Viral hemorrhagic fevers

Isolation and Decontamination

All VHF patients should be cared for using strict contact precautions, including hand hygiene double gloves, gowns, shoe and leg coverings, and faceshield or goggles. Airborne precautions should be instituted to the maximum extent possible. At a minimum, a fit-tested, HEPA filter-equipped respirator (such as an N-95 mask), a battery-powered, air-purifying respirator, or a positive pressure supplied air respirator should be worn by personnel sharing an enclosed space with or coming within six feet of a VHF patient. Multiple patients should be cohorted to a separate building or a ward with an isolated air-handling system. Ideally, VHF patients should be isolated in a negative pressure isolation room with 6-12 air exchanges per hour. Environmental decontamination is accomplished with hypochlorite or phenolic disinfectants.

Infection Control

Nosocomial Transmission

Transmission within healthcare settings has been noted for a number of hemorrhagic fever viruses, including Ebola, Marburg, Lassa, Machupo, and Crimean-Congo viruses (see References: Weber 2001).

  • Nosocomial and household transmission most often has been associated with contact with infected blood or body fluids (see References: Dowell 1999, Monath 1975).
  • In some instances, transmission has resulted from reuse of needles or accidental needlesticks (see References: Fisher-Hoch 1995, Guimard 1999).
  • In one situation, investigators postulated that a healthcare worker became infected with Ebola virus after touching her eyes with a contaminated glove (see References: Guimard 1999).
  • Person-to-person airborne transmission appears to be rare; one patient with Lassa fever who had extensive pulmonary involvement may have transmitted the virus by this route (see References: Carey 1972).
  • Airborne transmission of Machupo virus presumably occurred in one situation where a nursing student became infected after watching an instructor change the bed linens of an infected patient; the student had no direct or close contact with the patient or with any associated fomites (see References: Peters 1974).
  • Although person-to-person airborne transmission appears unlikely, the potential for airborne transmission of hemorrhagic fever viruses in the healthcare setting cannot be excluded (see References: Borio 2002).
  • In some Third World countries inconsistent use of protective gear can contribute to infection of healthcare workers. Reasons for poor usage include unavailability of the gear, adherence to traditional explanatory models of disease origin, and bonding with sick colleagues (see References: Borchert 2007).
  • Contact with cadavers has been shown to be a source of exposure during outbreaks of Ebola hemorrhagic fever (see References: CDC: Outbreak of Ebola hemorrhagic fever—Uganda, August 2000-January 2001; Roels 1999).

Isolation Precautions

Appropriate isolation precautions for patients with suspected or confirmed VHF include a combination of Airborne and Contact Precautions (see References: Weber 2001). Although airborne transmission of these agents appears to be rare, airborne transmission theoretically may occur; therefore, airborne precautions should be instituted for all patients with suspected VHF. According to the Working Group on Civilian Biodefense, the following precautions should be implemented for such patients (see References: Borio 2002):

  • Provide the following PPE for healthcare providers:
    • N-95 respirator or powered air-purifying respirator (PAPR)
    • Double (leak-proof) gloves
    • Impermeable gowns
    • Face shields
    • Goggles for eye protection
    • Leg and shoe coverings
  • Place the patient in a private room with:
    • Negative air pressure
    • 6 to 12 air changes per hour
    • Restricted access of nonessential staff and visitors
  • Dedicate medical equipment (eg, stethoscopes, glucose monitors, point-of-care analyzers [if available]).
  • Assure that healthcare providers adhere strictly to hand hygiene:
    • Clean hands prior to donning PPE for patient contact
    • After patient care, remove gloves, gown, and leg and shoe coverings and immediately clean hands
    • Clean hands prior to the removal of facial protective equipment to minimize exposure of mucous membranes to potentially contaminated hands
    • Clean hands again after all PPE is removed
  • Place all persons (including medical and laboratory personnel) who have had a close or high-risk contact with a patient suspected of having VHF during the 21 days following onset of symptoms (and before onset of appropriate barrier precautions) under medical surveillance (see References: Borio 2002).
    • High risk is defined as having mucous membrane contact or having percutaneous injury involving contact with secretions, excretions, or blood from a patient with VHF
    • Close contact is defined as those who live with, shake hands with, hug, process laboratory specimens from, or care for a patient with VHF
    • If a filovirus or arenavirus infection is confirmed for the index patient, then medical surveillance should be continued until 21 days after the last exposure
    • If the index patient has Rift Valley fever or a flavivirus infection, then medical surveillance needs to be continued until 21 days after the last exposure only for those who processed laboratory specimens from the infected patient prior to initiation of appropriate precautions (since these conditions are transmitted in the laboratory setting but not via person-to-person transmission)
  • If multiple patients with suspected VHF are admitted to one healthcare facility, cohort them in the same part of the hospital to minimize exposure to other patients and healthcare workers.

Environmental Decontamination

Hemorrhagic fever viruses have lipid envelopes and are not environmentally stable; therefore, these viruses would not be expected to persist in the environment following a bioterrorist attack. According to the Working Group on Civilian Biodefense, decisions about decontamination of the environment following an intentional release would depend upon the specific events surrounding the attack and should be made by experts who are familiar with the situation (see References: Borio 2002).

The Working Group on Civilian Biodefense and CDC make the following recommendations for environmental decontamination in the hospital setting (see References: Borio 2002; CDC: Update: Management of patients with suspected viral hemorrhagic fever—United States).

  • Environmental surfaces, inanimate contaminated objects, or contaminated equipment should be disinfected with an Environmental Protection Agency–registered hospital disinfectant or a 1:100 dilution of household bleach using standard procedures.
  • Contaminated linens should be incinerated, autoclaved, or placed in double (ie, leak-proof) bags at the site of use and washed without sorting in a normal hot water cycle with bleach.
  • Hospital housekeeping staff and linen handlers should wear appropriate PPE (as outlined in the section on isolation practices above) when handling or cleaning potentially contaminated material or surfaces.

The 1995 CDC guidelines for management of patients with VHF indicate that efforts should be made to decontaminate stool, fluids, and secretions before disposal. According to CDC, such fluids should be autoclaved, processed in a chemical toilet, or treated with several ounces of household bleach for 5 or more minutes before flushing or disposal (see References: CDC: Update: Management of patients with suspected viral hemorrhagic fever—United States). However, the Working Group on Civilian Biodefense has stated that since hemorrhagic fever viruses are not likely to survive standard US sewage treatment, such practices are unnecessary (see References: Borio 2002).

Find more information on this substance at: PubChem, PubMed