Outbreaks of Ebola virus disease (EVD), previously known as Ebola hemorrhagic fever (Ebola HF), have occurred more than 20 times since the first documented outbreak in 1976. Ebola is named after the Ebola River in the African country of Zaire (now Democratic Republic of Congo), which is where the first case of EVD occurred.
Ebola is one of three viruses in the filoviride family of viruses. The other two viruses are the Cueva and Marburg viruses. Five subspecies of Ebola virus are known to exist: Zaire, Sudan, Tai Forest and Bundibugyo, and all four are believed to have caused disease in humans. The fifth subvirus, Reston, is believed to infect and cause disease in primates. Reston can also infect humans, but has not been documented to have caused disease in humans.
Much investigation has been conducted to determine the host that carries Ebola virus, but to date, no natural host has been proven. Researchers, however, believe that the virus is carried by animals, with fruit bats being the most likely hosts. The World Health Organization (WHO) says infection of humans has been documented through the handling of infected chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines that have been found ill or dead in the rainforest. Pig farms in Africa are suspected to draw fruit bats and amplify outbreaks of EVD.
How Ebola spreads
Once human infection has occurred, EVD can be transmitted from person to person through close contact with bodily fluids. The virus spreads by direct contact through broken skin or mucous membranes with blood or other bodily fluids of infected people. It is also transmitted by direct contact with surfaces and materials (like bedding and clothing) and objects such as needles and syringes contaminated with these fluids. EVD is not spread through the air or by water or in general by food, although it may be spread by handling wild animals hunted for food and contact with infected bats. There is no evidence that mosquitoes or other insects can transmit the virus. Only mammals – for example, humans, bats, monkeys and apes – have shown the ability to become infected with and spread the virus.
Healthcare providers caring for EVD patients and families and friends in close contact with EVD are at the highest risk of becoming ill because they may come in contact with infected blood or other bodily fluids of sick patients. In Africa, healthcare workers have frequently been infected while treating patients with suspected or confirmed EVD. Infections occurred through close contact with patients when infection control precautions were not strictly practiced. Burial ceremonies where mourners have direct contact with the body of a deceased person may also be a source of the transmission of EVD.
Infected people remain infectious as long as their blood and body fluids, including, but not limited to, urine, saliva, sweat, feces, vomit, semen and breast milk, contain the virus. This is usually thought to be 21 days and those who have been exposed to an infected person or surfaces are watched for that amount of time. After that, if they have not developed symptoms, they are believed to be free of the virus. Men who have recovered from EVD can still transmit the virus through their semen for up to seven weeks after their recovery.
The incubation period for the EVD is two to 21 days from the time of infection to when symptoms appear. Humans are not infectious until they develop symptoms. Initial symptoms are the sudden onset of fever (above 101 degrees Fahrenheit), fatigue, muscle pain, headache and sore throat. This is followed by vomiting, diarrhea, rash, symptoms of impaired kidney and liver function and in some cases both internal and external bleeding (e.g., oozing from the gums or blood in stools). Laboratory findings may include low white blood cell and platelet counts and elevated liver enzymes. It may be difficult to distinguish EVD from other infectious diseases, such as malaria, typhoid fever and meningitis. Confirmation that symptoms are caused by EVD are made using the following investigations:
• Antibody-capture enzyme-linked immunosorbent assay (ELISA)
• Antigen-capture detection tests
• Reverse transcriptase polymerase chain reaction (RT-PCR) assay
• Electron microscopy
• Virus isolation by culture
Samples from patients are an extreme biohazard risk. Laboratory testing on non-inactivated samples should be conducted under maximum biological containment conditions.
Supportive care – rehydration with oral or intravenous fluids and treatment of specific symptoms – improves survival. No proven treatment is available yet for EVD. However, a range of potential treatments, including blood products, immune therapies and drug therapies, are being evaluated. No licensed vaccines are available yet, but two potential vaccines are undergoing human safety testing.
The African outbreak of EVD was brought to the United States for the first time in 2014, when a U.S. citizen living in Dallas, TX, was diagnosed. The person had traveled to Liberia, where the disease was contracted. Following unsuccessful treatment in a Dallas hospital, the victim died on Oct. 8 of complications caused by EVD. Several healthcare workers who had been involved in the patient’s treatment contracted EVD ,but were treated successfully. Healthcare workers returning from treating EVD patients in Africa were also exposed and several became ill upon their return to the U.S. Other healthcare workers became sick while in Africa and were flown to the U.S. for treatment.
Receiving EVD patients
One facility that received EVD patients was the University of Nebraska Medical Center (UNMC) in Omaha. UNMC has a 10-bed Biocontainment Unit, designed and commissioned in 2005 by the U.S. Centers for Disease Control and Prevention (CDC) to provide first-line treatment for people affected by bioterrorism or extremely infectious, naturally occurring diseases such as EVD. The facility is the largest of its kind in the U.S.
Highly contagious and deadly infectious conditions that can be handled in the unit include EVD as well as SARS, smallpox, tularemia, plague and other hemorrhagic fevers, monkeypox, vancomycin-resistant staphylococcus aureus (VRSA) and multidrug-resistant tuberculosis. Safety measures built into the Biocontainment Unit include air-handling equipment, high-level filtration and ultraviolet light that prevent micro-organisms from spreading beyond patient rooms. The unit is isolated from the rest of the hospital with its own ventilation system and secured access. A dunk tank is provided for laboratory specimens and a pass-through autoclave are also in place to ensure that hazardous infections are contained. Also in the unit is a special sterilizer for laundry so that contaminated bed clothing is not removed from the unit.
Patients are flown into Omaha’s Eppley Airfield and transported to the unit, in an individual isolation unit called a BIOPOD, by Omaha Fire Department EMS. Biocontainment Unit staff receive specialized training and participate in drills throughout the year.
Personal protective equipment (PPE) for EVD patient care follows guidelines developed by the CDC and World Health Organization (WHO). Three key principles are contained in the guidance from the CDC:
• Before working with Ebola patients, healthcare workers must have received repeated training and have demonstrated competency in performing all Ebola-related infection-control practices and procedures, and specifically in donning/doffing proper PPE.
• While working in PPE, healthcare workers caring for Ebola patients should have no skin exposed.
• The overall safe care of Ebola patients in a facility must be overseen by an onsite manager at all times, and each step of every PPE donning/doffing procedure must be supervised by a trained observer to ensure proper completion of established PPE protocols.
The CDC has issued interim guidance for 911 Public Safety Answering Points (PSAPs) for management of patients with known or suspected EVD. This guidance is intended for managers of PSAPs, EMS agencies, EMS systems, law enforcement agencies and fire service agencies, including individual emergency medical service providers (emergency medical technicians and paramedics) and medical first responders, such as law enforcement and fire service personnel.
Key points of the interim guidance for PSAPs:
• The likelihood of contracting Ebola in the U.S. is extremely low unless a person has direct unprotected contact with the blood or bodily fluids of a person who is sick with EVD.
• When risk of EVD is elevated in the community, it is important for PSAPs to question callers about residence in, or travel to, a country where an EVD outbreak is occurring; signs and symptoms of EVD; and other risk factors, such as direct contact with someone who is sick with EVD.
• PSAPs should relay this information to EMS personnel before they reach the location so they can follow proper PPE procedures.
• EMS staff should immediately check for symptoms and risk factors for EVD. Staff should notify the receiving healthcare facility before EMS arrives with the patient.
The information provided in this column is just an overview and by no means meant to be a complete coverage of CDC Interim Guidance. Organizations must obtain complete information from the CDC and other resources such as the WHO, UNMC and National Institutes of Health (NIH) to develop plans, standard operating procedures (SOPs) and training to deal with EVD and other infectious diseases. While EVD is a very serious disease, the handling and treating patients can be accomplished safely with proper preparation.
Thanks to UNMC Senior Media Relations Coordinator Taylor Wilson for photos, information sources and news release updates on UNMC’s Biocontainment Unit.
STAY SAFE: FOLLOW RECOMMENDED PLANNING AND TRAINING PROCEDURES
Emergency medical service guidance for pre-hospital Ebola virus disease (EVD) response issued by the U.S. Centers for Disease Control and Prevention (CDC) includes pre-hospital EMS, law enforcement and fire service first responders. The single most important aspect of pre-hospital response to EVD is ensuring that personnel wear proper personal protective equipment (PPE) and are fully trained on donning and doffing procedures. Advanced planning for EVD response and conducting drills are critical. PPE guidance for pre-hospital EVD response is the same as for hospital healthcare workers.
Except for the positive-pressure air-purifying respirator (PAPR), all PPE mentioned below is single use (disposable). Those donning PPE must ensure that no skin is exposed. If a PAPR is used, a full faceshield, helmet or headpiece should also be used. Any reusable helmet or headpiece must also be covered with a single-use hood that extends to the shoulders, fully covers the neck and is compatible with the selected PAPR.
Recommended PPE for use by trained personnel includes: a PAPR or N95 respirator in combination with a single-use surgical hood extending to the shoulders and single-use full faceshield; fluid-resistant or impermeable gown that extends to at least mid-calf without integrated hood; nitrile examination gloves with extended cuffs; fluid-resistant or impermeable boot covers that extend to at least mid-calf; and a fluid-resistant or impermeable apron that covers the torso to the level of the mid-calf if EVD patients have vomiting or diarrhea.
Preparation for the care and transport of EVD patients by emergency responders requires advanced planning, training and drills to ensure the best care of the patient and the safety of response personnel. Dispatch personnel play a critical role in gathering patient information and transmitting that information to the responders.
—Robert Burke
ROBERT BURKE, hazardous materials and fire protection consultant, a Firehouse® contributing editor, is a Certified Fire Protection Specialist (CFSP), Fire Inspector II, Fire Inspector III, Fire Investigator and Hazardous Materials Specialist, and has served on state and county hazmat teams. Burke is the author of the textbooks Hazardous Materials Chemistry for Emergency Responders, Counter-Terrorism for Emergency Responders, Fire Protection: Systems and Response and Hazmat Teams Across America. He can be contacted at [email protected].
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