A recent edition of the Veterinary Record contains a case report of Weil’s disease in a person that adopted a feral (wild) rat (Strugnell et al, 2009). Weil’s disease is a severe disease of the kidneys, liver and other body systems that can develop after acute leptospirosis (infection by Leptospira bacteria). This group of bacteria can infect a wide range of animals and is typically shed in the urine. The person that was affected adopted the rat after it was caught by her neighbour’s cat. The paper says that the rat was "urinary incontinent" – not something we usually notice about rats since they are not typically litter or house trained. I presume this means the rat was urinating frequently when out of its cage, including when it was being handled. Because of this, the owner reported that she "aimed" to wash her hands after every time she touched the rat.

A couple of weeks after adopting the rat, the woman was admitted to hospital because of lethargy, muscle aches, mild abdominal pain, cough and a bloody nose. Blood tests showed that she had decreased levels of white and red blood cells, as well as liver and kidney disease. After further testing she was diagnosed with leptospirosis. She had to be treated in the ICU, but eventually made a complete recovery. The adopted rat and the other rat that she owned were euthanized by the owner’s partner shortly after she was admitted to hospital. Testing of the adopted rat identified Leptospira in the kidneys.

This is another example of why wild animals should be left in the wild, and another case highlighting the need for veterinarians, physicians and public health personnel to work together.

More information on Leptospira and leptospirosis can be found on the Worms & Germs Resources page and in our archives.

  • Cassandra

    I am in fact the person that this article refers to. the rat in question was most certainly not a wild rat as you have stated, it was a fancy breed and was comepletely tame. We assume that it had escaped from someones home and somewhere along the line had come in contact with a wild rat, it had a wound on its tail which we now believe to have been the result of an altercation with an infected wild rat. I had the animal checked out with a vet as i had done with another domestic rat we had found in our garden previously and her opinion was that it was a healthy animal. neither rat we adopted looked anything like a wild rat (one was a husky rat and one an apricot dumbo rat) so i think it needs to be stressed that even if a rat in the wild looks like an escaped domestic animal it should still be treated with utmost caution

  • Scott Weese

    Great comments and nice to hear a first-hand account. Your point about rats that look like pets still being a risk is a good one. As well, this is a good reminder that even with a veterinary exam, you can never rule out the potential that an animal is carrying a zoonotic disease.

  • Dear Cassandra, I hope you’re case of leptospirosis wasnt too severe, my dad caught this 13 years ago as he was doing construction work near water where rats lived. He ended up needing a kidney transplant, but it never attacked his liver, thank goodness. It took 6 months for him to get a diagnosis and he has nearly died on a few occasions. It really is important to highlight the fact that you don’t have to have physical contact with a rat to catch this as it is transmitted through the urine!