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3. Food Animal 2 > Salmonella and Winter Dysentery > Flashcards

Salmonella and Winter Dysentery Flashcards

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1
Q

salmonella family

A

Enterobacteriaceae

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2
Q

how many salmonella serotypes? based on what? named for what?

A
  • 2200 serotypes based on 67 O-antigen (somatic) groups and numerous H-antigens (flagellar), Vi- antigen (capsular)
  • Name: place of isolation
    –i.e. Dublin, Montevideo, etc.
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3
Q

salmonella taxonomy

A

2 types: S. enterica & S. bongori

> S. enterica: 6 subspecies
60% S. enterica enteria

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4
Q

are salmonella serotypes host adapted?

A
  • The majority of serotypes are not-host adapted
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5
Q

three types of salmonella based on host-adaptation

A

– 1. Specific to humans:
* S. typhi and S. paratyphi

– 2. Type adapted to animal hosts (>virulent).
* S dublin in cattle; S abortusequi in horses, S. abortusovis in sheep; and S cholerasuis in pigs.

– 3. Un-adapted serotypes:
* can cause disease in humans and variety of animals. (S. typhimurium)

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6
Q

salmonella prevalence? In Ontario, new zealand, california dairy farms

A

Variable:
* Ontario: Calves in 22% farms shed Salmonella spp.
* New Zealand: 13-15% infection rate in dairy cattle
* California: 75% sampled dairies had evidence of infection

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7
Q

which serotypes of salmonella, in which serogroups, commonly cause disease in cattle?

A

10 serotypes in serogroups B, C, D and E common cause of disease in cattle

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8
Q

in what species are salmonella found?

A
  • Universally in all species
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9
Q

Salmonella Typhimurium isolates from both cattle and humans; how have these changed since the 80’s?

A

in the 80’s, almost 0 in both humans and dairy cattle
> increase in lockstep

Outbreak in dairy herds→human infection

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10
Q

6 most commonly isolated salmonella serotypes from dairy cattle

A

> 5000 isolates:
- Salmonella Dublin (23%),
- Salmonella Cerro (16%),
- Newport (14%),
- Montevideo (8%),
- Kentucky (8%), and
- Typhimurium (4%)
comprised the top 6 most commonly isolated sertotypes

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11
Q

salmonella transmission? environmental survival?

A
  • Direct or indirect contact
  • Infected animals are the source of infection → direct contact (animal-to animal) or by contaminating the environment (feed and water)
  • Can persist prolong periods (several months, even years) in the environment
  • Airborn
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12
Q

how/ where does salmonella survive in a carrier?

A
  • Survive in the phagolysosome of macrophage
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13
Q

types of salmonella carriers, their signs, and do they spread it?

A
  • Active carrier:
    – Shed the organism constantly or intermittently in feces (1 billion organism/day or 1 million/gram feces)
  • Latent carrier:
    – persistent infection (lymph nodes and tonsils) but not shedding
  • Passive carrier:
    – Acquire infection from contaminated environment but infection resolved when removed from that environment
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14
Q

salmonella source, pathogenesis? factors affecting disease and virulence?
(specifically S. dublin)

A
  • May penetrate:
  • Ocular, nasal, oral and intestinal membranes
  • Most often feco-oral transmission
  • Source: contaminated fed, water, contaminated milk
    ()
    S. dublin:
  • Invasion through intestinal wall of ileum and cecum→ mesenteric lymph nodes→???
  • Factor affecting type of disease:
    > Immune status, age, stress, virulence of strain
  • Factors affecting virulence:
    > adhesion-pilli, flagella, cytotoxin, enterotoxin, LPS, inflammatory response
    > S. dublin virulence plasmid mediates systemic infection in cattle by causing macrophage dysfunction
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15
Q

risk factors for salmonella disease

A
  • Challenge dose
  • Immunological status
  • Stress
    > transport, anesthesia/surgery, antimicrobials, food deprivation, parturition
  • Previous exposure
  • Colostrum intake (neonates)
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16
Q

salmonella Clinical findings

A
  • Septicemia
  • Acute enteritis
  • Chronic enteritis
  • Terminal dry gangrene of the extremities
  • Abortion
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17
Q

what animals commonly get septicemia from salmonella? what are the signs?

A
  • Common form in neonates
  • Signs: Depression, toxemia, fever, dyspnea, weakness, nervous signs (incoordination, nystagmus)
  • Diarrhea can occur but not common
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18
Q

what age group commonly gets enteritis from salmonella? what are the clinical findings?

A

– Older calves and adults
– Abortions, polyarthritis (calves), diarrhea (whole blood), agalactia
– Acute protein-losing enteropathy
– Abdominal pain
> Rolling, kicking, treading on feet, crouching, groaning, flank watching

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19
Q

what clinical findings might we see in a case of salmonella causing chronic enteritis?

A
  • With inappetance, reduced weight gain, and unthriftiness (after acute enteritis)
  • Abortions (no other signs)
  • Retained placenta (S. dublin)
  • Terminal dry gangrene (limbs, ears and tail tip)
20
Q

salmonella can cause terminal dry gangrene in calves. what signs will we see?

A
  • Lameness
  • Swelling
  • Skin sloughing of limbs

Also: * Endarteritis

21
Q

Nature of salmonella abortions: are salmonella abortions always accompanied by other signs?

A

Can occur spontaneously with no other signs of salmonellosis (S. dublin)

22
Q

salmonella morbidity and mortality (calves and adults)

A

Morbidity:
* 50% in calves
* 14-60% in cattle herds

Mortality:
* High in young calves (<12 weeks)
* 0-14% in adult cattle

23
Q

salmonella CBC findings

A
  • Leukopenia
  • Neutropenia
  • Severe degenerative left shift
24
Q

salmonella Serum biochemistry profile

A
  • Marked hyponatremia
  • Mild hypokalemia
  • Hypoproteinemia
25
Q

slamonella antimicrobial susceptibility: what does it look like, how can it change over time?

A
  • generally quite a bit of resistance
    >eryt, gent, TMS, Ampi, Rifa, chlor, pen neom
    > enro is intermediate
  • susceptible to tetra, some also to ceft, amik

> generally, can aquire and lose resistances over time based on antimicrobial use

26
Q

general diagnostic methods for salmonella

A
  • Culture
  • Fecal culture
  • Antigen capture ELISA
  • PCR
  • Milk bulk tank and filters
  • Serial blood culture
    ()
  • individual animal fecal culture using enrichment and selective media
  • composite fecal sampling
  • salmonella PCR (feces, milk, tracheal or bronchoalveolar lavage fluid)
  • blood, transtracheal wash, bronchoalveolar lavage, or joint fluid culture when bacteremia is suspected in claves
  • culture of post mortem samples: gastrointestinal tract, mesenteric lymph node, bile, and lung
  • environmental cultures
  • salmonella Dublin enzyme-linked immunosorbent assay: serum or milk
27
Q

Microbiology results - OVC cases of salmonella
PM results?

A
  • S. Dublin was isolated in all 5 cases from the lung tissues
  • The PFGE pattern was indistinguishable among all 5 isolates-OVC cases
  • Post-mortem examinations were consistent with septicemia in all 5 cases.
  • All 5 calves had suppurative bronchopneumonia and three also had suppurative enteritis.
28
Q

serology tests for salmonella dublin

A
  • ELISA test on serum or milk to
    identify S. dublin carriers
  • IgG to O-antigen
  • Detect:
    > uninfected
    > recently infected recovered
    > milk-shedding
29
Q

Differential diagnosis for salmonella diagnosis

A

–Coliform septicemia

30
Q

differential diagnosis for acute enteric salmonellosis

A

–Coccidiosis
–Acute intestinal obstructions
–Winter dysentery
–Mucosal disease (BVD)
–Bracken fern
–Otherpoisoning: arsenic,lead,plants

31
Q

differential diagnosis for chronic salmonellosis

A
  • Johne’s disease
  • Chronic molybdenum poisoning
  • Massive stomach fluke infections
32
Q

salmonella control; is it easy? why? methods?

A
  • Environmental contamination difficult to control
    > Survive in dry feces for years
  • Vaccination
    > Killed and modified lived
  • Adverse reaction
  • Lack of efficacy
  • outbreak control
33
Q

winter dysentery etiology; what kind of virus? reservoir?

A
  • Bovine coronavirus
    – Experimentally reproduced
    – Serologic response
  • Virus isolated from wild ruminants:
    – Sambar deer, waterbuck, white-tailed deer
34
Q

winter dysentery tropism

A
  • Tropism for intestinal and respiratory tract
35
Q

uncertainty around winter dysentery etiology

A

There is uncertainty among some people as to whether coronavirus is the cause of the disease

36
Q

where is winter dysentery found geographically?

A
  • Common in northern climates
    > Cattle housed from November-April
    > USA, Canada, Sweden, Germany, France
    > Also: Israel, Australia, New Zealand
37
Q

what age / group of animals is winter dysentery more common in?

A
  • Common in recently calved milking cows
38
Q

how does winter dysentery generally present in young animals?

A
  • Young animals may develop a mild form of the disease
39
Q

winter dysentery; morbidity and mortality

A
  • Morbidity: 30-59%
  • Mortality: < 1%
40
Q

transmission of winter dysentery

A

Transmission: Fecal-oral route
> Affected animals or asymptomatic carriers
> Highly contagious

41
Q

winter dysentery pathogenesis?

A
  • Virus has tropism for GI and respiratory tract
    – Mild enteritis of the small intestine
    – Respiratory disease in adult cattle and pneumonia in calves
  • Epithelial cells of colon crypts are destroyed by the virus
  • The mechanism leading to voluminous watery diarrhea is not clear,
    but may be related to inflammation
  • Inflammatory mediators may lead to hyper-secretion in the small intestine and large colon
42
Q

winter dysentery; Clinical findings, incubation

A
  • Incubation: 3-7 days
  • Explosive diarrhea for 4-7 days
  • Young animals: mild signs
  • Fever, decreased milk production, short-lasting anorexia, mild loss of body weight
  • Dark green to black liquid diarrhea
    ()
  • Nasolacrimal discharge and cough may precede or accompany GI signs
  • Short course of disease (2-3days)
  • Some cases develop a more severe form:
    > Dehydration, weakness, dysentery with or without blood
  • Some herds production may not return to normal after a prolong period
43
Q

winter dysentery diagnosis methods

A
  • Electron microscopy
  • ELISA test (fecal samples)
  • Paired serology testing (8 weeks apart)
44
Q

winter dysentery Differential diagnosis

A
  • BVDV/MD
  • Coccidiosis
  • Salmonellosis
  • Johne’s disease
  • Dietary
  • Copper deficiency
45
Q

are fatal cases of winter dysentery common? what would we see? what about on histo?

A

Fatal cases are rare
* Severe hemorrhage
* Hyperemia of colonic and cecal mucosa
* Frank blood in the lumen of large intestine

Microscopically:
* Widespread necrosis and degeneration of epithelium of large bowel

46
Q

winter dysentery Treatment / Prevention

A
  • Usually not required
  • Supportive therapy
  • Fluid and electrolytes
  • Some management practices, notably housing animals in stanchions and use of equipment that handles both manure and feed → associated with winter dysentery

3. Food Animal 2 (20 decks)

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