Leptospirosis is one of those diseases that keeps coming back, again and again.

When I was a vet student back in the '80s, it was well under control with routine vaccination in the U.S. Unfortunately, the vaccine itself became associated with a higher than average number of reactions, especially in puppies, and many veterinarians and breeders began excluding it from routine vaccination protocols.

I saw my first cases of lepto about 10 years ago, during an outbreak in Northern Oakland County that involved both people and dogs. Recent news of an outbreak in Macomb County makes a refresher on this disease quite timely.

Leptospirosis is of special concern, because it can infect people as well as dogs. Cats do not seem to be seriously affected. Lepto is a reportable disease in Michigan, meaning that all cases in animals must be reported to the state veterinarian for monitoring.

Lepto in animals is transmitted primarily through exposure to infected animal urine, with rodents being a common reservoir for the bacteria. The outbreak in Macomb right now seems to be associated with construction along the I-696 corridor, displacing infected sewer rats into local neighborhoods. The bacteria enters the body through mucous membranes or abraded skin, so dogs and humans who swim, drink pond or lake water, or run in fields frequented by wildlife are at higher risk. The dogs in Macomb who have died have been largely house pets in fenced backyards, with their home territories being invaded by infected wildlife. This clearly illustrates the need for vaccination of all dogs in certain situations.

Symptoms include high fever, lethargy, anorexia, vomiting, trembling and dehydration. The bacteria tends to settle in the kidneys, liver and spleen, ultimately causing kidney or liver failure, which can be fatal. Treatment is typically antibiotics, intravenous fluids, and supportive care. The sooner you take a symptomatic pet to your veterinarian for treatment, the better his chances of survival.

Remember that symptoms in people will be similar, and are often associated with exposure to contaminated water. A recent outbreak in Illinois followed a triathlon swim, where several human athletes developed flu-like symptoms that developed into jaundice and more serious complications.

Diagnosis is made by running a blood test called a titer. There are eight strains, or serovars, that are thought to infect domestic pets. The best vaccine we have protects against four of these serovars (L. canicola, L. icterohaemorrhagiae, L. grippotyphosa, and L. pomona), and should be given as often as every 6 months in endemic areas. Most Michigan veterinarians recommend vaccination for dogs that spend a lot of time in the woods, swim frequently, or live in semi-rural areas frequented by wildlife.

This most recent outbreak in Macomb County reminds us that even a pampered house pet can become infected if wildlife travel through the backyard.

Contact your veterinarian to ascertain whether your dog should be vaccinated against lepto, and come up with a plan for re-vaccination based on your own pets' risks. Avoid allowing your pet to drink from standing or still water, especially during hot summer months. If any symptoms develop, see your veterinarian immediately. Remember that lepto can infect people, too, and see your physician if you develop symptoms.

While is there is no current outbreak in the Ann Arbor area, it is always good to remember that lepto is a bacterial disease that exists in wildlife, and remains a risk factor for pets and people.

Dr. Cathy Theisen is a house call veterinarian in Ann Arbor, with 24 years experience in small animal medicine and surgery. Visit her website at www.cathythevet.net, or e-mail questions/comments to cathythevet@comcast.net.