Notice to Readers
Update: Management of Patients with Suspected Viral Hemorrhagic
Fever -- United States
In 1988, CDC published guidelines for managing patients with
suspected viral hemorrhagic fever (VHF) (1). Pending a
comprehensive review of the 1988 guidelines, this notice provides
interim recommendations that update the 1988 guidelines for
health-care settings in the United States. This update applies to
four viruses that cause syndromes of VHF: Lassa, Marburg, Ebola,
and Congo-Crimean hemorrhagic fever viruses; although the risk
and/or mode of nosocomial transmission differs for each of these
viruses, the limited data do not permit clear distinctions.
Background
In Africa, transmission of VHF has been associated with reuse
of unsterile needles and syringes and with provision of patient
care without appropriate barrier precautions to prevent exposure to
virus-containing blood and other body fluids (including vomitus,
urine, and stool). The risks associated with various body fluids
have not been well defined as most caregivers who acquired
infection had multiple contacts with multiple fluids. Epidemiologic
studies of VHF in humans indicate that infection is not readily
transmitted from person to person by the airborne route (1,2).
Airborne transmission involving humans has never been documented
and is considered a possibility only in rare instances from persons
with advanced stages of disease (e.g., one patient with Lassa fever
who had extensive pulmonary involvement may have transmitted
infection by the airborne route) (3). In contrast, investigation of
VHF in nonhuman primates (i.e., monkeys) has suggested possible
airborne spread among these species (4-7). Despite uncertainties
regarding the applicability to humans of data regarding airborne
transmission in nonhuman primates, such information must be
considered in the development of infection-control precautions
because information regarding exposure and transmission in humans
is limited.
The risk for person-to-person transmission of hemorrhagic
fever viruses is highest during the latter stages of illness, which
are characterized by vomiting, diarrhea, shock, and often
hemorrhage. VHF infection has not been reported in persons whose
contact with an infected patient occurred only during the
incubation period (i.e., before the patient became febrile; the
incubation period ranges from 2 days to 3 weeks, depending on the
etiology of the VHF {1}). In the 1995 Zaire outbreak, some
instances of Ebola virus transmission within a few days after onset
of fever were reported; however, other symptoms in the source
patients and the level of exposure to body fluids among these
secondary cases were unknown (CDC, unpublished data, 1995). In
studies involving three monkeys experimentally infected with Ebola
virus (Reston strain), fever and other systemic signs of illness
preceded detection of infectious virus in the pharynx by 2-4 days,
in the nares by 5-10 days, in the conjunctivae by 5-6 days, and on
anal swabs by 5-6 days (P. Jahrling, U.S. Army Medical Research
Institute of Infectious Diseases, unpublished data, 1995).
Reporting
All suspected cases of infection with Ebola virus and other
hemorrhagic fever viruses should be reported immediately to local
and state health departments and to CDC (telephone {404} 639-1511;
from 4:30 p.m. to 8 a.m., telephone {404} 639-2888). Specimens for
virus-specific diagnostic tests should be sent to CDC as rapidly as
possible according to instructions provided when contact is made.
General information regarding Ebola virus infection is available
through the CDC Ebola Hotline (telephone {800} 900-0681).
Recommendations
The following recommendations apply to patients who, within 3
weeks before onset of fever, have either 1) traveled in the
specific local area of a country where VHF has recently occurred;
2) had direct contact with blood, other body fluids, secretions, or
excretions of a person or animal with VHF; or 3) worked in a
laboratory or animal facility that handles hemorrhagic fever
viruses. The likelihood of acquiring VHF is considered extremely
low in persons who do not meet any of these criteria. The cause of
fever in persons who have traveled in areas where VHF is endemic is
more likely to be a different infectious disease (e.g., malaria or
typhoid fever); evaluation for and treatment of these other
potentially serious infections should not be delayed.
Because most ill persons undergoing prehospital evaluation and
transport are in the early stages of disease and would not be
expected to have symptoms that increase the likelihood of contact
with infectious body fluids (e.g., vomiting, diarrhea, or
hemorrhage), universal precautions are generally sufficient (8). If
a patient has respiratory symptoms (e.g., cough or rhinitis), face
shields or surgical masks and eye protection (e.g., goggles or
eyeglasses with side shields) should be worn by caregivers to
prevent droplet contact (8). Blood, urine, feces, or vomitus, if
present, should be handled as described in the following
recommendations for hospitalized patients.
Patients in a hospital outpatient or inpatient setting should be
placed in a private room. A negative pressure room is not required
during the early stages of illness, but should be considered at the
time of hospitalization to avoid the need for subsequent transfer
of the patient. Nonessential staff and visitors should be
restricted from entering the room. Caretakers should use barrier
precautions to prevent skin or mucous membrane exposure to blood
and other body fluids, secretions, and excretions. All persons
entering the patient's room should wear gloves and gowns to prevent
contact with items or environmental surfaces that may be soiled. In
addition, face shields or surgical masks and eye protection (e.g.,
goggles or eyeglasses with side shields) should be worn by persons
coming within approximately 3 feet of the patient to prevent
contact with blood, other body fluids, secretions (including
respiratory droplets), or excretions. The need for additional
barriers depends on the potential for fluid contact, as determined
by the procedure performed and the presence of clinical symptoms
that increase the likelihood of contact with body fluids from the
patient (8). For example, if copious amounts of blood, other body
fluids, vomit, or feces are present in the environment, leg and
shoe coverings also may be needed. Before entering the hallway, all
protective barriers should be removed and shoes that are soiled
with body fluids should be cleaned and disinfected as described
below (see recommendation 6). An anteroom for putting on and
removing protective barriers and for storing supplies would be
useful, if available (1).
For patients with suspected VHF who have a prominent cough,
vomiting, diarrhea, or hemorrhage, additional precautions are
indicated to prevent possible exposure to airborne particles that
may contain virus. Patients with these symptoms should be placed in
a negative-pressure room (9). Persons entering the room should wear
personal protective respirators as recommended for care of patients
with active tuberculosis (high efficiency particulate air {HEPA}
respirators or more protective respirators) (9).
Measures to prevent percutaneous injuries associated with the
use and disposal of needles and other sharp instruments should be
undertaken as outlined in recommendations for universal precautions
(8). If surgical or obstetric procedures are necessary, the state
health department and CDC's National Center for Infectious
Diseases, Hospital Infections Program (telephone {404} 639-6425)
and Division of Viral and Rickettsial Diseases (telephone {404}
639-1511; from 4:30 p.m. to 8 a.m., telephone {404} 639-2888)
should be consulted regarding appropriate precautions for these
procedures.
Because of the potential risks associated with handling
infectious materials, laboratory testing should be the minimum
necessary for diagnostic evaluation and patient care. Clinical
laboratory specimens should be obtained using precautions outlined
above (see recommendations 1-4 above), placed in plastic bags that
are sealed, then transported in clearly labeled, durable, leakproof
containers directly to the specimen handling area of the
laboratory. Care should be taken not to contaminate the external
surfaces of the container. Laboratory staff should be alerted to
the nature of the specimens, which should remain in the custody of
a designated person until testing is done. Specimens in clinical
laboratories should be handled in a class II biological safety
cabinet following biosafety level 3 practices (10). Serum used in
laboratory tests should be pretreated with polyethylene glycol
p-tert-octylphenyl ether (Triton(R) X-100) * ; treatment with 10 uL
of 10% Triton(R) X-100 per 1 mL of serum for 1 hour reduces the
titer of hemorrhagic fever viruses in serum, although 100% efficacy
in inactivating these viruses should not be assumed. Blood smears
(e.g., for malaria) are not infectious after fixation in solvents.
Routine procedures can be used for automated analyzers; analyzers
should be disinfected as recommended by the manufacturer or with a
500 parts per million solution of sodium hypochlorite (1:100
dilution of household bleach: 1/4 cup to 1 gallon water) after use.
Virus isolation or cultivation must be done at biosafety level 4
(10). The CDC mobile isolation laboratory is no longer available
(1).
Environmental surfaces or inanimate objects contaminated with
blood, other body fluids, secretions, or excretions should be
cleaned and disinfected using standard procedures (8). Disinfection
can be accomplished using a U.S. Environmental Protection Agency
(EPA)-registered hospital disinfectant or a 1:100 dilution of
household bleach.
Soiled linens should be placed in clearly labeled leak-proof
bags at the site of use and transported directly to the
decontamination area. Linens can be decontaminated in a gravity
displacement autoclave or incinerated. Alternatively, linens can be
laundered using a normal hot water cycle with bleach if universal
precautions to prevent exposures are precisely followed (8) and
linens are placed directly into washing machines without sorting.
There is no evidence for transmission of hemorrhagic fever
viruses to humans or animals through exposure to contaminated
sewage; the risk of such transmission would be expected to be
extremely low with sewage treatment procedures in use in the United
States. As an added precaution, however, measures should be taken
to eliminate or reduce the infectivity of bulk blood, suctioned
fluids, secretions, and excretions before disposal. These fluids
should be either autoclaved, processed in a chemical toilet, or
treated with several ounces of household bleach for greater than or
equal to 5 minutes (e.g., in a bedpan or commode) before flushing
or disposal in a drain connected to a sanitary sewer. Care should
be taken to avoid splashing when disposing of these materials.
Potentially infectious solid medical waste (e.g., contaminated
needles, syringes, and tubing) should either be incinerated or be
decontaminated by autoclaving or immersion in a suitable chemical
germicide (i.e., an EPA-registered hospital disinfectant or a 1:100
dilution of household bleach), then handled according to existing
local and state regulations for waste management.
If the patient dies, handling of the body should be minimal. The
corpse should be wrapped in sealed leakproof material, not
embalmed, and cremated or buried promptly in a sealed casket. If an
autopsy is necessary, the state health department and CDC should be
consulted regarding appropriate precautions (1).
Persons with percutaneous or mucocutaneous exposures to blood,
body fluids, secretions, or excretions from a patient with
suspected VHF should immediately wash the affected skin surfaces
with soap and water. Application of an antiseptic solution or
handwashing product may be considered also, although the efficacy
of this supplemental measure is unknown. Mucous membranes (e.g.,
conjunctiva) should be irrigated with copious amounts of water or
eyewash solution. Exposed persons should receive medical evaluation
and follow-up management (1).
Reported by: Hospital Infections Program, Div of Viral and
Rickettsial Diseases, and Div of Quarantine, National Center for
Infectious Diseases; Office of the Director, National Institute for
Occupational Safety and Health; Office of Health and Safety, CDC.
References
CDC. Management of patients with suspected viral hemorrhagic
fever. MMWR 1988;37 (no. S-3):1-15.
Baron RC, McCormick JB, Zubeir OA. Ebola virus disease in
southern Sudan: hospital dissemination and intrafamilial spread.
Bull WHO 1983;61:997-1003.
Carey DE, Kemp GE, White HA, et al. Lassa fever: epidemiological
aspects of the 1970 epidemic, Jos, Nigeria. Trans R Soc Trop Med
Hyg 1972;66:402-8.
Dalgard DW, Hardy RJ, Pearson SL, et al. Combined simian
hemorrhagic fever and Ebola virus infection in cynomolgus monkeys.
Lab Anim Sci 1992;42:152-7.
CDC. Update: filovirus infections among persons with
occupational exposure to nonhuman primates. MMWR 1990;39:266-7.
Johnson E, Jaax N, White, Jahrling P. Lethal experimental
infection of rhesus monkeys by aerosolized Ebola virus. Int J Exp
Pathol (in press).
Pokhodynev VA, Gonchar NI, Pshenichnov VA. Experimental study of
Marburg virus contact transmission. Vopr Virusol 1991;36:506-8.
CDC. Guidelines for prevention of transmission of human
immunodeficiency virus and hepatitis B virus to health-care and
public safety workers. MMWR 1989;38:(no. S-6):1-37.
CDC. Guidelines for preventing the transmission of Mycobacterium
tuberculosis in health-care facilities. MMWR 1994;43(no.
RR-13):33-34, 71-81.
CDC/National Institutes of Health. Biosafety in microbiological
and biomedical laboratories. 3rd ed. Atlanta, Georgia: US
Department of Health and Human Services, Public Health Service,
1993; DHHS publication no. (CDC)93-8395.
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