The microorganism that causes anthrax, the bacterium Bacillus anthracis, has infected people and animals since ancient times. Even though anthrax is rare, it is a severe infectious disease with a death rate ranging from 25% to 80% if medical treatment is not sought early. According to the Centers for Disease Control and Prevention, anthrax is one of the most likely agents to be used in a biological attack, because the anthrax bacteria exist in the natural environment, can be easily disguised in powders, sprays, food or water, and have been previously used as a biological warfare agent.
Anthrax spores are difficult to kill, as they can remain viable in the environment for decades. When the spores are inhaled by humans or animals, the bacteria awaken and reproduce to a disastrous effect.
If terrorists use anthrax as a bioagent on a ship or in a harbor, the U.S. Coast Guard must decontaminate the impacted area as quickly as possible to reduce the threat to personnel and civilians, while remaining ready to do its mission. The project Analysis for Coastal Operational Resiliency (AnCOR) aims to find the best, safest methods to decontaminate Coast Guard bases, stations, and vessels. The project is a partnership of the Department of Homeland Security (DHS) Science and Technology Directorate (S&T), the U.S. Environmental Protection Agency (EPA) and the Coast Guard. AnCOR, which started in 2018, focuses on addressing the wide-area release of a biological agent such as anthrax and uses non-pathogenic anthrax-like spores or anthrax surrogates in its studies and field demonstrations.
“The U.S. Coast Guard is charged with protecting the nation’s coastlines and waterways, including aiding the boating public,” said Don Bansleben, S&T Program Manager for AnCOR. “It is important that the Coast Guard continues mission essential functions, even in a contaminated environment.”
S&T, EPA and Coast Guard conduct first decontamination field test
The first major AnCOR field test took place at the Davie campus of the University of Florida in early 2020 and involved decontaminating a Coast Guard boat contaminated with non-pathogenic, anthrax-like spores. Three types of surrogates were used: B. anthracis Sterne strain (a harmless anthrax strain used for vaccination), B. atrophaeus var. globigii and B. thuringiensis subsp. kurstaki. Before this field test, EPA developed and tested different decontamination methods in a laboratory to see how effective they are on various types of surfaces found on Coast Guard boats - marine grade aluminum, glass, seat material, marine grade carpet, anti-skid material, and bumper material. To test the methods, EPA scientists prepared one-inch-diameter samples from those materials and contaminated them with spores from the three non-pathogenic surrogate species.
“EPA is supporting DHS S&T and the Coast Guard because of our extensive experience and knowledge in this area,” said Shannon Serre, a Chemical Engineer at EPA. “We've been working on decontamination of anthrax spores since 2002.”
Over the course of three weeks, three different decontamination methods were tested on a retired 25-foot Coast Guard response boat. EPA researchers and Coast Guard teams taped squares on 11 different surfaces on the boat—marine grade aluminum, cabin windows, seating, flooring, electronics, deck, motors, etc.—where they placed spores from the two non-vaccine strains of bacteria.
During each decontamination test, participants in protective gear followed the following steps:
Sampled the contaminated areas and then decontaminated the whole boat using three approaches.- Took post-decontamination samples to check for spores that survived.
- Checked if the boat electronics were still operational after the decontamination step (new electronics were installed between each test).
- Reset the boat and sent the samples for analysis.
During each decontamination round, participants sprayed the outside of the boat with pH modified bleach. Then, they tented the boat by wrapping it in plastic for the fumigation or fogging step. Each of the three decontamination rounds had different methods:
- First round: Participants fumigated the boat with methyl bromide gas for 48 hours and then removed the gas and captured it using barrels filled with activated carbon (methyl bromide is an ozone-depleting chemical and is not safe to be released in the atmosphere).
- Second round: Participants used household humidifiers to distribute hydrogen peroxide inside the wrapped boat and let it dwell for four days.
- Third round: Participants conducted fogging with peracetic acid (a disinfectant), which was left to work for 18 hours.
Results from this study will be published in a report later this year and will provide data on the efficacy of the decontamination approaches as well as cost considerations. The preliminary findings showed samples taken after the methyl bromide and peracetic acid decontamination rounds contained no viable spores; and after the hydrogen peroxide decontamination, some samples contained viable spores.
History of anthrax threats underscores need for AnCOR
“We are responsible for protecting U.S. Coastal areas,” said Dana Tulis, Director, Emergency Management at the Coast Guard. “AnCOR is important for the Coast Guard to cleanup contamination but also to ensure the Coast Guard’s assets and property are safe, so that we can keep the people we rescue safe.”
The Coast Guard has been concerned about biological attacks since 2001, when letters with anthrax spores were sent to two U.S. senators and two news agencies. This led to 22 people getting sick and five deaths. EPA disinfected the building where one of the letters was delivered.
“We pick anthrax because those spores are the most difficult to decontaminate, very persistent and toxic,” said Tulis. “If we can successfully decontaminate B. anthracis, we can decontaminate less toxic biological agents.”
The Coast Guard wants to be prepared if someone releases anthrax spores near water, as many of the country’s major metropolitan areas (e.g. New York, San Francisco, Los Angeles, Chicago, Boston, Miami, New Orleans) are along, or near, bodies of water.
This isn’t the first time that S&T and EPA worked together on an anthrax decontamination project. Several years ago, the two agencies embarked on a similar effort—the Underground Transport Restoration project—for the New York City subway system, which included a field exercise involving the decontamination of the subway after a simulated anthrax attack. AnCOR is a continuation of joint S&T-EPA projects focused on recovery from attacks with chemical or biological agents.
Future AnCOR milestones and other upcoming joint EPA and S&T projects
S&T, EPA, and the Coast Guard are planning to conduct a wide-area decontamination field test in October 2021 at a venue with similar properties as a Coast Guard station (storage buildings, boats, vehicles, and paved and non-paved surfaces). The purpose of this test will be to test and evaluate under realistic conditions decontamination options on various types of outdoor surfaces (porous and non-porous surfaces, including vegetation).
“We will be looking at how to sample for an event like that, what methods are suitable for decontaminating objects in outdoor areas, including grassy fields,” said Bansleben. “We hope that what we learn from these AnCOR tests will ultimately be applicable not only for an anthrax event but for decontamination after other types of biological events, including the easier-to-disinfect COVID-19 virus.”
AnCOR is scheduled to end in 2023 with a guidance document, prepared by EPA on decontamination and recovery from a biological event.
“We want to minimize exposure and maximize the response to a biological event quickly; and by doing all this work upfront with S&T and EPA, we will know exactly what decontamination methods work,” said Tulis. “Because a biological event is life-or-death, having the knowledge and experience upfront is critical.”