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Tick-Borne Diseases Are Found in All 50 States

January 22, 2008

Veterinarians and industry experts concerned with the spread of tick-borne diseases announced today the results of a disturbing study that found tick populations are not only increasing in number, but also in reach across the United States. The results, presented during the 2008 North American Veterinary Conference (NAVC) in Orlando, were part of a voluntary national veterinary reporting system that was developed by IDEXX Laboratories of Westbrook, Maine. The data uncovered the presence of at least three tick-borne diseases, Lyme disease (Borrelia burgdorferi), anaplasmosis (Anaplasma phagocytophilum) and ehrlichiosis (E.canis), in every state in the country. All three tick-borne diseases can cause mild to severe health complications and even death in humans and dogs, if left untreated.

“This information is important because it indicates the significant degree to which people and pets are being exposed to tick-borne diseases, and therefore, the risk of developing some very serious illnesses,” said Susan E. Little, DVM, PhD, Dipl. EVPC, Center for Veterinary Health Sciences at Oklahoma State University. “As veterinarians, we need to incorporate this information into our practice, continuing to stress the need for year-round tick control in dogs and the importance of routinely screening for ticks and tick-borne diseases.”

These commonly recognized diseases in dogs could cause multiple health problems. Lyme disease, commonly associated with both people and canines, can often present with fever, weight loss, arthritis and nausea in dogs. In people, if the disease is untreated, it can lead to medical problems such as neurological damage, heart complications and arthritis.

A recently recognized disease spread by ticks, anaplasmosis, can cause mild to severe illnesses in dogs and has been known to cause death in people. In ehrlichiosis, signs are very similar to anaplasmosis and include potential neurological complications. Among people, 13 percent of ehrlichiosis cases being reported are in children.

Common ticks of dogs in North America causing the biggest problem include the American dog tick (Dermacentor variabilis), the black-legged tick or “deer tick” (Ixodes scapularis in the East, pacificus in the West), and the brown dog tick (Rhipicephalus sanguineus).

To better understand where these problem ticks are migrating, the testing results of domestic dogs from thousands of veterinary practices across the United States during the time period of 2001 to mid-2007 were compiled in collaboration with scientists at IDEXX in a national prevalence study. Test results were generated from IDEXX’s reference laboratory network as well as from millions of SNAP® 3Dx® and SNAP® 4Dx® reported results. SNAP 4Dx allows for the immediate detection of exposure to Lyme borreliosis, ehrlichiosis and anaplasmosis as well as heartworm disease. Results uncovered the following:

Table 1. Percentage of Positive Test Results for Lyme disease, anaplasmosis and ehrlichiosis

Region

Lyme disease

 

Anaplasmosis

 

Ehrlichiosis

 

Co-infection

Northeast

11.6%

 

5.5%

 

0.3%

 

1.4%

Southeast

1.0%

 

0.5%

 

1.3%

 

0.1%

Midwest

4.0%

 

6.7%

 

0.4%

 

2.0%

West

1.4%

 

4.5%

 

0.6%

 

0.8%

Nationwide

5.1%

 

4.8%

 

0.6%

 

1.3%

Positive tests for Lyme disease were highest in the Northeast, while positive results for anaplasmosis was highest in the Midwest. In the Southeast, ehrlichiosis has been most widely reported.

Of particular interest to researchers, was that the number of Lyme positive dogs in Connecticut (where 18 percent of the dogs were reported to test positive for Lyme) were from 50- to more than 200-fold greater than those in the southeastern border states of Texas, Louisiana, Mississippi, Alabama and Florida. Also surprising was the high prevalence level of infection detected in the western states of southern California, Arizona and New Mexico.

“This is of serious concern to veterinarians,” said Dwight D. Bowman, M.S., Ph.D., Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University. “It tells us ticks are on the move and raising the risk of infection from tick-borne illnesses to regions where they are not only unfamiliar with these diseases and symptoms, but also perhaps unfamiliar with how to prevent illness and protect their pets.”

Ticks and Travel

Exposure to urban wildlife and a high incidence of Lyme disease in the northeastern states was expected based on the number of human cases reported. However, dogs testing positive to Lyme disease exposure were also found in the southeastern United States.

“We noticed a surprising number of cases in the South,” said Michael W. Dryden, DVM, Kansas State University College of Veterinary Medicine. “One explanation may be the continual urbanization of America, which is adding to the problem of tick migration in places where we haven’t seen prevalence in the past.”

In the South, the rate of ehrlichia positive dogs was more than twice the national average. Cases of ehrlichiosis due to the E. canis pathogen are considered more common in the southern U.S. where infestations of the brown dog tick are also more commonly seen, although in the absence of effective control programs, the brown dog tick can survive indoors in kennels and homes – virtually anywhere there are dogs. The report also found cases of heartworm in the South that was detected in more than 3 million dogs in 48 states. Evidence of at least one agent was found in dogs from every state considered.

What Pet Owners Can Do

Because displaced wildlife often find refuge and seek food in suburban areas, people and pets more often come into contact with the most common species of urban wildlife like raccoons, skunks or opossums. Exposure to urban wildlife may pose serious health risks to humans and their pets. More information about tick migration, images of various species of ticks and maps where positive results have occurred, can be found on www.dogsandticks.com.

The Companion Animal Parasite Council (CAPC) recommends year-round heartworm, flea and tick preventatives for the life of your dog, for all areas of the country. Industry experts also stress the importance of testing for co-infection if you are living in an at-risk area, or you travel to high tick-borne disease prevalence areas with your pets.

“CAPC is very pleased to be the organization charged with disseminating this very important information,” said Michael Paul, DVM, executive director of CAPC. “While it is disturbing that the incidence of these diseases is as high and their distribution as wide as was uncovered, it is important to realize that increased awareness will lead to greater testing surveillance. Year-round use of safe and effective tick control products available from veterinarians as advocated by CAPC, will do much to reduce the clinical incidence of these diseases.”

About the CAPC

The mission of the Companion Animal Parasite Council is to foster animal and human health, while preserving the human-animal bond, through recommendations for the diagnosis and year-round management of parasitic infections in dogs and cats. The CAPC is an independent council of veterinarians and other animal health care professionals established to create guidelines for the optimal control of internal and external parasites that threaten the health of pets and people. Its membership represents broad expertise in parasitology, human medicine, public health, veterinary law, private practice and association leadership. For more information about the CAPC, please visit www.capcvet.org.

About IDEXX Laboratories

IDEXX Laboratories, Inc. is a leader in companion animal health, serving practicing veterinarians around the world with innovative, technology-based offerings, including a broad range of diagnostic products and services, practice management systems and pharmaceuticals. IDEXX products enhance the ability of veterinarians to provide advanced medical care and to build more economically successful practices. IDEXX is also a worldwide leader in providing diagnostic tests and information for the production animal industry and tests for the quality and safety of water and milk. Headquartered in Maine, IDEXX Laboratories employs more than 4,500 people and offers products to customers in over 100 countries.




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