5. Cryptosporidiosis, toxoplasmosis, besnoitiosis of cattle, sarcocystiosis Flashcards
Cryptosporidiosis spp. in mammals?
Cryptosporidium parvum, C. muris
History of cryptosporidiosis in mammals
Infection in many domesticated animal species, especially young calves
What are clinical signs of cryptosporidiosis in mammals?
depends on parasite and host species, amount of ingested sporulated oocysts, etc.
- mild/sub-clinical infection – no symptoms
- 1-3 weeks calves -› acute diarrhoea or watery/pasty faeces with mucous shreds (exceptionally blood)
Clinical signs of Cryptosporidiosis in young calves?
Acute diarrhoea or watery/pasty faeces with mucous shreds (exceptionally blood) – in young calves aging 1-3 weeks
Clinical signs of C. parvum?
anorexia, fever, dehydration, and death
What are the main parasitological diagnosis methods of Cryptosporidiosis?
- flotation method (oocysts are small, difficult to distinguish from other things)
- differential staining methods (exprienced macroscopist required, labour intensive)
- classical biological characteristics (expensive and long)
- immunlogical methods (aspecificity due to cross-reactivity)
- molecular techniques (can be false positive - naked nucleic acids, non-viable microorganisms, and laboratory contamination)
Immunological methods of Cryptosporidiosis
IF with monoclonal antibodies, ELISA, reverse passive haemagglutination (RPH), etc. – aspecificity of antibody-based methods due to cross- reactivity with other microorganisms can be problematic
Necropsy findings of Cryptosporidiosis in mammals
- enteral catarrh in ileum
- cellular infiltration of propria with cryptosporidium stages (on the microvillous brush border of epithelial cells) by light microscopy and EM
- above mentioned disorders in digestive glands of abomasum – C. muris
Cryptosporidiosis ssp. in birds? What animal are most susceptible?
C. baileyi, C. meleagridis
Infectious in many species, especially young chickens
Сlinical signs of cryptosporidiosis in birds?
-mild/sub-clinical infection – no symptoms
- signs of respiratory disease (coughing, sneezing, dyspnoea, nasal discharges, conjunctivitis) – infection via air
- rarely diarrhoea
Necropsy findings of Cryptosporidiosis in birds?
- signs of inflammation of the air sacs, pneumonia, sinusitis
- histological changes may occur in small and large intestine, cloaca and bursa Fabricius and/or in trachea, bronchia, rarely in kidneys
spp. of Toxoplasmosis
Toxoplasma gondii
is toxoplasmosis zoonotic?
yes
Hosts of Toxoplasma gondii
- final host: species of Felidae
- intermediate host: lots of mammal and bird species
Clinical signs of toxoplasmosis
- **usually latent without any clinical signs*
RARELY: - in cat: encephalitis, enteritis, pneumonia
- in dog: anorexia, diarrhoea, pneumonia, CNS symptoms
- in horse: nervous signs (e.g. impaired vision)
- in swine: fever, apathy, diarrhoea, resp distress and CNS symptoms, pregnant sows may abort or give birth to weak piglets
- in pregnant women: abortion, premature delivery, mental disorders, blindness of newborn
- in pregnant sheep: abortion/weak newborns - frequently
Parasitological diagnosis of toxoplasmosis
DETECTION OF UNSPORULATED OOCYSTS WITH FLOTATION METHOD
- only in cat feces
- **sporulated oocysts have 2 sporocysts containing 4 sporozoites each
- indistinguishable from oocysts of Hammondia hammondi
IMMUNODIAGNOSTIC METHODS
- Sabin-Feldman dye test - specific antibodies disable staining tachyzoites by methylene blue
- complement fixation test - less reliable with bovine, swine and poultry
- ELISA, IHAT (no swine), IFAT
DEMONSTRATION OF TOXOPLASMS (tachyzoites, cysts) IN SAMPLES OF BIOPSY, CEREBROSPINAL FLUIDS
TISSUE CULTURE
MOUSE INOCULATION TEST - tachyzoites in ascites after 5-10 days, cysts in brain in 20-30 days (except for “RH” strains that kill all infected mice within 4-7 days after infection
MODERN METHODS IN HUMANS
- PCR from CSF
- neuroimagining and thallium-201 brain single photon emission CT
Necropsy findings in Toxoplasmosis
- aborted foetus of sheep and goat may be retained or mummified, numerous yellowish-white necrotic spots in placenta, lymphocytic infiltration of brain
- necrotic foci and granuloma in liver, spleen, lungs, brain etc do rabbits - disseminated toxoplasmosis
- disseminated toxoplasmosis in young dogs in conjunction with Rebarth’s disease, canine distemper - necrotic and inflammatory foci with cysts in organs
