salmonellosis

Question 1

host range of salmonella?

Answer 1

wide host range!
various animals + humans
only a few impt in cattle
can hide from immune system! = carriers

Question 2

what are the 3 important types of salmonella?

Answer 2

S. enterica dublin
S. enterica Mbandaka
S. enterica Typhimurium

Question 3

epidemiology of salmonella Mbandaka?

Answer 3

adults: D+ & malaise, also abortion
infected feed origin
mostly larger herds supplementing feed/housing all year
v rarely seen in humans

Question 4

epidemiology of salmonella typhimurium?

Answer 4

mainly calves
various CS
carrier animals
periodic epidemics e.g. DT104

Question 5

epidemiology of salmonella dublin?

Answer 5

host-adapted
affects both calves & adult cattle
latent/persistent carriers
assoc. w abortion
infreq. in humans, but potentially fatal:
-via infected livestock/unpasteurised milk

Question 6

transmission of salmonellosis?

Answer 6

cattle to cattle: carrier status impt! asymp. = shed intermittently esp in times of stress (shed millions of bact per day in faeces); neighbouring herds, marts, shows, bulls
slurry: persist in slurry for months, a year for soil
fomites: farm visitors, animals, birds, vehicles, equipm
feed/water: watercourses & feedstuffs contaminated by other stock & widlife

Question 7

is routine monitoring done for salmonellosis?

Answer 7

no
no one knows scale of exposure to salmonella
rely on lab diagnoses from clin cases: req material to be submitted

Question 8

risk factors of salmonellosis?

Answer 8

buying in cattle/co-grazing
high stocking density, group pens 
poor hygiene
concurrent dx - fluke, BVDV? 
season 
age/stage - calves <3mths, cattle in 1st 2 wks of lactation

Question 9

CS of salmonellosis

Answer 9

range of CS 
severity depends on infective dose & age/stage
-acute/chronic enteritis 
-abortion
-septicaemia
-reduced productivity 
-poor calf health

Question 10

CS of acute enteritis?

Answer 10

calves >2wk & adults
high fever
severe D+, sometimes bloody
anorexia
colic
abortion
severe dehydration
fatalities can be up to 75%

Question 11

CS of chronic enteritis?

Answer 11

may follow acute enteritis 
reduced weight gain
intermittent D+
inappetence
stressors can trigger dx: poor nutrition, long transport times, calving, mixing, crowding

Question 12

CS of septicaemia?

Answer 12

mainly seen in neonatal calves (<2-3wks)
depression
fever
lethargy 
laboured breathing
nervous signs
rapid death (6-48h) 
dry gangrene of extremities after initial phase
joint infections

Question 13

CS of abortion?

Answer 13

usually 5-8mth pregnancy
+/- fever & anorexia
retained placenta & reduced lactation
abortion storms: up to 25% of herd

Question 14

impacts of poor calf health due to salmonellosis?

Answer 14

pneumonia
poor growth rates
ill thrift
meningitis

Question 15

diagnosis of indiv clin cases of salmonella?

Answer 15

faecal culture: faecal sample NOT swab; pooling decreases se; rmb prev use of abs will affect culture
PM: culture range of tissues; in abortions culture foetal stomach contents
serology: best results = calves 3-10mths; poor seroconversion <12wks old; cross reactivity; retrospective due to time taken to seroconvert

Question 16

diagnosis @ herd lvl for salmonella?

Answer 16

carrier animals: shedding may be intermittent - 3 serology tests over 8mths?
culture slurry samples/faeces of cases
serology:
-bulk milk tank = good for continued monitoring (dairy)
-serology of all animals (bloods)
-serology of a subset of animals: calves; those showing CS; 10 youngest calves over 12wks

Question 17

tx for salmonella?

Answer 17

early tx essential for septicaemic salmonellosis
S. dublin usually sensi to most abs
controversy re. use of antimicrobials for intestinal salmonellosis - more likely to induce carrier statuss
intestinal cases may cure clinically but not bacteriologically

Question 18

control for samonella?

Answer 18

in -ve herd, prevent entry: biosecurity

if alr infected, biocontainment (& biosecurity)

Question 19

how to maintain biosecurity?

Answer 19

maintain closed herd or
source new stock from high health status
quarantine all incoming stock for at least 4wks
avoid shared equipm, bulls & grazing areas
maintain good fences
protect feed & bedding from vermin
use mains water (not natural source)
provide farm clothing for visitors or clean & disinfect boots/clothing before entering/leaving
investigate abortions, scour cases or other illnesses as early as poss
consider herd vax w bovivac S (MSD)

Question 20

how to maintain biocontainment (+biosecurity)?

Answer 20

segregate & treat clin cases
all buildings should have good drainage & waste removal
clean & disinfection calving/maternity pens & building btwn occupancies
remove calf from dam asap
colostrum management
do not feed milk from ill cows to calves
only spread slurry on arable land
strict personal hygiene
zoonotic risk - esp. older ppl & children = do not consume unpasteurised milk

Question 21

what vax is there for bovine salmonellosis?

Answer 21

bovivac S (MSD)
only licensed vax for salmonellosis!
contains both S. typhimurium & dublin
inactivated vax