Overview of the Issue

Why is it so important to control fleas on our pets? With as closely bonded as we are to our pets (i.e., sleeping on us, in our beds, sharing utensils, kissing, etc.) - it is vital to our human health as well as our pet health to control fleas...

Flea-Associated Diseases

 Zoonotic diseases

 Cat scratch disease (Bartonella henselae)

 Cat flea typhus (flea-borne spotted fever)

 Murine typhus (Rickettsia typhi)

 Bubonic or septicemic plague

 Intermediate host of parasites

 Dipylidium caninum, tapeworm

 Dipetalonema reconditum, subcutaneous filarid nematode of dogs

 Feline infectious anemia

 Flea allergy dermatitis in dogs, cats, and people

Human Bartonellosis

 In people, B. henselae is most common cause of cat scratch disease, bacillary angiomatosis, peliosis hepatis, and bacterial endocarditis
(Peliosis hepatis = vascular condition, when severe it can manifest as jaundice, hepatomegaly, liver failure and hemoperitoneum.)

 B. henselae documented as a cause of chronic disease syndromes such as fever, headaches, polyarthritis, and chronic fatigue syndrome, in immunocompetent veterinary health care providers and Bartonella researchers

Most medical doctors may not recognize this differential and should be informed if you are exhibiting these symptoms:

 B. henselae, B. clarridgeiae, and B. koehlerae are transmitted to cats by the cat flea (Ctenocephalides felis).

 In healthy cats in shelters, Lappin amplified DNA of a Bartonella species from 56.9% of healthy cats exposed to fleas and from 100% of the fleas collected from the cats.

 Possible routes of transmission of B. henselae among cats include flea bites, contamination of open wounds with feces of infected fleas, ingestion of infected fleas or flea feces, and fighting.

 B. henselae survives in flea feces for days after being passed by infected C. felis.

 Infected flea feces are likely to contaminate cat claws during grooming® Bartonella inoculated into the human when scratched.

 Open wounds in humans (e.g., hangnails) can be contaminated with infected flea feces.

 In a recent study, use of imidacloprid (Advantage Multi®) was shown to prevent the spread of B. henselae from infected cats to negative cats in the presence of C. felis.

Flea Biology

 Most common flea species infesting dogs and cats = cat flea (Ctenocephalides felis)

 Female flea jumps on pet® lays eggs within 24 hrs and can lay up to 40–50 eggs/day

 Fleas typically stay on a host and do not readily move from pet-to-pet

 Pets acquire fleas from an infested premises (shaded, protected habitats such as under bushes, shrubs, porches, crawlspaces) or flea parks (a.k.a., dog parks), groomer, vet office, etc.

 Flea distributors: stray dogs/cats, opossums, raccoons, foxes, coyotes

 Flea-infested animals move through neighborhood or yard, flea eggs drop out of their hair (i.e., like salt shakers!) and develop into adult fleas within 3–8 weeks.

 Problems in the home begin when a few of those fleas jump onto the pet and within 24 hrs deposit eggs in the home

Flea Allergy Dermatitis (FAD) Pathogenesis

 Flea saliva is introduced into the host during a blood meal

 Animals respond individually to a variety of antigens

Flea saliva contains inflammatory or immunologic properties:

 Histamine-like compounds

 Proteolytic, cytolytic and anti-coagulant enzymes

 Complete protein antigens (150-14 kD IgE: binding peptides)

 Ctef1 first novel major allergen for canine FAD; 80 kD protein in C. felis saliva

Immunologic mechanism:

 Type I (immediate) hypersensitivity (mins–1 hr)

 Late phase IgE-mediated response (4–2 hrs)

 Cutaneous basophil hypersensitivity (24–12 hrs)

 Type IV (delayed) hypersensitivity (28–24 hrs)

 Upregulation of mast cell proteases during sensitization - generalized selective release of mast cell tryptase after flea antigen exposure

 T_H2 response occurs

Immunologic response depends on: genetic predisposition, duration and degree of flea exposure.

Predisposition: The atopic state in conjunction with flea exposure lead to a combination of atopic dermatitis (AD) and fleabite hypersensitivity.

Intermittent exposure to fleas leads to more severe clinical signs, although hypersensitivity can be triggered with either intermittent or continuous exposure.

Chronic flea exposure in non-allergic dogs - partial or complete tolerance.

A good intradermal test (using pure flea saliva as reagent is best; although Greer whole-body flea extract is also good) will give better sensitivity than the in vitro tests. Intradermal testing detects more than IgE mediated disease.

FAD Diagnosis

Patient history: seasonality, frequency of swimming/bathing, flea control used: how often used, other animals in household indoor/outdoor and their respective flea control; when was last time used the flea control and how applied product, are fleas evident, etc.

This is where you will find the answer to most problems with flea control!

 Most owners are not using the product as they should or we are not instructing them to do it the correct way.

 Clinical signs (e.g., pruritus and/or excess grooming in cats; especially caudal half of body)

 Response to treatment

What's missing in this list? Evidence of fleas and flea dirt!

Most pets with flea allergy have no evidence of flea infestation.

FAD Treatment

 Individually tailored plan

 Most important = flea control!

 Address additional underlying allergies

 Treat secondary infections: bacterial and yeast infections

 Symptomatic therapy (control pruritus): short-term glucocorticoids, antihistamines/EFA rarely effective

Flea Control Objectives

 Relieving pet discomfort

 Kill fleas on pets

Treat all in-contact animals for at least three consecutive months.

Ask if rabbits, ferrets, or hedgehogs as pets - cat flea hosts

 Eliminate premises infestation

Administration of residual insecticides that kill newly acquired fleas within 24 hrs before they can reproduce.

Administer insect growth regulators (IGRs) to stop reproduction.

Application of insecticides and/or IGRs onto the premises in cases of severe infestations or FAD.

Outdoor premises: See www.drmichaeldryden.com/fleas/3/fleas

Bayer Advanced Lawn Complete Insect Killer (Imidacloprid and beta-cyfluthrin= pyrethroid] or professional service for flea treatment

 Prevention

Year-Round Flea Control Program

How to choose?

 Consider diagnosis or desired effect.

 Flea allergy/infestation, tick prevention, mosquito bite prevention, scabies mite prophylaxis, Demodex mite tx, heartworm prevention, lice tx, etc.

 Evaluate formulation: know benefits and side-effects of active ingredients

 Delivery system that facilitates application of active ingredient

 Consider residual activity on pet and premises.

 Consider owner compliance: multi-pet household?

Pearls of Wisdom

 A flea infestation cannot be eliminated within a few days.

 Treatment can take 3–8 weeks (typically 3 months) before flea infestation is eliminated due to home/yard infested with flea eggs, larvae, pupae and adults emerging daily.

 Remember fleas you see on the pet today, came from flea eggs laid 3–8 weeks ago.

 Haphazard use of an excellent product gives poor results.

 If a single monthly dose is missed on a single pet, flea control is likely to fail because of the flea eggs dropping off the untreated pet and continuing to develop and emerge in the environment.

 We cannot treat only the scratching dog; we must also treat the cat that may falsely appear to be flea-free.

Conclusion

 Effective flea control starts with effective client communication.

 Clients need to be educated on the objectives of a flea control program, taught how to properly administer a product, and given a detailed explanation of what to expect once a flea product is administered and the pet is back in the infested premises.

 If we set realistic client expectations through education, we can meet them, but if we allow clients to set their own expectations, we will rarely be successful.

References

1.  Miller WH, Griffin CE, Campbell KL. Canine and feline fleabite hypersensitivity. In: Muller and Kirk's Small Animal Dermatology. 7th ed. St. Louis: Elsevier, 2012;405–414.

2.  www.drmichaeldryden.com