What is Leptospirosis?
Leptospirosis also known as Weil's Syndrome is a type of bacterial infection that is spread by animals. It is caused by a strain of bacteria called leptospira.
It is caused by bacteria of the genus Leptospira. The bacterial infection is spread by the urine of infected animals from many species, both domesticated (such as dogs and horses) and wild infected animals (such as rodents or wild pigs). It is termed a zoonotic disease or a zoonosis because it occurs in wild animals. The bacteria can survive in freshwater and soil for months. The disease is most common in temperate and tropical climates. The infecting bacteria occur worldwide (for example, in the United States, Leptospira has been found in Hawaii's freshwater ponds and waterfalls).
What are the types of leptospirosis?
There are two main types of leptospirosis infection:
Mild leptospirosis is where a person develops flu-like symptoms, such as headache, chills and muscle pain.
Severe leptospirosis is where a person goes on to develop severe, sometimes life-threatening symptoms, including organ failure and internal bleeding. This is caused by the bacteria infecting major organs, such as the liver and kidneys.
Mild leptospirosis is the most common type of leptospirosis, accounting for 90% of cases. It is unclear why a few people go on to develop serious symptoms.
Risk factors for developing severe leptospirosis include:
Being under five years old
Being over 65 years old
Already having a serious health condition, such as pneumonia
Leptospirosis is most common in tropical areas of the world. However, it is becoming increasingly widespread in urban areas that have low levels of sanitation, such as in poor areas of large cities in the developing world.
What are the causes and risk factors of leptospirosis?
The cause of leptospirosis is bacteria (genus Leptospira and species interrogans), a Gram-negative spirochete (spiral-shaped bacteria). The Leptospira bacteria infect many types of animals (many wild animals, rodents, dogs, cats, pigs, horses, cattle, for example) that subsequently contaminate water, lakes, rivers, soil, and crops when they urinate because the bacteria are present in urine. The bacteria then infect humans when they invade through breaks in the skin or mucus membranes or when people ingest them. The bacteria multiply in the liver, kidneys, and central nervous system. Person-to-person transfer of this disease is rare.
In general, human leptospirosis is considered weakly contagious. This is because, like other animals, humans can shed leptospirosis in the urine during and after illness.
Risk factors include occupational exposure in people to with farm animals, wild animals, and to contaminated water and soil (farmers, slaughterhouse workers, veterinarians, miners, military personnel, disaster workers and victims, for example). People who participate in outdoor activities such as camping or kayaking are also at higher risk for infection. Any exposure to sewage or animal waste, including stools from infected dogs, increases the risk of getting leptospirosis. Heavy rainfall may cause the bacterial infection to increase in a population that experiences flooding.
What are leptospirosis symptoms and signs?
The symptoms and signs of leptospirosis are variable and are similar to those seen in many other diseases (dengue fever, hantavirus, brucellosis, malaria, and others).
In humans, Leptospirosis can cause a wide range of symptoms, including:
Jaundice (yellow skin and eyes)
Many of these symptoms can be mistaken for other diseases. In addition, some infected persons may have no symptoms at all.
The time between a person's exposure to a contaminated source and becoming sick is 2 days to 4 weeks. Illness usually begins abruptly with fever and other symptoms. Leptospirosis may occur in two phases:
After the first phase (with fever, chills, headache, muscle aches, vomiting, or diarrhea) the patient may recover for a time but become ill again.
If a second phase occurs, it is more severe; the person may have kidney or liver failure or meningitis. This phase is also called Weil's disease.
The illness lasts from a few days to 3 weeks or longer. Without treatment, recovery may take several months.
How do physicians diagnose leptospirosis?
Your doctor will make diagnosis based on the patient's history and physical exam. Only specialized labs perform serological serology tests for leptospirosis serogroups (specific types of the bacteria that react with certain antibodies). Health care professionals may perform definitive tests by isolating the bacteria from the patient (blood or CSF) or by a positive microscopic agglutination test (MAT). Other tests (ELISA, PCR, urine dipsticks) may provide additional evidence of infection. Patients with severe symptoms should be treated as confirmatory tests are time consuming.
What is the treatment for leptospirosis?
Leptospirosis is treated with antibiotics, such as doxycycline or penicillin, which should be given early in the course of the disease.
Some patients may require IV antibiotics and supportive hospital care such as rehydration.
Prevention and vaccination
The risk of acquiring leptospirosis can be greatly reduced by not swimming or wading in water that might be contaminated with animal urine, or eliminating contact with potentially infected animals.
Protective clothing or footwear should be worn by those exposed to contaminated water or soil because of their job or recreational activities.
A leptospirosis vaccine is not currently available in the U.S.; however, high-risk workers in some European and Asian countries may have access to a vaccine.
What is the prognosis of leptospirosis?
the prognosis of leptospirosis is good. Many people become infected and spontaneously recover without treatment. However, the prognosis worsens as the symptoms increase. People with Weil's disease may have a prognosis ranging from good to poor, depending on their response to treatment. Pregnant women who become infected have a high rate of fetal mortality, especially if they acquire the disease early in pregnancy.