lepto Flashcards
what is the distribution of leptospirosis?
worldwide
is lepto zoonotic?
yes
affects all mammals
CS of lepto? (broad view)
broad range from mild, subclin infection to multiple organ failure & death commonly: -headache -fever -lethargy -malaise
what is the genus species of leptospira?
serovar
e.g. have serovar 1a which has ag 2a & induces ab 3a in host
serovar 1b has ag 2b & induces ab 3b in host
aetiology of lepto?
aerobic, gram -ve spirochete
fastidious, slow-growing, corkscrew-like motility
what other spirochetes are there?
brachyspira (intestinal dx in pigs)
treponema
borrelia (lyme dx in humans)
what are the cattle host-adapted types of leptospirosis?
USA & much of the world:
L. borgpetersenii serovar Hardjo type hardjo-bovis (HB)
primarily in UK:
L. interrogans serovar Hardjo type hardjo-prajitno (HP)
what is leptospira commonly referred to as?
Leptospira Hardjo
slide 8 for how leptospira hardjo looks like
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transmission of lepto?
shed in bodily fluids e.g. urine, milk, vag discharge, semen penetrates MMs (eye, mouth, nose, genital tract) persists in environ. in moist conditions chronic carriers - often asymp., intermittent shedding, often sero-ve/low titres
risk factors of lepto?
open vs closed herd 2x
bulls vs AI 4x
sheep co-grazing w cattle 6x
cattle have access to waterways 8x
pathogenesis of lepto?
infection of non-immune animals
bacteraemia - multiplication systemically, liver etc.
ab pdtn from d5
from d7 limited to immunologically privileged sites:
-brain
-joints
-kidney tubules: shed into urine for 18mth
-repro tract
-seminal vesicles in bull
-uterus, placenta & foetus in cow
-multiples in foetus
check slide 16&17 for images
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CS of L. Hardjo (more specific)?
acute phase usually subclin (apart from lactating cows)
repro dx
-infertility: lepto sets up inflammation in uterus & can cause death of early embryo
-low CR
-abortion
-stillbirths
-weak calves
milk drop
when does abortion occur after lepto infection?
6-12wks after infection
usually last 3mths of gestation
tend to affect young cattle more freq
live born calves weak & unviable
how does lepto affect milk yield?
milk drop syndrome
- sudden onset fever & agalactia
- all 4 quarters of udder soft & flabby, producing quantities of yellow/orange secretions which may contain small clots
- may affect >50% of cows @ 1 time
- milk has high leukocyte count hence high SCC
what is another name for milk drop syndrome?
flabby bag
what are the CS in calves & youngstock for lepto? (<2mths old)
often non-host adapted serovars!!
- meningitis, anorexia, severe depression
- opthalmitis, hypopyon, optic disc oedema, congestion of retinal vessels
- pyrexia (40.5-41.5)
- opisthotonus, trismus, muscle tremors, paddling
CS of lepto in calves >2mths old?
often non-host adapted serovars!!
anorexia
dullness
rarely pallor, petechiation, jaundice, haemoglobinuria
diagnosis of lepto? (direct methods)
dark ground microscopy e.g. identify leptospires in urine
culture & identification (difficult!)
PCR (most common): identify DNA in secretions, urine & bodily fluids
immunofluorescence/peroxidase in tissue
diagnosis of lepto (indirect methods)
look for ab
serology ELISA: blood, milk
how to diagnose lepto via ab levels?
ab lvl rise @ 1st & may be assoc. w clin dx
then falls
abortion can take place w low lvl of ab (up to 12wks after infection)
ab is present in serum of carriers & vax animals
how to diagnose lepto on herd basis?
easy!
serology: rising titre in paired samples taken 14d apart; indiv samples w titres >1:100 indicates chronic/active infection
abortion: foetal serology, culture
bulk milk ELISA now regularly used for surveillance
aim of lepto tx?
reduce no. of infected animals
min. urinary shedding
reduce spread of organism to other cattle & other species including man
