Spider bites and MRSA: A medical dilemma

A customer shows you a blackish, oozy bite on his hand and asks if it could be a spider bite. The wound looks like pictures of brown recluse spider bites you've seen on the Internet, but no spider was seen. How do you respond? A recent paper by Jeffery Ross Suchard, MD, in Orange California, in the Journal of Emergency Medicine (2011. Vol 41, No. 5, pp. 473-481) addresses this difficult dilemma.

The paper notes that previous studies have found that spider bites are often confused with other arthropods, or other diseases (in one paper cited, 80% of spider bite reports were erroneous).  Suchard reports on a survey he conducted of 182 emergency room patients admitting themselves for what they believed to be a "spider bite".  Only 7 (3.8%) of these patients were diagnosed by emergency room personnel with actual spider bites.  One hundred and fifty-six patients (85.7%) were subsequently diagnosed with skin infections.  At least in this California clinic, the author reports, clinically confirmed spider bites were rare, and when confirmed, were most commonly black widow spider bites.

Of course California is not Texas, nor Oklahoma, nor Missouri.  Neither is it home to native populations of brown recluse spiders like these states.  Nevertheless, even in brown recluse-endemic areas, numerous papers have appeared in recent years suggesting that spiders, including brown recluse spiders, are often erroneously blamed for wounds thought to be spider bites (e.g., Vetter and Furbee. 2006. Caveats in interpreting poison control centre data in spider bite epidemiology studies. Public Health 120: 179-181).  Many purported spider bites are increasingly being attributed to staph and other bacterial infections.  In some areas, methycillin-resistant Staphylococcus aureus (MRSA) is the most common culprit.  Such misdiagnoses are potentially dangerous because MRSA can be deadly if not treated appropriately.  And if you don't believe me that MRSA and brown recluse bites can look alike, click here.

But there's danger in the other direction too, as pointed out in another paper published this year.  Rogers et. al (2011. Annals of Emergency Medicine 57(2): 138-140) describe a case study that illustrates the danger of misdiagnosing a real brown recluse spider bite as MRSA.  In their case a patient with a brown recluse spider bite underwent what was, ultimately, an unnecessary surgery as a result of an initial misdiagnosis of MRSA.

The message we should be hearing from this research is to be slow about jumping to conclusions about spider bites. Ultimately it's a doctor's determination to make.  And I figure that if even doctors have a difficult time diagnosing a spider bite, I am going to be wary of offering an opinion about a suspect bite.

The pest control profession can, however, provide customers with good spider identifications, and help monitor for the presence of venomous spiders. Sticky cards are pretty effective at trapping brown recluse spiders, the most likely culprit of an ulcer-like spider bite.  Of course, if a spider is caught in the act of biting, or found near the victim, by all means collect and preserve it properly. And remember that spiders do not commonly bite people.  If a customer complains of multiple "bites", chances are low that spiders are the culprit.

Both infections and spider bites can be serious. Anyone with a dark, weepy wound should be referred immediately to a local doctor or emergency room. Worry about assigning blame later.

Bed Bug program in Houston

If you work in pest control around the Houston area and want to learn more about the bed bug business, now's your golden opportunity. Dr. Paul Nester with Texas AgriLife Extension is hosting a bed bug workshop in collaboration with the Greater Houston Pest Control Association this week, on Thursday, December 1. The program will be held at the Harris County Extension office at Bear Creek (3033 Bear Creek Drive, Houston 77084) and will run from 9:00 am to 3:30 pm.

Paul has taken pains to include a diverse group of trainers from both the university and from industry.  Speakers include myself (history, identification and facts about bed bugs), Raleigh Jenkins with ABC Home and Commercial Services (control "nightmares"), Dr. Kate Johnson with Research Associates Labs (detecting bed bugs with DNA), Dr. Bob Davis (products labeled for bed bug control), Dr. Robert Puckett with Texas A&M University and Howard Franklin with ThermaPure Texas (control strategies), and Jay Jorns with JNJ Pest Control (the art of bidding).   Continuing education units will be provided.  Click here for the complete schedule.

This is a unique opportunity, both to learn from experts in the field, and to take part in a small, personalized, training environment. If you're interested, you can reserve a spot between now and Thursday by calling 281-855-5600 and asking for Diana Todd. Registration cost at the door is $45 per person. This is a great opportunity to build your business. Hope to see you there.

EPA improves pesticide search tool

Back in August I reported on a new label search engine web site from the EPA. I complained at the time that the Pesticide Product Label Search was not a full-functioned database that allowed searching for all products labeled for a given site or pest (which it's not).

After reflection, and perhaps in the spirit of Thanksgiving, I've decided that perhaps my summer criticism was a little harsh.  Or maybe it's the new portal to the site, called Pesticide Chemical Search, that has mellowed my judgement.  In any case I think all of us in the pest control industry should have this new web-based application bookmarked on our phones and computers.  While not meeting all of our searching needs, it does provide an excellent and unique point of contact to search pesticide labels, toxicology information, and registration history and resources. To check it out, go to:
www.epa.gov/pesticides/chemicalsearch

To find pesticide labels for a given chemical, search on the Quicklinks Label Information link to go to the Pesticide Product Label System.  If you have a particular active ingredient in mind, simply type in the pesticide common name, like deltamethrin, and you will have one-stop access to all kinds of scientific studies, toxicology information and registration status for that product. When searching on deltamethrin, for example, I clicked on the Science Reviews tab to find 15 otherwise obscure EPA scientific study reports on the compound. This is a good way to brush up on the safety information for a given product before speaking with a customer with chemical safety concerns.  This site would also be invaluable for service managers researching what products they want to use in their company.

My only bone to pick with this site during my quick tour this morning was under the Laws and Regulations tab.  This site offers a choice to review regulations by business sector, and there is no sector for pest control.  That seems like a huge oversight to me.  Also, once you visit one of these sub-pages it is hard to get back to the PCS homepage.

But, overall I like the revamped application a lot.  There is even a short instructional video on how to use the PCS site.  So on this Thanksgiving holiday, thanks to EPA for making government a little more transparent.

The Bed Bug Chronicles: Part II

Yesterday I presented some of my highlights of the 2011 Entomological Society of America (ESA) annual conference, most of which had to do with bed bugs.  Today I wanted to share some notes on bed bug monitoring, a subject which I think will be key to developing effective IPM programs for this pest.

Some of my almost indecipherable notes from a bed bug
talk at ESA

Apparently I'm not alone in this belief.  There were several papers at ESA this year on monitoring-related topics. The ability to detect bed bugs early, before they become abundant in an apartment or hotel room, is critical to quick elimination of infestations. A good monitoring method should be inexpensive (if it's to be deployed in hundreds of hotel rooms or apartments), easily checked, and effective at detecting bed bugs at low infestation levels.  To date, the ideal monitoring tool does not exist; but much work is going into the search.

For cockroaches, the simple sticky trap has performed quite well as a cheap and effective monitoring tool.  Unfortunately, bed bugs are not readily captured with sticky traps, for reasons that have not been well studied.  The best alternative approach so far is use of various pitfall trap designs.  Pitfall traps consist of a container into which insects fall and cannot get out.  These work well with bed bugs because bed bugs are not very good climbers on slick surfaces. The first successful manufacturer of pitfall traps was the ClimbUp Insect Interceptor trap, sold by Susan McKnight Inc., and designed to be placed under bed posts.  When placed correctly it traps bed bugs either exiting or climbing on to beds.

Narinderpal Singh and Changlu Wang (Rutgers University) have been using the ClimbUp to investigate ways to make pitfall traps more attractive to bed bugs.  They found that CO₂ was more effective at luring bed bugs to ClimbUp pitfall traps than heat. However they also tested several volatile compounds as potential lures. The compounds nonanal, spearmint oil, octenol, and coriander mixed together was more effective than any of the compounds individually.  They also found that when these compounds were added to CO₂ they attracted more bed bugs than CO₂ alone. Of these four compounds, nonanal (aka nonanaldehyde or pelargonaldehyde) was the most attractive. This compound is emitted by humans and was recently found to be highly attractive to Culex mosquitoes.

Figuring out how to take basic scientific research like this and turn it into a successful product for PMPs has generally been role of the specialty products industry.  The chemical manufacturer FMC has been busy doing just that with bed bug monitoring.  For over two years FMC has been developing technology to build a better bed bug trap. The result of this project is a prototype of a new bed bug trap they announced to bed bug researchers at the meeting.  Tentatively called Verifi™, the trap uses a combination of CO₂, pheromone (scent produced by other bed bugs) and kairomones (host odor components) to tempt bed bugs to enter their trap.

The Verifi™ trap design is based on the idea that bed bugs have two basic search behaviors: host searching when looking for a meal, and harborage seeking after consuming a meal. When searching for a host, bed bugs use both CO₂ and host odors as orientation cues. When searching for harborage, they use scents associated with groups of other bed bugs, called aggregation pheromones. The good folks at FMC claim to have identified and produced two lures that effectively mimic host odors and aggregation pheromone. The aggregation pheromone is cleverly vented through one side of the trap to lure bugs into a dark harborage area. The kairomone and CO₂ canister are designed to lure bugs into a pitfall trap. When the trap is checked by a PMP both harborage and pitfall sections of the trap can be observed to detect and monitor bed bug activity.

Data presented at the meeting by university personnel who tested a trap prototype in field situations looked promising.  One of the major advances that FMC seems to have made is in the technology needed to provide a slow release of attractants used in the lures. One of the big questions I was left with, however, was cost.  A lot of engineering has gone into this trap and cost will certainly be a factor. Nevertheless, I hope the industry will put this product through the most rigorous testing protocol--the real world--when it comes out in 2012.

Unfortunately for science, discovery of compounds that are attractive to bed bugs is a lucrative, and therefore often secretive, activity. For this reason, FMC is not sharing its “secret attractants” with others. Even some university researchers, like Emma Weeks (University of Florida), who is working on bed bug aggregation pheromones, are remaining tight-lipped about their research results until the research, and presumably patents, are published.  Weeks reported finding some 21 compounds that were active in attracting bed bugs to filter paper.  Meanwhile, until more is known and better options come around, we should all work on our visual bed bug inspection skills, perhaps the most basic and indispensable monitoring technique of all.

The Bed Bug Chronicles: Part I

Lake Tahoe is only a short drive from the casinos of Reno.

One of the meetings I try to make every year is the Entomological Society of America annual conference.  It's the only place in the world where you can see more entomologists than bugs in a given day--over 2400 of them this year.  This year's meeting took place in Reno, the prettier of the two big gambling destinations in Nevada.

The ESA conference is lots of great information packed into a grueling marathon of paper sessions that seem to go on forever.  So today you're the lucky ones because you get to experience ESA without the gluteus maximus crampus (sore patootie).

For a week there were more entomologists than insects
in Reno.

This year's bed bug theme is a continuation of last year, though I think the papers and the research are getting better scientifically every year.  Of course no one person can take in the whole conference, so my highlights are admittedly selective.  There were many good talks on urban entomology that I did not attend.

• The lab of Changlu Wang (Rutgers University) continues to be a great source of practical research relating to bed bugs (BB) and other urban pests. This meeting Changlu reported on practical uses of carbon dioxide to control bed bugs. He found that putting 3 lbs of dry ice in a 42 gallon (3 mil-thick) garbage/yard waste plastic bag was sufficient to suffocate all stages of bed bugs in up to 22 lbs of clothes, when held for 24 hours. This amounts to a cost of approximately $4 to disinfest 22 lbs of clothes or other items that would fit in the bag. This adds another practical method for do-it-yourselfers looking for an inexpensive way to ensure disinfestation of personal items.
• In a related study, Dini Miller from Virginia Tech, found that Nuvan Prostrips (dichlorvos) achieved incomplete BB adult (4%), nymph (6%) and egg (45%) mortality when used at the label rate on clothing in 42 gal. yard waste bags. On hard items (e.g., books, computers, shoes and other personal items) Nuvan strips at the label rate achieved 48% mortality for adult BBs, 84% mortality for nymphs and 100% mortality for eggs. [According to Miller, to follow the label rate for a 42 gal. bag, one must cut a single Nuvan strip into 22 pieces (1/22 strip/bag)] If a whole strip is used in the bag (22X label rate), and the strip is held for 14 days, all nymphs and adults were killed, but only 63% of eggs were killed. Nuvan is commonly used as a fumigant by our industry, and does kill BBs; however this study suggests that it will not guarantee a kill of all BB life stages, even at higher than label rates (which we would, of course, never suggest).
  
• Susan Jones from Ohio State University tested bed bugs from six populations (five pyrethroid resistant populations, and one susceptible population) and found that three commonly sold “bug bombs” (total release aerosols) were ineffective in killing resistant bed bugs (0-30% mortality) held in open containers only 2-7 feet away from the aerosol emitter. The susceptible strain (unlikely to be found today in the field) was killed (100% mortality) under the same conditions.
       When provided with harborage to hide in during application, even the susceptible strain had very low (10-15%) mortality. These results confirm current recommendations by most Extension publications that “bug bombs” do not provide effective control for bed bugs for consumers.
  
• Joell Olson, of Ecolab in MN, reported on the effectiveness of cold temperatures for killing BBs. She found the egg stage to be the most resistant to cold. Her research suggested that items to be disinfested be held in a chest freezer (<= -13 degrees C) for a minimum of four days. This is longer than previously reported freezing times for BBs. 
• Many conference participants came away from the meeting with a greater appreciation for bed bug resistance to commonly used insecticides. Pyrethroid-resistant BBs are now predominant throughout the United States, with few susceptible populations remaining. Although I was unable to attend many of the resistance papers, I did catch one by Reina Koganemaru, a PhD student Dini Miller’s lab (Virginia Tech). With the aid of scanning electron microscopy she documented increased cuticle thickness in pyrethroid resistant bed bugs. Steven Kells (University of Minnesota) collected a different kind of data that supports Koganemaru's findings. Using both BBs and German cockroaches, Kells exposed both pests to Phantom insecticide (chlorfenapyr). He then washed and cut up his subjects and found 9X more insecticide on the outside of bed bugs compared to cockroaches. Similarly 9X more insecticide was found internally in the cockroaches compared to BBs. So, in addition to known target site (kdr) and enzyme-based detoxification resistance mechanisms, resistant bed bugs are thick-skinned as well. This suggests to me that surfactants/penetrants added to current bed bug insecticides might be one way to increase the effectiveness of existing products.
• I unexpectedly came away from this meeting with a much greater appreciation for the role of bacteria in entomology. Bacteria got my attention during the Founder’s Memorial Award lecture by Angela Douglas, from Cornell University. In talking about the role of bacteria in the bodies of insects, Dr. Douglas stunned me with the fact that 90% of the cells in an insect are bacteria (the same ratio is reported for humans). This is possible because of the tiny size of bacteria compared to the cells in our bodies. The relationship between insects and bacteria is far more complex and important to the ecology of pest control than I’d previously appreciated. Wolbachia, an intracellular parasite (lives in the cells of its hosts) is a type of rickettsial bacteria that has now been found in bed bugs. This same genus plays an important role in mosquito biology and reproduction. In some cases, Wolbachia has evolved to play important symbiotic roles (beneficial to both host and parasite) in insects. For example, some mosquitoes are unable to reproduce successfully without this bacterium in their bodies, while males of some mosquitoes are rendered sterile by Wolbachia infections. We don’t know exactly what roles Wolbachia plays in the ecology of bed bugs, but its presence opens up some doors for possible biological control options for bed bugs. Indeed Wolbachia is thought to play a role in the bed bug immune system. Remove Wolbachia and the survivorship of bed bugs goes way down after traumatic insemination (the bed bug equivalent of rough sex).

My next post I will cover some of the papers related to monitoring for bed bugs.

Bill Stepan

I'm sorry to report that our friend, Bill Stepan, passed away this week in Houston.  Bill was Orkin branch manager in Houston, and had served for many years in the pest control industry.  Bill was both a skilled professional and a very nice person to know.

According to an email from Leslie Smith at the Texas Department of Agriculture, there will be a visitation on Wednesday, November 16, from 4:00 PM to 8:00 PM at Garmany and Carden Funeral Home Chapel, 1201 4th Street, Rosenberg, TX 77471(281-342-4671).  A funeral Service will be Thursday November 17 at 2:00 PM at Calvary Baptist Church, 4111 Airport Ave., Rosenberg, TX 77471 (281-232-0372).  Bill battled aplastic anemia in the last years of his life, and requested that anyone wishing to make a memorial Donations to The Aplastic Anemia Foundation, American Liver Foundation, or The National Kidney Foundation.

Stink bug sighting

Last July I wrote about the brown marmorated stink bug (BMSB).  This insect is a new invasive pest from Asian and has been spreading pretty rapidly across the eastern states.  Last month I got a report from John Rourk, ACE with Certified Termite and Pest Control in Corpus Christi, about what may be the first confirmed report of this pest in Texas.

Fall aggregation of BMSB and other stink bugs under light outside a home.
Photo by Leske, 2010.  (not from Texas)

According to Rourk, he received a call from a resident about a large number of bugs in their travel trailer after a recent visit to Pennsylvania. When he got to the residence he saw two stink bugs flying from the RV flying towards the residence. He also found and collected three specimens from the RV and was told by the owner that they had already killed “more than we can count.” He he was unable to find any more evidence of activity or live specimens in the RV or on the premises.

Rourk knew what he was doing when he collected specimens. The only way to confirm an unusual or exotic pest is to collect it. A photograph is better than nothing but is still not as good as a specimen (dead or alive). According to Dr. Roy Parker, Extension entomologist at the Texas AgriLife Center at Corpus Christi, the identity of Rourk's specimens has been confirmed by the Texas A&M University entomology museum, and has been reported to USDA.

In a 2010 report by USDA's Plant Epidemiology and Risk Analysis Laboratory (APHIS/PPQ), BMSB is projected to be agriculturally important in east Texas and the panhandle regions. According to the report, once BMSB invades a new area it is very difficult to control because of its high mobility and large number of host plants.

Called by some the "Interstate bug" because of its habit of hitching rides on trucks, RVs and vans, the BMSB will often be found clustered in engine compartments or other warm protected areas of vehicles.  Besides being an agricultural pest, once it becomes established it also becomes a household pest as a fall invader (see picture).

Just because the BMSB was found in an RV in Texas does not mean it is likely to have become established here. Several hurdles have to be leaped before an invasive pest can establish a viable breeding population. Dispersing bugs may not be able to find one another for mating and reproduction in a new area.  There may not be a critical density of acceptable host plants at the point of introduction, and weather conditions must be favorable at time of import.  According to USDA, we still don't know the minimum population level needed for successful establishment of BMSB into a new area, although the insect has been successfully introduced to at least seventeen states. Since 2003, however, BMSB has been intercepted or trapped in at least seven states (Florida, Illinois, Maine, Mississippi, Missouri, Rhode Island, and South Carolina) where they do not appear to have established breeding populations.

Remember, as a PMP you are on the cutting edge of surveillance for new pests. Observations made by the pest control industry are, and will continue to be, an important part of urban entomology research and knowledge about insects.