Rat Owner Dies from Leptospirosis: Was his Cuddly Pet Rat the Source of Infection?

Report from a day in the lab

Dr. Christine Süß-Dombrowski


The owner of a rat died from leptospirosis. Where could he have caught this serious infectious disease? Possibly from his own pet? This report is about a pet rat that was brought to us for examination. Its owner had fallen seriously ill, dying shortly thereafter from leptospirosis. It is suspected that his own pet could have been the source of infection.

Photo: archive picture, Karsten Paulick/Pixabay, CC0 Public Domain.

Photo: archive picture, Karsten Paulick/Pixabay, CC0 Public Domain.


The rat of the deceased man was brought to CVUA Stuttgart for examination. It could not be ruled out that the source of infection in the man had come from the animal.

The still young looking white rat appeared to be in very good nutritional condition and well-taken care of. It had smooth, shiny fur, and showed no outer signs of any disease. A macroscopic and histological (cellular level) examination also revealed no signs of disease in the inner organs. It was only the histological Warthin-Starry special stains that made it possible to detect the masses of spiral bacteria in the otherwise healthy kidneys.


Histological (cellular level) cross-section of the rat’s kidney, with Warthin-Starry silvering: spiral bacteria in interstitium. Photos: Dr. Christine Süß-Dombrowski, CVUA Stuttgart.

Histological (cellular level) cross-section of the rat’s kidney, with Warthin-Starry silvering: spiral bacteria in interstitium. Photos: Dr. Christine Süß-Dombrowski, CVUA Stuttgart.


We were able to confirm suspicion of a leptospiral infection in the rat by means of polymerase chain reaction (PCR). Gene sequencing and identification of the pathogen as Leptospira interrogans serogroup icterohaemorrhagiae was conducted at the Federal Institute for Risk Assessment (BfR) Berlin.

Info Box


Leptospirosis is a generalized, bacterial infectious disease affecting humans and animals. The leptospiral pathogens can be divided into many different serogroups and serovars of the Leptospira interrogans (L.) species: e.g. L. icterohaemorrhagiae, L. grippotyphosa, L. canicola, and L. pumona, among many others. They cause illnesses of varying severity in humans and animals.


Leptospires are spiral, up to 20 µm long, mobile bacteria. They exist world-wide, mainly in rodents such as rats and mice, but also in house pets, pigs and cows, as well as in dogs and wild animals (boar, foxes, hedgehogs and rabbits). Both infected and healthy animals eliminate large quantities of leptospires through their urine. The pathogens end up in water, soil and on objects. They can survive for a long time in constantly moist soil with a neutral pH-value. Dryness and soap as well as disinfectants are simple and effective means of killing leptospires.


Infection occurs via skin injuries and mucous membranes when working in the soil, bathing, diving, or going barefoot on moist subsoil. Humans also become ill from rat and mice bites, although the simultaneous exposure to the eliminated urine would be the likely cause of infection. Infections occur more often during the summer months. Symptoms of leptospirosis in humans can be mild and flu-like, or extreme and even deadly, depending on the disease provoking properties of the pathogen and the strength of the infected person’s immune system. Antibiotics are effective against leptospirosis, if they are taken early enough.


Dogs should be regularly vaccinated against leptospirosis. This vaccine serum is permitted for dogs in Germany.

It is assumed that the man who died of leptospirosis was infected by his own rat. We would like to stress once again that the rat’s outer appearance and organs were completely healthy, and that no hint of disease was evident. It is therefore of utmost importance for rat owners to maintain a hygienic environment and to keep a reasonable distance from their rat. They should especially not come into contact with the rat if they suffer from any skin lesions. People with weak immune systems should avoid any bodily contact with rodents and their eliminations.


According to the Baden-Württemberg Department of Health‘s report on infections, No. 27/2017, human cases of leptospirosis are not unique. Thus far in 2017 there have been seven cases, four of which were during the month of July. The highest number occurred in 2016, at a total of 21 cases, with five each occurring in August and September. Those most strongly affected, according to the infection report, are men (75%) between the ages of 40 and 60 years. In seven cases the probable risk of exposure was given as contact with rats or surface water.


In addition, we wish to point out that people staying in areas with marshy, wet soil should wear water-tight, protective clothing, in order to avoid contact with the mud and moist soil. All dogs, but especially those who love the water and hunting dogs, should be regularly vaccinated against leptospirosis.



[1] H. Kraus/ A. Weber et al.: Zoonosen, 3. Aufl.; Deutscher Ärzteverlag

[2] M. D. McGavin, J.F. Zachary : Pathologie der Haustiere; Verlag Elsevier Urban und Fischer

[3] Robert Koch Institut


Translator: Catherine Leiblein


Print article      Share: Facebook. Twitter. Google+. LinkedIn. Share it via Email.


Report published on 07.08.2017 13:56:24