Leptospirosis in Wild Animals

Leptospirosis is an acute disease caused by pathogenic bacteria of the genus Leptospira. Wild and domesticated animals are essential for the maintenance of pathogenic leptospires in nature. Many wild animals, including rodents, are perfectly adapted to Leptospira and show no signs or lesions. The best reservoirs of the infection are animals that have prolonged leptospiruria (presence of spirochetes of the genus Leptospira in the urine) and generally do not suffer from the disease themselves. For example, this is true of rats which harbor icterohaemorrhagia and rarely have lesions. Leptospira locate in their kidneys and are eliminated in the urine contaminating the environment and foods, a major factor in the transmission cycle of the disease. Rats, mice, field moles, squirrels, hedgehogs, gerbils, amphibians and reptiles are considered reservoir hosts.

In several areas of the world, studies in wild animals have demonstrated the presence of leptospira in many rodents, edentata, and carnivore species and they may act as infection sources.2

The infection in man and animals is contracted directly or indirectly, through skin abrasions and nasal, oral, and conjunctival mucosa. Indirect exposure through water, soil or foods contaminated by urine from infected animals is the most common route1.

Among South American animals, marsupials, such as opossums and nine-banded armadillo, have different variations of leptospira.

Reptiles, including South American species of venomous and nonvenomous serpents, are considered to be reservoirs, because leptospira can be found in clinically normal reptiles. They get infected by ingesting infected rodents2.

Leptospira interrogans is one of the few bacteria known to cause mass mortality in pinnipeds. Periodic autumn outbreaks of leptospirosis in California sea lions are generally associated with severe renal disease in juvenile males and, less commonly, abortions.3


  1. Zoonoses and Communicable Diseases Common to Man and Animals. Pedro N. Acha, Boris Szyfres, Pan American Sanitary Bureau
  2. Biology, medicine, and surgery of South American wild animals. Murray E. Fowler, Zalmir S. Cubas
  3. Marine mammals ashore: a field guide for strandings. Joseph R. Geraci, Valerie J. Lounsbury