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Hantavirus Infection:
Are Herpetoculturists at Risk?

by Richard Meyer, Jr.

But on January 20, 1994 a young man, David Rosenberg, 22, passed away. It appears Rosenberg had contracted this rare disease, a disease that is hosted by some species of rodents. Rosenberg had cleaned a warehouse owned by his father, and had inhaled large quantities of dust. As with many industrial warehouses, these had their share of rodents (basically an infestation.) Naturally, in the dust that Rosenberg inhaled were particles of dried rodent urine and feces.

Immediately after the article appeared in the local newspapers, I began to receive calls regarding the hantavirus infection. The calls came from rodent breeders and just the average person who feeds domestically bred rodents to their snakes and lizards. Was there a danger of them getting the hantavirus infection from these rodents?

I decided to find out exactly what the hantavirus infection was all about and could it affect those of us who raise and feed domestic rodents to our reptiles. I collected various newspaper articles, contacted workers at the Federal Centers for Disease Control and Prevention in Atlanta, Georgia (who were more than willing to speak with me and sent information regarding the hantavirus) and did research at the library.

What is the "hantavirus"?
The hantavirus infection is not a new disease, just a relatively uncommon one in the U.S. Until the spring of 1993, hantaviruses were chiefly seen in Asia and Europe. The hantavirus was first observed during the Korean War, when thousands of American GIs developed a mysterious disease. Scientists knew the disease was caused by rodents, but it was another 20 years before the virus was finally isolated.

The hantavirus is hosted by certain, but not all species of rodents. Each hantavirus strain seems to have a preferential rodent host. The Hantaan hantavirus (a river in Korea) is hosted by a field mouse, the Seoul strain (Korea) by a rat, the Puumala hantavirus in Europe is carried by the vole. In the U.S. the deer mouse (Peromyscus maniculatus) may be the primary host of the Southwestern hantavirus (a.k.a. Muerto Canyon strain), the Florida strain is carried by the cotton rat. Other rodents which have been found to be carriers of the hantavirus infection through blood tests include the pinon mice (P. truei), the brush mouse (P. boylii), and western chipmunks (Tamias spp.). While none of theses rodents live in the Northeast, P. luocopus, a close relative of the deer mouse, is the most common house mouse in the Northeast U.S. Other small mammals may also be carriers of the hantavirus. Seven strains of hantavirus have been identified to date. Some strains of hantavirus attack the kidneys, while others attack the respiratory system. This seems to be the case of David Rosenberg (the results are still pending as to which strain led to his death.)

How does the hantavirus spread?
The hantavirus is transmitted by a rodent host. Generally, humans have gotten the virus after they have inhaled particles of dried rodent saliva, feces and urine. The virus may be transmitted to humans when dried materials contaminated by infected rodent excreta are disturbed (i.e. dust), introduced to broken skin, the eyes or possibly when ingested in contaminated food or water. The disease may also be transmitted when people are bitten by infected rodents. Biting may be the main mode of transmission of the virus from rodent to rodent.

Insects are not known to play a role in the transmission of hantaviruses and to date there are no cases of person to person transmission. While cats and dogs are not known to be hosts of the hantaviruses they may bring infected rodents (i.e. when they catch a mouse or rat) into contact with humans.

The hantavirus does not seem to cause any illness in its rodent hosts. The duration and period of maximum infectivity has not been determined.

What are the symptoms of the hantavirus?
There are various symptoms caused by the hantavirus, many of these are flu like: high fever, cough, headaches and nausea. As the disease progresses other symptoms will begin to appear, shortness of breath as the lungs fill with fluid, which may lead to respiratory failure.

Who is at risk?
Generally, the people who face the greatest risks are those whose occupation or leisure activities brings them into contact with rodents or the infected areas rodents inhabit.

Are people who breed domestic rats and mice potential victims of the hantavirus? After numerous conversations with county, state and federal workers, the consensus I got was, there is a possibility that these people are at a higher risk than the general population of contracting the hantavirus. But since the hantavirus is relatively rare, this possibility is quite small. With some basic precautionary measures these people should be at little risk. People who only purchase their mice or rats for feeding are at an even smaller risk.

The one thing I did find out was the "freezing" (i.e. frozen rodents) does not break down the virus. The virus has survived prolonged exposure to freezing temperatures, as low as -60°F. Heat will destroy the virus, but who is going to bake their food rodents (isn't that an appealing thought -- "Rodent Under Glass".)

Preventing the Hantavirus
There are some basic steps that you can take to help prevent the hantavirus:

1. Try to make your rodent breeding area or home as rodent proof as possible. Prevent wild rodents from entering these areas. Set traps, close up any holes ¼" or larger where "wild" rodents may enter by using sheet metal or steel wool.

2. Do not leave uncovered food or beverages in your breeding room or home. Make sure the food is kept in rodent proof containers.

3. Keep the breeding room clean. Dispose of all soiled bedding after cleaning the cages. Sanitize the cages and the areas around the cages. When cleaning around the cages (i.e. floors, shelves) it is a good idea to wet down the areas with a disinfectant then clean them. This will help keep down airborne particles (a major way the hantavirus spreads.) The hantavirus has a lipid (fat) envelope which is broken down by most disinfectants (i.e. dilute hypochlorite "bleach" solutions, detergents, ethyl alcohol (70%), and most general household disinfectants.) For a bleach solution use a 32:1 ratio of water to bleach (i.e. 32 oz. of water to 1 oz. of liquid bleach.) Spray this on the cages, wipe down, then rinse with clean water.

4. Disinfect your hands after handling any rodents. Soap or a mild bleach solution are highly effective. Do not touch or rub your eyes when handling rodents. Keep your hands away from your face as well. If you have cuts on your hands, make sure you clean them immediately after handling the food animals, or wear gloves. If you get bit by a rodent flush the wound with betadine, hydrogen peroxide or any other good disinfectant.

5. Keep spring loaded traps in your rodent breeding room. Dispose of any wild rodents by burning or in covered trash containers. Disinfect any traps which catch rodents.

Need more information on the hantavirus?
If you feel you have come in contact with the hantavirus, contact your local physician. If you would like more information concerning the hantavirus, there are a few places you can call. You may call your local or state health departments, or you might try the Federal Centers for Disease Control and Prevention (Atlanta, GA) Call (800) 532-9929 for a recorded message on the hantavirus, followed by an operator, who will connect you with a spokesperson at the FCDCP. They will mail you a booklet on the hantavirus upon request. In conclusion, I feel that if certain precautions are followed, the hantavirus should pose little problem for the herpetoculturist.