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Lecture 19

WFSC 301 Lecture Notes - Lecture 19: Antibody, Necrosis, RodentPremium

3 pages69 viewsSpring 2017

Department
Wildlife & Fisheries Sci.
Course Code
WFSC 301
Professor
Walter Cook
Lecture
19

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Tuesday, March 28, 2017 at 1429 PM
Lecture 19: Leptospirosis
Etiologic Agent: Leptospira interrogans
Also called:
Swamp fever, Mud fever, Autmun fever, hemorrhagic jaundice
Gram negative, aerobic, and motile spirochete
240+ pathogenic strains that have yet to be differentiated
Description:
Many types of wildlife and domestic animals can harbor and transmit this
bacerium via urine
Increased rainfall or flodding can cause an outbreak by spreading organisms
throughout the environment
Endemic to warm, tropical environments but is more prevalent in the spring
and summer
Infection to humans varies and is dependent upon occupation and living
conditions
Can infect many mammals including humans but few species are resistant to
it - including cats
History:
First spread amongst sewage workers
Primary reservoir: rat
Adolf weil recorded the symptoms to be jaundice, fever, hemorrhage and
kidney failure
Host: Is zoonotic
Bovine
• Swine
Equine
Canine
Rodentia
• Caprine
Ovine
Feral animals
Hard to diagnose animals and humans due to lack of diagnostic testing so many patients
are not treated properly. Humans are also unaware of animals having the bacterial
disease due to the lack of external gross lesions
Geographic distribution: Worldwide conern
Endemic in humid and subtropical climates
Signs in animals: Highly variable
Cattle
- calves: more acute infections; fever, anorexia, conjuctivitis, diarrhea,
jaundice, hemolytic anemia, signs of pneumonia
- Adults: early signs are not often present and first signs are usually
abortions and or stillbirths
Sheep & goats
- similar to cattle
• Swine
- piglets -- similar to calves and may grow more slowly
- often subclinical in herds when infected
- Late-term abortions, infertility, stillbirths, fever, agalactia, jaundice
Horses
- Foals -- low fever, anorexia, jaundice, conjuctivitis, anemia. May also
result in kidney failure
- Recurrent uveitis -- weeks to months after subclinical infections;
periods of fever, conjunctivitis, corneal edema, photophobia,
blespharospasm, lacrimation and corneal opacity
Dogs
- Highly variable
- Vomiting, diarrhea, abdominal pain, weight loss, grey stool, jaundice,
abortions
- Can result in chronic kidnye disease or death
- Hemorrhagic disorders can occur, including hemorrhagic gastroenteritis
and pulmonary hemorrhaging
Signs in Humans:
Biphasic in nature
- Incubation (7-12 days)
- 1st phase: fever, headache, myalgia, vomiting, diarrhea, abdominal
pain; sometimes accompanied by nonproductive cough
- 2nd phase: immune response ocurs
Can progress to acute organ failure, hemorrhaging, and coagulation
disorders; less than 10% of cases
Most cases are sublethal and only consist of the two [hases usually self
limiting
Transmission:
Environment is most common source of infection
- Live bacteria shed in urine, contaminates environment
- Bacteria enter host via mucosa or skin abrasions and then enter
bloodstream
Bacteria can live for weeks to months in the environment
Other forms of transmission
- direct contact with urine or bodily fluid of infected animals
Gross lesions
Post morten lesions in systemic infection
- Kidney may be pale or molted in color, fibrotic scarring
- Liver may have necrotic patches
- Hemorrhaging on various organs
Diagnosis:
Detect antibodies from culture of blood, urine or tissue
Microscopic Agglutination Test (MAT)
- gold standard
• ELISA
• PCR
Antibodies can be found for a long period after infection
Treatment and prevention
Treated with antibiotics and supportive care
- Chances of recovery are high
- risk of permanent kidney or liver damage
Some vaccines available
- dogs, cattle and swine
- Vaccine does not provide full protection from every strain
Avoiding infected animals and contaminated environments
- Wear protective clothing if you need to be around infected animals
- Avoid swimming in potentially contaminated waters
Control rodent populations
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