Staying Safe From High-Consequence Infectious Diseases

The scourge of COVID continues and in some places is worse than ever. But COVID isn’t the only infectious disease that can threaten EMS providers, and they need knowledge and tools to deal with a range of disease threats both common and rare.

Emergency physician Alex Isakov, MD, MPH, FAEMS, discussed some big threats and how to deal with them in a Wednesday session at EMS Today, “High-Consequence Infectious Disease Awareness: Protecting the EMS Healthcare Worker.” The show is being held virtually this year because of COVID.

EMS providers deal daily with infectious diseases in patients, Isakov noted, and are well trained for it. They are protected by a combination of standard and transmission-based precautions. A general strategy for infectious disease threats of high consequence—that is to say, that can cause death or severe illness—involves three I’s: identify, isolate, and inform. Without a framework to deal with such threats, Isakov stressed—especially the rarer ones—healthcare providers can risk exposure.

COVID-19

Naturally COVID, and its currently surging delta variant, occupied a major portion of the presentation. Eighteen months into the pandemic, we’ve identified its basic parameters: transmission through respiratory droplets and suspended droplet nuclei; not as transmissible as, say, TB, but even common conversation can create droplets. Incubation takes 2–14 days, typically around five, maybe less with delta. Alarmingly, victims can be contagious before or without showing symptoms. Cases, hospitalizations, and deaths in the U.S. are now overwhelmingly among those who haven’t received a COVID vaccine. COVID’s total U.S. death toll is around 635,000.

Identification of COVID cases in 9-1-1 responses rests on knowing its indicators and patients’ potential exposure history. The virus’ signs and symptoms are nonspecific, but the most unique is a frequent loss of taste and smell. Call-takers have an important role in identification alongside field crews.

Isolation of COVID patients entails masking the patient and limiting personnel on scene, caution with aerosol-producing procedures, separation of the ambulance’s driver and patient compartments, introduction of fresh air with the exhaust fan on high, exhaust filters on ventilation equipment, and use of PPE: standard plus contact plus airborne and eye precautions for care providers.

The inform element is fairly standard across high-consequence infectious disease threats: let other responders know what you’ve found or suspect; inform your receiving facility in advance; and notify public health authorities per protocol.

While much more transmissible than the original COVID, the delta variant isn’t the last we’ll see, Isakov warned. Others may be more or less transmissible and virulent.

Middle Eastern Respiratory Syndrome

MERS, which emerged in Saudi Arabia nearly a decade ago, is a novel coronavirus too—one that likely leapt to humans from camels. The good news is that MERS has remained fairly geographically isolated; the bad news is that it has a case fatality rate of around 34%.

MERS isn’t terribly common; as of June 2021 there had been only 2,574 lab-confirmed cases, and only two in the U.S. (both victims isolated and recovered). But a cluster in South Korea in 2015, resulting from travel to the Arabian Peninsula, resulted in 185 cases, 35 deaths, 700 schools closed, and more than 3,000 quarantined.

Travel history is absolutely key to identifying MERS—relevant countries include those in the Arabian Peninsula and neighboring. Isolation looks similar to COVID, and treatment is supportive.

Influenza

We deal with flu every year, and each year around 50,000 Americans die from it. Those at elevated risk include the older and young, pregnant, and chronically ill. Novel influenza strains are possible, and in fact public health experts had expected the next pandemic would involve that, not a coronavirus.

Recent novel flus have included bird flus (H7N9, H5N1), swine flu (H3N2v), and the 2009 H1N1 pandemic. They typically don’t spread easily from person to person but can have high case fatality rates in humans. H7N9, for instance, has occurred in multiple waves over the last eight years, resulting in more than 600 deaths, with a CFR of 39%.

Standard and droplet precautions are sufficient for typical influenza, but with novel flu—again, travel history to an affected area is key—may also trigger contact, airborne, and eye precautions. Novel flus can easily become pandemics due to efficient spread and lack of immunity.

Viral Hemorrhagic Fevers

The best known of the VHFs may be Ebola, an outbreak of which in West Africa in 2014–2016 resulted in more than 28,000 cases and spread to the U.S. Across affected countries case fatality rates for this frightening disease range from 42%–66%.

The Marburg virus, which reappeared this month in Guinea, is similar to Ebola in many ways, with the exception that there’s no vaccine for it. Following the last Ebola outbreak, a vaccine for one strain (Ervebo) was developed and FDA-approved.

Travel history to Africa is the identification key here, and diarrhea is a common symptom of VHFs. It is important with these patients to prevent unprotected exposure to all bodily fluids. Standard, contact, droplet, and airborne precautions are warranted—N95s, face shields, double gloves, the works—with particular attention to protecting skin breaks and mucous membranes.

Along with fellow responders, the receiving facility, and public health authorities, notify the relevant chain of command in suspected VHF cases for activation of special procedures or resources. Care again is supportive.

Hierarchy of Controls

Isakov cited portions of NIOSH’s hierarchy of controls for considering these types of EMS responses and viral hemorrhagic fevers in particular. The first level relevant to prehospital care is the third overall, engineering/environmental controls—isolating workers from the hazard. In the ambulance that means separating the patient and driver compartments, fresh air in both, the patient compartment exhaust on high, and internal draping for “wet” cases like VHF patients with vomiting or diarrhea.

The next/fourth level is administrative controls—changing the way people work. With VHFs that includes limiting use of sharps and aerosol-producing procedures, prepping the patient with a surgical mask, impervious suit or sheet, and possible undergarment for diarrhea; and distancing for nonessential personnel.

The final level of the hierarchy—and least effective on NIOSH’s inverted pyramid—is PPE. With VHF cases it can vary from suspicion to confirmation; abide by CDC guidelines and use checklists and trained observers to ensure safety.

Recovery entails cleaning and disinfecting vehicles, managing waste, coordination with public health, and surveillance of crews for one incubation cycle.

Additional Resources

• CDC’s Infectious Disease National Centers
• EMS Infectious Disease Playbook
• National Emerging Special Pathogens Training and Education Center

John Erich is the senior editor of EMS World.