ANSC 315 Lyme Disease

Cause of Lyme Disease

• Bacteria: Borrelia burgodorferi

  • spirochete

• Vector: 3-host ticks

• Reservoir Hosts: small mammals, birds

• Transmission: bacteria multiply rapidly in midgut of tick once attached to host — takes about 48 hours until transmission becomes efficient

2 Year Life Cycle of the Deer Tick

Eggs → Larvae → Nymph Dominant → Nymph → Adults

Epidemiology

• typically northeast, upper central states — 90% of cases

Risk of Infection

1. Opportunity of being bitten by an infected tick

2. Density of vector ticks

3. Proportion of ticks infected

4. Duration and nature of susceptible host’s activities in affected area

Signs & Symptoms in Dogs

• lameness, fever, anorexia (2 months after infection) — arthritis

• renal disease

• CNS disorders

• myocarditis

Diagnosis of Lyme Disease

• History: exposure to tick

• Antibody tests

• EIA, IFA: high sensitivity, low specificity

• New SNAP test (IDEXX): synthetic peptide that is highly conserved and is more specific

• Can’t distinguish exposure from infection

Treatment for Dogs

• antibiotics

• clinical signs

• not necessarily a good idea to use if serologically positive but not clinically affected animals

Vaccination

to vaccinate or not to vaccinate… that is the question!

Prevention of Lyme Disease

• ***Reduce exposure to ticks***

• environmental control

• individual animal collars (amitraz, permethrin), topicals

• thorough inspection of animals

• rapid removal of ticks

• vaccination of unexposed animals — controversial

Public Health

Are Dogs a Source of Infection for Humans?

• NO

BUT dogs can bring ticks into household