VIOLIN: Vaccine Investigation and Online Information Network

I. General Information

1. NCBI Taxonomy ID:

2. Disease:

Leptospirosis

3. Introduction

Leptospirosis (also known as Weil's disease, Weil's syndrome, canicola fever, canefield fever, nanukayami fever, 7-day fever, Rat Catcher's Yellows, Fort Bragg fever, and Pretibial fever) is a bacterial zoonotic disease caused by spirochaetes of the genus Leptospira that affects humans and a wide range of animals, including mammals, birds, amphibians, and reptiles. The disease was first described by Adolf Weil in 1886 when he reported an "acute infectious disease with enlargement of spleen, jaundice and nephritis". Leptospira was first observed in 1907 from a post mortem renal tissue slice. In 1908, Inada and Ito first identified it as the causative organism and in 1916 noted its presence in rats. Though recognised among the world's most common zoonoses, leptospirosis is a relatively rare bacterial infection in humans. The infection is commonly transmitted to humans by allowing water that has been contaminated by animal urine to come in contact with unhealed breaks in the skin, the eyes, or with the mucous membranes. Outside of tropical areas, leptospirosis cases have a relatively distinct seasonality with most of them occurring August–September/February–March.

Leptospirosis is caused by a spirochaete bacterium called Leptospira spp. that has at least 5 serovars of importance in the United States and Canada causing disease in dogs (Icterohaemorrhagiae, Canicola, Pomona, Grippotyphosa, and Bratislava).There are other (less common) infectious strains. Genetically different leptospira organisms may be identical serologically and vice versa. Hence, an argument exists on the basis of strain identification. The traditional serologic system is seemingly more useful from a diagnostic and epidemiologic standpoint at the moment (which may change with further development and spread of technologies like PCR).

Leptospirosis is transmitted by the urine of an infected animal and is contagious as long as it is still moist. Although rats, mice and moles are important primary hosts, a wide range of other mammals including dogs, deer, rabbits, hedgehogs, cows, sheep, raccoons, possums, skunks, and certain marine mammals are able to carry and transmit the disease as secondary hosts. Dogs may lick the urine of an infected animal off the grass or soil, or drink from an infected puddle. There have been reports of "house dogs" contracting leptospirosis apparently from licking the urine of infected mice that entered the house. The type of habitats most likely to carry infective bacteria are muddy riverbanks, ditches, gullies, and muddy livestock rearing areas where there is regular passage of either wild or farm mammals. There is a direct correlation between the amount of rainfall and the incidence of leptospirosis, making it seasonal in temperate climates and year-round in tropical climates.

Leptospirosis is also transmitted by the semen of infected animals. Slaughterhouse workers may contract the disease through contact with infected blood or body fluids.

Humans become infected through contact with water, food, or soil containing urine from these infected animals. This may happen by swallowing contaminated food or water, or through skin contact. The disease is not known to be spread from person to person and cases of bacterial dissemination in convalescence are extremely rare in humans. Leptospirosis is common among water-sport enthusiasts in specific areas as prolonged immersion in water is known to promote the entry of the bacteria. Surfers and whitewater paddlers are at especially high risk in areas that have been shown to contain the bacteria, and can contract the disease by swallowing contaminated water, splashing contaminated water into their eyes or nose, or exposing open wounds to infected water. Occupations at risk include veterinarians, slaughterhouse workers, farmers, sewer workers, and people working on derelict buildings. Rowers are also sometimes known to contract the disease (Wiki: Leptospirosis).

4. Host Ranges and Animal Models

Leptospirosis is transmitted by the urine of an infected animal and is contagious as long as it is still moist. Although rats, mice and moles are important primary hosts, a wide range of other mammals including dogs, deer, rabbits, hedgehogs, cows, sheep, raccoons, possums, skunks, and certain marine mammals are able to carry and transmit the disease as secondary hosts (Wiki: Leptospirosis).

Table of Contents