Lyme – Ohio Under Attack February 2017 Dwight D. Bowman, MS, PhD lecture Midwest Vet Convention
What is different about ticks now? Tick biology has not changed, it is the same tick biology that your parents or grandparents learned in vet school. At that time the one host tick of cattle (Rhipicephalus Annulatus) was most concerning, but three-host ticks were also part of education. They were not worried about Lyme disease so they mainly considered Dermacentor and Amblyomma species of hard ticks.
Typical route of Lyme disease, as carried by I Scapularis (black legged deer tick) is from host 1 (such as white footed mouse) to host 2 (tick nymph) to adulthood and then to host 3 (white tailed deer). The adults typically feed for 5 to 7 days, primarily on white tailed deer but also on bobcats, cattle, dogs, foxes, horses, humans, opossums, raccoons and other mammals. Brown dog ticks and lone star ticks also carry these diseases. Seasonal activity is year round with a spike in the warm summer months. There are more hosts invading pet and human areas than before. Exposure comes from pets and humans visiting or residing in potential tick habitats, urbanization and invasion of wildlife habitats, preservation of natural vegetation, less frequent use of pesticides and free roaming pets.
Cornell studied black legged ticks in two counties of New York from Oct 2009 to May of 2010. Harvesting of nymphs showed that regardless of winter conditions, over 80% of the ticks survived at both sites. In other words, a cold winter does not restrict the population of ticks.
The White Tail Deer distribution and density has increased steadily since 1950, particularly down the East coast and moving West. Along with the WTD came the deer tick. In 2011-2012 in Duchess County, NY, nearly 30% of trapped ticks carried Lyme disease Borrelia bacteria, over 10% carried Babesia parasite, 8% carried Anaplasma bacteria and double and triple infected ticks were also discovered (carrying all three diseases).
Ohio has ticks carrying Lyme and other diseases coming from Michigan, which has ticks coming from Ontario, Indiana and Wisconsin. Out of 982 thousand dogs tested in the Northeast, 11.6 thousand had antibodies to Lyme (over 40%). In comparison, west coast percentages are much lower.
Infections in Ohio have increased from 1 out of 252 tested in 2011 to1 out of 106 in 2016. Companion Animal Parasite Council (CAPC) numbers are not yet available for 2016. Human cases begin to rise when an area reaches 5% positives. PA is over 5%, mostly at 13%. Westerville, Ohio tests in 2016 showed daily positive results for Lyme. This data is from Antech and Idexx tests and is from pets, not shelter dogs, due to lack of funds of shelters. Lyme must come from a tick bite, but the seroprevalence in dogs is a useful indicator of that is happening in the human population. In Ohio, 5 counties exceeded 5% in 2014, 6 counties exceeded 5% in 2015 and 10 counties exceeded 5% in 2016. Again, CAPC numbers are not yet published.
Prevention is the key to controlling the spread of Lyme and like disease. Permethrin impregnated clothing and horse blankets (Buzz Off) are helpful. However, the brown dog tick is resistant to the preventatives.
Tick borne viruses are not a known problem here at this time, but they may be in Europe. It takes 10 to 15 minutes after a bit for the virus to transmit. Soft bodied ticks may be a threat of this type.
Preventives that kill the tick before it can bite (Vectra) or quick kill products are the best course for now for the pets, and DEET or treated clothing is the best for humans.
Additional Map Information: Yellow pins represent Lyme positive dogs, Red pins represent Ehrlichia positive dogs and Blue pins represent Anaplasma positive dogs that we are seeing at the Granville Veterinary Clinic.