
shots or information you may need. CDC's health recommendations
for international travel are provided on CDC's Travelers' Health
website: http://www.cdc.gov/travel/.
You may wish to check your health insurance plan or get additional
insurance that covers medical evacuation in the event of illness.
Information about medical evacuation services is provided on the
U.S. Department of State website: http://www.travel.state.gov/medical.html.
Identify in-country health-care resources in advance of your trip.
While you are in an area where avian influenza cases have been
reported:
At this time, CDC recommends that travelers to countries experiencing
outbreaks of this disease in poultry should avoid areas with live
poultry, such as live animal markets and poultry farms. Large amounts
of the virus are known to be excreted in the droppings from infected
birds.
As with other infectious illnesses, one of the most important and
appropriate preventive practices is careful and frequent hand hygiene.
Cleaning your hands often using either soap and water or waterless
alcohol-based hand sanitizers removes potentially infectious materials
from your skin and helps prevent disease transmission.
Influenza viruses are destroyed by heat; therefore, as a precaution,
all foods from poultry, including eggs, should be thoroughly cooked.
If you develop respiratory symptoms or any illness that requires
prompt medical attention, a U.S. consular officer can assist in
locating appropriate medical services and informing family or friends.
See this website for more information about what to do if you become
ill while abroad http://www.cdc.gov/travel/other/illness-abroad.htm.
It is advisable that you defer further travel until you are free
of symptoms.
After your return:
Monitor your health for 10 days.
If you become ill with fever or respiratory symptoms during this
10-day period, consult a health-care provider. Before your visit
to a health-care setting, tell the provider about your symptoms
and recent travel so that he or she can be aware you have traveled
to an area reporting avian influenza.
Information for health care providers wishing to test for or report
cases of influenza A (H5N1) and SARS can be found at this website
http://www.cdc.gov/flu/han020302.htm
EMPLOYEE TRAINING
All employees with potential occupational exposure, as described
in this document, should be trained on the hazards associated with
exposure to influenza A (H5N1) and the protocols in place in their
facility to isolate and report cases or reduce exposures.
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1 US Department of Agriculture, Animal and Plant Health inspection
Service, http://www.aphis.usda.gov/lpa/issues/ai_us/ai_us.html [Back
To Text]
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2 Nicholson KG, et al, "Influenza," The Lancet, Vol 362,
November 22, 2003, p 1733. [Back To Text]
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3 World Health Organization, "Avian influenza frequently asked
questions," http://www.who.int/csr/disease/avian_influenza/avian_faqs/en/
[Back To Text]
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4 World Health Organization, "Avian influenza – fact
sheet" http://www.who.int/csr/don/2004_01_15/en/ [Back to Text]
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5 Centers for Disease Control and Prevention, http://www.cdc.gov/flu/avian/index.htm
[Back to Text]
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6 Mandell GL, Bennett JE, Dolin RD. Principles and Practices of
Infectious Diseases 4th Ed. Churchhill Livingstone, New York. 1995.
p. 1547. [Back to Text]
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7 Mandell GL, Bennett JE, Dolin RD. Principles and Practices of
Infectious Diseases 4th Ed. Churchhill Livingstone, New York. 1995.
p. 1553. [Back to Text]
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8 World Health Organization, "Avian influenza frequently asked
questions," http://www.who.int/csr/disease/avian_influenza/avian_faqs/en/
