The National Academies: What You Need To Know About Infectious Disease

The National Academies

What You Need To Know About Infectious Disease


Leptospirosis is a disease caused by bacteria carried in the urine of infected animals. Many different kinds of wild and domestic animals may carry the bacterium (e.g., cattle, pigs, horses, dogs, rodents, wild animals). If an infected animal urinates on soil or in a lake, stream, river, or other body of fresh water, the bacteria can live there for weeks or months. Infection occurs when a person comes in contact with the contaminated urine, soil, or water and the bacteria enter the body through the mouth, nose, eyes, or broken skin. Drinking contaminated water can also cause infection. Person-to-person transmission is rare. Leptospirosis can be found all across the world, but it is most prevalent in temperate or tropical climates. Infection rates tend to peak during rainy seasons and may reach epidemic proportions during floods, when rodents (most often the source of humans’ exposure to the bacteria) move into cities.

Symptoms of leptospirosis may appear anywhere from 2 days to 4 weeks after exposure. Many people have no symptoms but when they do occur, they tend to start abruptly. Symptoms include chills, fever, headache, jaundice, red eyes, vomiting, diarrhea, stomach pain, and rash. In some cases, this initial phase of illness passes and the patient appears to have recovered. But a second, more serious phase of illness may occur, during which the patient may experience kidney or liver failure or meningitis. The illness lasts from a few days to 3 weeks or longer. Without treatment, recovery may take several months. In more serious cases, life-threatening infections in the kidneys, liver, brain, lungs, and heart may occur.

The disease can be treated with antibiotics, typically doxycycline or penicillin, which should be prescribed early in the course of the disease. For more advanced cases, the antibiotics may be given intravenously. Untreated cases can be fatal.

The best ways to prevent infection are to avoid swimming or wading in water that may be contaminated with animal urine and to eliminate contact with potentially infected animals. Protective clothing or footwear should be worn by those exposed to contaminated water or soil as a result of their work or recreational activities.


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What do you know about infectious disease?

True or False: Our bodies contain at least 10 times more human cells than bacterial cells.

  • Sorry, that’s incorrect.

    Our bodies contain at least 10 times more bacterial cells than human cells. 

  • Correct!

    Our bodies contain at least 10 times more bacterial cells than human cells. 

Infectious Disease Defined


A unit of length equal to one one-billionth (1 X 10-9) of a meter.

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