Technical Bulletin 111

TECHNICAL BULLETIN 111

HANTAVIRUS AND ARENAVIRUS:

Occupational Assessment,

Exposure and Building Remediation

Picture courtesy of CDC/Dr. Loren Hetai

BY: PATRICK J. MOFFETT REA, CHMM

TABLE OF CONTENTS:

TABLE OF CONTENTS...... Page 2

Purpose for this Article...... Page 3

Where Does Hantavirus Come From?...... Page 4

History of the Disease and Its Consequences...... Page 5

Employee Symptoms...... Page 5

Employee Treatment...... Page 6

Hantavirus and Arenavirus Differences...... Page 6

Calling Your Local Agency...... Page 8

Compliance and Regulations...... Page 9

Accepted PPE for Cleanup...... Page 9

Decision Logic Tree...... Page 10

Risk Management...... Page 13

Professional Cleanup...... Page 14

Closing Comments...... Page 20

About the Author...... Page 21

HANTAVIRUS AND ARENAVIRUS

PURPOSE FOR THIS ARTICLE

A previous version of this article was published for western U.S. smoke and fire damage restoration contractors (restorers) who are exposed to mice populations. Restorers are cleaning and deodorizing homes and businesses from community-wide wildfires. Because of wildfires, the northern and southern California population of field rodents migrate into the surrounding building community because of a lack of food and shelter. While hantavirus or arenavirus is in every county in California, the viruses arealso present in most U.S. states and Canadian provinces.

Restorers are unknowingly exposeemployees, temps and subcontractors to dangerous health situations when they enter rodent infected buildings. It is believed that restorer’s employees are facing higher exposure levels of dust potentially having hantavirus and the new world arenavirus when they crawl in attics and under the buildings or anytime they disturb settled dust that can easily become airborne.

This article is meant to advise restorers thatpotential exposure to hantavirus and arenavirus cannot be seen just because you see settled dust. The main indicator of the presence of rodent borne viruses is seeing their feces and urine or their nesting and other physical signs. Also, this article is designed to create a heightened awareness that a risk management processes must be completed before allowing employees to work in and under potentially contaminated buildings. Meaning, anytime restorers crawl into and under buildings, appropriate personal protective clothing is required.Working around buildings where mice or rat droppings and urine is present requires immediate risk management decisions to be made. Exposure to rodent-borne viruses seldom occurs but when it does, the exposure results to employees are a high fatality rate.

WHERE DOES HANTAVIRUS COME FROM?

“Hantavirus, a distant cousin of the Ebola virus, is a rare, serious respiratory disease. The earliest identified case in the United States was in 1975. This disease gained national attention in September 1993 when 17 people died from it in the Four Corners area of the southwestern United States where Arizona, New Mexico, Colorado, and Utah meet” (Oregon OSHA, Standards and Technical Resource Section).

The primary disease-borne rodent is the common deer mouse that is found in every county in California and many other U.S. states and provinces in Canada. The deer mouse (Peromyscus maniculatus) cannotbe easily distinguished from other mice and small rats; neither can we identify the difference between virus infected and unaffected feces and urine just by looking at it. “There is no way to tell an infected rodent from a non-infected rodent by visual inspection. It is also difficult at times to differentiate deer mice from other rodents. Therefore, all rodents should be treated as potentially infectious and regarded with proper precautions”(County of Riverside California, Office of Environmental Health).

It is believed hantavirus that is affecting the deer mouse population is not new and it has been among the deer mouse population for a long time. Only recently have scientists been able to identify the virus (CDC). Hantavirus pulmonary syndrome (HPS) is a recently recognized viral zoonosis. The first recognized cases were caused by a newly described hantavirus – Sin Nombre virus (previously known as Muerto Canyon virus) that was isolated from Peromyscus maniculatus (deer mouse) (American Journal of Medicine Jan. 1996).

While the deer mouse (Peromyscus maniculatus) that spreads hantavirus is the most common human vector, the first evidence that New World rodents spreading the arenaviruses occurred in Los Angeles and Orange counties and northwestern San Diego County, and the first evidence that Peromyscus and Reithrodontomys rodent species are naturally infected with New World arenaviruses into other mice populations including rats which carry arenaviral infections.

Besides the California mouse Peromyscus californicus, other mice and rats carry dangerous viruses including the white-throated wood rats in Colorado, white-footed mouse in New York State and Pennsylvania, house mice (Mus musculus) in Maryland, wood rats in Arizona, Utah, Texas and New Mexico, rice rats in Texas to cotton rats in Florida. While the deer mouse isn’t known tolive in Louisiana, the vector for causing the Bayou virus, also a hantavirus, possesses a different rodent reservoir vector yet to be discovered.

HISTORY OF THE DISEASE AND ITS CONSEQUENCES

Hantaviruses are a family of four previously-identified viruses found in rodents. Besides the U.S., these viruses cause serious health problems in other parts of the world including the Far East and Scandinavia; and it was a source of illness affecting American troops in 1952-53 during the Korean Conflict.

The virus responsible for U.S. deaths in the past 50 years is a fifth strain that is apparently unique to North America. The North American strain attacks the lungs instead of the kidneys as the other four strains do. The North American medical term for the hantavirus disease is called Adult Respiratory Distress Syndrome (ARDS) and it is also known as Hantavirus Pulmonary Syndrome (HPS). “The causative agent of HPS is the Sin Nombre virus,a previously unknown hantavirus that was both documented in individuals with HPS” (Los Angeles County Public Health).

Hantaviruses have evolved with specific rodent hosts such as the Deer Mouse. In humans, infection can result in severe complications and a high rate of mortality. Worldwide, there are over 100,000 clinical cases per year of hantavirus disease. The primary syndrome caused by hantaviruses in the New World is Hantavirus Pulmonary Syndrome (HPS) which has a mortality rate of approximately 45% (Pacific Southwest Regional Center of Excellence).

Infected rodents shed live virus in saliva, feces and urine. Humans are infected when they encounter and inhale aerosolized microscopic particles that contain dried rodent urine or feces.The U.S. and Canadian strain appears to be extremely dangerous to humans who are infected with it. More than half of the population known to be infected by the virus dies. The actual mortality rate is likely to be lower because less severe cases probably go undetected and diagnosed. While hantavirus is dangerous, its means of transmission is so unusual that most people are very unlikely to encounter the virus, however, it poses little threat to the general California population but it poses a higher rate of infection to workers who must work in and clean up rodent infestations or work in extremely dusty buildings.

EMPLOYEE SYMPTOMS

Illness is typically detected in one to two weeks but the range may be as wide as a few days and up to six weeks. The Adult Respiratory Distress Syndrome(ARDS) initially appears similar to the flu where high fever, muscle aches, coughs and headache occurs. However, in some cases after several days, respiratory problems increase where the lungs fill with fluid and the person diesfrom respiratory failure.

EMPLOYEE TREATMENT

At the moment, it appears there is no generallyeffective treatment for hantavirus. Physiciansexperiment by administering ribavirin, an antiviral drug, to infected patients. Too few people have been treated to draw any conclusions about the ribavirin treatment’s effectiveness.

Persons with arenavirus may fair much better as far as clinical treatment is concerned. There is presently only one vaccine for arenavirus infection; the live attenuated Junin Candid 1 vaccine. In a double blind study in 6500 male agricultural workers in the endemic area, the vaccine was found to be effective and without adverse effects. The Candid 1 vaccine is licensed as an investigational new drug in the U.S. (Pacific Southwest Regional Center of Excellence).

HANTAVIRUS AND ARENAVIRUS DIFFERENCES

Common Vectorborne Routes

To a layperson being infected by one virus over another is not significant. They are concerned about health implications and what can be done to make them well again. Both hantavirus and arenavirus are generally spread to humans by rodent contact that include inhalation of aerosolized droplets of urine and feces and the respiratory saliva secretions of rodents (CDC). Other means of infection include but are not limited to the inhalation of dust or other organic matter contaminated with infectious virus and contact of infectious materials.

Hantaviruses occur in wild rodents throughout the world,who shed it throughout life in urine and feces. Transmission occurs between rodents. Transmission to humans is through inhalation of aerosols of rodent excreta. Recent evidence suggests human-to-human transmission may occur on a rare occasion (MERCK).

Hantavirus and Arenavirus

As already stated, hantavirus pulmonary syndrome (HPS) is a frequently fatal rodentborne viral zoonosis. The virus family Arenaviridae, genus Arenavirus, includes 3 North American species. The North American species are Bear Canyon virus (BCNV), Tamiami virus (TAMV), and Whitewater Arroyo virus (WWAV). The human health importance of the North American arenavirus species has not been rigorously investigated. Specific members of the subfamilies Neotominae and Sigmodontinae in the rodent family Cricetidae are the principal hosts (reservoirs) of the hantaviruses known to cause HPS in North America and the 3 North American arenaviruses.

CDC Says:

The rodent hosts of arenaviruses are chronically infected with the viruses; however, the viruses do not appear to cause obvious illness in them. Some Old World arenaviruses appear to be passed from mother rodents to their offspring during pregnancy, and thus the virus remains in the rodent population generation after generation. Some New World arenaviruses are transmitted among adult rodents, likely via fighting and inflicting bites. Only a portion of the rodents in each host species is infected at any one time, and in many cases only in a limited portion of the host’s geographical range. The viruses are shed into the environment in the urine or droppings of their infected hosts.

Human infection with arenaviruses is incidental to the natural cycle of the viruses and occurs when an individual comes into contact with the excretions or materials contaminated with the excretions of an infected rodent, such as ingestion of contaminated food, or by direct contact of abraded or broken skin with rodent excrement. Infection can also occur by inhalation of tiny particles soiled with rodent urine or saliva (aerosol transmission).

The types of incidental contact depend on the habits of both humans and rodents. For example, where the infected rodent species prefers a field habitat, human infection is associated with agricultural work. In areas where the rodent species’ habitat includes human homes or other buildings, infection occurs in domestic settings.

Some arenaviruses are associated with secondary person-to-person and nosocomial (health-care setting) transmission. This occurs when a person infected by exposure to the virus from the rodent host spreads the virus to other humans. This may occur in a variety of ways. Person-to-person transmission is associated with direct contact with the blood or other excretions, containing virus particles, of infected individuals. Airborne transmission has also been reported in connection with certain viruses.

Contact with objects contaminated with arenaviruses materials, such as medical equipment, is also associated with transmission. In these situations, use of protective clothing and disinfection procedures (together called barrier nursing) help prevent further spread of illness. In the environment the public and workers are being warned about coming in contact with rodent infestations or dusty, dirty and vacant buildings. Also, the public is being warned about contact with dusty garages, storage areas, attics and crawlspaces.

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Arenaviruses are rodent-borne enveloped RNA viruses that are now classified as potential bioterrorism agents by the Centers for Disease Control and Prevention (CDC). Importantly, five members of the arenavirus family are capable of causing severe hemorrhagic fevers in humans. They are considered Category A bioterrorism agents because of the combination of high morbidity/mortality rates and airborne transmission (Pacific Southwest Regional Center of Excellence).

CALLING YOUR STATE AGENCY OR YOUR INDOOR ENVIRONMENTAL PROFESSIONAL

In California if you are concerned about signs of rodent feces and urine contact your local County Department of Public Health Agency and more importantly, their division called Environmental Health Services. Sometimes Environmental Health Services will refer you to another department or division called Vector Control. Don’t think you are getting the run-a-round because each bureau has a different function and responsibility. In answering medical questions all agencies will tell you to seek qualified advice from your medical doctor or emergency medical assistance if you think you have been infected.

More than likely an environmental health enforcement officer will not come out as a first responder to your situation unless the community is known to have an active outbreak of hantavirus or arenavirus. Generally the County Vector Control (rodent trapping agency) will come out first and see what is going on. If you are already working in a building having rodent droppings and urine, your employee exposure to disease causing viruses may have already occurred by the time Vector Control gets there.

County Vector Control officials and even the county environmental health enforcement officer is limited on what they can say or do, other than to tell you to stay out of rodent infested environments, and if you attempt to cleanup rodent feces and urine yourself, you should do so with proper precautions such as those outlined in this article.

Hantavirus bulletins and fact sheets will be mailed to you or you can pick them up from Vector Control agencies. For example:

The County of San BernardinoEnvironmental Healthsays: “Deer mice are the most abundant, widely distributed andprobably the most common carrier of the virus. It is difficult toproperly identify [deer] mice. All rodents should be avoided.”
Chris Conlan, the San Diego County of Environmental Health’s supervising vector ecologist said in a recent article “a broom plus mice droppings equals bad.”
The County of Riverside Environmental Services Division says, “Deer mice are abundant throughout California, especially in rural and semi rural areas. These mice will readily enter people’s homes, work places, and other buildings for food and shelter. You can tell if a building is rodent infested by sighting live mice (especially at night) or observing carcasses, droppings, urine stains, nests, or signs of rodent chewing.”
The County of Los Angeles Environmental Health says, “…late spring and summer is the usual peak period for hantavirus infection.”

For a live video broadcast of hantavirus issues go to:

COMPLIANCE AND REGULATIONS

Outside of a research or clinical laboratory setting, hantavirus and arenavirus are not believed to be a regulated state of Californiabiohazardous waste. However, the improper handling and management of potential hantavirus and arenavirus contaminated materials; or a willful disregard for protecting the public and cleanup workers, may fall under different state jurisdictions such as DOH, DEHS, EPA and OSHA.

ACCEPTED PPE FOR CLEANUP AND SANITIZING

Restorers who are trained in remediating fire damage, chemical, sewage and water damage are expected to be some of the more knowledgeable and skillful cleanup specialists. As such, they will have the equipment necessary to vacuum up, clean and sanitize and dispose of rodent infected waste.

Once employees (trained technicians) are informed about the hazards they face, the restorer can start with the cleanup once technicians have appropriate PPE and engineering controls are established.

Appropriate PPE in buildings include but is not limited to:

Minimum of a P-100 Face Mask

Disposable Tyvek-like (asbestos-grade) full body protective clothing

Slip-on Tyvek-like booties

Double glove with inner glove being a thin surgical-like latex glove; rubber Playtex-like outer glove with cuffs

Non-fog goggles that are slash resistant