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QuestionsCategory: Flea InfestationsHelp me understand
starla asked 1 month ago

This is gonna be a bit long, but I hope you can help me understand what’s going wrong. Because I’m pretty confussed at this point!

In the summer of 2015 we got fleas. We gave them advantage spot-on drops but found out this didnt work very well. We changed to Vectra felis and this worked a lot better. I’m afraid to use toxins in the house because I read that permethrin is toxic to cats and it seems to be in every home-spray on the Dutch market (We live in The Netherlands). Eventually we found a spray called eco-style wich contains only coconut oil and citrus oil. We used this in our home on the carpet, chairs etc. It seemed to work combined with the vectra spot-on and vacuuming almost every day.
But on the end of every month the vectra seemed to work a bit less and there’d be some fleas until te next treatment again. I guess those few days with less protection was the reason we didnt really completely get rid of the fleas.. they probably managed to lay eggs every end of the month. Still this got better and better and we were without fleas for some months, and then back for a few days and then a few months without again.

We sold our house and in oktober 2016 we moved to a temporary rental home and most of our personal belongings went into storage for a few months. When the fleas came back during that period we got our cats a program injection at the vet and still kept treating them with vectra as well. We figured that with those two combined there should be no way for the fleas to continue. We tought that even if the vectra worked less at the end of the month the program injection would at least make sure those fleas wouldnt be able to reproduce. This went very well from then on and we hadnt seen any fleas or itchy cats from november 2016.

We moved to our new home in midst december and all went well, so far no fleas. Our belongings that came back from the storage we stored them all in the attic (our appartment is on the 1th floor and the attic is on the 4th floor, not connected to our apt) just in case there would be pupae in those.

A few months went by without fleas and I regained the trust that we finally had this under control. For this months (march) treatment I decided to change from vectra to comfortis. I guess thats where something went wrong.. one of the cats problably spit out the comfortis pill. Because one week later we were at the vet for their yearly checkup and a new program injection (I had been 5 months ago, and it would stop working after 6 months so we wanted to be in time) and she discoverd al lot of flea feces on cat L, the other cat Z had no feces on her.

The fleas probably came from a few boxes that my husband brought from the attic into our apt. He brought them in a day after the comfortis treatment. Our cats are indoor cats but they do have a cattio on our balcony, so its unlikely they came from outdoors I think.

Since the cats were also on program I figured the fleas on cat L must have been infertile but had been living on her because they werent killed off by a spot on/comfortis. We thought it would be no problem and it would just be a matter of time for them to die out again. Just a few fleas from those boxes who managed to live a little while without reproducing.

On the day we went to the vet and discovered the flea feces we imediately gave the cats a treatment with Stronghold (our new vet didnt have vectra in stock)

This is 2,5 weeks ago now. When I comb cat L I still find feces on her but really a lot less then when we were at the vet (you could see them without combing then), she still is itchy and grooms a lot.. and yesterday evening I found a alive flea on her, a really tiny one.. just 0,5 mm or so. Cat Z seems to be a bit more itchy and grooming but I havent found anything on her.
So now I’m just really wondering whats going on. Does program just not work? Are there still fleas coming from pupae in our stuff that we moved from attic into the apt? I guess Stronghold doesnt work so well? If the fleas really were infertile they should be around after 2,5 weeks right? 

Can you help me understand what went wrong and what I should do to fix it again? I have already ordered vectra at the vet and will be treating the cats with it on friday (stronghold treatment is 3 weeks ago by then)

Thanx in advance and sorry this is so long!

2 Answers
Adam Retzer FleaScience answered 1 month ago

Sorry to hear about your flea problems.

Wow, it sounds like you’ve changed treatments quite a bit. I should mention, it’s generally recommended not to switch treatments because it increases the odds that fleas can build resistance.

Permethrin is toxic to cats. And many flea sprays for carpets do contain permethrin. However, the permethrin (or other adulticides) isn’t the important ingredient. The crucial active ingredient is the insect growth regulator (IGR). Specific ingredients are pyriproxyfen (Nylar) or methoprene (Precor). You can find these alone in concentrates, without any other toxic chemicals.

IGRs are considered safer than other insecticides, because they target insect hormones. Exposed eggs and larvae aren’t able to mature into adults. The nice thing about IGR treatments to the environment is that they last for 7 months. So they can prevent re-infestation.

I’m not sure what products are available in the Netherlands. But here’s an example of what I’m talking about: Martin’s IGR

I’m not yet very familiar with Program or other oral meds. From the literature I’ve read, it’s almost always recommended to use spot-on flea drops (like Vectra, Advantage II, or Frontline Plus). These 3 all contain similar ingredients. An adulticide to kill adult fleas, and an IGR to sterilize the females (should they survive long enough to mate and lay eggs). Stronghold only has an adulticide, and it differs from the ingredients found in the other flea drop brands.

The pupae may have survived on your belongings, such as rugs, pet bedding, cat trees, or other items the cats frequently accessed.

Fleas usually take 8+ weeks to eradicate. This is why monthly pet treatments are recommended for 3 months at least. And why regular vacuuming regime is recommended for this duration as well. And, as mentioned, one environmental treatment of IGR last 7 months.

The flea life cycle, from egg to adult, lasts 17-26 days. However, after maturing, adult fleas can stay inside their cocoons and enter into a quiescent state. This dormant-like state can last up to 5 months. The pre-emerged adults cause the most control problems. Most fleas won’t even this state, but some will.

The pre-emerged adults rapidly wake up and emerge once they detect heat and pressure. Vacuums simulate the cues that trigger emergence. This is why it’s recommended to continue vacuuming, even after it seems like the infestation pressure has diminished.

Switching back to the Vectra sounds like a good idea. It may also be a good idea to try to find an IGR concentrate and apply it to the environment. Vacuum every other day when establishing control, for a couple weeks. Then lower the vacuuming routine to a few times per week, for a couple months. Weekly laundering of pet bedding (or other items the cats sleep on) is another good way to kill developing fleas without insecticides.

Hope this helps. Let me know if I left anything out.

Warm regards,

starla answered 1 month ago

Hi Adam,
Thanks so much for reading and answering all that! 🙂
Do you think the fleas we have might be resistant? My story may be a bit chaotic but I don’t think we changed treatments that much, but ofcourse I want to hear if you disagree!
What we did was this:

  • We basically always had them on vectra, except for before we had fleas and one month after the start (advantage) and in march 2017 (comfortis + stronghold)
  • as an “extra” they get a program (lufenuron) injection every 5 months (his is an IGR injection for cats which works for about 6 months)
  • for our home (before we moved) we used ecostyle spray a few times
  • bedding and other textiles etc had all been washed often (and everything not able to be washed was thrown away) before moving.

The reason I’m so confused about the fleas we have is that we had been without fleas for about 3 months (and by then the cats were 5 months on program IGR) and I thought that the combination of vectra and program would make the fleas die out and make it impossible to come back as they would not be able to have viable eggs. But it seems something is not working?! Or was that theory just wrong to begin with?
Is there a difference between IGR injections for the cat and IGR spray used in the environment? In how effective it is I mean. 
In theory with the use of the program injections it shouldnt be possible for there to be new viable eggs right? 
If the theory is that this infestation is just from pupae from moved boxes then shouldnt those fleas be dead by now? even without a working adulticide spot-on adult fleas dont live this long right? 
It’s been 6 days since we treated the cats with vectra again and I can tell they are still itchy, still grooming a lot and scrathing more than normal. Vectra always worked pretty well so I think this is really strange. Is this a sign of the fleas becoming resistant to it then?
On the other hand, if it didn’t work at all the problem would be much bigger by now right?
Anyway, although I don’t understand this situation, maybe it is time we start using a IGR for the environment. I looked into it and in the Netherlands we don’t have concentrates. But I consider using Bolfo Fleegard spray. It contains a combination of 0,04% Cyrfluthrin and 0,05% Pyriproxyfen.. do you thinks this would work?
I’m already washing pet beds and other textiles again every few days and vacuuming every other day. 
Sorry for all the questions again.. just trying to make sense of it all!
Hartelijke groeten, 

Adam Retzer FleaScience replied 1 month ago

The fleas likely haven’t become resistant. It’s just recommended not to switch treatments much, because if everyone did this, it could rapidly increase fleas’ potential resistance. Then, as a world community, we would have less options for control. However, currently there’s no evidence that fleas are resistant to modern insecticides. This is studied often, and the latest report from a few months ago confirms this.

The lufenuron should work to prevent eggs and larvae from developing (from eggs laid from exposed adults). It’s a bit different from pyriproxyfen and methoprene. It inhibits chitin production, as opposed to suppressing growth through juvenile hormone analogs. Regardless, the end result should be the same.

The IGR applied to the environment is useful because it adds a second layer of protection. The environment is where fleas develop. I think applying an IGR to the environment would be a good direction to go. 95-99% of infestations are composed of eggs, larvae, and pupae. So, for every adult you see, there are around 100 immature stages in the environment.

The Bolfo Fleegard should work, as it contains pyriproxyfen. Cyfluthrin is a pyrethroid insecticide, which is the most common type of indoor insecticide. Permethrin is also a pyrethroid, but as you mentioned previously, it is toxic to cats. This product containing cyfluthrin is the safer option.

The Eco-style spray (coconut oil and citrus oil) probably didn’t have much effect. The reduction you saw following treatment was likely due to the vacuuming. I’ve never read anything confirming that essential oils are effective control agents for fleas (and I’ve looked).

It is strange that the fleas re-appeared after 3 months. Perhaps a couple were in the quiescent cocooned state. The pupae (pre-emerged adults) can survive for up to 5 months. They could have emerged and re-triggered the infestation. Or perhaps you are dealing with an entirely new infestation in your new location. And it’s strange that they had a chance to reproduce with your cats being treated. I’m not sure what’s going on here.

Even after the Vectra treatment, cats are likely itching because they are acquiring new fleas from the environment. The fleas have a chance to bite before succumbing to the insecticide, but they shouldn’t live long enough to mate. It’s unlikely the fleas are becoming resistant.