salmonellosis Flashcards
host range of salmonella?
wide host range!
various animals + humans
only a few impt in cattle
can hide from immune system! = carriers
what are the 3 important types of salmonella?
S. enterica dublin
S. enterica Mbandaka
S. enterica Typhimurium
epidemiology of salmonella Mbandaka?
adults: D+ & malaise, also abortion
infected feed origin
mostly larger herds supplementing feed/housing all year
v rarely seen in humans
epidemiology of salmonella typhimurium?
mainly calves
various CS
carrier animals
periodic epidemics e.g. DT104
epidemiology of salmonella dublin?
host-adapted
affects both calves & adult cattle
latent/persistent carriers
assoc. w abortion
infreq. in humans, but potentially fatal:
-via infected livestock/unpasteurised milk
transmission of salmonellosis?
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
is routine monitoring done for salmonellosis?
no
no one knows scale of exposure to salmonella
rely on lab diagnoses from clin cases: req material to be submitted
risk factors of salmonellosis?
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
CS of salmonellosis
range of CS severity depends on infective dose & age/stage -acute/chronic enteritis -abortion -septicaemia -reduced productivity -poor calf health
CS of acute enteritis?
calves >2wk & adults high fever severe D+, sometimes bloody anorexia colic abortion severe dehydration fatalities can be up to 75%
CS of chronic enteritis?
may follow acute enteritis reduced weight gain intermittent D+ inappetence stressors can trigger dx: poor nutrition, long transport times, calving, mixing, crowding
CS of septicaemia?
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
CS of abortion?
usually 5-8mth pregnancy
+/- fever & anorexia
retained placenta & reduced lactation
abortion storms: up to 25% of herd
impacts of poor calf health due to salmonellosis?
pneumonia
poor growth rates
ill thrift
meningitis
diagnosis of indiv clin cases of salmonella?
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
diagnosis @ herd lvl for salmonella?
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
tx for salmonella?
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
control for samonella?
in -ve herd, prevent entry: biosecurity
if alr infected, biocontainment (& biosecurity)
how to maintain biosecurity?
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)
how to maintain biocontainment (+biosecurity)?
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
what vax is there for bovine salmonellosis?
bovivac S (MSD)
only licensed vax for salmonellosis!
contains both S. typhimurium & dublin
inactivated vax
