What PMPs Need to Know About Hantavirus

Using your knowledge could lead to add-on services.

By Heather Gooch
Managing Editor

Dwayne Howell received his wake-up call in 1993. That was the year the Southwestern United States was stunned by the outbreak of what was first termed "the Navajo disease," then the Four Corners outbreak and finally, today known as the Sin Nombre hantavirus. As president of General Pest Control in Durango, Colo., Howell found that the often-fatal hantavirus pulmonary syndrome (HPS) that stemmed from the Sin Nombre virus had hit close to home. One woman who died was the wife of a friend, someone for whom he had done some general pest control work, although never any rodent work. Another was the lady friend of a man whose restaurant was serviced by General.

"We all got together and thought, 'This is pretty serious. We need to start taking some precautions here,' " recalls Howell. General had been using baits and rodenticides, but the company decided it was time for a change. Today, the firm has a three-pronged plan for rodent control-trapping, exclusion and monitoring.

"Policy changes didn't just happen overnight, but they did happen fairly quickly, probably within just a few weeks," Howell tells Pest Control. "We took a look at what the health department was recommending to the public and then looked at what we were doing, whether we measured up. We asked ourselves, are we doing the right things? Are we putting our customers at risk by what we're doing? Are we doing pest control the best that we can? Is going out to a job and throwing out some rodenticide really the best way to do rodent control? All of us came up with the same answer-no, that's a temporary solution."

They knew that rodenticide alone could create other problems, such as insects feeding on dead rodents or odors arising from carcasses trapped in inaccessible locations. Then, of course, there was the risk of hantavirus. In addition, it wasn't fixing the long-term problem, that of why the rodents were entering the structure in the first place.

"In the past, we had been guilty-and I know other pest control companies have been guilty, too-of going out to a job and saying, 'Well, you wouldn't have this problem if you would fix this or do this,' " Howell explains. "We decided that instead of just telling the customer about the problem, we would offer to fix it for them. It was a tremendous hit."

Opening New Doors
Another add-on service stemming from General's new take on rodent control was treating new construction sites.

"We're in a vacation home area, up in the mountains. When a house is under construction, that's a prime time for rodents to enter into the house, because the workers are out eating lunch, leaving trash all around. Then at night, the house is left wide open, and the mice can just take up residence there," Howell notes. "So, we offer a rodent control program, that we go weekly to these homes under construction and do the trapping. In addition, we can do rodent-proofing, showing the builder what things they can be doing during construction to help eliminate potential problems. It's also a good time to bring up termites and the other services we offer."

Proving to Howell that General was going in the right direction was a rodent exclusion program conducted by the National Parks Service in 1995 in three of its mobile homes. "They were able to eliminate 90 percent of their rodent problem with exclusion alone-no trapping, no rodenticide at all," he stresses. "When they supplemented this with some trapping, they estimated the cost to be about $600 per mobile home."

While General primarily uses snap traps and electric traps for its accounts, it will still use rodenticides as a perimeter treatment where warranted, such as in barns, gas wells or other outdoor environments.

"There's probably a handful of accounts that we were servicing previous to making these changes that still want baits," Howell admits. "All the rest of the accounts, however, we were able to switch over to traps and exterior baiting only."

Protect Your People
To Bruce Carter, president of Carter Services, Inc., Farmington, N.M., and president of the New Mexico Pest Management Association (NMPMA), there are three issues at stake regarding hantavirus-pest management professionals have a responsibility to protect their customers, their employees and their industry.

"I believe that, as professionals trained in rodent control, we should know all of the potential consequences. We should treat every case like an HPS case," he intones. "Some may say it's overkill, 'We don't have hantavirus in Ohio,' for example. My contention is, yes, you do-it just hasn't reared its ugly head yet. Your responsibility to your customer is to inform them, no matter how small the chance, about hantavirus."

Chris Craig, president of Assure Pest Control, Edmonton, Alberta, Canada, readily agrees. He tells Pest Control that there have been fatalities reported throughout Canada linked to hantavirus transmitted by deer mice, as well as to Alberta's southern neighbor, Seattle, Wash.

"A lot of guys are still going in, grabbing the bait stations bare-handed and popping them open to check the baits inside," Craig laments. "PMPs shouldn't be using a lot of bait, but rather going to glue boards and snap traps. It's just the simple fact that you start putting a lot more bait in, you're just creating more mouse feces. I don't mean to be crude, but the more rodent feces that are spread around, the more chance there is of contracting the virus. A lot of people don't even look at that aspect of it."

As for protection for their employees, Carter urges PMPs to give their technicians "the proper ammunition to do their jobs." This includes tangible items such as coveralls, rubber gloves and bleach-and-water or disinfectant-and-water solutions. There are also the intangible items, such as a comprehensive knowledge of the hantavirus risk, so they can inform their customers, and the company's support to go this extra mile.

To protect the industry, Carter says, be ahead of the game. "When the Centers for Disease Control and Prevention (CDC) or your health department mandates to do rodent control 'this way,' you can tell them that you already are," he explains.

Carter acknowledges that PMPs may meet with some opposition in their accounts, that the equipment and the extra precautions taken with rodent cleanup may be looked upon as overkill. However, he points to Mike Reed, president of Bob Reed Pest Control, Inc. in Roswell, N.M., where the incidence of hantavirus is not as common as it is in the northern part of the state. After Carter conducted a hantavirus class for the NMPMA members there, Reed contacted him and said, "I need to start thinking about what might happen if hantavirus hits here."

Carter replied, "Here's the problem in what you're saying. You're lying in wait for hantavirus to arrive. Take a proactive stance, instead. If it hits, you're ready to combat it. Every time the phone rings for a rodent problem, tell them that this is what you have to do."

Sure enough, the first case of HPS in Reed's area was confirmed-shortly after a commercial account had allowed him to do a program that included hantavirus precautions. Carter notes that Reed was commended not only for the successful elimination of rodents, but for the protection he gave his customer. Had the plant's workers contracted HPS while on the job, the plant could have been held accountable.

If a client does not agree to a hantavirus mitigation program, you still must educate them of the risk, says Carter, adding that it may even be a good idea to have a place for customers to sign off on a contract, stating that they were informed.

Managing Editor Heather Gooch is Pest Control magazine's Web master, as well as a regional vice president of the American Society of Business Press Editors (ASBPE) Cleveland, Ohio, chapter.

Photo caption: General Pest Control Technician Terry Bowers cleans out a mouse infestation in a hot tub. Note his use of gloves, coveralls and a respirator as hantavirus precautions.

Hantaviruses are Cropping Up in California

By Hanif Gulmahamad
Contributor

The overwhelming majority of rodent control work done by structural pest management professionals (PMPs) in southern California usually involves commensal rodents. Most PMPs believed, or were led to believe, that commensal rodents are not reservoirs for Hantavirus, hence, they thought that they had nothing to fear from this disease. These assumptions may no longer be valid.

The genus Hantavirus (family Bunyaviridae) consists of at least 14 viruses, including those that cause hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). Hantaviruses are primarily rodent-borne, although other animal species have been reported to harbor these viruses. Hantaviruses are most frequently transmitted to humans by inhalation of virus-contaminated aerosols of rodent excreta. There has been no known human-to-human transmission of hantaviruses in the United States as of this writing.

The U.S. Connection
HPS was first described in 1993, when a cluster of cases occurred in the Four Corners region of the U.S. (New Mexico, Arizona, Colorado and Utah). Six species of hantaviruses have been implicated in causing HPS, including:
- Sin Nombre (SN)-The principal reservoir is the deer mouse (Peromyscus maniculatus). This virus is reported from the U.S. and Canada.
- New York (NY)-The principal reservoir is the white-footed mouse (P. leucopus). This virus has been found in the U.S. and Canada.
- Black Creek Canal (BCC)-The principal reservoir is the cotton rat (Sigmodon hispidus). This virus has been reported from the U.S.
- Bayou (BAY)-The principal reservoir is the rice rat, (Oryzomys palustris). This virus has been found in the U.S.
- The Andes (AND)-The principal reservoir is the long-tailed pygmy rice rat (Oligoryzomis longicaudatus). This virus is reported from Argentina.

There is also an unnamed virus, whose principal reservoir is the vesper mouse (Calomys launcha). This virus has been reported from Paraguay.

More than 250 cases of HPS have been reported throughout North and South America. Most of the cases of HPS in the U.S. and Canada have been caused by the SN virus. From May 1993 to May 1999, 217 cases of Hantavirus had been reported from 30 different states. A 43 percent mortality rate from Hantavirus infection has been recorded nationwide.

In California alone, 25 cases of Hantavirus have been reported since 1993. Eleven of these cases, or 44 percent, have been fatal. Three cases of HPS were identified in California residents during 1998. In addition, one case of non-pulmonary acute Hantavirus infection was identified in a California resident, and one HPS case was diagnosed in a Colorado resident who was visiting California.

In 1993, the SN virus was reported from many of Orange County, Calif.'s rural habitats. It has been predominantly associated with deer mice, and there is currently no evidence linking the SN virus with commensal rodents.

Two other Hantaviruses have been isolated from rodents in Orange County, including the Isla Vista virus, which is associated with the California vole (Microtus californicus), and the El Moro Canyon virus, which is associated with the harvest mouse (Reithrodontomys meglotis). Neither virus, however, has yet to be found associated with Hantavirus human disease cases.

Hantavirus Antibodies
A study by a team of researchers led by L.C. Cullman reported that low titres of Seoul-like antibody (an HRFS-causing hantavirus whose principal reservoir is the Norway rat) were detected in at least 5.5 percent of 72 Rattus spp., which were live-trapped at various urban sites in downtown Los Angeles and four of its suburban areas between March 1996 and July 1997.1 In a follow-up study, the same researchers live-trapped 120 Norway rats and 25 roof rats between March 1996 and January 1998 in inner-city alleys and at suburban rodent-infested sites in Los Angeles County. Serological studies on the trapped rodents reveal that both species tested positive for the Seoul virus antibody.

The recent detection of hantavirus antibody in commensal rodents in the U.S. is not a new discovery. Hantaviruses have been isolated from Norway rats in Baltimore, Md., New Orleans, La., and Philadelphia, Pa. Serological surveys conducted during the 1980s indicated that Hantavirus-like antibodies were commonly associated with urban Norway rat infestations in many U.S. cities.2

In 1998, Cullman et al. concluded that the positive-testing Norway and roof rats were trapped in areas where frequent human contact is likely.

Dr. Hanif Gulmahamad is an urban and structural entomologist with Terminix in Anaheim, Calif.

1 Cullman, L.C., B. Hjelle, C. Tarleton and M. Rood. 1996. The Detection of Seoul-like Virus Antibody in Urban and Suburban Rats in Los Angeles, Calif. Presented at the Fourth International Conference on HFRS and Hantavirus, Atlanta, Ga., March 5-7, 1998.

2 Tsai, T.F. 1985. Serological and Virological Evidence of a Hantaan Virus Related Enzootic in the United States. Jour. Infectious Diseases 152(1): 126-136.

Hantavirus case confirmed in Oregon 11:49 AM PDT on Friday, May 20, 2005 By TERESA BELL, kgw.com Staff   HILLSBORO -- Health officials say a Washington County resident is suffering from the rare and sometimes deadly Hantavirus.   kgw.com graphic     The woman, whose name was not released, is recovering at home, according Emilio DeBess, the public health veterinarian for the Oregon Department of Human Services. He said the woman is in her 60's and recovering well; her condition is not life-threatening.   Investigators think she most likely became infected with Hantavirus while in her basement, where some rodent droppings were spotted.   Rodents such as deer mice or wild mice may carry Hantavirus and excrete the virus in urine, droppings and saliva. People can be infected by inhaling concentrated virus particles that become airborne when rodent droppings or nests are disturbed.   "Hantavirus cases are rare both in Oregon and around the nation," DeBess said. "But it can be a deadly disease, and we want people to know there are precautions they can take to avoid being exposed to the virus."   Also Online Hantavirus fact sheet DeBess said the first signs of illness appear one to six weeks after exposure. Early symptoms include fatigue, fever and muscle aches, which may progress to coughing and shortness of breath as lungs fill with fluid.   "The primary way to protect yourself from Hantavirus is to control rodents and keep them from nesting in and around your home," DeBess said.   Anyone who finds rodent droppings or nests in their home or in outside areas such as garbage cans, woodpiles, sheds or barns, is urged to take the following advice:   -- Do not sweep, brush or vacuum the droppings or nesting materials, because you will stir up dust and increase the chances of inhalation.   -- Spray the droppings and nests with a household disinfectant, such as Lysol or bleach mixture, and allow them to soak for at least 15 minutes.   -- Wear rubber gloves when cleaning up droppings, seal all materials in double plastic bags and dispose of in the trash.   This is the Oregon's sixth reported case of Hantavirus; five cases were reported between 1993 and 1997. Washington state has reported 28 cases since 1993.   Since Hantavirus was first identified in 1993, a total of 379 laboratory-confirmed cases have been reported nationally. It has been reported in 31 states, the majority in the southwestern United States, and about three-fourths of cases have been in rural areas.