Prion/Protozoa/Parasitic Infections Flashcards
1
Q
What is Toxoplasma gondii?
A
Obligate intracellular protozoal parasite
Cats get it from eating rodent containing encysted bradyzoites –>
Cats are definitive host and excrete infectious oocytes in their feces
- T. gondii can sexually reproduce in their intestines
- because cats don’t have Δ-6-desaturase in their intestine = a lot of linoleic acid
- all other hosts are intermediate hosts
Oocysts can survive and remain infective for many months in cold/dry climates
2
Q
What happens in the immune response to T. gondii?
A
stimulates production of IL-2 and IFN-γ by the innate immune system –>
elicit a CD4+ and CD8+ T-cell and NK cells
IFN-y also activates of IDO and TDO (responsible for degrading tryptophan)
- starves the parasite
- can result in depletion of tryptophan in the brain of the host
3
Q
What are the clinical signs associated with a T. gondii infection?
A
Can be seen in cats that are immunosuppressed or intermediate hosts
- including marine mammals, penguins, and birds
Non-specific signs of sickness, can affect any body organ
- tissue cysts (can be maintained for life of animal)
- liver, brain, GI, kidneys, lymph nodes, hearts, etc
Skin can have pyogranulomatous dermatitis +/- necrotizing vasculitis
- with intrahistiocytic toxoplasma organisms
4
Q
How do you diagnose T. gondii infections?
A
FNA of cutaneous cysts (or other organs) to show them in macs
PCR
paired serum samples showing 4-fold rise in titer over 2-3 weeks
5
Q
What is the typical treatment for T. gondii infections?
A
clindamycin (good CNS penetration)
6
Q
What is canine Caryosporosis?
A
intracellular protozoan parasite in
- snakes and raptors (primary hosts)
- rodents (secondary host)
rare in dogs but can make pustules, plaques, nodules, panniculitis
7
Q
How do you diagnose canine Caryosporosis infections?
A
Histopath: pyogranulomatous dermatitis/panniculitis and intralesional organisms
PCR and DNA sequencing
8
Q
What is the treatment of canine Caryosporosis infections?
A
TMS, pyrimethamine and high-dose clindamycin (20 mg/kg twice daily)
- dog as able to get clinda monotherapy but relapsed when stopped
9
Q
What is Neospora caninum?
A
a coccidian protozoa (obligate intracellular parasite)
Oocysts passed in the feces of the definitive host (canids) –>
- can shed for months
ingested by an intermediate host (ex. cattle, goats, sheep, horses)
can also have transplacental transmission
10
Q
What is the lifecycle of Neospora and Toxoplasma?
A
intermediate host ingest oocyst –>
release rapidly dividing tachyzoites –>
disseminate through host –>
differentiate into bradyzoites –>
form cysts in muscle and tissue
11
Q
What are the clinical signs associated with a Neospora caninum infection?
A
Neuromuscular degeneration
Abortion esp in cattle and dogs
- Aborted tissues contain large amounts of tachyzoites and bradyzoites
Many clinical signs depending on where cysts are
- cysts in skin can be draining nodules, ulcerative dermatitis
Clinical signs tend to be worse in younger dogs/those affected in utero
12
Q
How do you diagnose Neospora caninum infections?
A
Histopathology: nodular pyogranulomatous dermatitis
- tachyzoites in keratinocytes, macs, neuts, endothelial cells
- eosinophilic necrotizing dermatitis with infarcts
PCR, IHC or serology
13
Q
What is the treatment for Neospora caninum infections?
A
Clindamycin
(or TMS)
14
Q
Which breed of dog may be predisposed to atypical cutaneous protozal infections (canine Caryosporosis and Sarcocystis)?
A
Rottweilers
(personal observation, the case reports both in Rottweiler puppies)
15
Q
What can Sarcocystis cause in dogs?
A
multiple cutaneous abscesses with intralesional protozoa
(dog died, treatment was not attempted)
16
Q
What can Sarcocystis cruzi cause in cattle?
A
loss of tail switch (“rat tail”)
may develop alopecia of pinnae, neck, rump, and distal limbs
fever, anorexia, hypersalivation, lameness, anemia, and abortion
17
Q
What can Sarcocystis capricanis cause in goats?
A
poor hair coat and patchy alopecia
18
Q
What is babesiosis?
A
caused by a hemoprotozoan parasites of genus Babesia
- Babesia canis (more common in greyhounds and Gulf Coast)
- Babesia gibsoni (more common in pitties)
19
Q
How is canine babesiosis spread?
A
Bite of infested ticks (multiple species)
Spread of infected blood or saliva
- dog fighting
20
Q
What are the clinical signs associated with canine babesiosis?
A
waxing/waning fever, lethargy, reduced appetite, anemia, hematuria, etc
oral/cutaneous petechiae/ecchymoses due to leukocytoclastic vasculitis
can also cause alopecia, scale, pad hyperkeratosis, pododermatitis, onychodystrophy
CAN LOOK LIKE SLE (should have negative/low ANA)
21
Q
How do you diagnose canine babesiosis?
A
Serum titers
- B. canis: 1:80 or higher
- B. gibsoni: 1:320 or higher
22
Q
How do you treat canine babesiosis?
A
doxycycline (though you may not eliminate parasite)
sometimes clindamycin or azithromycin
23
Q
What is trypanosomiasis?
A
More common in horses in Africa, Asia, and Central/South America
Trypanosoma trypanosomes are found principally in the blood and tissue fluids
- a few invade tissue cells
- have a terminal kinetoplast, flagellum and tapered ends
transmitted by blood-sucking arthropods and insects
can cause dependent edema, urticarial plaques, and ulcers
- “silver dollar spots”
regional variant names are Nagana, Surra, and Dourine
- Dourine is transmitted via coitus
- Nagana is through tsete flies (glossina) like African Sleeping Sickness
REPORTABLE
24
Q
What is the treatment for equine trypanosomiasis?
A
diminazene, suramin, quinapyramine
but many horses remain inapparent carriers
25
What is besnoitiosis (globidiosis)?
rare disease of horses and goats in Africa and South and Central America
caused by Besnoitia bennetti (probably through eating oocysts) or vectors
nodular disease with parasitic cysts
- with scleral “pearls” (can be elsewhere inside body)
- nodular dermatitis
may be febrile, depressed, weak, and show signs of upper respiratory disease
26
What are Giardiasis spp. associated with in Cockatiels and Lovebirds and how is it treated?
feather plucking over the torso and self-inflicted trauma to the wing webs
metronidazole, orally twice daily, for 7–10 days
- +/- Vitamin E since it can do the same thing
27
What can lice/keds transmit in raptors?
haemoprotozoan parasites such as Haemoproteus sp.
- can lead to hemolytic anemia
28
What are the clinical signs of protozoal infections in fish?
General lethargy, anorexia and death
- Tetrahymena corlissi = ‘guppy killer’
- Pleistophora hyphessobryconis = ‘neon tetra disease’ (infects muscle)
Excess mucus (‘slime disease’) = dull color and grey-blue sheen to skin
White spots on skin (up to 1 mm)
- Ichthyophthirius multifiliis = "Ich/white spot" in freshwater fish
Chichilids can have "hole in head" disease due to Spironucleus spp.
29
What is scrapie?
a fatal, degenerative disease affecting the nervous systems of sheep and goats
- not transmissable to himans
one of several transmissible spongiform encephalopathies cause by prions
affected animals will compulsively scrape skin against rocks, trees or fences
- seems to be severe pruritus, is bilateral, esp tail head
other signs include excessive lip smacking, ataxia, tremors, and collapse
30
What are the clinical signs of bovine spongiform encephalopathy (“mad cow
disease”)?
licking, wrinkling nose, head rubbing, and neurological disorders
31
What is the vector of leishmaniasis?
female sandflies
- Phlebotomus in the Old World (Europe, Africa, and Asia)
- Lutzomyia in the New World (American continent)
are more common in warmer seasons
are active from dusk to early night then again at dawn
32
What are the three main clinical presentations of leishmaniasis?
infected macrophages can be found in parasitized tissues
- cause granulomatous inflammatory reactions that lead to most symptomatology
1) cutaneous leishmaniasis
- considered most common in humans and dogs
- good for being infectious
2) mucocutaneous/mucosal leishmaniasis
3) visceral leishmaniasis
- L. infantum most frequently causes this
Can also be the designation form 1988:
1) asymptomatic dogs
- some cannot be detected by conventional serological tests
- shown to be highly competent to transmit the parasite to the vector
2) oligosymptomatic dogs (maximum of three clinical signs)
3) symptomatic dogs (severe signs of the disease)
33
What is the most common species of Leishmania in dogs?
L. infantum/L. chagasi
- L. chagasi more common in Americas, now thought to be the same
there are at least 53 species with at least 20 species causing disease
34
What can Leishmania spp cross react with on IFA or ELISA?
Trypanosoma cruzi (anywhere from 18-50%)
35
Where is L. infantum endemic?
Mediterranean basin, southern America, and Central and Southwest Asia
36
What is the infective stage of Leishmania?
promastigotes
37
What is the main reservoir host of Leishmania infantum?
dog are considered the main reservoir hosts in urban areas
cats, rabbits/hares, wild rodents, other canids can be hosts as well
- may be some regional variation in primary reservoir hosts
38
What is the lifecycle of Leishmania?
In mammal:
- sandflies inject meta cyclic promastigotes during blood meals -->
- phagocytized by macrophages -->
- become amastigotes which multiply -->
- break out of macrophages and infect other monocytic cells -->
In sandfly:
- cells with amastigotes transferred during feeding -->
- amastigotes released in the midgut
- transform into procyclic promastigotes (flagellated) -->
- procyclic promastigotes become metacyclic promastigotes -->
- migrate to the pharyngeal valve
39
How is Leishmania able to live inside macrophages?
remodeling of the parasitophorous vacuole
- hinders the macrophage signaling pathways
40
What is the immune system response to Leishmania in humans and dogs?
may not progress to a noticeable form of the disease
- 10-50% of seropositive dogs have no clinical signs
persistent disease is associated with a mixed Th1/Th2 response
related to nutritional/immune state of dogs, dog age/breed, and parasite strain
Th1 cytokines (IFN-γ, TNF-α, and IL-2)
- activate macrophage (M1) to eliminate it with nitric oxide and other ROS
- CD8+ cells can kill affected macrophages and help with more Th1
- CD4+ T can also lyse infected macrophages
- results in productive antibodies (ex. IgG2b,c)
- provides lifelong immunity to reinfection
Th2 cytokines (IL-10, IL-13, IL-4, and TGF-β)
- lead to a humoral response and M2 macrophages so it can survive
- results in non-productive antibodies (ex. IgG1)
41
Which TLR is significantly upregulated in damaged skin of sick dogs with Leishmania and is associated with disease progression?
TLR2
42
Which TLR is down regulated in the unaffected skin in infected dogs when
compared with skin from more severely affected dogs?
TLR7
43
What are the clinical signs of Leishmaniasis?
infected macrophages can be found in parasitized tissues, causing granulomatous inflammatory reactions that lead to most symptomatology
44
What is the main cause of death in canine leishmaniasis?
Renal failure (glomerulonephritis due to immune-complex deposition)
- proteinuria and high blood creatinine levels
45
What are the general clinical signs of canine leishmaniasis?
May not show signs until months or years after exposure
Bimodal distribution pattern: usually <3 years or >8-10 years
Most dogs present with poor BCS/cachexia and anorexia
- esp with visceral leishmaniasis in pancreas, spleen, and/or bone marrow
Main skin signs include nodules, ulcers, and pustules, and exfoliative dermatitis
Ocular damage, coagulation disorders, splenomegaly, bone marrow, etc
Lymphadenopathy is not correlated with parasite load or clinical state
46
What are the cutaneous signs of canine leishmaniasis?
Main skin signs include nodules, ulcers, and pustules, and exfoliative dermatitis
- Alopecia, pale mucosa, and erythema are common
- Often causes onychogryphosis
- Silvery white asbestos like scaling
- Mostly on head, pinnae and extremities +/- generalized
- Nasodigital hyperkeratosis, alopecia, periocular alopecia (lunettes)
- nasal depigmentation with erosion
Associated with lichenoid/interface dermatitis in absence of parasites
May get lesions are pressure points
- potentially because infected cells are transported there when injured
47
Why do dogs with leishmaniasis often have splenomegaly ?
presence of amastigotes and to the macrophage infiltration
- spleen is one of the most affected organs (skin and bone marrow too)
spleen concentrates high parasite burden and has morphological changes
- hypertrophy and hyperplasia of the red pulp
- infiltration of mononuclear and plasma cells
- hypertrophy and hyperplasia of white pulp trying to make more macs
48
In which organ is the response to Leishmania established for dogs and the process of cell activation occurs?
The spleen
49
Which TLRs play a role in splenic innate immunity during canine leishmaniasis infections?
TLR-5 and TLR-9
50
In which organ is responsible for the persistence of the disease including relapses for Leishmania in dogs?
bone marrow (a densely parasitized organ)
- hematopoiesis in early stage -->
- pancytopenia, non-regenerative anemia, histiocytic hyperplasia -->
- ending in medullar aplasia
translate into haematological and coagulation disorders
51
What is the correlation between cutaneous parasite load, disease severity and vector infectivity in canine Leishmaniasis?
Skin parasite load (though variable) seemed to increase with disease severity
Parasite load is correlated with the vector infectivity
- some may be super-spreaders
52
Why do dogs with leishmaniasis often have hepatomegaly?
In the liver it establishes itself in Kupffer cells
- formation and maturation of granulomas
- removes pathogens and their antigens from the circulation
Can progress to hepatitis
53
What is resistance to canine leishmaniasis associated with?
higher levels of total T lymphocytes (CD4+ and CD8+) and CD21+ B cells
- converse for increased susceptibility
strong lymphoproliferative response of PBMCs to Leishmania antigen
54
How do you diagnose canine leishmaniasis?
PCR
- rtPCR is preferred because it can be converted into quantitative PCR
- may have best results lymph node or bone marrow
- can also do biopsies, blood, conjunctival, and oral swabs, and hair
indirect fluorescent antibody test (IFAT) - considered "serologic gold standard"
- good in Chagas disease-free areas
- variable time to antibody production but titers usually high if sick
- pair with another test (can't always differentiate between exposure and disease)
ELISA
- ELISA usually uses Q antigen and kinesin-derived antigens (ex. rK39)
Cytology especially of the bone marrow or lymph node (or FNA)
- 52–85% sensitivity for bone marrow
- 52–58% sensitivity for lymph node aspirates
Histopathological and IHC
Culture base on blood agar
- difficult and takes a month to determine if negative
- grows in 64–100% of cases
Xenodiagnoses
55
What species get leishmaniasis?
Humans, dogs > cats, horses and other domestic animals (ex. sheep and cattle)
56
What is the structure of a Leishmania amastigote?
circular or oval in shape, 2-4 mm in diameter, and contain around, basophilic nucleus and a small, rodlike kinetoplast
- inside of macrophages
- best seen with Giemsa stain
57
What is the most common species of Leishmania seen in horses?
Americas: L. braziliensis
Europe: L. infantum
58
What are the histopathologic findings associated with cutaneous Leishmania?
Lymphohistiocytic/(pyo)granulomatous inflammation with vasculitis
- +/- hyperkeratosis
9 histopath patterns noted w this variable dz
Destroys sebaceous glands (causes exfoliative dermatitis)
2-4 um organisms, round basophilic nucleus and rodlike kinetoplast
Visible with routine stains, Giemsa is the best
59
What do PCR primers typically target when testing for Leishmania?
minicircle kinetoplast DNA and internal transcribed spacer 1 ribosomal DNA
60
What is xenodiagnosis?
involves feeding a suspected infected host to an intermediate host, such as an insect, and then examining the intermediate host for the presence of parasites
61
What is the treatment for canine leishmaniasis?
Usually includes allopurinol, antimonials, miltefosine
- antimonials are meglumine antimoniate and sodium stibogluconate
- antimonials have been replaced by amphotericin B in some places for humans
- widespread resistance to meglumine antimoniate
Consider treatment based on severity of disease
- mild disease: allopurinol alone
- moderate to severe: allopurinol + antimonials/miltefosine
Monitor treatment at 1 mo, 3-4 mo, and then every 6-12 mo
- Antibody titer can be used to anticipate relapses
Other medications to consider
- the aminoglycoside paromomycin/aminosidine
- domperidone
- fluroquinolones (increase killing by macrophage)
- pentamidine
- spiramicin
- metronidazole
- ketoconazole
62
What is allopurinol resistance in Leishmania associated with?
decrease in S-adenosylmethionine synthetase copy numbers
63
What is the prognosis for canine leishmaniasis?
Complete elimination is very difficult
- relapses are common
- parasite load can be decreased to asymptomatic levels with chemotherapy
- in some areas, culling is recommended
64
What is the dominant sterol in the Leishmania cell membrane?
ergosterol
65
What is the effect of miltefosine on proteinuria in dogs with leishmaniasis?
decrease proteinuria
66
What are ways to prevent canine leishmaniasis?
Insect repellant (deltamethrin and permethrin)
Keeping animals in at dawn and dusk
Vaccination in some locations (4 licensed)
- creates differential isotype humoral immune response
- not super reliable for telling the difference
67
What are the typical clinical signs of cutaneous leishmaniosis in horses?
Lesions are usually multiple
commonly on muzzle, periocular, pinnae, axillae, groin, scrotum, legs, and neck
papules and nodules, 5-20 mm in diameter
- can become alopecic, crusted, and ulcerated
- neither pruritic nor painful
horses are typically otherwise healthy
many horses undergo spontaneous remission within 3-5 months
68
Is serology a good way to test for Leishmania in horses?
Not reliable
Antileishmanial antibodies are typically absent or present at very low titers in serum
69
What morphologic features can you use to tell ticks apart?
Scutum (shield made of chitin)
Mouthparts (palps and toothed hypostome)
Festoons (short grooves located on the back margin)
- lacking in Ixodes
70
Adult male American Dog Tick (Dermacentor variabilis)
71
Adult female American Dog Tick (Dermacentor variabilis)
72
What is the lifestyle of the American Dog Tick (Dermacentor variabilis)?
3-host lifecycle (use 3 different hosts in their lifecycle)
- Larvae and nymphs mainly infest small mammals
- Adult stages prefer medium-sized hosts
found over most of North America
Most active April-early August
predominantly along forest edges and in areas with little or no tree cover
can transmit Rocky Mountain Spotted Fever and Tularemia
73
Why are ectoparasites rare in chinchillas?
Their dense haircoat
74
What are the important mites in ferrets?
Psoroptidae: Otodectes cynotis
Sarcoptidae: Sarcoptes scabiei
75
What are the important ticks in ferrets?
Ixodes ricinus
76
What are the important insects in ferrets?
Fleas
77
What are the important helminths in ferrets?
Hypoderma spp.
Cuterebra spp.
Dracunculus insignis.
78
What are the important ectoparasites in gerbils?
Demodex meroni
fur mite Acarus farris
79
What are the important mites in guinea pigs?
Sarcoptidae – *Trixacarus caviae and Sarcoptes scabiei
Atopomelidae – Chirodiscoides caviae
Myocoptidae – Myocoptes musculinus
Cheyletiellidae – Cheyletiella parasitovorax
Demodicidae – Demodex caviae
80
What are the important lice in guinea pigs?
Gliricola porcelli
Gyropus ovalis
81
What are the important mites in hamsters?
Demodex criceti
Demodex aurati
Notoedres notoedres
Notoedres cati
Sarcoptes scabiei
Trixacarus caviae
Ornithonyssus bacoti
82
What are the important insects in hamsters?
fleas - C. felis felis
83
What are the important mites in hedgehogs?
Caparinia tripilis.
Sarcoptes spp.
Otodectes spp.
Notoedres spp.
Chorioptes spp.
Demodex erinacei.
Trombicula autumnalis.
84
What are the important ticks in hedgehogs?
Ixodes hexagonus, Ixodes ricinus, Ixodes trianguliceps.
85
What are the important insects in hedgehogs?
Flies – Lucilia, Calliphora.
Fleas – Archaeopsylla erinacei.
86
What are the important mites in mice?
Myobidae – fur mites Myobia musculi, Radfordia affinis.
Myocoptidae – mange mites Myocoptes musculinus, Trichoecius rombousti
Dermanyssidae – Liponyssoides sanguineus, Dermanyssus gallinae.
Psorergatidae – Psorergates muricola.
Demodicidae – Demodex musculi.
87
What are the important insects in mice?
Lice.
- Polyplax serrata.
Fleas.
- Xenopsylla spp.
- Nosopsylla spp.
88
What are the important endoparasites in mice?
Pinworm (Syphacia obvelata)
89
What are the important ticks in rabbits?
Haemaphysalis leporis-palustris
90
What are the important mites in rabbits?
Listrophoridae – Leporacarus gibbus.
Psoroptidae – Psoroptes cuniculi.
Cheyletiellidae – Cheyletiella parasitovorax.
Psorergatidae – Psorobia lagomorphae.
Demodicidae – Demodex cuniculi.
Sarcoptidae – Notoedres cati, Sarcoptes scabiei.
Trombiculidae – Neotrombicula autumnalis.
Notoedres
91
What are the important mites in rats?
Myobidae – Radfordia ensifera.
Sarcoptidae – Notoedres muris, Sarcoptes scabiei var. cuniculi, Trixacarus diversus,
Trixacarus caviae.
Dermanyssidae – Liponyssoides sanguineus.
91
What are the important insects in rabbits?
Lice.
– Haemodipsus ventricosus.
Fleas.
– Spillopsyllus cuniculi.
– Ctenocephalides felis and canis
– Cediopsylla simplex.
– Odontopsyllus multispinous.
– Echidnophaga gallinacea.
Green bottle fly (Lucilia spp) myiasis
92
What are the important insects in rats?
Lice – Polyplax spinulosa (the spined rat louse).
93
What are the important endoparasites in rats?
Pinworms (Syphacia obvelata)
94
What are the most important mites in caged birds?
Burrowing skin mite: Cnemidocoptidae (C. pilae), Epidermoptidae. (Myialges)
Surface skin mite: Dermanyssidae (D. gallinae), Ornithonyssus spp.
Feather mites Protolichus lunula and Dubininia melopsittaci
Quill mites (Syringophilidae)
95
What are the most important mites in raptors?
Burrowing skin mite – Cnemidocoptidae (C. pilae).
Surface skin mite – Dermanyssidae (D. gallinae), Ornithonyssus spp.
Feather mites.
Quill mites.
96
What are the most important ticks in raptors?
Ixodes ricinus
97
What are the most important insects in raptors?
Lice.
Blow flies.
Louse flies/Keds.
Mosquitos.
Beetles.
98
Which parasites can migrate into subcutaneous tissue in snakes?
Cestode, Spirometra.
Trematodes, Spirorchidae.
Spirurids.
Pentastomids are zoonotic
99
What are the most important ectoparasites in snakes?
Helminths. (Dracunculus)
Filarioidae
Mites. (Ophionyssus natricis)
Ticks. (Aponomma transversale)
100
What are the most important mites in lizards?
Trombiculidae – chigger mites.
Macronyssidae – Ophionyssus acertinus.
Pterygosomatidae.
101
What are the most important ticks in lizards?
Ixodidae: Amblyomma, Aponomma, Hyalomma, Ixodes and Haemaphysalis
102
What are the important dermatological parasites of chelonians?
Helminths (spirorchid flukes)
Mites.
Ticks.
Blow flies (cause myiasis)
Leeches.
103
Adult male Blacklegged/Deer Tick (Ixodes scaluparis)
104
Adult female Blacklegged/Deer Tick (Ixodes scaluparis)
105
What is the lifestyle of the Blacklegged/Deer Tick (Ixodes scaluparis)?
three-host tick
- white-tailed deer are their reproductive host
-whole cycle takes ~2yrs
encountered predominately in deciduous forest as well as tall grasslands
the eastern half of the United States
active October-May
transmit Lyme disease, Babesiosis, Anaplasmosis, and Tick paralysis
106
Adult male Lone Star Tick (Amblyomma americanum)
107
Adult female Lone Star Tick (Amblyomma americanum)
108
What is the lifestyle of the Lone Star Tick (Amblyomma americanum)?
three-host tick
- actively seeks hosts
found mostly in woodlands with dense undergrowth
eastern, southeastern, and south-central United States
carry ehrlichiosis, tularemia and possibly Rocky Mountain Spotted Fever
109
Adult male Gulf Coast Tick (Amblyomma maculatum)
110
Adult female Gulf Coast Tick (Amblyomma maculatum)
111
What is the lifestyle of the Gulf Coast Tick (Amblyomma maculatum)?
3-host ticks
found in coastal areas along the Atlantic coast and Gulf of Mexico
- New Jersey to Texas
- extending their range into Oklahoma and Kansas
like ears
112
Adult male Brown Dog Tick (Rhipicephalis sanguineus)
113
Adult female Brown Dog Tick (Rhipicephalis sanguineus)
114
What is the lifestyle of the Brown Dog Tick (Rhipicephalis sanguineus)?
three-host tick but hosts tend to be of one species
found throughout the United States (more common in the south)
can spend their entire life cycle indoors
complete their life cycle in as few as three months
Trasmit Rocky Mountain Spotted Fever, babesiosis, ehrlichiosis
115
What is the soft shell tick that can be found in ear canals?
Otobius spp
Otobius megnini in cats and dogs
have sharp spines
116
What are black flies?
Simulium spp.
small flies but severe nuisances
vectors of various viral, protozoal, and filariid diseases
eggs are laid on stones or plants just below the surface of the water
populations are largest and most active in spring and early summer
- especially morning and evening
adults can fly long distances
frequently bite areas of low hair density
117
What are stable flies?
Stomoxys calcitrans
cause of annoyance and disease transmission
- viral, protozoal, and helminthic
- cause pruritic/painful papules and wheals with central crust
- prefer the neck, back, chest, groin, and legs of horses
- can cause lesions on face or ears of dogs
Eggs are laid in wet straw, bedding, or manure
one cause of insect-bite hypersensitivity
- both male and female feed on blood meal
118
What are horn flies?
Haematobia (Lyperosia) spp
ubiquitous cause of annoyance and disease transmission
- protozoal and helminthic
small (3-4 mm), strong flying, blood-sucking insects
spend their entire adult life on the host
lay their eggs in fresh cow manure (not horse manure)
prefer ventrum when sunny/warm and topline when rainy/cool
- H. irritans is a cause of ventral midline dermatitis
119
What are Musca spp. flies?
do not have biting mouth parts
feed from wounds, secretions from the eyes/nose, mouth, and blood
Eggs are laid in feces, manure, or decomposing material
- M. autumnalis (face fly) needs fresh cow manure
- M. domestica carries Habronema spp.
120
What are “keds” in horses?
Louse flies (ex. Hippobosca equina)
121
Which flies cause ventral midline dermatitis in horses?
Haematobia (Lyperosia) irritans (the horn fly) and Culicoides spp. gnats
122
What are bots in horses?
Gasterophiliasis
Adult flies (botflies) are active in summer
females glue their eggs to the hairs of horses -->
hatch in response to temperature increases and licking -->
penetrate skin or mucosa -->
develop in the stomach -->
pass with the feces -->
pupate in the ground
Can cause 1- to 2-mm wide grayish-white, crooked streaks in the skin
- hair becomes rough and falls out
123
What is hypodermiasis?
common disorder of cattle and in many parts of the world
- occassionally affects horses
cause by Hypoderma bovis and H. lineatum
fix their eggs (1 mm long) to the hairs of the legs -->
hatch and penetrate skin
can from nodules with breathing pores
- like the topline near the withers in horses
can be associated with neurologic disorders due to migration
124
Psoroptes spp
(suckers are a small, shallow cup on a long stalk with jointed pedicel)
125
Dermanyssus gallinae
126
Chorioptes or Psoroptes
127
Sarcoptes scabiei
128
Sarcoptes scabiei
129
Trombicula autumnalis
130
Chorioptes
(suckers are deeply cup-shaped with a short stalk)
131
Otodectes
132
Ornithonyssus
133
Babesia
134
Leishmania
135
Hypoderma
136
What is myiasis?
blowfly strike
genera Calliphora, Condylobia, Lucilia, Protophormia, Phormia, and Wohlfahrtia
eggs are laid in wounds
137
What is habronemiasis aka summer sores?
A nematode infection in horses
larvae are laid in moist areas or wounds and penetrate skin -->
can get into mouth and move to stomach -->
adults live in inhabit the horse’s stomach
if in nose can spread to lungs
can stay in skin and cause a hypersensitivity reaction
use intermediate hosts Musca domestica and S. calcitrans
138
Biopsy from a nodular wound on a horse.
Habronemiasis
139
Skin scraping from the neck of a horse.
Onchocerciasis
140
What is onchocerciasis?
Usually caused by O. cervicalis
Adult worms (up to 30 cm long) inhabit the ligamentum nuchae
- in a necrotizing (pyo)granuloma with mineralization
- nothing kills adults, just microfilaria
Microfilariae are most numerous on the ventral midline then face and neck
- dying microfilaria cause local hypersensitivity
- usually pruritic alopecia, scaling, and crusting
- can have ocular sighs
Culicoides spp. gnats are intermediate hosts
141
What is oxyuriasis?
pin worms, thread worms
common in stabled horse
causes pruritus ani
142
What does Pelodera strongyloides cause?
A nematode that can invade skin and cause eosinophilic parasitic folliculitis
- associated with poor husbandry
potential preference for ventral midline in horses
preference for paws, ventrum, thighs in dogs
usually non seasonal
143
Pelodera
144
Trombicula
145
What is the horse chewing louse?
Werneckiella equi
146
What is the horse sucking louse?
Haematopinus asini
147
What mites do cattle typically get?
Chorioptes bovis > C. texanus
Psoroptes ovis (bovis)
Sarcoptes scabiei var bovis
Demodex bovis
Dermanyssus gallinae (if close to birds)
Raillietia auris
148
What is the bovine chewing louse?
Damalinia (Bovicola) bovis
149
What are the bovine sucking lice?
Haematopinus eurysternus
Linognathus vituli
Solenopotes capillatus
150
What mites do horses typically get?
Psoroptes ovis (equi) and cuniculi
Sarcoptes scabiei
Chorioptes bovis (equi)
Trombicula
Dermanyssus gallinae (if near birds)
Forage mites
151
What is the horse fly?
Tabanus spp.
152
What mites do goats typically get?
Chorioptes bovis (caprae)
Psoroptes ovis (caprae) and cuniculi
Sarcoptes scabiei var caprae
Demodex caprae
Dermanyssus gallinae (if near birds)
Raillietia caprae (ear mites)
153
Which psoroptic mite has a predilection for ear canals?
Psoroptes cuniculi
154
What are the caprine chewing lice?
Damalinia (Bovicola) caprae, D. crassipes, and D. limbata
155
What are the caprine sucking lice?
Linognathus stenopsis and L. africanus
156
Chewing louse - belongs to Mallophaga
Werneckiella, Damalinia, Trichodectes, Felicola
157
What causes "warbles" in goats?
Przhevalskiana silenus (P. crossi, P. aegagi, Hypoderma silenus, and H. crossi)
158
Sucking louse - belongs to Anoplura
Haematopinus, Linognathus, Solenopotes
159
What is screw-worm?
Callitroga hominivorax and C. macellaria in the Americas
can invade intact skin
160
What mites do sheep typically get?
Chorioptes bovis (ovis) - aka foot or scrotal mange
Psoroptes ovis and P. cuniculi
Sarcoptes scabiei var ovis
Demodex ovis
Psorergates (Psorobia) ovis
161
What is the ovine chewing louse?
Damalinia (Bovicola) ovis
162
What is the ovine sucking louse?
Linognathus ovillis and L. pedalis
163
What mites do pigs typically get?
Sarcoptes scabiei var suis
Demodex phylloides
164
What is the porcine chewing louse?
Don't typically get them
165
What is the porcine sucking louse?
Haematopinus suis
166
What is hookworm dermatitis?
caused by Ancylostoma and Uncinaria larvae
- present in grass and soil during spring and summer
- associated with poor husbandry
Ancylostoma can complete lifecycle through skin, Uncinaria usually doesn't
3rd stage larva enters the skin
cause signs: papules, erythema, alopecia, pawpad hyperkeratosis, pawpad spongy feeling, distal limb swelling, claw abnormalities, pruritus, and sometimes arthritis
test a fecal
167
What is schistosomiasis?
"swimmer's itch"
Trichobilharzia and Austrobilharzia affect waterfowl -->
Schistosoma (free swimming larvae) accidently enter mammal skin
- cause pruritus, macules, papules, wheals
168
What is dracunculiasis?
caused by Dracunculus spp.
get larva from water (or eating infected crustaceans)
cause fistula, local pruritus, fever
larvae released from fistula in the presence of water
169
What is heartworm dermatitis?
Caused by Dirofilaria immitis
Adult worms can be found in abscess-like lesions in the skin of dogs and cats
- especially on the legs (cat > dog) and head
Cause angiocentric pyogranulomatous dermatitis with microfilarial segments
170
What is Mammomonogamus auris?
free-living nematode
typically infect nasal sinus and trachea of mammals
can infect the middle ears of cats
- Unilateral or bilateral
- can see parasite through tympanic membrane
can be an incidental finding or cat that is head shaking
Can do a myringotomy and aspirate parasite or benign neglect
171
How do arachnids differ from insects?
absence of wings
presence of 4 paired legs in adults
fusion of head and thorax
172
What does Dermanyssus gallinae do?
“Red mite” – red when engorged
Poultry > cage birds > dogs, cats, humans
Clinical signs: erythema, papulocrusted lesions, and pruritus
- dorsum and distal extremities
Bugs come out at night; die in cold or hot temps
Diagnosis: skin scraping
173
What is the cat fur mite?
Lynxacarus radovsky
174
What are the clinical signs of trombiculosis?
Adults live in decaying vegetation (like Pelodera)
usually are in grass/wooded areas
are orange/red in color
entire life cycle = 50-70 days (long)
clinical signs: pruritic papulocrusted lesions
- legs, feet, ventrum, and face
seasonality: late summer, fall
175
What is Otodectes cyanotis?
Psoroptic mite that lives preferentially on ears
Males – suckers on all legs
Females – suckers on first two pairs of legs
Life cycle = 30 days
- Adults live 2 months
- Off-host survival time = 15 days
Highly contagious and more common in young animals
Mites are not host specific
176
Where do Psoroptes live in the skin?
Surface
177
Where do Chorioptes live in the skin?
Surface
178
Where do Sarcoptes live in the skin?
mites burrow into the upper layer of the skin but never below the stratum corneum
179
What happens with IDATs of dogs and cats with Otodectes cyanotis?
they are positive to other mites (Df, Dp, As, etc)
will become negative after infestation is eliminated
180
What is cheyletiellosis?
Caused by three species that can travel between hosts and are obligate parasites
- Cheyletiella yasguri – most common cause in dogs
--> have a heart-shaped sensory organ
- Cheyletiella blakei – cats (hide in nasal cavity)
--> have cone shaped sensory organs
- Cheyletiella parasitovorax - rabbits
Are zoonotic
181
Cheyletiella
182
Where do Cheyletiella live in skin?
Mites do not burrow but move rapidly in “pseudotunnels” of epidermal debris
183
How do Cheyletiella eggs differ from lice eggs?
Cheyletiella ova are nonoperculated, smaller than louse nits, and attached to hairs by
fine fibrillar strands
Louse ova are operculated and closely glued to hair
- Lynxacarus is similar
184
What is Demodex canis?
Normal canine follicular mite
Long-bodied
Mites of all 4 stages can be found in the lymph nodes, etc
- usually dead and represent drainage
185
What Demodex lifestage is this?
larva
186
What Demodex lifestage is this?
nymph
187
What Demodex lifestage is this?
adult
188
What is Demodex injai?
Occupy canine hair follicle down to sebaceous glands
- often associated with seborrhea
- frequently on topline
- may have a low number, do multiple scrapes
Long-bodied
WHWT, Shih Tzus are predisposed
189
What is Demodex cornei?
Canine Demodex associated with the stratum corneum
Short-bodied (~1/3rd length of D. canis)
190
What are the forms of canine demodicosis?
Localized
- one to several small, circumscribed, erythematous, scaling areas of alopecia
- most commonly on face and forelegs
- most cases occur in dogs 3-6 months of age
- most resolve spontaneously, rare to progress
- may cause ceruminous otitis externa
Generalized
- many localized lesions affecting multiple locations or 2+ feet
- most cases occur in dogs 3 to 18 months of age
- can cause pododermatitis (Old English Sheepdogs at risk)
- hereditary basis
- can have peripheral lymphadenopathy and secondary infections
- should treat (though 305-50% can recover spontaneously)
Adult onset
- usually experience the disease at 4+ years of age
- associated with immunosuppression
- need treatment
191
What dog breeds are at increased risk for demodicosis?
American Staffordshire terrier, Staffordshire bull terrier, Shar-Pei, WHWT, Boston terrier, English bulldog, Shih Tzu
192
Why should you spay female dogs with demodicosis?
It has a genetic predisposition and estrus can make it worse
193
What immune dysfunction do dogs with chronic, generalized demodicosis have?
depressed T-cell function
decreased Th1 and increased Th2 response
increased numbers of CD8+ cells and decreased numbers of CD4+ cells
194
In which dogs can D. canis be difficult to find?
Shar-Peis or dogs with fibrosis (especially in the interdigital region)
195
What is Demodex cati?
Normal feline follicular Demodex
long and thin body
can cause localized disease (usually on head) or generalized disease
- related to immune status
196
What breeds of cats have increased risk for generalized demodicosis?
Siamese and Burmese cats
197
What is Demodex gatoi?
Superficial Demodex mites in cats
Short and tick bodied
Contagious
May find them in fecals > superficial scrapes due to grooming behavior
198
What mites do dogs tend to get?
D. canis
D injai
D. cornei
Sarcoptes scabiei var. canis
199
What is the lifecycle of Sarcoptes scabiei and Notoedres cati?
Entire life cycle = 3 weeks
Copulation happens within a molting pocket on the skin surface -->
Female excavates a burrow in the stratum corneum -->
lays eggs in the SC -->
eggs hatch as larvae -->
burrow to the surface of the skin for feeding -->
find their way to the molting pocket
200
Where is the anus on Sarcoptes scabiei versus Notoedres cati?
Sarcoptes scabiei – anus is terminal
Notoedres cati – anus is in dorsal location
201
What tends to be the clinical picture of a cat with Sarcoptes scabiei?
Pruritic crusts, severe pododermatitis and claw abnormalities
202
What is Notoedres cati?
Burrowing mite that affects cats > foxes, dogs, rabbits, humans
- can transiently affect humans
- mites are smaller than Sarcoptes
Direct contact is mode of transmission
distribution is similar to sarcoptic mange
- pinnae, face, distal extremities, anus
203
Notoedres cati
204
What are the typical lesions associated with spider bites?
become necrotic (black) within 24 hours
- may also cause neurological signs
Histopath: nodular to diffuse necrotizing dermatitis and panniculitis
205
Do lice undergo true metamorphosis?
No
206
What is the canine sucking louse?
Linognathus setosus
207
What is the canine chewing louse?
Trichodectes canis
May act as intermediate host for Dipylidium caninum (dog tapeworm)
208
What is the feline chewing louse?
Felicola subrostratus
209
210
What are fleas?
Wingless with laterally compressed bodies
Three sets of legs (one from each body segment)
Spend their entire adult life on the host
211
What is the flea that is most common in dogs and cats?
Ctenocephalides felis felis
212
What is the human flea?
Pulex irritans
213
What is the rabbit flea?
Spilopsyllus cuniculi (likes pinna and periauricular region)
214
Which flea (from Brazil) can burrow into the skin and cause significant damage?
Tunga pentians
215
Which poultry flea can affect horses, dogs, and cats in warmer climates and has a predilection for the face?
Echidnophaga gallinacea
216
What is the life cycle of fleas?
lifecycle is usually 3-4 weeks in most households
Adult lays her eggs on the dog/cat 1-1.5 days after first blood meal -->
Egg is not sticky, so it falls off into the environment -->
3 larval stages and 1 pupal stage
217
What do fleas need to emerge from egg?
temperature, physical pressure, CO2
218
What disease can fleas be vectors for?
D. caninum
Rickettsia felis
Rickettsia typhi
Bartonella hensleae
Bartonella clarridgeiae
Hemoplasma (Mycoplasma)
Promastigotes of Leishmania spp.
219
What are the histopathologic findings of mosquito bite hypersensitivity in cats?
eosinophilic interstitial to diffuse dermatitis +/- intraepidermal eosinophilic microabscesses +/- nodular eosinophilic granulomatous with collagen flame figures
- Infiltrative and necrotizing eosinophilic mural folliculitis is common
220
What stage of the Cuterebra is visible in soft tissue?
3rd instar
Rabbits and rodents are definitive hosts
Animals will pick up the eggs from the environment
221
What are Hymenoptera?
Venomous insects that are not parasitic
- Bees, wasps, hornets
Ovipostor is adapted for stinging
Paired venom glands that express toxin during sting
Bees (and certain wasps) have the whole poison apparatus break off
- can continue to release venom
Clinical signs: redness, edema, inflammation, anaphylaxis, IMHA
- can cause facial eosinophilic folliculitis and furunculosis in dogs
222
What are Solenopsis invicta?
Fire ants
cause erythema, pruritus, swelling, pustular rash within 15 min
- usually resolve in 48 hours
Histopath: intraepidermal neutrophilic pustule with interstitial neutrophilic dermatitis
223
What are Thaumetopoea spp.?
Pine and oak caterpillars
Dogs > cats in the Mediterranean
Clinical signs: acute onset facial pruritus, urticaria, angioedema (face), swelling of the
tongue, ptyalism
224
What are Musca domestica?
Houseflies
Look like stable flies (same family) but have different mouthparts
225
What is Pneumonyssoides caninum?
A canine nasal parasite
226
What is Trixacarus caviae?
sarcoptid mite in guinea pig
causes severe hypersensitivity reaction (so animals may not be affected)
- old age, concurrent disease or hypovitaminosis C contribute
intense pruritus leading to severe self trauma on shoulders, dorsum and flanks
- can look like seizures
can cause abortion
227
What is Notoedres muris?
sarcoptid mite in rats and hamsters
mainly the ears, face, genitalia and tail
rats can sometimes get nasal ‘horns’
228
What is the most common cause of visceral larval migrans in cats and dogs?
Toxocara (roundworms)
229
What is the most common cause of cutaneous larval migrans?
Ancylostoma (hookworms)
230
Knemidokoptes
231
What are the Knemidokoptes spp. and what do they cause?
Affect birds
Knemidokoptes mutans - also known as the scaly leg mite
Knemidokoptes pilae - scaly face mite
232
What is the relationship between the seroprevalence of Leishmania in cats versus dogs in the same geographical region?
seroprevalence of Leishmania infection in cats is lower
than in dogs from the same locations and a lower PCR prevalence in cats than in dogs is also reported from similar geographical areas
233
What are the most common clinical findings of FeL due to L. infantum?
most common clinical signs reported in FeL include skin or mucocutaneous lesions and lymph node enlargement
Some cats showed only dermatological lesions alone
- some have systemic signs too
234
What are the most common dermatological findings of FeL due to L. infantum and to other Leishmania species?
Dermal abnormalities include nodules, ulcerations or more rarely exfoliative dermatitis
generalized or localized
235
What are the most common dermatopathological features of FeL due to L. infantum and to other Leishmania species?
a granulomatous dermatitis (diffuse)
epidermis may present hyperkeratosis, acanthosis and ulceration
Leishmania amastigotes have always been identified in the affected skin
may also have eosinophilic granuloma and PF
236
What are the most common differential diagnoses in L. infantum endemic areas for dermatological features?
nodules: cryptococcosis, sporotrichosis, histoplasmosis, sterile or eosinophilic granuloma, mycobacterioses, and a wide variety of cutaneous neoplasms
ulcerative lesions: squamous cell carcinoma, idiopathic
ulcerative dermatitis, indolent ulcer, mosquito-bite dermatitis, atypical mycobacteriosis and feline leprosy,
cutaneous vasculitis, erythema multiforme and cold-agglutinin disease
other: dermatophytosis, systemic or cutaneous lupus erythematosus,
exfoliative dermatitis, PF, sebaceous adenitis/mural, folliculitis complex and paraneoplastic alopecia
237
What clinicopathological findings may alert the clinician to the possibility of FeL due to L. infantum?
Mild to severe normocytic normochromic non-regenerative anemia
Moderate to severe pancytopenia
Hyperproteinemia with hypergammaglobulinemia
Renal proteinuria and increased serum creatinine
Relative lymphocytosis and an increase in serum ALT
238
What is Stage I Canine Leishmaniosis (CanL)?
Negative to low positive antibody levels
Dogs with mild clinical signs such as solitary lymphadenomegaly or papular dermatitis
Usually no clinicopathological abnormalities observed
239
What is Stage II Canine Leishmaniosis (CanL)?
Low to high positive antibody levels
diffuse or symmetrical cutaneous lesions such as exfoliative dermatitis/onychogryphosis, ulcerations (planum nasale, footpads, bony prominences, mucocutaneous junctions), generalized lymphadenomegaly, loss of appetite, and weight loss
Clinicopathological abnormalities such as mild nonregenerative anemia, hypergammaglobulinemia, hypoalbuminemia, serum hyperviscosity syndrome
Treatment: Allopurinol + meglumine antimoniate or miltefosine
240
What is Stage III Canine Leishmaniosis (CanL)?
Medium to high positive antibody levels
may present signs originating from immune-complex lesions (e.g., uveitis and glomerulonephritis)
Chronic kidney disease (CKD) IRIS Stage I with UPC = 1–5 or Stage II (creatinine 1.4–2 mg/dl)
Treatment: Allopurinol + meglumine antimoniate or miltefosine
241
What is Stage IV Canine Leishmaniosis (CanL)?
Medium to high positive antibody levels
Pulmonary thromboembolism, or nephrotic syndrome and end-stage renal disease
Clinicopathological abnormalities
listed in Stage II CKD IRIS Stage III (creatinine 2.1–5 mg/dl) and Stage IV (creatinine >5 mg/dl) or nephrotic syndrome: marked proteinuria UPC >5
242
How do you test for parasite-specific immunity to Leishmania after vaccination?
leishmanin skin test
ex vivo include lymphocyte proliferation assays
production of IFN-g
measurement of other proinflammatory cytokines
assessment of enhanced macrophage leishmanicidal activity
- superoxide analyses or ROS
243
What is the treatment for Psoroptes?
Pyrethrin, pyrethroid, or lime sulfur every 7-14 days for 3-4 weeks
Ivermectin or moxidectin
- do not kill eggs
Isoxazolines
244
What is the treatment for Sarcoptes?
topical malathion, lindane, coumaphos, methoxychlor, lime sulfur
- 2+ treatments at 14-day intervals
Ivermectin or moxidectin
macrocyclic lactones
- selamectin, moxidectin, milbemycin
Isoxazolines
245
What is the treatment for Chorioptes?
shaving and 2% selenium sulfide shampoo
lime sulfur at 7-14 day intervals
0.25% fipronil spray
- extra-label use of an EPA pesticide
higher doses of ivermectin weekly x4
- may fail as it is a surface mite
246
What is the treatment for Demodex?
isoxazolines
moxidectin + imidacloprid
high dose ivermectin
daily oral milbemycin
amitraz
247
What should you not to give to chelonians for parasites?
Ivermectin
248
Which biting louse affects birds?
Mallophaga
249
Which parasite causes scaly leg or scaly face in birds?
The burrowing mite Knemidocoptes
250
What are Harpyrhynchid spp?
Parasites that affect psittacines
attach to feather bases and in severe cases cause hyperkeratotic epidermal cysts
251
What parasiticide should be avoided in African Grey parrots?
Itraconazole
