New Forms Of Old Disease, Leptospirosis, Threaten Dogs In U.S. -- Humans Also Are Susceptible

"We're especially concerned about some of the new types of lepto, such asgrippotyphosa, that we first documented in the New York City metropolitanarea in dogs, but which probably is not confined there.  We're findinggrippotyphosa in the Northeast and in other areas of the country," saidPatrick McDonough, a veterinary bacteriologist at the Cornell DiagnosticLaboratory. That laboratory is the official diagnostic center for animaldisease control in New York state and each year conducts more than 700,000diagnostic tests for animals of all species, including humans.

While currently available vaccines do protect against some serovars(serological varieties) of leptospirosis, newer serovars, such asgrippotyphosa and pomona, are not included in that protection, McDonoughnoted, saying:  "There is room for improvement in the vaccinationprotocols."  Worldwide, there are more than 200 known serovars ofleptospirosis infecting many kinds of mammals, including rodents andcattle.

Leptospirosis is spread by a spirochete (or spiral shaped) bacteria calledleptospires in the urine of rodents and other infected animals, as well asin water, such as pond water.  The leptospires enter the body throughmucous membranes or through abraded skin.

For dog owners, the first signs of leptospirosis in a pet often are severaldays of anorexia, vomiting, lethargy, depression, muscle pain and sometimesdiarrhea or bloody urine.  Veterinarians examining dogs with leptospirosisfind depression, fever, dehydration, jaundice and abdominal pain.  Thedisease damages the animal's liver and kidneys, sometimes resulting inrenal failure and death.

If the disease is caught in time, McDonough said, it can be successfullytreated with penicillin and -- when the kidneys have recovered -- with alengthy course of tetracycline drugs.  During their recovery, dehydratedanimals need intravenous fluids and "good, supportive nursing care," headded.

"Until vaccines are upgraded to include these new types of lepto, we'readvising dog owners to watch for flulike illnesses in their pets,"McDonough said.  "If the dog has been exposed to the urine of anotherdomestic animal or a wild animal, either directly or in ponds or run-offwater that collect urine, and if you notice these flulike signs, the petshould be tested for lepto."

Noting that leptospirosis is a zoonotic disease that can pass from animalsto humans, Cornell Diagnostic Laboratory Director Donald Lein said theinfection can be an occupational hazard for people who work with animals."This used to be called 'milkers' disease,' and there is real potential forits spread among dairy farm workers, as well as people handling otheranimals."  He said that personnel in large dairy farms, where hundreds ofcows are milked several times a day, must work in pits ateye-nose-and-mouth level to a continuous stream of cows -- and to anaerosol form of their urine that could contain leptospires.

"Leptospirosis is a disease that's been around for a long time,"McDonough said.  "Now we're recognizing new types.  Certainly in differentareas of the country there are endemic types of lepto that aren't found inother areas, and each area might have its unique lepto problem."

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Lepto Facts

from the Diagnostic Laboratory

College of Veterinary Medicine, Cornell University

What causes leptospirosis?

Leptospirosis is caused by spirochete (or spiral-shaped) bacteriacalled leptospires.  The leptospires live in fluids from infected animals,including urine, saliva, blood and milk.  The disease-causing organisms aretransmitted by direct contact with the fluids or with an infected animal,as well as by indirect contact, including contamination on vegetation, foodand water, soil and bedding materials.  Disease transmission is increasedin crowded conditions.  The disease may be carried for years in animalsthat serve as host reservoirs without the animals showing clinical signs ofthe disease.  The leptospires enter the body through mucous membranes orthrough breaks in the skin.

Where are leptospires found?

The leptospires cannot survive for long outside their idealenvironment: water or other fluids, moderate temperatures around 25 degreesCelsius (77 degrees Fahrenheit) and neutral or slightly alkaline pH.Stagnant water or slowly flowing streams may carry the leptospires;worldwide, leptospirosis infection increases with flooded conditions.  A1996 outbreak of leptospirosis among white-water rafters was traced by theU.S. Centers for Disease Control and Prevention to contaminated river waterin Costa Rica.  Leptospires are known to survive in urine-soaked soil forsix months.  Summer and early fall are the most likely times forleptospirosis transmission to dogs.  Milk from infected dairy cows maycarry leptospires, although heat from the pasteurization process shouldkill the microorganisms.

What are the symptoms of leptospirosis?

In general, the disease resembles the flu with fever, headache,chills and myalgia (muscle pain).  Dog owners may notice vomiting,lethargy, depression, muscle pain and sometimes diarrhea or bloody urine inthe pets.  The disease damages the liver and kidneys and, if untreated, maycause death.

How is leptospirosis treated?

Dogs are treated with a course of antibiotics and with intravenousfluid to overcome dehydration.  Diagnosis is based on clinical signs andlaboratory tests, including tests for the disease-causing organism,urinalysis and blood tests.

Can vaccination prevent leptospirosis in dogs?

Currently available vaccines for dogs cover only theicterohaemorrhagiae and canicola forms of leptospirosis but not certainemerging forms in dogs, such as grippotyphosa and pomona.  Vaccine makersare now attempting to include protection for emerging forms ofleptospirosis.

Do humans catch leptospirosis?

Leptospirosis is a so-called zoonotic disease that can betransmitted from animals to humans.  People can catch the disease fromwater that is contaminated by infected wild or domestic animals, as well asfrom more direct contact with animals, such as rodents, raccoons, skunksand cattle.  A well-known Hollywood actress is now recovering fromleptospirosis.  Public health authorities  suggest keeping dogs away fromchildren's play areas, including sandboxes and wading pools.

Why are cats not affected by leptospirosis?

Tests for antibodies show that some cats are exposed to thedisease, but cats almost never show clinical signs of leptospirosis.  Someexperts believe that cats have developed a kind of immunity toleptospirosis from their longtime association with rodents.