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
-
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
-
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
