Parasitic Skin Disease Flashcards
What is the identified agent for nodular dermatitis in canids in Southern Europe?
Straelensia cynotis, a trombidoid larval mite, was identidied as a cause of nodular dermatitis in dogs in Southern Europe.
What species of Ctenocephalides is the most common?
felis felis
The flea penetrates the epidermis with its ______
maxillae
In fleas, the ______ is inserted in the capillary vessel, allowing blood to be sucked by three pumps (one cibarian, two pharyndeal) though the feeding tube formed by the maxillae together.
epipharynx
In fleas, a salivary pump pushed saliva through the _____.
laciniae
The sialomes of cat and rat fleas are comprised of what components?
The enzymes families of phosphatases (inactive), CD-39-type tryptase, adenosine deaminases and esterase, as well as antigen 5 members and defensins
Fleas, in contrast to mosquitoes, has a sialome that is comprised of good portion of _______, none of which have a known function but they may act as inhibitors of hemostasis or inflammation.
small polypeptides
They are also unique in terms of the expansion of phosphatase family that appears to be deficient of enzyme activity and has an unknown function
The third pair of legs are used for jumping. Modifications of the hind leg include an enlarged muscular femur and an elastic protein called ______ in the integument.
resilin
Resilin is compressed during the flexion of the coxa in the metathorax, and then rapidly relaxed.
What is the name of the hedge hog flea?
Archaeopsylla erinacei
What are the two species of fleas on birds?
Echidnophaga gallinacean, Ceratiophyllus gallinae
What are the two species of fleas on rodents?
Xenopsylla cheopis, Nosopsyllus fasciatus
What are the 8 stages of the flea life cycle?
The flea has four life stages: egg, larva, pupa and, finally, adult. The speed of development depends on the temperature and humidity of the environment so growth to an adult flea can take just a few weeks to several months.
Describe the host phase of flea life cycle?
o The adult stage of both C.felis felis and C. canis lives permanently in the hair coat of its host.
o In normal conditions, when fleas are in the dog or cat, they walk.
o Fleas have a tendency to leave their host when the hosts temperature decreases or when the host-population is very high.
Describe early onset of blood feeding
o Once the adult (imago) has colonized a new host, it will take its first blood meal very rapidly.
o About 25% of cat fleas start to feed within 5 minutes of being free in the coat and about 97% have taken a blood meal within 1 hour
o Although C. canis takes its meal more slowly, 72.5% of fleas begin blood feeding within the hour.
Flea blood feeding and lifespan
o It is clearly established that blood-feeding is necessary for mating and laying viable eggs, the number of blood meals and their frequency remain unknown.
o It is thougth that fleas will continue to bite and have blood meals until they die.
o Their lifespan is considered to be 2-3 weeks.
First flea eggs
o Female fleas lay their first eggs between 24-36 hours after colonizing a host.
o Eggs are pearly white, oval with rounded ends and approximately 0.5mm long. They are laid in the coat and subsequently fall to the ground.
o Egg production reaches a peak (around 15-20 eggs per day) during the second and third week. It will continue to lay eggs until it dies.
o Egg production usually peaks during the night.
Describe the environmental phase and factors affecting egg and larval development
o Once on the ground, eggs require favorable environmental conditions (humidity and temperature) to develop further.
Ideal conditions are 70% humidity and 30c
o The environmental phase has a major implication in control because of the development of larval and pupal states and because pupae remain dormant in the environment for an extended period of time.
First Larval instars
o The first-instar larvae hatch from eggs in the immediate environment. They tend to move to the depth of the carpet and not move very far from where they hatched.
o They search for suitable food, particularly dried blood flea feces but also other debris including non-viable flea eggs.
Second Larval installs
The second instar tend to move away from carpets, making vacuuming a rather ineffective procedure, since it only removed 15-27% of the larvae.
However, regular vacuuming of pet resting places can remove 90% or more of flea effs as well as flea feces.
Pupal stage
o The third-instar larvae becomes a pupa encased within a cocoon formed out of carious bits of environmental debris stuck together.
o Pupae are often found in well-protected areas such as the back of carpets, skirting boards and cushion seams.
o Inside further imagos remain dormant for several months (“pupal window”) until stimulated to hatch by triggers such as vibrations, increased carbon dioxide levels or temperature.
o Pupae are resistant to freezing, desiccation, insecticides and insect development inhibitors.
Imago
o Once stimulated, imago tear open the cocoon probably as a consequence of agitated movements and jumps onto the first mobile, warm object = animal.
o The young, unfed adult is susceptible to adulticides and insect development inhibitors.
The unfed flea survives longer in the environmental than the fed fleas.
How long is the flea life cycle?
o The entire life cycle can be completed in 13 to 14 days under optimal conditions but can take up to 7-9 months.
How do you prevent a new flea life cycle from developing?
o Preventing a new life cycle would required killing all the adults in the first 24-36 hours of infection and/or applying an insect development inhibitor either to the adult or to the immature stages before pupa formation.
o Vacuuming is not very effective due to the mobility and positive geotaxis of the larvae.
Fleas are vectors for what diseases?
Bartonella, B. henselae, Rickettsia typhi, R. felis
Fleas are the intermediate host for what organisms?
o Dipylidium canium, the double pored tape worm, needs C felis as an intermediate host.
o Fleas can also be intermediate hosts for Rodentolepus nana.
Chorioptic or Scrotal Mange
The causative mites, Chorioptes bovis, live and feed on the skin of sheep, goats, cattle and horses. In sheep, both rams and ewes can carry the mite, however it is often of more significance in the rams, where the mites can cause a hypersensitivity reaction. This hypersensitivity reaction leads to an increase in testicular temperature, resulting in poor fertility, testicular hypoplasia or testicular atrophy. This means you may have a temporarily or permanently unsound ram.
What are the two kinds of cholinesterase inhibitors?
Carbamates and organophosphates
Carbamates are safe for cats at 3 and 5% concentrations. avoid in white haired dogs. Avoid in cats.
Organophosphates a the most toxic insecticides available. These are potent cholinesterase inhibitors. Do not use on kittens or adult cats.
Dinotefuran is what class of insecticide?
It is a third-generation neonicotinoid class insecticide that binds to nicotinic receptors in the nerve synapse, causing continues nerve stimulation and death of the insect.
Its in Vectra (combined with pyriproxyfen) - flea control for cats and dogs
Its also in Vectra 3D which is licensed for dogs only because permethrin is added to formulation; not sure which mites it would work on.
What preventative is a volatile citrus oil extract use in some botanical flea control products? Its insecticidal properties appear to be desiccant in nature because epicuticular old are removed. Efficacy is poorly define and adverse reaction have been seen in dogs and cats.
d-Limonene
Fipronil is an insecticide and acaricide in the phenylprazole class. It acts as an antagonist at what receptor?
It acts as an antagonist at the insect y-aminobutiyric acid receptor (GABA).
Fipronil is a spray or a spot on application product for flea and tick control in dogs and cats,
HIGHLY toxic to rabbits.
What acaricidal agents act by inhibition of monamine oxidase? They are also prostaglandin synthesis inhibitors and alpa-adrenergic agonists.
Formamidines
Amitraz is available as a rinse, spot on with Fipronil (Certifect). In the US- rinse is licensed for use only generalized dermodicosis.
Side effects of amitraz often include transient sedation, pruritus, hypothermia, bradycardia, hypotension and hyperglycemia.
What is the vehicle thought to contribute to Amitraz toxicity?
Xylene
**Don’t use in small dogs
What are the two different groups of insect growth regulators?
1) juvenile hormone analogs
2) chitin synthesis inhibitors
What role do insect growth regulators play in development of insect?
Juvenile hormones are natural chemicals in insetcts that control early stages of their metabolism, morphogenesis and reproduction. final maturation and pupation of flea larvae process only in the presence of appropriate levels or absence of the hormone for that stage of larval growth.
What are available topical agents (juvenoids), with biochemical activities that mimic those of the natural juvenile hormones?
Methoprene, fenoxycarb and pyriproxifen
Application the premises by spray or fogger prevents maturation of pupal fleas is they are exposed to it. These DO NOT affect the adult flea.
Basically - during feeding, the flea is exposed tot he agent and eggs laid are exposed to high levels before they fall off the host into the environment and therefore, do not hatch.
What is an insecticide of the chloronicotinyl nitroguanidine class?
Imidacloprid
This binds to the fleas nicotinic receptor on the post-synaptic neuron and blocks impulse transmission.
Advantage - Imidacloprid (adult fleas and lice)
Advantage II - Imidacloprid + Pyreproxyfen (more flea stages)
K9 Advantix - Imidacloprid + Permethrin (ticks and fleas)
Advantage Multi - Imidacloprid + Moxidectin (hearworms, sarcoptic mange, ear mites and fleas in cats and dogs)
Metaflumizone is a semicarbozone insecticide that blocks ___ channels in insects, results in nerve paralysis.
Sodium channels
**It was in Promeris and it got pulled from the market
What is the insecticide that is a volatile oil extract of the chrysanthemum flower. It has fast knockdown but no residual activity.
Pyrethrins
There is no cholinesterase suppression. Pyrethrin demonstrates a rapid kill but low toxicity, rapid inactivation and lack of tissue reside and buildup. These are toxic to fish and bees.
Effective abasing fleas, lice, otodectes and mosquitos.
Pyrethrin at a low concentration is effective if it is synergized with what compound? This forms a stable complex with cytochrome P450, limiting metabolism of pyrethrins in insects.
piperonyl butoxide
What is an insecticide and an acaricide marketed outside the US. It interacts with ligand-gated chloride channels especially those gated by GABA. It is a contact poison.
Pyriprole
Permethrin is what type of insecticide?
It is a Pyrethroid - these chemicals are modeled after pyrethrin and include allethrin, bioallethrin, remethrin, tetramethrin, deltamethrin, fenvalerate, and permethrin.
Quick kill the is improved but the addition of a synergist and pyrethrin. Newer ones are most UV stable.
Permethrin is the most popular agent. It has a low toxicity, stable, repellent activity. Just don’t use it in cats.
What is the insecticide that is a natural organic compound, is derived from the root of the Derris plant? It is similar to pyrethrins in having low toxicity, rapid action and quick degradation.
Rotenone
Spinetoram exists the insect nervous system, leading to paralysis and death. It alters the function of ___ and ___ ion channels at different biding sites than other insecticides.
Nicotinic and GABA
Systemic endectocide were developed from ______ produced by the fermentation of various actinomycetes. This class of dugs include avermectins and milbemycins.
macrocyclic lactones
All at least partly act by potentiating the release and effects of GABA. GABA is a peripheral NT in susceptible nematodes, arachnids and insects.
Avermectins and milbemycins are also agonists of glutamate-gasted chloride channels.
These drugs do not cross the BBB and make them relatively safe.
High-dose ivermectin can cause neurotoxicity in dogs younger than 3 months, in most animals if given massive dosages or in a verity of herding breeds, most notably the collie. Signs include mydriasis, hypersalivation, lethargy, ataxia, tremors, coma and death. This is associated with altered function of what protein?
P-glycoprotein
Pgp is encoded by Multiple Drug Resistant Gene (MDR-1) or ABCB1. It limits penetration of substances into the CNS. With decreased Pgp activity, a drug enter the CNS freely and exerts whatever positive or negative effects it might have.
The ____ mutation in the MDR1 gene is well known in various herding breeds and their crosses. When they receive doses of ivermectin higher than 0.1 m/kg, neurologic signs develop. Dogs homozygous for mutation are very susceptible to intoxication, whereas dogs heterozygous for the mutation are of intermediate sensitivity.
Nt230(del4)
Ivermectin is a derivative of ivermectin B from fermentation of _______.
Streptomycin avermitilis
Parasite paralysis is the main action of ivermectin, but hit also suppresses reproduction.
Ticks are not killed, nut their egg production and molting are suppressed.
____ is derived from fermentation products of streptomycin hygroscopic. It is similar to ivermectin activity with the notable addition of efficacy in the control of various intestinal parasites.
Milbemycin
It was combined spinosad = Trifexis
___ is derived from fermentation products of streptomycin cyaneogriseus.
Moxidectin
US - labeled for flea - Advantage Multi
This is also licensed for the treatment of various nematode, hypodermic, mites, lice and hornet flies in cattle.
_______ is derived from fermentation products of streptomycin avermitilis. It the US, it is marketed for the treatment and control of various nematodes, mites and lice in cattle and swine.
Doramectin
What is a semi-synthetic ivermectin produce by a new strain of S. avermitilis. It prevents, heat worm, kills adults flea and prevents eggs from hatching and it control ear mites on dogs and cat?
Selemectin
Following topical application, selamectin is identified in sebaceous glands, hair follicles and basal layers to the epithelium
It is safe in ivermectin sensitive dogs, puppies and kittens 6 weeks and older.
What is a benzylphenol urea compound that inhibits chitin synthesis. Chitin is a major component of the flea exoskeleton but is not found in mammals. With altered shining synthesis, embryogenesis and itching does not occur.
Lufenuron
What is an oral flea development inhibitor. It belong to the triazine group pf compounds? it does not inhibit chitin synthesis but it increases its stiffness so the exoskeleton cannot expand. Needs to be given once daily to work.
Cyromazine
Nitenpyram is an agent that acts at what receptor?
Nicotinic acetylcholine receptor.
It is a novel oral administered flea adulticide. It exerts it action at the post-synatptic nicotinic acetylcholine receptor of the insect.
Unlike imidacloprid, which isa paralytic, nitempyram produced hyperexitability. No activity after 48 hour.
What insecticide is derived from a soil-dwelling bacterium, Saccharopolyspora spinosa, and has activity abasing insects. Its activity occurs at the nicotinic acetylcholine receptor but does not interact with down insecticidal binding sites of other nicotinic or GABA-ergic insecticides.
It produces hyper excitability, paralysis and death of the insect.
Spinsad
The larvae of Ancylostoma braziliense, Ancylostoma caninum and Univinaria stenocephala case a characteristic skin lesion in humans that is called what? The skin lesions these larvae produce in dogs or cats are not as severe because these animals are their specific hosts.
Creeping eruption caused by hookworm dermatitis.
Skin lesicon are often incidental to completion of the norm life cycle, with the larvae quickly abadoning the skin and moving tother parts of the body. Percutaneous entry can lead to complete of the life cycle larvae penetrating by this route rarely mature. Larvae are present in the grass and in soil of runs.
Cutaneous hookworm lesions are more prevalent in areas with predominant infections with what species? This species produced marked dermatitis son skin penetration but rarely completes the life cycle by this route.
U. stenocephala
Which hookworm species can complete their life cycle via skin penetration?
A. canium
In hookworm infections, what stage of the larvae enter the dos skin on areas of the body that frequently contact the ground. They enter primary at en area of desquamation on the skin.
Third-stage larvae
How do you diagnose hookworm dermatitis?
Diagnosis is made with reasonable certainty by the clinical signs, a positive fecal examination finding hookworm eggs and history of poor housing and sanitation.
Rhabditic dermatitis is a local erythematous nonseasonal pruritic dermatitis caused by a cutaneous infection with larvae of what species?
Pelodera strongyloides
Under filthy condition, the larvae of the free-living nematodes P. Strongyloides may invade the skin of dogs.
How do you diagnose and treat Pelodera?
Diagnosis is made by skin sraping which reveal small motile nematode larvae. Larvae and adult can be identified in contaminated litter by using the Baermann technique.
Biopsy reveals varying degrees of perifolloculitis, folliculitis and furunculosis.
Treat with a parasiticidal dip or ivermectin.
What insect of ducks, shore birds, voles, mice or muskrats (natural hosts) penetrate the skin of humans, or other warm-blooded animals that are abnormal hosts, and cause a pruritus dermatitis?
Schistosoma - “swimmers itch”
The miracidia hatch and need to find a snail within 12 hours or diet. They form spoprocytes in the nail and hatch in 4 weeks as cercaria. Then they have 24 hors to find a warmblooded natural host. In the natural host, they fo to the liver and intestinal wall to lay offs and passed in feces. The cercariae penetrate the skin of the abnormal host and produce clinical disease.
These parasites are trematodes
What parasite affects dogs and wild carnivores of North America. The intermediate host is a Cyclops (crustacean) that is ingested form contained water by the host.
Dracuculiasis
The larvae develop in the host during a period of 8-12 months. The adults develop in the subcutaneous tissue the abdomen and limbs. Usually a nodule forms and eventually a fistula develops. When the host enter cool water the female worm is stimulated to release larvae - escaping through the fistula.
Chronic single to multiple nodules on the limbs, head or abdomen. Treatment is just removing them.
What parasite causes heartworm disease?
Dirofilaria immitis
Diagnosis for dermatitis is usually with peripheral eosinophil and positive Knott test for microfilaria.
