At a size of only 0.1 mocrons, it can make it through most filters. since most filters are 0.2 microns. The bacteria settles in the kidneys of its host and is transmitted to humans from animals, rats, mice, mongoose and domestic animals such as pigs, cows, goats and dogs. Syphillis and Lyme Disease are similar spirochetes. At one time it was seen as an occupational disease of sugar cane, rice paddy and meat packing workers. However the shift has been to a recreational disease for kids, gardeners, swimmers and tourists who come into contact with fresh water.
Veterinarians are more likely to see the disease than medical doctors.
Dogs can contact Lepto by drinking from an outdoor water dish that a rat has contaminated. An infected dog may become a carrier. It is a world wide disease. The Phillipines has a high incidence rater. It is also common in India during floods.