Sunday, February 20, 2011

Another reason not to own a pet rat

A pair of European doctors wrote about the trials of a 37-year-old man who came down with Weil's disease, a severe form of leptospirosis.  The case report appeared in the recent issue of The Lancet Infectious Diseases.

The individual showed up in the emergency room complaining of a sudden fever, muscle pain, and a severe headache.  Notable were the signs of jaundice and conjunctival suffusion (reddening of the eye), which suggested leptospirosis.

Figure from Jansen and Schneider, 2011
Shortly after he was admitted, the patient had to be moved to the intensive care unit because his kidneys were failing.  Blood tests for Leptospira antibodies came back negative, most likely because it was too early in the infection for antibodies to appear.

An infectious diseases specialist noted that the patient suffered from the classic signs of Weil's disease:  kidney failure, jaundice, and an enlarged spleen.  Accordingly, the patient was started on intravenous penicillin, the favored treatment for severe leptospirosis.  Further blood tests conducted during the second week of treatment finally revealed antibodies to Leptospira.  The patient completely healed within several weeks.  The only question that remained is how the patient got infected with Leptospira.

At some point the patient admitted that he owned four pet rats.  Since rats can silently carry Leptospira in their kidneys, his pets were sacrificed to check their kidneys for the presence of the spirochete.  All four kidneys turned out to be culture positive for Leptospira interrogans, serovar Icterohaemorrhagiae or Copenhageni (the typing test couldn't distinguish the two serovars).  The patient's antibodies reacted against the same serovars, suggesting that the source of the infection was tainted urine from his pet rats.

Although cases of leptospirosis acquired from pet rats appear to be rare, anyone who wishes to own a rat should be aware that rats can be carriers of a potentially deadly spirochete.  This is yet another reason why rats should be obtained from a responsible breeder.

For another case, check out this post from the Worms & Germs Blog (make sure you read the comments for the complete story).


Jansen, A. and Schneider, T. (February 2011).  Weil's disease in a rat owner.  The Lancet Infectious Diseases 11(2):152.  DOI: 10.1016/S1473-3099(10)70106-7

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