Page 144 - WSAVA2018
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 25-28 September, 2018 | Singapore
A mature larva will move to an undisturbed location
to spin a cocoon. The cocoon’s sticky silk collects
debris from the environment, such as carpet fibers,
and becomes camouflaged. Mature flea larvae are 4-5 mm long, and 0.5 mm wide. While forming cocoons,
the larvae fold themselves in half. Flea cocoons are envelopes of thin, white, silk-like material. The fibers
are soft, moist, and sticky. They’re wrapped loosely around the larvae. As a result, environmental debris easily adheres to cocoons. This detritus may consist
of sand, dust, soil, carpet fibers, or any other small fragments of dry material. The larvae purposefully collect and integrate these particles into their cocoons with a few silk threads. Flea cocoons are difficult to detect. Adhering debris originates from the same environment where the cocoons rest, giving them a near perfect camouflage. Within homes, larvae pupate at the base of carpeting. Once adulthood is reached, fleas can remain in a motionless, dormant state inside their cocoons. This quiescent period lasts up to 5 months, but it ends when a nearby host triggers their emergence. The presence of heat or pressure causes them to exit the cocoons within 5 seconds. After emerging, a flea will climb atop nearby objects, such as carpet fibers, where it’s able to jump onto a passing host. There, the flea orients itself towards sources of light. As a result, fleas tend to gather near openings where light enters, such as vents, crawl spaces, window sills, and other entrances.
The complex flea life cycle means that there are a number of challenges for veterinarians who help clients control fleas in their homes: the physical resilience and rapid multiplication in flea numbers; their ability to find alternative hosts; and the presence of environmental conditions in the home that are conducive to flea survival. In addition, there is a need to select an appropriate form of treatment from among the many options available and to manage the client’s expectations of what is possible to achieve. Clients need to be aware which strategies will and will not be effective: e.g. neither removing pets from a flea-infested house nor leaving the house vacant (to starve fleas) is likely to work, since immature stages live for a year or more, can survive winter temperatures and will only hatch when they feel vibrations (from a passing human, animal or vacuum cleaner), or sense the CO2 given off by a potential host [5].
Flea-borne diseases
Fleas are important clinically as causes of pruritus, flea bite dermatitis, and in young animals with severe infestations anemia. Fleas are intermediate hosts for filarial nematodes and the tapeworm Dipylidium caninum and vectors
for various pathogens, including Bartonella henselae, Rickettsia felis, Haemoplasma species and Yersinia pestis. Cat fleas can also transmit Rickettsia typhi, a causative agent for murine typhus - normally transmitted by the rat flea Xenopsylla cheopis [6].
The cat flea, C. felis, is the most frequently encountered parasite on both cats (98%) and dogs (93%), and is also the flea species with the most potential for transmitting zoonotic diseases. Yersinia pestis causes both bubonic (abscesses and lymphadenitis) and pneumonic forms
of plague, with clinical signs of fever, inappetence, lymphadenopathy and subcutaneous abscesses. Cats seem to be more clinically susceptible than many species. In feline patients the abscesses can be difficult to distinguish from cat bite abscesses. In around 10% of human cases the disease is transmitted by cats, through passing on infected fleas, or directly via scratches, bites or air droplets.
Cats are infected with the tapeworm D. caninum, which has a worldwide distribution, via C. felis. Fleas ingest tapeworm eggs and the tapeworm is transmitted when an infected flea is swallowed by a cat or dog, after
which there is a pre-patent period of 2–3 weeks. In most infected pets the condition is asymptomatic, although the proglottids may be detected in the faeces or on the perianal area. Tapeworms may cause anal pruritus, which may lead the affected animal to ‘scoot’ along the ground, rubbing its anal area, which can embarrass dog owners. Other signs can include diarrhea, weight loss and failure to thrive. Control is achieved through anthelmintic
dosing with praziquantel, along with flea treatment to prevent reinfection and hygiene measures to remove the contaminated faeces.
Bartonellosis is the main flea-borne bacterial disease circulating in pets - Bartonella henselae or B. clarridgeiae are the usual variants in cats while B. vinsonii subsp. berkhoffii is the most common in dogs, along with B. henselae. The prevalence is much lower
in dogs than cats and there is some suggestion that it
is an opportunistic pathogen in this host. Bartonellosis
is normally transmitted through skin contact with the contaminated flea dirt, and the disease has a worldwide distribution. Testing of healthy animals is currently not recommended. Clinical signs may appear when the bacteria are released from the infected cells into the circulation and will consist of endocarditis in cats and dogs, and other inflammatory diseases such as recurrent pyrexia, uveitis and immunemediated polyarthritis. The bacterium may also cause vascular proliferative disease, particularly in human patients. This pathogen appears to have co-evolved with the feline host, which may show no obvious clinical signs, but due to its regular release from infected cells it may have role in various chronic disease conditions.
Another emerging zoonotic disease is fleaborne spotted fever caused by the Rickettsia felis or R. typhi. The pathogen has a worldwide distribution and is transmitted via bites from infected fleas, which are capable of vertical transmission through the egg. Cats are rarely symptomatic and are not known to be reservoirs. Dogs

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