Cattle and Sheep Infectious Diseases: GI Disease Pathogens, Johhne's Flashcards

Question

How does BVD cause mucosal disease?

Answer 1

Foetal infection during day 45-120 may lead to PI in the calf May remain healthy for upto 5 years Causes lesions of MD characterized by small ulcers that only affect epithelial cells, death usually \<2 weeks of clinical signs, some become chronically ill Clinical signs: * Fever * Tachycardia * Tachpnea * Poor/absent rumen contractility * Profuse, watery, foul-smelling diarrhoea * Ulcers in mouth may become necrotic * Mucopurulent nasal discharge

Answer 2

No treatment Prevention- detection and eradication of PI animals- strict biosecurity

Answer 3

Epidemiology- faeco-oral transmission, high morbidity, low mortality, occurs in winter months of housed cattle Clinical signs- sudden onset of diarrhoea among majority of herd, fever, milk drop, inappetance, recovery within a few days Treatment- none Control- hygiene, reduce overcrowding

Answer 4

Aetiology- bovine papular stomatitis virus, a parapox Epidemiology- most common in young- zoonotic Clinical signs- lesions on face, muzzle, mouth, udder, oesophagus and forestomach possible, may lead to ulceration and secondary infection Treatment- supportive, resolve spontaneously Control- hygiene, reduce overcrowding

Answer 5

Mycobacterium avium subspecies paratuberculosis (MAP) Slow growing acid-fast aerobic microorganism Obligate intracellular pathogen, but can survive for 1+ year in the environment There is a slow growing type S (for sheep) or faster growing type II C (for cattle) Type I has stong host preference for sheep

Answer 6

Disease worldwide Incidence highest in animals kept intensively as is common in the dairy industry For every clinical case there are 15-25 additional infected animals MAP has a very high host range Prevalence- 50%+ of European herds Mode of transmission ingestion \> transplancental Newborn calves most susceptible- contaminated colostrum primary source Incubation period longer then latent period Some animals can excrete MAP in faeces without being infected- pass-through shedder

Answer 7

Age- resistance to infection increases with age, infection becomes more dificult in calves 4+ months of age Genetics Herd management- minimise calf-cow contact Soil type- affects persistance in environment Thermal resistance- recovery of viable MAP from milk after standard pasturization

Answer 8

Estimates from £100 to £200 a year This is attributable to decreased milk production, premature culling, decreased fertility, decreased carcass value, reduced feed efficiency, delayed genetic improvment due to involuntary culling, replacement costs

Answer 9

Organism localises within the submucosa and mesenteric lymph nodes of the terminal small and large intestine This triggers an inflammatory response with the acumulation of more macrophages and lymphocytes Granuloma formation with multinucleated giant cells Results in decreased absorption and ensuing chronic diarrhoea Reduced protein absoption and increased leakage leads to protein losing enteropathy and consequenctly muscle wastage, hypoproteinaemia and oedema Immune response- cell-mediated then humoral

Answer 10

Silent infectoin- no clinical signs, animals may shed, tests will not detect but faecal culture may be successful Subclinical disease- no specific clinical signs, may show other abnormalities such as infertility, low sensitivity to faecal culture, negative to most serologic tests Clinical disease- typically occur after 2 years of age, gradual loss of body weight, normal or increased appetite, drop in milk production Advanced disease- typically not seen on farms as affected cattle culled, intermandibular oedema and 'pipestream' faces

Answer 11

Bacterial Cultrue Microscopic examination PCR Culture of blood and milk Tissue biopsy ELISA

Answer 12

Culture requires incubation of 4-8 weeks for liquid culture media and 8-16 for solid culture media Sensitivity varies with stage of infection: 70% in clinical to 25% infected Specificity is high 98% pass through shedding explains the 2% false positives

Answer 13

Ziehl-Neelson stain shows acid-fast bacteria Results are available \<1 hour False positives possible

Answer 14

Majority of commercial tests use the IS900 sequence becasue it is present in multiple copies within the MAP genome because is it present in multiple copies It is also present in environmental mycobacteria, reducing specificity

Answer 15

Culture of blood and milk- MAP found in the udders of 35% of clinically affected cows Tissue biopsy- full thickness biopsy of ileum and associated lymph node- MAP not present in all samples

Answer 16

Tests are based on humoral response to MAP and are typically only useful later in the course of the disease An IFN-y assag can be used but has low specificity

Answer 17

ELISA test for antibodies against MAP and has the highest sensitivity and specificity of the available tests- particularly in subclinical cases Milk samples facilitate the detection of MAP infected animals Sensitivity is highest in early of late in milk

Answer 18

Terminal small intestine, cecum and first section of the colon are typically affected The intestine is three to four times thicker then normal with corrugated mucosa, promient lymphatics and enlarged lymphnodes

Answer 19

Salmonellosis Coccidiosis GI helminths Secondary copper deficiency

Cattle and Sheep Infectious Diseases: GI Disease Pathogens, Johhne's Flashcards

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