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Key Points
- Mucocutaneous exposure to biological fluid from macaque monkeys can
result in infection with Cercopithecine herpesvirus 1, commonly known
as B virus.
- Eye splashes appear to be common in the primate industry.
- Dendritic corneal lesions characteristic of other ocular herpes virus
infections may not be present
- All personnel who work with macaques should wear eyewear conforming
to established standards for eye and splash protection.
- If exposure prevention fails, the adequacy and timeliness of wound
or exposure decontamination procedures are critical factors in determining
the risk for infection.
Description of Hazard
On October 29, 1997, a 22-year-old researcher at a primate-center
field station was assisting with a routine group capture of rhesus
macaques (Macaca mulatta) in a free-ranging corral. Personnel conducting
the capture wore uniforms, disposable latex gloves, and surgical masks.
Eye protection was not worn. During the transfer of an unidentified
macaque into a squeeze cage, undetermined liquid from the animal entered
the researchers eye. The worker wiped her eye at the time of exposure.
Approximately 45 minutes later she flushed her eye with tap water
for 23 minutes. There was no medical treatment or consultation at
the time of the exposure. The researcher subsequently developed a
Cercopithecine herpesvirus 1 (B virus) infection; despite intensive
antiviral therapy, she died on December 10, 1997. This incident is
the first documented case of a B virus infection resulting from an
ocular exposure to macaque secretions.
On November 8, 1997, the researcher sought medical attention for the
first time because the exposed eye was red and swollen. At this time,
the emergency department physician specifically looked for dendritic
lesions of the cornea that are characteristic of ocular herpes infections.
Although dendritic corneal lesions were reported in a previous fatal
B virus infection, they were not seen in the present case. On the
basis of the reported circumstances of the contact, it was initially
concluded that B virus infection was unlikely. This case is reported
in the following:
CDC (Centers for Disease Control and Prevention) [1998]. Fatal Cercopithecine
herpesvirus 1 (B Virus) Infection Following a Mucocutaneous Exposure
and Interim Recommendations for Worker Protection. Morbidity and Mortality
Weekly Report (MMWR) 47(49):10731076,1083; December 18, 1998.
About B Virus
B virus infects > 70% of surveyed captive adult macaques, but not other
nonhuman primates (NHPs). Like humans infected with Herpesvirus simplex
virus, monkeys infected with B virus have a lifelong infection, with
intermittent reactivation and shedding of the virus in saliva, conjunctival
fluid, or urogenital secretions. Although virus shedding is more frequent
during the mating season (roughly March to June) and when an animal
is ill, under stress, or immunosuppressed, there are often no signs
of shedding. Macaques should always be regarded as potentially infectious.
There have been approximately 40 known cases of fatal human B virus
infection described in the English language literature. Previously
reported human infections usually have been attributed to macaque
bites or scratches, injuries from needles used near a macaques mucous
membranes or central nervous system, or contact with infectious products
from the macaques. Incubation periods may be as short as 2 days, but
more commonly they are 2 to 5 weeks. Most documented infections have
occurred among biomedical research employees who worked with macaques.
Laboratory workers handling only infected central nervous system or
primary monkey kidney cell lines have also been exposed and, in at
least one instance, infected. One case of person-to-person transmission
has been reported.
Recommendations for Preventing B Virus Infections
Published recommendations for the prevention and treatment of B virus
infections in exposed persons include the following:
CDC (Centers for Disease Control and Prevention) [1987]. Guidelines
for the Prevention of Herpesvirus simiae (B Virus) Infection in Monkey
Handlers. Morbidity and Mortality Weekly Report (MMWR) 36(41):680683,
687689; October 23, 1987.
Holmes GP, et al. [1995]. Guidelines for the Prevention and Treatment
of B-Virus Infections in Exposed Persons. Clinical Infectious Diseases
20:421439.
Protective eyewear criteria have been established by the American
National Standards Institute (ANSI):
ANSI [1989]. Practice for Occupational and Educational Eye and Face
Protection, Z87.11989. American Society of Safety Engineers, Des Plaines,
IL.
Actions You Should Take
- Preventing worker exposure to biohazardous material is the best protection
against infection. All organizations that work with macaques or other
NHPs should obtain the documents cited in this report (as well as
other guidelines and educational materials) and review the occupational
health hazards associated with working with NHPs. Employers should
ensure that worker protection programs, policies, and procedures are
in place to control infection risks from NHPs. Employers should conduct
training and periodic assessments to ensure that worker protection
programs are effective. In particular, all employees who come into
contact with macaques or macaque tissues should be trained about the
risks of B virus and other infections and the importance of preventive
measures.
- Each institution working with NHPs should develop a written, comprehensive
personal protective equipment (PPE) program that clearly identifies
the PPE required for each specific task or working area of the facility
and addresses training, inspection and maintenance, and periodic assessment
of program effectiveness. Mandatory PPE should be selected based on
a thorough worksite hazard assessment that considers all work procedures
and associated hazards (including biohazards), potential routes of
exposure, and potential adverse health outcomes.
- Reviews of injuries and biohazard exposures among workers exposed
to NHPs suggest that mucocutaneous contact with NHP body fluids is
common; in one survey, 16 of 17 contacts with primate body fluids
involved ocular exposure. Although the 1987 Centers for Disease Control
and Prevention (CDC) Guidelines for the Prevention of Herpesvirus
simiae (B virus) Infection in Monkey Handlers discourages handling
fully awake macaques, macaque handlers should be protected with appropriate
eye protection when it is necessary to remove physically active animals
from cages. The incident described in this report indicates that proper
eye protection should also be mandatory during activities such as
entering areas containing macaques, conducting captures, and transporting
caged macaques. Other activities that require eye protection should
be determined by the hazard assessment. Appropriate protective eyewear
selection should be based on a number of factors, including the nature
and extent of the hazard, nature of the work, associated degree of
risk, and requirements of the individual user. Protective eyewear
should meet or exceed the criteria established by ANSI. Eye protection
must be comfortable, accommodate the need for corrective lenses (eyeglasses),
and be adjustable to ensure a secure fit. It may be necessary to provide
several different types, styles, and sizes. Personal eyeglasses are
not PPE.
- Protective goggles designed for splash protection (available with
antifog lenses for humid environments and in models that preserve
peripheral vision) should be worn to protect the eyes against splash
hazards in combination with a mask designed to protect other mucous
membranes. Face shields are commonly considered secondary eye protectors
that are worn in combination with protective goggles. Although previous
guidelines for the prevention of B virus indicate that face shields
may be sufficient, ocular exposures have occurred to workers wearing
face shields. In one incident, an animal technician was splashed in
the eye with an unknown fluid while wearing a combination surgical
mask/face shield during the transfer of a monkey within cages. The
"face shield" worn during this exposure, a surgical mask with attached
plastic eye shield, did not provide adequate protection. To minimize
the potential for mucous membrane exposure, face shields must prevent
droplet splashes to the head from running down into the eyes and prevent
mucous membrane exposure around the edges (sides, top, and bottom
to below the chin). Decisions to use face shields as the sole means
for preventing ocular exposure should be made only after full consideration
of both the limitations of face shields and Occupational Safety and
Health Administration (OSHA) regulations.
- If exposure prevention fails, the adequacy and timeliness of wound
or exposure decontamination procedures are critical factors determining
the risk of infection. Institutions that house or conduct procedures
involving macaques or potentially contaminated tissues should develop
institution-specific post exposure procedures. Such procedures will
ensure appropriate diagnostic testing and infection control. First,
animal handlers should be instructed to immediately and thoroughly
cleanse all bites, scratches, and/or mucosal surfaces or abraded skin
exposed to macaque biologic materials and to report these exposures
immediately. Following an eye exposure, existing guidelines recommend
immediately flushing the eye for at least 15minutes. Existing guidelines
should also be followed for cleansing bites, scratches, or other wounds.
Second, post exposure procedures should provide potentially exposed
workers with direct and rapid access to local physicians knowledgeable
about the infectious risks of exposure to NHPs, hazards of B virus
infection, signs and symptoms, and treatment, as well as other biohazards
associated with NHPs. These physicians should be available on an on-call
basis in the event of an exposure. The employer should ensure that
direct access to the knowledgeable consultant is available immediately
following exposures and at any time the worker is concerned that potential
occupational exposure to B virus may be relevant to worker symptoms.
When possible, a veterinarian should assess the clinical and virologic
status of the source animal. Post exposure procedures should also include
routing diagnostic specimens to the B Virus Research and Resource
Laboratory (at Georgia State University in Atlanta).
- Medical personnel who evaluate primate handlers with conjunctivitis
after an eye exposure to potentially infectious material should be
aware that the absence of dendritic lesions of the cornea, like the
absence of herpetic skin vesicles, does not reliably rule out B virus
infection.
- These recommendations will be reviewed and may be revised or augmented
following additional consideration by a working group to be convened
by the CDC Office of Health and Safety.
For More Information
Additional information about B virus and preventive measures can be
obtained from the following:
National Institute for Occupational Safety and Health (NIOSH)
at 1-800-356-4674
or visit the NIOSH Homepage
B Virus Research and Resource Laboratory
Georgia State University
P.O. Box 4118
Atlanta, GA 303024118
404-651-0808
Centers for Disease Control and Prevention
1600 Clifton Road
Atlanta, GA 30333
404-639-2888(Callers should indicate the need for additional information about B virus.)
Acknowledgments
The principal contributors to this publication are Max Kiefer, MS,
CIH; Scott Deitchman, MD, MPH; Richard Ehrenberg, MD; and Jerome Flesch,
MS, of NIOSH; and Louisa Chapman, MD, MSPH, of the National Center
for Infectious Diseases. Desktop publishing provided by Kristina Dragon
and Susan Kaelin of NIOSH.
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