PAVE & NAVLE REVIEW-PART I

Updated 2010

Dr. R. Pinckney

Parasitology Review

• Companion Animal Parasite Council (www.capc.org)

• www.zukureview.com

• NAVLE review – free to students and sends NAVLE questions daily

CYTAUXZOON felis

Fatal disease of domestic cats

Cytauxzoon felis

• Sporadic, but rapidly and uniformly fatal disease of domestic cats.

• Numerous cases reported in the south central U.S.

• Prevalence rates have spread to other states

• Bobcat & other wild felids are reservoir hosts.

C. felis in wild felid populations in the U.S.

• A study was conducted to determine the distribution, prevalence & intraspecific variability.

• 14 states: CA, CO, FL, GA, KS, KY, LA, MO, NC, ND, OH OK, SC & WV

• Blood or spleen samples from hunter/trapper killed felids (n = 706) were tested for C. felis by PCR

• B. C. Shock et al., 2010, AAVP meeting

2010 C. felis study

• Prevalence rates (n = 706):• 79% in Missouri (39 bobcats)• 65% in Oklahoma (20 bobcats)• 63% in North Carolina (8 bobcats)• 57% in South Carolina (7 bobcats)• 55% in Kentucky (74 bobcats)• 36% in Florida (45 bobcats)• 33% in Louisiana (1 bobcat, 1 cougar, 1 serval)• 31% in Kansas (39 bobcats)• Greater intraspecific variability (based on PCR) exists in wild

felids compared to previous reports in domestic felids.• These data indicate that C. felis is widespread and quite

diverse in wild felid populations.

LIFE CYCLE

• Ixodid ticks (Dermacentor variabilis & Amblyomma americanum) are intermediate hosts.

• 1-2 µm piroplasms (light blue cytoplasm & dark nucleus) in red blood cells

<

LIFE CYCLE

• Schizogony occurs in mononuclear phagocytes (macrophages) that occlude vessels of the lung, lymph node, spleen & other organs

CLINICAL SIGNS

• Anorexia (depressed appetite)

• Depression

• Fever (> 104 F)

• Dyspnea (difficulty breathing)

• Dehydration, icterus

• Leucopenia, thrombocytopenia

• Death

PATHOLOGY

• Hepato- and splenomegaly

• Icterus

• Congestion of mesenteric veins

• Petecchial hemorrhages (lungs, lymph nodes, epicardium and urinary bladder)

OCCLUSION OF VESSELS BY PARASITIZED MACROPHAGES

DIAGNOSIS

• Clinical signs & history

• Piroplasms in RBC’s

• Merozoites in macrophages lining the vascular channels in most organs

Treatment & Control

• Prognosis is grave

• Supportive therapy

• Survival of a domestic cat with naturally acquired cyauxzoonosis (J Am Vet Med Assoc, 1995, 206: 1363-1365)

• Blood transfusions

• Vector control

BABESIA

Pyriform, round or oval parasites of RBC’s of mammals

Geographic Distribution

• Worldwide (ubiquitous)

• Bovine babesiosis (South America, Mexico & the US!)

• Equine (South & Central America, Caribbean, Africa, Middle East, eastern & southern Europe and the US!)

LIFE CYCLE• Ticks are intermediate hosts

• Boophilus annulatus and B. microplus [Rhipicephalus] (Bovine)

• Dermacentor (Equine; Transplacental)

• Ixodes (Humans)

• Rhipicephalus (Canine)

LIFE CYCLE• Transovarian transmission (except B. equi)

• Piroplasm passes to the tick ovary and is incorporated in the egg, larva, nymph & adult stages

• Transtadial transmission (primarily in males)

• Larvae can survive for 200 days in the environment!

• PPP is ~ 10-21 days following tick exposure.

Boophilus (Rhipicephalus)

• Boophilus means “cattle loving”

• Theobald Smith and Frederick Kilborne discovered the parasite in 1912 and it was eradicated from the U.S. in 1943.

• The ticks have been re-introduced into the U.S. from calves imported into Texas from Mexico.

• Outbreaks have been observed since 2004.

White-tailed deer & Boophilus

• Ticks detected on the WTD population

• Complicating eradication and control measures

• Integration of ecologically based approaches to re-eradicate Boophilus from WTD

• Using systemic and topical acaracides

• Medicated (w/ivermectin) corn in the non-hunting season

Distribution of B. bigemina

CLINICAL SIGNS: BOVINE

• Fever (Texas Cattle Fever)

• Hemoglobinuria (“red water disease”)

• Anemia

• Icterus

• Splenomegaly

• REPORTABLE DISEASE IN THE U.S.

Control Challenges

• WTD and free-ranging non-native ungulates help sustain Boophilus populations in south Texas even in the absence of cattle.

• Scheduled dipping every 7 to 14 days for 9 months.

• Or vacating the premises and dip cattle twice (14 days apart), get a “clean” check & vacate pasture for 9 months

• Imidocarb diproprionate (Imizole®)

• BM-86 vaccine (85-90% effective) against B. annulatus & less effective against B. microplus

Canine Babesiosis

• Rhipicephalus is the intermediate host.

• B. gibsoni (1 – 2 µm piroplasms)

• B. canis (2 – 5 µm long, large piroplasms)

• B. conrade (“Spanish isolate” see on the West coast of the U.S.)

• B. c. vogeli

• B. c. rossi (most pathogenic in S. Africa; seen in foxes in N. Carolina) – Haemaphysalis tick is the IH

CLINICAL SIGNS: CANINE

• Intravascular hemolysis (acute phase)• Extravascular hemolysis (destruction of RBC’s)• Different strains and species (pathogenicity)• Concurrent infections (e.g., Ehrlichia, Anaplasma)• Age of the animal• Immune status• Treat with imidocarb

DIAGNOSIS

• Demonstration of intraerythrocytic piroplasms in blood or histopath sections (pairs or tetrads)

• Serology (Complement Fixation) – not sensitive in the chronic phase (use ELISA or PCR)

• IFAT (> 1:80); cross-reactivity with other Babesia species

• False negative results in young pups

• IHAT or PCR (human, bovine & equine)

Equine Babesiosis

• The U.S. has been diligent to prevent B. equi and B. caballi from entering the U.S. for the past 30 years.

• Recently there has been an increase in the number of persistently infected horses entering the U.S.

• The genus Theileria remains controversial• 2008 – Twenty seropositive horses in Florida• Dermacentor nitens is the IH for B. caballi• Amblyomma cajennense was found to be a

biological vector of B. equi• No transovarial transmission with B. equi

CLINICAL SIGNS: EQUINE

• Abortion

• Similar clinical signs as in other domestic species

• Hepatomegaly

Diagnosis & Treatment

• Quarantine seropositive horses

• Persistence of antibody – CF test is not sensitive in the chronic phase, use ELISA

• Confirm with nested PCR

• Imidocarb is more effective against B. caballi than B. equi

• The goal is to reduce parasitemia associated with initial infection (acute phase)

TREATMENT & CONTROL

• Canine, bovine & equine: Imidocarb diproprionate (Imizole®)

• Tick control

Gasterophilus (PAVE, 2006)

• Horse (donkey, mules, zebra) bot flies

• Female glues eggs to the legs, nostrils or lips of the host (depending on species of fly)

– G. intestinalis

– G. nasalis

– G. hemorrhoidalis

• Larvae migrate in the mouth to the pharyngeal area and to the stomach

• PPP ~ 10-12 mo.

• Found throughout North America

◄ Eggs

Treatment and Control• Should be carried out 2X a year

• 1st dose (ivermectin) given about one month after 1st killing frost when larvae are in stomach and no more adult flies remain

• 2nd dose is given in fall or mid-summer for killing instar stages (Pave, 2006)

• Frequent grooming removes eggs before they become infective

• Eggs are very resistant to insecticides

Oestrus ovis• Nasal bot fly of sheep, goats, and some wild

ruminants.

• Adult flies are most active during the summer months.

• They live ~ 28 days

• Found throughout the US and New Zealand (wherever sheep are raised).

• PPP ~ 8-10 mo

Characteristics• Adults (~12mm) are most active

during the summer months

• Flies hide in warm corners or crevices and in the early morning

• They can be seen sitting on walls or other objects in the sun

• Undergoes modified form of complex metamorphosis

Life Cycle• Fly season lasts from early summer to autumn

• In cool season, pupation occurs in the fall rather than the summer and pupae can over-winter in the soil

• Adult female fly may deposit as many as 60 larvaearound the nostrils of the sheep, goats, and some wild ruminants.

• (Rare) cases in humans and dogs have been reported.

• Larvae crawl into nasal passages and may crawl into the frontal and nasal sinuses

Life Cycle• Larvae attach themselves to the

mucous membranes w/ 2 large, black oral hooks

• Larvae reach full growth (25-30mm) by the following spring

• Larval period lasts from 8-10 mo.

• Work their way out or are sneezed out of the nostril

• Larvae pupate in soil for 3-6 wks

• Adults may live for 28 days

◄

CLINICAL SIGNS• Animals may press their noses

against the ground.

• Animals often form a circle with their heads toward the center

• Sneezing, head-shaking, and stomping are common indications of the flies attacking.

CLINICAL SIGNS• Larvae irritate the nasal

mucosa, inducing thick mucus exudate on which they feed.

• Thickening of the nasal mucosa.

• Mucopurulent discharge (snotty nose)

• Impaired respiration • Larvae that enter the

sinuses occasionally reach the brain and produce fatal results (“False gid”)

Nasal Human Myiasis

• Oestrus ovis larvae have been reported in an HIV+ patient in the UK

• 64 yr-old man complaining of nasal obstruction & rhinitis; referred to a psychiatrist! (Spain, 1997)

• Five, 3rd instar larvae were expelled

• The man showed no signs of immunosuppression.

Basic Morphology• Soft ticks lack a scutum

• Hard ticks have a scutum

– Dorsum of adult male is covered by the scutum

– Covers only anterior part of dorsum in immatures and

females

– Ornate if patterned

– Inornate if unpatterned

• Only adult female ticks engorge

– Makes keying difficult

• Hard ticks may have festoons

– Semi-rectangular areas adjacent to posterior margin of

the dorsum (PAVE)

Ixodes

• Anal groove is distinct & curves around the anus anteriorly; usually uniting in a point or arch

• Inornate

• Festoons absent

• Medium-long club shaped palps; long mouthparts (PAVE, 2007)

• Vector: Lyme disease (Borrelia burgdorferi); Babesia microti humans

< ANAL

GROOVE

PAVE, 2007

Dermacentor

• Ornate (dark brown w/ white)

• Festoons (PAVE, 2006)

• Short-medium palps

• Basis capitulum is rectangular in shape

• 1 or 3 host tick (depending on spp)

• Vector: RMSF, Babesia, Ehrlichia (transtadial or interstadial, 2007)

Rhipicephalus

• Hexagonal basis capitulum

• Inornate scutum

• Palps are short

• Festoons (Pave, 2006)

• 3-host tick; Kennel/House pest

• Intermed. host: Babesia canis (Canine Piroplasmosis); Tropical Canine Pancytopenia (Ehrlichia canis)

Amblyomma • Ornate

• Festoons (Pave, 2006)

• Long palps

• 3-host tick

• Vector: RMSF, Heartwater disease (Cowdria) Ehrlichia ruminatum – lethal disease of cattle

• African tortoises imported into Florida (J. Parasitol, 2000, 86: 700-704)

PAVE, 2006

Fecal Techniques

• PAVE, 2007

• Direct Smear (trophozoites)

• Fecal Flotation (Centrifugation vs. Standing)

• Sedimentation (fluke eggs)

• Baermann Technique (larvae)

• Fecal Egg Count Reduction Test (FECRT) for determination of anthelmintic resistance (Haemonchus and small strongyles)

• 2007 – McMaster’s Technique

NEMATODE EGGS FOUND IN

DOG AND CAT FECES

NEMATODE EGGS FOUND IN

RUMINANT FECES

NEMATODE EGGS FOUND IN PIG

FECES

NEMATODE EGGS FOUND IN

HORSE FECES

EGGS FOUND IN POULTRY FECES

Trichuris (PAVE, 2007)

• Eggs are lemon or

football shaped,

bipolar plugs, very

resistant in the

environment.

72 - 89 µm X 37 – 40 µm

Capillaria

or

Eucoleus

PAVE, 2006

Capillaria aerophila - Bronchial

Capillariasis

• = Eucoleus aerophilus

– In trachea and bronchi in dogs, cats, foxes

– Eggs striated appearance (in feces)

– Direct life cycle or earthworms (facultative

paratenic hosts)

– Diagnosis: eggs in feces, need to

differentiate from Trichuris

Urinary Capillariasis

• Urinary bladder

– Capillaria (=

Pearsonema)

feliscati (cats),

Capillaria plica

(dogs)

– Adults occur in

urinary bladder and

the pelvis of the

kidney.

– Eggs passed in

urine, difficulty

urinating (cystitis)

Eucoleus boehmi

• Nasal capillariasis (mucosa of the nasal cavity, frontal and paranasal sinuses)

• Hosts: dogs, foxes, wolves

• Life cycle similar to C. (Eucoleus) aerophila

• Earthworm (paratenic host)

• Rx. Ivermectin or fenbendazole

(60 µm X 30 µm) The surface of the egghas a “pitted appearance”

Notoedres cati (PAVE, 2007)

Notoedres

◄Anus is dorsal

(ZOONOTIC!!)

Sarcoptes

▲Anus is terminal

ZOONOTIC!!

Sarcoptes scabiei

• Dogs, ferrets, wild canids, rabbits - intense prurituswith a ventral distribution

• Highly contagious; ZOONOTIC!

• Horses, cattle, sheep, goats, swine: intense pruritus; usually starts on trunk

• REPORTABLE DISEASE IN ALL LARGE ANIMAL SPECIES EXCEPT SWINE (U.S.A.)

Suborder: Astigmata

• Psoroptes spp: (cuniculi & ovis)

– Infests external ear canal in rabbits

– Has been seen in goats

• Chorioptes:

– Affects cattle, sheep, horses, goats, hedgehogs, & rabbits

• Otodectes: (Pave, 2006)

– Infests the external ear canal and adjacent skin of dogs, cats, foxes, & ferrets

Psoroptes

Otodectes or Chorioptes

BREAK TIME

HISTOMONAS (“Hexamita”) MELEAGRIDIS

• FLAGELLATE PARASITE OF TURKEYS, CHICKENS & OTHER BIRDS

• HISTOMONIASIS OR “BLACK HEAD DISEASE”

• ECONOMICALLY IMPORTANT IN “RANGE BIRDS”

• PAVE, 2007

Histomonas meleagridis (PAVE, 2007)

PATHOLOGY

“Blackhead Disease”

Paragonimus (PAVE, 2007)

• Lung fluke

• Snails are the first intermediate host

• Crayfish is the second intermediate host

• Zoonotic!

• Paratenic hosts: frogs

• Dx. Radiograph and fecal flotation or sedimentation tests

Dicrocoelium dendriticum

• Liver fluke of ruminants

• Chronic infections: lower wool production

• Ants (2nd intermediate host) eat the slime balls

• Metacercariae in the ant neuron (behavior changes)