Hantavirus Awareness on the Farm
Maxine Kinne

A local television news feature about hantavirus sent me poking through the material saved for this article, including a 10-page report from the Center for Disease Control and Prevention (CDC) in Atlanta.

Hantavirus has been recognized in Asia and Europe for many years, but the first U.S. cases were documented in 1993 when several people in the Southwest died from a mysterious respiratory ailment. Earlier cases here may have gone unrecognized as the symptoms differ from the hemorrhagic Asian strain. Since the Four Corners outbreak, cases have been reported in a majority of states from border to border.

The flu-like symptoms generally follow a pattern with rapid onset of fever, headache and muscle aches followed by breathing difficulty, bleeding, kidney failure, shock, and death in most cases. According to the CDC, rural residents, workers, visitors and farmers are among the highest risk group, and they encourage people who develop abnormal respiratory symptoms from 14 to 45 days after possible exposure to contact their physician.

Several varieties of rodents and western chipmunks carry the virus, most notably the deer mouse which lives across most of North America. The virus apparently does not cause disease in them or in farm animals. As rodent populations increase, so do the number of those potentially carrying the disease. People are infected by inhaling dust containing dried urine and feces from infected rodents and possibly by handling dead rodents. The virus is also infective through skin wounds or the eye membrane, and it can be ingested in contaminated food or water.

For every reproductively amazing rodent you see, there are 10 others you don't. After an average gestation period of 22 days, the female bears up to 12 pups and rebreeds 3-4 days later. Sexual maturity occurs in the offspring at 3 months old and reproduction snowballs after that. Each female can have hundreds of offspring each year.

It's better to feed barn cats than a zillion mice. Keep at least one good mouser. We didn't have an outside cat for many years, and mice actually came out to watch me milk and wait for spilled. Our first barn cat had a feast!

With good mousers I hesitate to use poisoned bait for fear they'll get into it or catch and eat poisoned mice. Bait is very palatable, and other animals find it appealing. If you do use bait, use self-enclosed bait stations where rodents travel and congregate. Make sure no children or animals have access to them. Be very careful with poisoned bait and follow the bait label directions!

A variety of traps are available. Even though spring-loaded traps that kill rodents outright are icky to deal with, they're cheap and reliable. Place the traps where animals and children do not have access to them. I found that using peanut butter as bait worked very well. When you get the peanut butter smeared and stuck where the bait is supposed to go, rodents can't extract it easily enough to escape. Should the bait disappear without springing the trap, work with the trap to provide a better hair-trigger action.

The CDC recommends using peanut butter as bait in mechanical traps. Further, they say, "Wear rubber or plastic gloves while handling rodents and contaminated traps. Place the carcasses in a plastic bag containing a sufficient amount of a general-purpose household disinfectant (or 3 tablespoons bleach per 1 gallon of water) to thoroughly wet the carcasses. Seal the bag and bury it in a 2- to 3-foot-deep hole or burn it. If burying or burning are not feasible, contact your local or state health department about other appropriate disposal methods. Rebait and reset all sprung traps. Before removing the gloves, wash used traps in the bleach solution, then wash gloved hands in the bleach solution then in soap and water. Thoroughly wash hands with soap and water after removing the gloves."

The Victor Tin Cat or other non-lethal traps will leave you with some regret. Once you capture anything, it must be drowned. Then the soggy corpses have to be disposed of. If the trap isn't emptied frequently, the hungry mice turn cannibalistic. This mess is even worse than the waterlogged carcass scenario, and you will seriously consider pitching the whole works out into the street.

As much as possible, reduce rodent shelter and food and water sources within 100 feet of the house, barns and other outbuildings. Clean up grain spills and store grain in rodent-proof metal containers. Store hay on pallets and consistently use traps or bait in the space underneath. Elevate woodpiles and other stacked items. Cement foundations or three inches of gravel may discourage rodent burrowing. Maintain a continuous rodent control program.

Some cases of hantavirus have been associated with cleaning barns and other outbuildings; disturbing rodent-infested areas and burrows while hiking, camping,, planting or harvesting crops; and having wild rodents in the home. The CDC recommends wearing an approved respirator while removing soiled barn bedding, sweeping or otherwise stirring up dust due to airborne virus contamination. Most of us probably won't go to the expense and hassle of buying and wearing an approved respirator, but the CDC encourages you to do so if you are in an area that has had a confirmed case of hantavirus. In these areas, it might also be wise to avoid eating, drinking and smoking in or near the barn.

Rodents can carry other diseases that affect both humans and their farm animals. The deadly threat of hantavirus may force us all to make a serious attempt to reduce the number of rodents who call our farms home.

Where is the Pied Piper of Hamlin when you need him?



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