Paul,
I've been following your
permaculture podcasts, blogs, buying some DVDs, etc and really enjoying your information and your colorful commentaries.
I appreciate your discussion on flea control and the sincere attempt to use the least harmful methods.
I have been a small-animal veterinarian for over 25 years and have more than a little education and experience with the flea life cycle, treatment, and associated dermatology problems in pets. (and more than I want to know about the owner's dermatologic reaction sometimes!)
Contrary to what people sometimes expect, rural pets do not typically carry more fleas than urban pets. Urban pets are far more likely to have flea problems because the concentrated environment is so attractive for fleas.
In either case,
fleas are happy to populate in a house. Even a very clean house. Flea-infested does not mean dirty.
By the way, we have parasitologists that have studied this extensively. (As an aside they also have some interesting fields where they are studying ticks. I'd like to take the
permaculture approach along with their information together and write about environmental tick management, but that's just an interesting digression for now). Female fleas start dropping eggs within 24 hrs of getting on your pet, and they do indeed drop thousands of eggs, many of which survive to the pupae stage (each female flea produces 40-50 eggs per day). As you indicated in your article, the pupae can survive for months. But they can also go through the pupae stage in as little as two weeks. Most people have thousands of fleas in their home by the time notice they have a flea (that again is borne out by studies where volunteers accepted parasitologists to survey their home at the time of flea reports).
One of the most important points is that adult fleas aren't too likely to leave the pet. You may have realized that, but the emphasis is important because if you don't thoroughly and quickly kill the adults on the pet, they keep dropping eggs. Ongoing flea infestations always come down to owners modifying/cheating on recommended protocols and then spending hours per week trying to vacuum, chase, powder and scream the rest of the fleas away. Flea eggs are non-sticky, so eggs drop off the pet readily. Vacuuming and cleaning helps, but eggs will still survive in microscopic cracks and crevices.
Your light-trap monitoring is not very accurate. That has also been studied, and only an intermittent-light device correlates with actual flea counts. (Fleas are drawn to a change in light, not just to "light".) Further, you need to count male vs female fleas to understand whether the fleas are being brought in by a host or whether you have eliminated new flea introduction, and the remaining fleas represent an aging population.
I'll dispute the idea that fleas are merely a "nuisance". They are for some pets or people. But for the sensitive individuals (which are many), it takes very few flea bites to get in a condition where the pet now needs two or three medications to return them to a healthy and comfortable condition. And it's (in my experience) extremely rare to see a flea infestation continue to be only a nuisance. (I've also added some of the diseases transmitted by fleas, much more common than plague)
I have seen small dogs and cats die from flea anemia, and I have given blood transfusions to hundreds of others who were close to death.
Let me suggest that using something with not only a good safety record, but also good effectiveness, will actually lower the overall need of applying foreign substances in or on the animal or their environment. Even a mild flea reaction causes skin inflammation, affects the skin lipid layer, and increases stress hormone response.
While trying to avoid products that worry you, don't forget that fleas are a parasite. That's an obvious negative. As far as I know, there is no symbiotic effect that fleas give to the animals.
I'm also not the least bit comfortable with diatomaceous earth on the skin, and therefore likely inhaled. While the individuals you spoke with may not have viewed their personal lungs on a microscope, such work has been done (both microscopically and with imaging). There is evidence of abscess formation and fibrosis or granulomas still present months later. Some people will euphemistically call this fibrosis "scar tissue". Fibrosis of the lungs can affect respiratory capacity, and granulomas can theoretically be a precursor to cancerous growths. Granted, I am not aware of any cases of serious lung disease from light exposure to diatomaceous earth, but damage does indeed occur. This needs to be accordingly contrasted with the fact it must be constantly reapplied directly on an insect, having probably at least some affect on the pet's skin, and not getting rid of all the fleas. Why would you not weigh the effectiveness and safety of DE rather than assuming its advantages outweigh its disadvantages, compared to other treatments?
Diatomaceous earth is probably a reasonable environmental preventative, as you describe. But where there is already a flea infestation, there is no way the DE is going to reach each individual flea, especially with the fleas on the pet continuing to drop more eggs. It was probably not helpful to tell someone with an animal
shelter to prevent fleas by putting DE on the edges. Those fleas are coming in with the pets, not from the outside. The eggs are dropping and will continue to populate there if each pets' fleas are not eliminated as it enters the shelter.
One other thing: fleas are a host for tapeworm eggs. The more fleas a pet has, the more likely they are to swallow more fleas, and the more likely they are to need tapeworm treatment. The only effective tapeworm treatment is another chemical (a seemingly safe one, but another one).
**I came back to make some important edits/additions because I first typed this note quickly. Let's summarize the potential damage from fleas. Where I know the percentages with fair accuracy, I'll include them. Where I can only estimate them from my experience, I'll put a qualitative anecdoctal statement.
The Cat Scratch Fever issue is particularly significant for humans that own cats, and it just wasn't on my mind when I first responded.
Flea presence (this means any exposure and/or bites, not necessarily severe infestation) can cause
1)
Tapeworm in dogs and cats ("Very high" percentage in my experience, over 50% of the pets who have fleas will have tapeworms). The fleas are a host to the egg of the Dipylidium tapeworm. Cats and dogs lick themselves, swallowing a flea, and the tapeworm grows in the intestine. Tapeworms live for years if not treated, causing vomiting, diarrhea, and hypoproteinemia. It is my understanding that humans in the household, especially children are occasionally infected with tapeworms.
2) Bartonellosis in felines, transmissible to humans as "
cat scratch fever". Unfortunately, many pediatricians do not understand the pathogenesis of cat scratch fever. Docs tend to tell people to "get rid of the cat" when someone gets cat scratch fever. However, flea control will prevent transmission. First, the Bartonella organism is present in a very high percentage of cats (30% ?) and probably transmitted by fleas and other insect vectors; ticks may also be an agent. But the important factor here is that Bartonella only lives in blood. A cat scratch itself, while painful and always a potential for infection, doesn't spread cat scratch fever. The problem is the flea-infested cat, which will inevitably have tiny bits of flea dirt around its nail (containing flea excrement, including digested blood and surviving Bartonella bacteria). Thus if your cat has fleas and scratches a human, the chance of them transmitting cat scratch fever are fairly high. With no flea infestation the chance is close to zero. (Surveys show about 20-30% of the cats with fleas carry Bartonellosis. If you can guarantee you cat will never scratch you, not even when afraid, then you have little risk of getting cat scratch fever from them and their fleas. Although you could still get the bacteria if you handled the cat when you had an open wound.)
This bacteria can cause systemic disease, including heart valve infection in humans. Get a real case of cat scratch fever, and you will be in the hospital... where of course you are at risk for picking up more infections.
Some bartonellosis has also been found in flea-infested dogs (and their fleas) but the clinical significance to dogs, or whether or not they transmit it to humans, is uncertain.
3)
Rickettsial diseases. Rickettsial diseases include things like Lyme disease, Typhus, spotted fever, etc. Tested fleas have been found to carry various rickettsial bacteria in numbers ranging from 20-60%. Cats infected with fleas have antibodies to some of these bacteria, meaning they have been exposed to them. The percentage of times that fleas actually transmit these diseases to animals though is not known at this time. There have been at least some human cases of the type of typhus bacteria found in fleas.
4)
Feline Mycoplasma. Transmitted by fleas, and causes immune problems that can eventually cause anemia in the cat. In US and Australia, approximately 20% of the cats infested with fleas were found to have Mycoplasma. Some of the cats can probably handle this with their immune system, so it is a smaller number that actually develop the anemia to a clinical extent. (no one knows yet how many) I've seen this in my practice but I really can't come up with a feeling for how common it is.
5)
Flea allergy dermatitis. Some pets and people are so allergic to the flea bite that you can scarcely find fleas when they start to get pruritis. Often this pruritis is severe enough to require glucocorticoid treatment (which of course has its own side effects). The dermatitis weakens the skin leading to pyoderma, so the person or pet may also need antibiotics. Because it's tough to convince a dog or cat not to scratch where they itch, a more severe pyoderma may develop in specific areas (called a "hot spot") requiring the meds, plus perhaps topical medications and sometimes even restraint devices (ie cone of shame) to prevent self-trauma. The lipid layers in the skin become damaged, and the pet or person is more susceptible to any other infectious agent, plant material, etc they come in contact with.
More severe flea infestations: (ie greater numbers)
1)
Anemia. Plain and simple, fleas suck blood. Smaller pets like kittens and puppies or older pets who are not very mobile can have so much blood ingested by the fleas that they require blood transfusions, succumb to secondary illness, or die before treatment.
2)
Severe pruritis. Even without an allergy problem, enough fleas will cause self-trauma and some of the problems of flea allergy dermatitis.
3)
Hair loss, stress, and general debilitation. Pets with a severe infestation often come to our practice with complaints of lethargy, inappetance, and sleeplessness. Their owners are often also lethargic from being awake hearing their pets scratch at night
Fleas are no joke and they are not merely a nuisance. They are a parasite, they transmit other parasites, they cause direct illness and secondary illness.
Saying a low-level flea infestation isn't a big deal seems to me like saying what you
feed yourself isn't that important, because you will only be a little less healthy if you eat junk.
Before we had highly-effective treatments, I think there was actually a lot more chemical exposure. When people get frustrated enough they'll start spraying everything (and sometimes have to, because the infestation has gotten so bad).
Paul you live in Montana, and I'm guessing that's not a great climate for fleas. That may be partially responsible for your thoughts that fleas can be controlled in the way you describe. I would, however, wager that if I hand you a dog with fleas and you attempt to rid the dog of fleas by combing, diatomaceous earth, and the other methods you suggest, that I can still find fleas on the pet when you are finished (assuming of course you devote only your normal effort to it and not an effort ascribed to an exceptionally-large wager
)
Finally, you asked about information on poisoning from flea products. You can probably find this under the EPA's "adverse events" reporting. Be aware though that "reporting" just means someone saw a problem that they associated with the product. If they put a topical product in the eye and the dog's eye became red, that's an adverse event. The most common cause of adverse events to topical flea products are when dog-labeled products are applied to cats. Second most likely is giving the wrong amount. Another common problem is buying flea products online, which can turn out to be counterfeit. The products I have seen (or found legitimate reporting of serious problems) are those cheap ones in Walmart I have already mentioned and am not going into by name at the moment.
I've been asked not to mention non-organic flea products, so I am now befuddled as to what to discuss here.
Diatomaceous earth is inorganic, and the thread is almost entirely about DE.
Failure to prevent fleas is a potential cause of toxicity and disease, as I have highlighted. Fleas also often create a situation where medications are needed to treat secondary problems. I would think a discussion of safety and disease prevention would be more relevant.
I will emphasize that you ASK your veterinarian about what to use. They should be able to explain their recommendation based on your climate and your pet's individual environment. Some veterinarians are more educated on flea life cycle than others. If they don't want to talk to you about what they recommend, go elsewhere. In this country, if you prevent fleas on your dogs and cats, it is very unlikely you will have flea problems with the humans. There are exceptions of course where wildlife get close. I had 1 client who finally discovered raccoons living in the chimney were the source of repeated flea problems in their home. If you start a treatment, pay attention to the full protocol. Treating just once may make you think the problem is solved, until those remaining flea pupae hatch out again later.
If someone thinks their flea risk is low and they can try to prevent it with the environmental methods such as the diatemaceous earth, that is reasonable. I personally feel we have too high a probability of serious problems in the midwest to recommend that approach.
Keeping in the vein of
permaculture, I suspect fleas do have some greater role in our environment. But I'm comfortable with minimizing their numbers on the pets and people closest to me.