Monday: Your crew responds to the local public health department clinic for an emergency transfer. On arrival, you find the clinic staff with a 26-year-old patient in acute respiratory distress. They advise you that the patient came into the office this morning complaining of flu-like symptoms and rapidly decompensated. You and your partner prepare and transport the patient to the emergency department (ED) without incident.
Tuesday: Doctors' offices, clinics and EDs throughout your community report a rapid, atypical increase in patients with severe flu-like symptoms. Most patients present with respiratory distress, fatigue and fever.
By afternoon, your system decides to place an extra unit on the road to accommodate the increased emergency calls and advises all crews to take extra blood and body-fluid precautions when transporting patients who complain of flu-like symptoms. During the evening news, you hear that two people have died because of the illness.
Wednesday: More than 50% of your EMS calls are related to the flu-like illness that has now affected more than 1,000 city residents. Three health-care workers are confirmed to have developed the illness. All EMS personnel have been called in and briefed regarding patient contact precautions. Local, state and federal officials are working to identify the cause of the illness.
This scenario portrays the onset of a natural pandemic illness or a bioterrorism incident. Terrorist attacks using biological agents present an enormous challenge for the entire health, medical and public safety community. Regardless of the type of agent involved, the response community has to be well-coordinated and educated to identify the problem, protect themselves and take necessary steps to reduce transmission, morbidity and mortality. EMS plays an integral role in responding to these situations, assisting in epidemiologic surveillance, risk communication, prehospital care and transportation.
Bio-agents have been used as weapons for thousands of years and in very creative ways. In the 6th century B.C., Assyrians (from the region now known as Turkey) placed rye ergot in the water wells of their enemies. By the 4th century B.C., Scythian archers were dipping their arrows in blood, manure and decomposing bodies to cause deadly infections in the enemy. In the 2nd century B.C., Hannibal was reportedly hurling venomous snakes onto enemy ships.
In 1346, during the siege of Kaffa (in present-day Ukraine), as a plague epidemic raged, invading armies hurled the infected corpses of their own men over the walls of enemy castles and forts. The resultant epidemics contributed to the defenders' surrender. In the mid-17th century, Polish soldiers experimented with placing rabid dog saliva into shell casings. A century later, British soldiers presented blankets previously used by smallpox victims to Native Americans in Pennsylvania, causing a devastating smallpox outbreak.
In Manchuria, China, during World War II, Japanese Army Unit 731 conducted experiments on human subjects to test the effects of germ warfare and chemical weapons, the extreme cold and the sudden loss of air pressure. Thousands died in and around the camp from the experiments themselves and from plague epidemics released by the experimentation. Although most of the victims were Chinese, the victims also included Russians, Mongolians and Koreans.
In 1979, weapons-grade anthrax was accidentally released from a secret biological weapons plant in the Soviet Union. Of 79 victims with documented infections, at least 68 died. (Because of the secrecy surrounding this incident, the actual numbers of dead may be higher than generally known.) American scientists later determined that four different strains of anthrax were released during this accident.
It's easy to see that the potential use of bioweapons is a serious reality that we must prepare to manage.
Biological agents are naturally occurring organisms that can replicate, especially inside the human body. They are frequently odorless and tasteless, and usually don't cause skin irritation.
The initial exposure to a victim is often undetected, allowing individuals to become infectious and potentiate the spread of the agent. However, outside of a viable host or "vector," many bio-agents degrade over time, minimizing secondary risk to responders.
Biological vs. chemical weapons
Compared with chemical weapons that require sophisticated and expensive manufacturing processes, many bio-agents are easily obtained and can be grown with basic laboratory equipment. It has been estimated that $1's worth of a biological weapon spread over a square kilometer can produce the equivalent morbidity, mortality and disruption of $2,000's worth of conventional weapons.
Biological weapons are considered particularly effective because of their ability to disrupt and overwhelm medical capabilities in a given area.
Bio-agents tend to cause the most harm when inhaled. Therefore, terrorists may spread the agent throughout the atmosphere as a fine powder or vapor cloud. Aerosolized agents are most effective when released from dusk to dawn in moderate temperatures and light winds.
Other potential areas that can be targeted for agent dispersal include food and water stores, as well as heating, ventilation and air-conditioning (HVAC) systems. However, remember that bio-agents are naturally occurring, and individuals can accidentally come into contact with them during day-to-day activities.
Most bio-agents present symptoms characteristic of an influenza-like syndrome. Correct initial diagnosis may, therefore, be difficult if a bio-agent isn't suspected. EMS providers should be suspicious if large numbers of patients suddenly complain of flu-like symptoms and are all at the same stage of illness. Increase your suspicion if patients are concentrated in specific neighborhoods or if they present symptoms during times of the year when influenza isn't expected.
For the majority of agents, standard precautions are sufficient to protect responders and the general public from illness. A few agents that require more extensive precautions and have moderate to high human-to-human transmission will be discussed later.
When considering the diagnosis and treatment of patients affected by bio-agents, it's helpful to group the agents into categories that are based on etiology or threat. Bacterial agents include, but aren't limited to, anthrax, plague, tularemia, salmonella, cholera, glanders and brucellosis. Although they cause a significant amount of illness, mortality from these agents can be reduced if diagnosed and treated early with antibiotics.
Viral agents, such as viral hemorrhagic fevers (VHFs), smallpox and several equine enchephalitides, are much like the common cold; they can't be "cured," but one can manage victims effectively with supportive care.
Botulism, ricin, staphylococcal enterotoxin B and T-2 mycotoxin are examples of biological toxins that are known to be threats. Biotoxins are the naturally occurring toxins produced by living organisms. Victims of these agents require extensive supportive care.
The Centers for Disease Control and Prevention (CDC) classifies bio-agents into three categories based on the threat potential they present. Anthrax, plague, tularemia, smallpox, VHFs and botulism are considered high-priority agents.
AnthraxƒBacillus anthracis is a spore-forming bacteria found nearly everywhere in the world. Routes of exposure include cutaneous, inhalation and oral ingestion through the consumption of insufficiently cooked, contaminated meat from cattle, deer and other large herbivores.
The infective dose for anthrax is approximately 8,000Ï50,000 spores (inhaled). Anthrax has an incubation period of one to 60 days with most cases occurring one to six days post exposure.
Cutaneous anthrax is remarkable for the black eschar (scab) that develops at the site of infection. Treated early, little morbidity or mortality occurs.
Pulmonary anthrax is more severe. These patients initially experience a non-specific prodrome of flu-like symptoms, including fever, myalgia (muscle pain), headache, non-productive cough and mild chest discomfort. Symptoms may improve for a day or two before the abrupt onset of pulmonary failure, high fever and hemodynamic collapse. Chest X-rays may demonstrate a widened mediastinum, pulmonary effusions and edema. Approximately 50% of all cases are accompanied by hemorrhagic meningitis.
Early treatment and supportive care can reduce the mortality of pulmonary anthrax from nearly 100% to 45Ï75%. Gastrointestinal (GI) cases have a mortality rate of approximately 50%. Human-to-human transmission is possible by unprotected contact with cutaneous lesions. Therefore, standard precautions are advised.
Recommended antibiotics for the management of inhalational anthrax include ciprofloxacin or doxycycline for 60 days, along with the use of one or two additional antibiotics, such as rifampin, vancomycin, penicillin, ampicillin, chloramphenicol, imipenem, clindamycin or clarithromycin. Prophylactic therapy can also be administered for individuals believed to be exposed and includes the use of ciprofloxacin or doxycycline. In the United States, a vaccine is presently indicated only for those who work directly with anthrax, individuals who work with potentially infected animal hides, furs or meat, and military personnel. The vaccine is reportedly 93% effective in preventing illness.
PlagueƒFleabites or those of other arthropodal vectors are the most frequent mode of transmission of Yersinia pestis, the bacterium responsible for plague, to humans. The resulting infection most often results in bubonic plague, manifested by markedly enlarged and painful lymph nodes. Bubonic plague cannot be transmitted to others.
If the lymphatic system can't contain the infection, septicemic plague can result as the organism multiplies in the blood. Further spread to the lungs or direct inhalation of Yersinia pestis results in pneumonic plague, which can be easily transmitted to others. The incubation period for pulmonary exposures ranges from one to six days with an average of two to four days. Contact with infected blood and tissue can also spread the organism.
Pneumonic plague presents with sudden onset of high fever, headache, chest pain, malaise, cough and hemoptysis. Chest X-rays often demonstrate pulmonary infiltrates or consolidation. The pneumonia progresses rapidly, resulting in dyspnea, stridor and cyanosis. GI symptoms include nausea, vomiting, diarrhea and abdominal pain.
Death is frequently caused by respiratory failure and circulatory collapse. The mortality rate of untreated pneumonic plague is 90Ï100%. With appropriate treatment, mortality drops to approximately 5%.
Early treatment with antibiotics reduces mortality in already-infected individuals and reduces morbidity in those recently exposed. Recommended therapy is either streptomycin or gentamicin for 10 days. Alternate antibiotics include doxycycline, ciprofloxacin or chloramphenicol. Respiratory isolation may also be required for pneumonic plague patients. An N-95 mask or similar airway protection will prevent human-to-human spread of pneumonic plague. Research continues, but a vaccine likely won't be available for several years.
TularemiaƒThe bite of a vector (e.g., ticks, deerflies, mosquitoes), skin or mucous membrane contact with blood or tissue from an infected animal (e.g., rabbits, muskrats, squirrels) or ingestion of contaminated food or water can transmit the Francisella tularensis bacteria and cause tularemia. The bacteria can persist in cool, moist environments for extended time periods.
After an incubation period of one to 14 days, with an average of three to five days for symptom onset, disease resulting from intentional aerosol release would primarily cause typhoidal tularemia, which presents with fever, prostration and weight loss. Pneumonia is common, presenting with substernal discomfort and a non-productive cough, which may be fulminating (i.e., rapid, sudden, severe). GI illness presents with abdominal pain, nausea, vomiting and diarrhea.
An expected mortality rate of 33% without treatment can be reduced to less than 2% with treatment. Person-to-person transmission of tularemia has not been reported. Patients with known direct contact with aerools (aerosols) should be decontaminated with warm water and soap following clothing removal. Equipment and environmental decontamination can be performed with a hypochlorite solution that readily kills the organisms.
Treatment for tularemia includes supportive care and administration of either streptomycin or gentamicin. Alternative antibiotics include doxycycline, chloramphenicol and ciprofloxacin. Infected patients don't need isolation because person-to-person spread is unlikely.
SmallpoxƒWith the elimination of the natural spread of Variola major, the viral agent that causes smallpox, any occurrence of smallpox today would be a world health emergency.
After an average incubation period of 10Ï12 days, the illness begins with generalized fever, rigors, headache and backache. Severe abdominal pain and delirium are sometimes present, and patients suddenly appear very ill. Two to three days later, the rash appears and progresses over seven to 10 days.
Lesions progress from macules (small colored areas or spots) to papules (small, solid, raised pimple-like bumps) to vesicles (small sacs or blisters containing clear fluid) to pustules (small blisters generally filled with pus). The rash typically presents on the head and distal extremities (centrifugal distribution) and then spreads toward the trunk. Note the clinical differences between smallpox and chicken pox.
Approximately 10% of smallpox cases will present in either hemorrhagic or malignant form and have a more severe clinical course. Hemorrhagic smallpox has a shorter incubation period and is characterized by a severe, prostrating prodromal illness followed by hemorrhagic skin lesions. In the malignant form, the lesions remain soft, flattened and velvety to the touch.
During the incubation period, patients are non-infectious. Once fever and the onset of symptoms occurs, person-to-person transmission is likely from airborne droplet exposure or by contact with skin lesions or secretions.
Patients are considered more infectious if they are coughing or if they have a hemorrhagic form of smallpox. Although the risk of human-to-human transmission is high, spread can be effectively prevented by standard and airborne-droplet precautions (e.g., an N-95 mask). Keep all patients in isolation.
There is no "cure" for smallpox. Supportive care, along with antibiotics for treatment of occasional secondary bacterial infections, is the mainstay of treatment. Vaccinia immune globulin (VIG) is indicated for treatment of adverse events from the smallpox vaccine and may be administered as post-exposure treatment for those who cannot receive the vaccine. It's unlikely to be of much benefit to a patient already exhibiting symptoms of smallpox. Cidofovir is an antiviral medication that, in animal models, appears to protect against orthopoxvirus growth after experimental inoculation. It may be effective in treating smallpox (and adverse events from the smallpox vaccine), although it has never been used in humans for this purpose. The CDC considers it investigational and a second-line therapy.
The smallpox vaccine is very effective if there's a successful "take" (scarring at the administration site). Mortality is approximately 1% in infected individuals who have been previously immunized. Mortality rates are approximately 30% in unimmunized individuals. Individuals immunized more than 15 years ago are unlikely to have sufficient titers to prevent infection.
Post-exposure immunization is very effective in limiting morbidity and mortality from smallpox if administered early in the incubation period. It was this effectiveness that allowed the World Health Organization to perform "ring vaccination" and effectively eliminate the natural spread of smallpox in the 1970s.
Viral hemorrhagic fevers
Viral hemorrhagic fevers (VHFs) consist of a group of viruses that include the Arenaviridae, Bunyaviridae, Filoviridae and Flaviridae families. The incubation period of VHFs varies from two to 21 days, depending on the causative organism.
VHFs are a group of illnesses that disrupt capillary membranes and cause bleeding at multiple body sites. The primary route of exposure is by vector transmission or via body secretions. However, not all routes of exposure have been fully explained. After the incubation period, initial symptoms include high fever, headache, fatigue, abdominal pain, myalgia and prostration. In more advanced disease, hematemesis, bloody diarrhea, generalized mucosal hemorrhage, conjunctival injection, petechial rash, altered mental status and cardiovascular collapse can occur.
Case fatality rates of patients with VHF vary from less than 10% (dengue fever) to approximately 90% (Ebola). VHFs have the potential to be transmitted by fine aerosols, airborne droplets and contaminated body fluids. Human-to-human transmission is variable, and standard precautions, including airborne-droplet protection, are advised. Also recommended are patient isolation, strict use of personal protective equipment (PPE) and decontamination procedures (if necessary).
Treatment for VHFs is supportive. The antiviral drug ribavirin may shorten the course of those VHFs caused by arenaviruses. Yellow fever is the only VHF with an effective vaccine, which is required for visitors to endemic areas of South America and Africa. Vaccines for many other VHFs are in various stages of research and development.
BotulismƒAs the only biotoxin on the CDC Category A list, botulinum toxin excreted by Clostridium botulinum bacteria is considered one of the most lethal poisons known. Exposure routes include oral ingestion of contaminated foods, inhalation and open wounds. The most frequent accidental source of poisoning is the ingestion of improperly home-canned foods. Exposure during an incident of bioterrorism might also include inhalation of aerosolized particles or cutaneous contamination of open wounds. Incubation periods can range from six hours to 10 days with most symptoms occurring within 12Ï36 hours of exposure.
Botulinum toxin prevents the release of acetylcholine presynaptically, thus blocking neurotransmission. A characteristic descending paralysis results when individuals are exposed to botulinum. Multiple cranial nerve palsies (paralysis) are often the first symptoms noted.
Bulbar palsies are prominent early, with eye symptoms, such as blurred vision, mydriasis, diplopia and photophobia, in addition to bulbar signs, such as ptosis, dysarthria, dysphonia and dysphagia. Skeletal muscle paralysis follows with a symmetrical, descending and progressive weakness, which may cause abrupt respiratory failure. Deep tendon reflexes may be present or absent.
The mortality rate from botulism is 60% if untreated and less than 5% if appropriate supportive care is provided. This includes monitoring and respiratory support. Recovery takes months, and those who survive may have fatigue and shortness of breath for years.
A trivalent botulism antitoxin, available from the CDC, can be administered if laboratory confirmation is established. Although this may shorten the illness course slightly, recovery can still take months. Those who survive may have fatigue and shortness of breath for years. No preventative or prophylactic therapy for botulism poisoning currently exists.
PPE & decontamination
Standard precautions should be observed for all aspects of patient care for any of the known and confirmed Category A agents. Prevention of direct contact with all bodily fluids must include gloves and splash/spray protection for the eyes and face. Additional precautions should include gowns and hand-washing prior to and following patient contact.
In cases of pneumonic plague, smallpox and VHFs, the CDC recommends the use of airborne and droplet precautions. This includes the N-95 mask for responders and a surgical mask for patients. These PPE recommendations are applicable to all aspects of patient and postmortem care.
During an announced bioterrorism attack or if the agent is unknown, higher PPE levels may be recommended (Levels AÏC). Follow local protocols for appropriate PPE decisions.
In a known or announced exposure or if victims are contaminated with an unknown substance, use general decontamination principles. Remove all contaminated clothing and personal items. Perform a full body wash with water and soap, followed by a rinse. Decontamination may not be necessary if the patient has already bathed and changed clothes. Keep in mind that victims of bio-agents most likely won't present with symptoms until days after exposure.
Cleaning and disinfection of EMS equipment and apparatus can be accomplished by routine measures using approved disinfectants. Surfaces can be cleaned with a 10% bleach or phenol solution. Handle linens as with all other patientsƒexcept in cases of smallpox; these linens should be autoclaved prior to routine laundry procedures.
Response to a bioterrorism event or major disease outbreak will require the emergency response community and the media to work together to obtain and provide vital information, find and treat affected victims, and advise the public of appropriate actions to take. This includes all EMS agencies, fire and police departments, hospitals, clinics, physician groups, communications centers, and television and radio stations. EMS personnel must prepare to respond to such incidents and assist with disease surveillance, risk communication, and care and transport of patients.
Most victims of a bio-agent will present for treatment days after the exposure and may rapidly overwhelm the ability of EMS and hospital systems to provide care in a community. EMS providers should familiarize themselves with clinical indicators (i.e., signs and symptoms), patient management guidelines, and personal protective and decontamination measures to assist with identifying and responding to both intentional and unintentional infectious disease outbreaks.
Centers for Disease Control and Prevention:www.cdc.gov
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Geoffrey T. Miller, NREMT-P, is associate director for research and curriculum development for the Division of Disaster and Terrorism Preparedness and Division of Emergency Medical Skills Training at the Center for Research in Medical Education at the University of Miami School of Medicine. Contact him via e-mail email@example.com.
Joseph A. Scott, MD, FACEP, is an assistant professor, Division of Emergency Medicine and the director of emergency medical skills training at the Center for Research in Medical Education at the University of Miami School of Medicine.
Angel "AlÓ Brotons, EMT-P, is the associate director for operations and instructor development for the Division of Disaster and Terrorism Preparedness and Division of Emergency Medical Skills Training at the Center for Research in Medical Education at the University of Miami School of Medicine.
Obed Frometa, EMT-P, is the educational programs coordinator for the Emergency Medical Skills Training Division at the Center for Research in Medical Education at the University of Miami School of Medicine.
David Lee Gordon, MD, is a professor of neurology and medicine and assistant director of the Center for Research in Medical Education at the University of Miami School of Medicine.