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Can Lyme Disease in Dogs Spread to People?

Reviewed by Dr. Alexis Seguin, DVM, MS, DACVIM on Thursday, September 3, 2015
Posted April 02, 2014 in Dog Diseases & Conditions A-Z

According to the CDC and CBS News and the the incidence of Lyme disease in humans is much higher than in previous years—with 300,000 new cases a year reported primarily in 13 states in the Northeast and upper Midwest. 

Dog Snout

What is Lyme disease?
First described in 1975 the disease was first identified in Lyme, CT which gave it its name. The disease is caused by a bacteria (spirochete) called Borellia burgdorferi which is transmitted by a tick bite. The type of tick involved in the spread of the disease is called Ixodes spp. which feeds on animals at all stages of its life (larvae, nymph, adult).

How does Lyme disease spread?
Immature ticks become infected when they feed on infected rodents. The organism is then transmitted to a second host when the nymph or adult tick feeds. Ixodes scapularis and Ixodes pacificus feed on deer. Expanding ranges of deer herds have resulted in an increased distribution of infected ticks.

Subsequently, when the nymph or adult tick attaches to a new host and feeds, the infective organism is deposited at the site of attachment over a period of hours. The organism thus infects the new host be it a dog or a human.

Even though the vector tick is called the deer tick, its feeding habits are not restricted to deer. They also feed on dogs and so are frequently in close proximity to people who have dogs. There is no evidence that Lyme disease can spread directly from dogs to humans. However, the same type of tick that could infect a dog can also feed on people. There is a potential for humans to be infected due to the fact that we tend to spend time in the same places as our dogs do If our dogs are picking up ticks, we certainly could be as well. 
When are people likely to be affected by Lyme disease?
In a 2011 CDC study, it was determined that there is a definite association between the incidence of canine infections and human infections. CAPC reports some of the findings from that study:

  • "Human Lyme disease incidence was effectively zero when the canine seroprevalence was <1.3 percent."
  • "Among 14 states with canine seroprevalence >5 percent, median annual human Lyme disease incidence was about 100-fold higher (24.1 cases/100,000 population) and positively correlated with canine seroprevalence."

In other words, in places where Lyme is more

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Mike has more than 35 years of experience in companion animal veterinary practice and is a valued member of IDEXX’s Pet Health Network team since 2013.