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:
High fever
Headache
Chills
Muscle aches
Vomiting
Jaundice (yellow skin and eyes)
Red eyes
Abdominal pain
Diarrhea
Rash
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.
