5.10 Spirochaetales Flashcards
Spirochaetales 4 genera
-Leptospira
-Borrelia
-Treponema: bovine digital dermatitis, ovine footrot
-Brachyspira: swine dysentery
physical characteristics of spirochaetales; shape, flagellum, movement, stain
- Slender, helically coiled, spiral organisms
- Wrapped around internalized flagellum
- Move corkscrew, flexing or serpentine
- Don’t stain well with Gram stain
- Use dark field or silver stain
what results would we see on a biochem test if we have a leptospirosis infection?
- Elevated creatinine, and blood urea
- Elevated creatine phosphokinase, muscle enzymes
- Elevated bilirubin, alkaline phosphatase
- Bruno has acute renal failure and hepatitis
clinical signs of leptospirosis in dogs
-fever
-decreased appetite
-weakness or reluctance to move from pain
-diarrhea
-increased drinking
-jaundice
leptospira characteristics; aerobe/anaerobe, shape, special features, growth medium, classification, pathogenicity
- Aerobic spirochetes
- Hooked ends (interrogation mark = interrogans old name)
- Grow in semi-solid rich media 10-14 days (or much longer)
- Dark field, FA, not Gram
- Classification: >60 species, then serovars
- Some species are pathogens, some are non-pathogenic (environmental) and some intermediate
why was leptospira previously known as interrogans
it has hooked ends that look like question marks
what classifications are there for leptospira hosts? how long does it stay in each and where?
-maintenance hosts: different serovars adapted to animal reservoir
> Characteristically lifetime, kidney (+ genital tract) carriage
-non-maintenance (“accidental” = “incidental”) hosts: a few weeks in kidneys
where in the body does leptospira live? how does it leave?
- Home: proximal convoluted tubule of kidney=> shed urine
where do leptospira live in the environment?
– Fastidious bacteria
– survive only in wet (moist),
– warm environments 4-6 weeks; “fall fever”, “mud fever”
what are environmental sources of infection of leptospira?
contaminated:
-water
-mud
-soil
what creatures are resistant to disease caused by leptospira? what animals are susceptible?
resistant:
-rodents
-cats
susceptible:
-dogs
-guinea pigs
-cattle
-horses
-sheep
-humans
what animals are chronically colonized with leptospira and commonly contaminate the environment?
rodents; mice, rats
peracute signs of leptospirosis infection
DIC, hemorrahages, haemoglobinuria, death
acute/ subacte signs of leptospirosis infection
Fever, hepatitis, nephritis, abortion (mastitis)
chronic signs of leptospirosis infection
Abortion; chronic nephritis (pig, dog); recurrent uveitis (horses) Infertility pigs, cattle??
subclinical signs of leptospirosis infection
Antibody rise only (or mild ‘flu-like illness)
leptospira serovars that infect pigs and their symptoms
pomona: Abortion; chronic nephritis
bratislava: small litters, stillbirth, infertility
leptospira serovars that infect cattle and their symptoms
pomona: abortion, haemoglobinuria, mastitis
hardjo: abortion, stillborn, weak calves; mastitis
leptospira serovars that infect horses and their symptoms
pomona: abortion; recurrent uveitis (periodic ophthalmia)
leptospira serovars that infect dogs and their symptoms
canicola: acute or chronic renal failure (interstitial nephritis)
grippotyphosa, pomona: fever, hepatitis, acute renal failure
parts of the horse affected most by leptospira
-eyes
-kidneys
-female repro tract
how do we diagnose leptospirosis?
-Serology using paired serum samples
> Microscopic Agglutination Test
» Can be hard to interpret
-SNAP test: detect IgM
-PCR: both blood and urine
control of leptospirosis
- Vaccines work well
- Vector control
-yearly vaccination can stop cycle
treatment for leptospirosis
- Treatment: Doxycycline (2 weeks), ampicillin
symptoms of borrelia infection
-dull, depressed, anorexic, dislikes exercise
-lameness, swollen joints
what bacteria causes lyme disease?
borrelia
physical characteristics of borrelia; gram stain, shape
- Gram-negative spiral shape, rods
what creature spreads borrelia?
- Arthropod infections (many tick-borne)
most significant borrelia organism in canada?
Borrelia burgdorferi most significant in Canada
what is the geographical region where borrelia is an issue?
Problem in eastern, central, western US associated with resurgent deer populations (source of food for adult ticks)
vector for berrelia burgdorferi
- Ixodes scapularis: (black-legged “deer” tick) in eastern/central USA
- Ixodes pacificus in western US, SW British Columbia
main host of Borrelia burgdorferi? what is a major source for adult ticks? where?
Main host white-footed mouse, many bird species:
persistently bacteremic
- Deer major source adult ticks
- Populations along north shore lakes Erie and Ontario, dramatic recent increase in Thousand Islands area, spreading
life cycle of Ixodes scapularis
- adult females drop off host to lay eggs
- eggs hatch into six-legged larvae
- larvae attach to and feed on first host and may acquire B. burgdorferi
- larvae molt into nymphs after leaving first host
>infected nymphs feed on humans, transmitting B. burgdorferi - nymphs attach to and feed on second host and may acquire B. burgdorferi
- nymphs molt into adults leaving second host
>infected adults feed on dogs and sometimes humans, transmitting B. burgdorferi - adults attach to the third host for feeding and mating
how is borrelia burgdorferi spread to animals and people?
- Spread to animals and people from nymphal and adult tick bite (although adult noticed early and often removed before transmission occurs)
signs of Borrelia burgdorferi in people
In people chronic erythematous skin rash (not always!), followed by fever, muscle and joint ache, meningitis
* Weeks or months later:
-peripheral neuropathy, arthritis, myocarditis
symptoms of Borrelia burgdorferi for dogs
- Dogs: fever, anorexia, arthritis; protein-losing glomerulopathy; rarely progressive renal failure
symptoms of B. burgdorferi in horses
- Horses: arthritis, uveitis, encephalitis
-neuroborreliosis: a rare form of Lyme disease that can present as fever, muscle wasting, difficulty eating, skin sensitivity, and other neurologic signs
is lyme disease easy to diagnose in horses?
not easy
-clinical signs are often vague and are similar to signs caused by other diseases
can an infection of Lyme disease from a horse be passed to other animals?
no, the horse is a dead end host
- cannot pass the infection to horses or other animals
how do we diagnose and infection of B. burgdorferi?
- Diagnosis: history, clinical signs + serology (SNAP test)
Why is PCR not commonly used?
* Difficulty diagnosing in endemic areas since subclinical infection (exposure) common
can we use PCR to diagnose B. burgdorferi? why?
PCR not commonly used
* Difficulty diagnosing in endemic areas since subclinical infection (exposure) common
how do we control B. burgdorferi?
Vaccine for dogs in endemic areas
(antigenic variants issue, and short-lasting vaccine antibody)
What is the habitat of the black legged tick?
wooded, brushy areas
