6. Hepatozoonosis of dog, babesiosis, theileriosis, encephalitozoonosis

Question 1

Hepatazoonosis of dog

Answer 1

Causative agent:

• Europe: Hepatozoon canis (obligate heteroxenous, wild carnivores also susceptible)
• Biological vector: Rhipicephalus sanguineus (brown dog tick), transstadial transmission

Clinical signs:

• frequently asymptomatic
• fever, lethargy, anorexia, emaciation, anaemia, swelling of lymph nodes, lacrimation, nasal discharge, weakness of limbs, muscle pain or stiff gait, perhaps bloody diarrhea, death

Parasitological diagnosis:

• blood smear: elliptic gamonts (8-12um) in neutrophil granulocytes

Necropsy findings

• in all infected organs inflammatory infiltrates, necroses (mostly in the liver, spleen, bone marrow)
• histology: schizont (50-100 um) wall unilaminar, nuclei on the periphery (cartweel like)

Question 2

Babesiosis

Answer 2

Species:

• Equine: B. caballi
• Cattle: B.divergens, B. bovis, B. bigemina, B.major
• Dog: B. canis, B. vogeli, B. gibsoni

Case history: tick infestation of animal

Clinical signs:

• mild or inapparent - due to previous infection, low pathogenicity
• Anorexia, anaemia, fever, jaundice of mm., haemoglobinuria (not in horses), weakness, dyspnoea
• rarely diarrhea which may alernate with constipation
• abortion may occur in cows
• rarely signs of nervous system (eg. incoordination) before death
• Keratitis and iridocyclitis, nervous signs may occur in dogs
• intermittent fever for several months, gradual emaciation and anemia
• chronic babesiosis

Parasitological diagnosis:

• detection of piroplasms in red cells of blood films staned with Giemsa (red nucleus, blue cytoplasm) - seldom succesfull
• Small babesia (< 3um): appear as paired near edge of cells eg. B. divergens
• Large babesia (3-5um): appears at acute angel in red cells, eg B. bigemina
• they are pyriform, round, elongated or cigar-shaped
• serodiagnostic methods, eg ELISA, IFAT, CFT
• transfusion of blood into splenectomized animals - detection of parasites in blood smear of recipient following latency

Necroscopy findings

• Anemia, jaundice, splenomegaly
• sub-epicardial and sub-endocardial haemorrhages
• Red/brownred urine in bladder
• Degeneration of liver and kidneys
• Catarrh with petechiae in gastro-intestinal mucosa

Question 3

Theileriosis

Answer 3

History:

• Horses, ruminants in Southern-europe, Africa, Asia: T. equi, T. annulata
• Tick infestation of animal

clinical signs:

• anorexia, aneamia, high fever, digestive problems (abandoned rumination)
• diarrhea with mucus and blood in feces
• swelling of lymph nodes
• petechial haemorrhages on vulva, under tounge
• dyspnoea, tachycardia
• jaundice, emaciation, intermittent fever = chronic form

Parasitological diagnosis:

• detection of schizonts in biopsy samples of lymph node stained with Giemsa
• Koch´s bodies ca 12 um in the cytoplasm of the lymphocytes
• detection of merozoites in red cells of blood films staines with Giemsa
• merozoites are 0.5-2.7 um, rod shaped and bue; round, oval and ring-shaped forms
• Serodiagnostic methods eg: IFAT

Necroscopy findings:

• haemorrhages in serous and mucous membranes
• swelling of lymph nodes and spleen
• ulcers in abomasum and intestine, pulmonary oedema, cachexia = in chronic cases

Question 4

Encephalitozoonosis

Answer 4

zoonosis!

Mainly in mammals: Encephalitozoon cuniculi

History: many domesticated animal species, especially rabbit

Clinical signs:

• usually asymptomatic
• rarely neurological signs - torticollis or wry neck, paralysis and seizures: in rabbits
• iritis, keratitis, blindness in dogs and foxes

Parasitological diagnosis:

• detection of spores (1,5x2,5 um, elliptic or ovoid) in urine of ca 1/3 of rabbits - microscopic examination of stained sediment using oil-immersion
• immunological methods: IFAT, CIA (carbon immunoassay), IIR (india ink reaction) ink particles adhere to spores fixed on slidem if antibodies are present in serum - evaluation of test under oil-immersion microscopy

Necroscopy findings

• macroscopic: 2-4 mm large greyish dents on the surface of the kidney of rabbits and dogs
• histology of kidney: chronic interstitial nephritis
• histology of brain: multifocal granulomatous encephalitis - perivascular infiltration by lymphocytes, necrotic foci surrounded by macrophages, lymphocytes containg developing stages of parasite
• encephalitozoa are Gr+ and PAS+, Ziehl-Neelsen +
• thickend and nodular vessels in arteries of viscera, especially in superficial coronary arteries which can be seen by naked eyes.