pa blood tissue protozoa dogs cats

8/14/2019 Pa Blood Tissue Protozoa Dogs Cats

1/17

Blood and Tissue Protozoa

of Dogs and Cats

Babesia CanisTrypanosoma cruzi

Leishmania

L. donovani

L. chagasi

L. tropica Cytauxzoon felis

Hepatozoon canis


2/17

Babesia canis

Endemic in southern Florida and sporadic elsewhere, especiallyin the southern states

Large, pleomorphic organisms in RBC are typical

Classic paired pyriform bodies of other Babesia species are rarelyseen in B. canis

B. gibsoni is rare, but

increasingly seen in the

USA and is found in dogs fromAsian enzootic areas

Small, singular annular bodies in

RBC are typical


3/17

Babesia canis

Major strain differences in pathogenicity

Vector of transmission is the brown dog

tick, Rhipicephalus sanguineus

May be transmitted transovarially ortransstadially

Incubation period 10 days-3 weeks

Transmission possible by ticks, transplacentally orby blood transfusion

Pups, young dogs are more susceptible than adults,

especially kennels


4/17

Clinical Signs

Signs and pathogenesis are

referable to regenerative

hemolytic anemia

In clinical cases, aggregates of

parasitized RBC-fibrin sludging of capillary beds

tissue anoxia, vascular damage,especially brain, heart, kidneys,

intestines acidosis, DIC shock and death


5/17

Clinical signs of Babesia

Acute Disease:

Fever, anemia, icterus, splenomegaly, hemoglobinuria, azotemia, acidosis

Low numbers of organisms (< 1% or RBC have parasites) are found, even in

the acute phase

Parasitemia is transient at 3-4 days, reappears at 10 days and peaks at 3 weeks.Chronic Disease:

Immunity (premunition) leads to a balance of the parasite and host immunity

Organisms are rarely seen in blood in chronic infections

Stress may lead to recrudescence and sporadic episodes of hemolytic crisis (eg. Pregnancy may activate infection Transplacental transmission to pups) Adult dogs and previously affected dogs are typically asymptomatic,

chronic carriers.


6/17

Diagnosis of Babesia Spleen / liver impression smears

of a puppy that died RBC with organisms become

sticky and are taken out of

circulation.

Note multiple parasites in someRBCs.

Organisms were found in 1:40 is diagnostic of

current or previous clinical disease


7/17

Kennel History:BabesiaOutbreak

Two affected litters were born in this kennelhousing 23 adult dogs

Numerous brown dog ticks (R sanguineus) ofall stages (larvae, nymphs, adults) were found

Serologic testing by IFA of dogs in

outside runs revealed that about

had titers > 1:40

Bitches of affected litters had titers

>1:1000

Typical

greyhoundkennel

management


8/17

Treatment and Control

Imidocarb diproprionate (Imazole ) is the treatment of choice

Also effective against Ehrlichia canis, often found concurrently with Babesiaand

also transmitted by R sanguineus

Diminazene aceturate (Ganaseg , Berenil ) is also effective

Phenamidine isothionate and trypan blue are older, less effective drugs

No accepted effective treatment exists for B gibsoni.

Tick control is essential to break the two-month tick life cycle

Weekly dip of all dogs plus once per month kennel spray recommended

Insecticide resistance common in kennels sprayed frequently

Dip and quarantine all incoming dogs for 3 weeks

Eliminate serologically positive carriers A vaccine is available in Europe, elsewhere


9/17

Trypanosoma cruzi

T. cruzi

causes Chagas disease, a majorhuman disease in South America.

Reduviid bugs reside in cracks and

crevices,

especially in mud brick houses

They emerge and feed on mucous

membranes at night

Circulating trypomastigotes in blood

meal develop in reduviid vectors

(kissing bug, assassin bugs)

Infect by stercorarian transmission,

(organisms deposited by defecation

on bite wound); dog ingestion of bug

Transfusions; Transplacental possible


10/17

Distribution of T. cruziin the USA

In the USA, Chagas disease

is a sylvatic disease circulating

in opossums, raccoons, otherwild mammalian hosts

Can incidentally infect and

cause clinical disease in ruraldogs, esp young< two years


11/17

3 clinical phases of T. cruzi

Acute Phase: circulating organisms present

coincides with invasion, multiplication and rupture of cells, especially in cardiac

muscles

Acute myocarditis, with ventricular tachycardia, right heart failure, ascites,hepatomegaly, anemia, and sudden death may occur, +/- neurological signs

Intermediate Phase:

Asymptomatic with no parasitemia for years

Chronic Phase: dilatational cardiomyopathy in dogs and human

death due to congestive heart failure or arrhythmias

Megacolon may occur in man (Charles Darwin reputedly died of this!)

Chronic disease pathogenesis is obscure


12/17

T. cruziamastigotes in cardiac tissues

Circulating trypomastigotes occur

concurrently in hosts with amastigotes,especially in the cardiac musculature

Low numbers of trypomastigotes may be

found in thin blood smears

Giemsa stained thick smears are moreaccurate, especially if examine buffy coat of a

microhematocrit tube Organisms seen 3-6 day after infection; peak at 2-3 weeks in acute phase

Xenodiagnosis: feed reduviid bug on host, hold 20-40 days, examine Culture by LIT medium or cell culture inoculation with blood

CDC offers IFA diagnosis of veterinary cases; PUBLIC HEALTH -Human

infection via mucous membrane exposure; Lab infections; a BL-2 pathogen

Rx: Acute-benznidazole nifurtimox Su ortive care Vector Control-S ra s


13/17

Leishmania spp. = Leishmaniasis

A major veterinary and public health disease in LatinAmerica, Africa, Asia and the Mediterranean basin where20-40% of dogs and 1-2% of children are infected

Dogs are main reservoir in the old world; wildlife S Amer

A small focus occurs in the Southwest USA;

Especially in military family dogs from endemic zones

Recent recognition of significant disease in Foxhounds in

the Eastern USA

Epidemiology is obscure, possibly transmitted via dog bites

Visceral leishmaniasis typically causes cutaneous lesions

in

dogs, with alopecia, depigmentation, hyperkeratosis, in

addition to lymphadenopathy, deep visceral organ

involvements.

Amastigotes of

Leishmania spp. in

macrophage of dog


14/17

Leishmania amastigotes

Amastigotes are round organisms with a nucleusand diagnostic dark cylindrical kinetoplast

Circulate in the blood intracellularly in monocytes

In the visceral form, amastigotes nests occur in

phagocytes in major vascular organs rich in RE

cells

3-7 month incubation period after a transient

cutaneous lesion (L. donovani, L. infantum)

Rodents are common reservoirs

In cutaneous forms (L. tropicacomplex), lesions confined to skin

Dogs: Finding amastigotes by biopsy of skin, lymph nodes, spleen or

liver is diagnositic


15/17

Sandfly intermediate hosts

Phlebotomus spp. (sandflies) are

intermediate hosts

Infection by ingestion of organism

in monocytes

Sandflies are found in protected,

internally humid foci such as

rodent burrows, mainly in arid

climates Transmission is seasonal (after wet season) and tends to be focal where

favorable sandfly environments occur

Treatment of leishmaniasis: Megumine antimoniate, Na stibogluconate

SID for 3 weeks


16/17

Cytauxzoon felis Causes a rapidly fatal disease in cats after < 7

days of illness Signs referable to occlusion of

vasculature by schizonts in MN phagocyte

lining

of all organs, especially lungs

Sporadic in rural cats in South, Southcentral

USA; Tick vector (Dermacentor, Ixodes?) with a

bobcat reservoir suspected. There is both a tissue and RBC phase of the life cycle

Merozoites parasitize 1-4% of circulatiing RBC 1-3 days prior to death

Signs are depression, anorhexia, dyspnea, icterus, anemia, terminal 103-

107o F febrile period

Dx: via organism in Giemsa or Wrights stained RBC, bone marrow or

impression smears

Rx: Saved 6/500 cats by supportive care, parvaquone, 10-30mg/kg SID, 3d


17/17

Hepatozoon canis Occurs sporadically in dogs, usually < six months

old in TX, LA, OK Infection is by ingestionof R. sanquineus, in whichsporogony occurs

Signs include intermittent fever, stiffness ofmuscles and periosteal inflammation due to

release of merozoites from tissue schizonts Periosteal bone proliferation in proximal long bones visible by radiograph isdiagnostic

In the dog, schizogony occurs in phagocytic cells of the RE cells of major

organs, myocardium and skeletal muscles

They produce merozoites which produce gametocytes that circulate in the

blood in neutrophils, monocytes for tick vector

Dx: Find gametocytes in blood smears or schizont by muscle biopsy

Rx: Acute: Sulfadiazine+Clindamycin+ Pyrimethimine; Chronic: Decoquinate

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