lepto

Question 1

what is the distribution of leptospirosis?

Answer 1

worldwide

Question 2

is lepto zoonotic?

Answer 2

yes

affects all mammals

Question 3

CS of lepto? (broad view)

Answer 3

broad range from mild, subclin infection to multiple organ failure & death
commonly:
-headache
-fever
-lethargy
-malaise

Question 4

what is the genus species of leptospira?

Answer 4

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

Question 5

aetiology of lepto?

Answer 5

aerobic, gram -ve spirochete

fastidious, slow-growing, corkscrew-like motility

Question 6

what other spirochetes are there?

Answer 6

brachyspira (intestinal dx in pigs)
treponema
borrelia (lyme dx in humans)

Question 7

what are the cattle host-adapted types of leptospirosis?

Answer 7

USA & much of the world:
L. borgpetersenii serovar Hardjo type hardjo-bovis (HB)
primarily in UK:
L. interrogans serovar Hardjo type hardjo-prajitno (HP)

Question 8

what is leptospira commonly referred to as?

Answer 8

Leptospira Hardjo

Question 9

slide 8 for how leptospira hardjo looks like

Answer 9

-

Question 10

transmission of lepto?

Answer 10

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

Question 11

risk factors of lepto?

Answer 11

open vs closed herd 2x
bulls vs AI 4x
sheep co-grazing w cattle 6x
cattle have access to waterways 8x

Question 12

pathogenesis of lepto?

Answer 12

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

Question 13

check slide 16&17 for images

Answer 13

-

Question 14

CS of L. Hardjo (more specific)?

Answer 14

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

Question 15

when does abortion occur after lepto infection?

Answer 15

6-12wks after infection
usually last 3mths of gestation
tend to affect young cattle more freq
live born calves weak & unviable

Question 16

how does lepto affect milk yield?

Answer 16

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

Question 17

what is another name for milk drop syndrome?

Answer 17

flabby bag

Question 18

what are the CS in calves & youngstock for lepto? (<2mths old)

Answer 18

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

Question 19

CS of lepto in calves >2mths old?

Answer 19

often non-host adapted serovars!!
anorexia
dullness
rarely pallor, petechiation, jaundice, haemoglobinuria

Question 20

diagnosis of lepto? (direct methods)

Answer 20

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

Question 21

diagnosis of lepto (indirect methods)

Answer 21

look for ab

serology ELISA: blood, milk

Question 22

how to diagnose lepto via ab levels?

Answer 22

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

Question 23

how to diagnose lepto on herd basis?

Answer 23

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

Question 24

aim of lepto tx?

Answer 24

reduce no. of infected animals
min. urinary shedding
reduce spread of organism to other cattle & other species including man

Question 25

lepto tx?

Answer 25

dihydrostreptomycin 25mg/kg (repeat after 7d)

-off datasheet: problems w milk loss if whole herd tx

Question 26

what other abs can be used other than dihydrostreptomycin for lepto?

Answer 26

amoxycillin 15mg/kg
oxytetracycline 20mg/kg IM
tilmicosin 10mg/kg SC

Question 27

what cautions are there when using tilmicosin for lepto tx?

Answer 27

if admin. during dry period or to pregnant animals, milk should not be used for human consump until 36d after calving

Question 28

control for lepto?

Answer 28

identification & removal of carriers
vax
test/treat/vax replacements
hygiene w special attention to water supply

Question 29

what vax are there for lepto?

Answer 29

leptavoid H (MSD) - HP
spirovac (zoetis) - HB
farmers advised to boost w spirovac!

Question 30

how to vax and control lepto in the field? (dairy)

Answer 30

close contact w workers
raise replacements separately hence heifers are naive
complete vax course in heifers before breeding
spring boosters

Question 31

how to vax & control lepto in field (beef)

Answer 31

youngstock usually acquire some lvl of immunity