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HomeHealth articleschemoprophylaxisWhat Is the Mode of Transmission in Leptospirosis?

Leptospirosis, a Bacterial Disease - Things You Need to Know

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Leptospirosis, a Bacterial Disease - Things You Need to Know

4 min read


It is a bacterial infection, where humans get infected from contaminated water and show flu-like symptoms.

Medically reviewed by

Dr. Preetha. J

Published At April 6, 2017
Reviewed AtMarch 15, 2024


Leptospirosis is an important zoonotic disease, which is common in the post-monsoon season. It is caused by Leptospira bacteria, which is a member of the family called Spirochetes. It is so-called because of its spiral shape. The disease can range from a minor and symptomless form to a serious life-threatening one, which can be fatal if left untreated.

What Causes Leptospirosis?

Leptospirosis is brought on by a bacteria known as Leptospira interrogans. The organism resides in the kidneys of many mammals. Their pee causes it to enter the soil and water.

Scratches, open sores, or dry spots on the skin are examples of skin breaks through which the germs can enter the body if one is near soil or water where an infected animal has urinated. Additionally, it may enter through the mouth, nose, or genitalia. They pass through the bloodstream and accumulate in the kidneys. The kidneys filter out harmful or extra materials from the urine. Bacteria leave the body through urine and may cause the spread of infection to other animals or humans.

What Is the Mode of Transmission in Leptospirosis?

  • Leptospirosis is transmitted through surface water contaminated with the urine of infected animals. Pathogenic bacteria enter the host through minor cuts and abrasions over the skin. Swallowing contaminated water can theoretically cause the disease, but few cases are reported. Human-to-human transmission also has not been reported.

  • People who are at risk are sewage workers, farmers, veterinarians, military personnel, sewer, and slaughterhouse workers. Any person who is exposed to running surface water is at risk of developing leptospirosis.

  • Leptospirosis typically shows seasonal variation. The disease burden is significantly more in the post-monsoon season. Both rural and urban populations are equally affected, and the prevalence is a little bit higher in rapidly urbanizing cities may be because of inadequate sewage treatment facilities and improper drainage systems. Poor sanitation leading to rodent infestation can cause leptospirosis outbreaks, especially in underprivileged areas.

What Are the Clinical Features of Leptospirosis?

Clinical features of leptospirosis are diverse, ranging from undiagnosed asymptomatic illness to rapidly progressing fatal forms called Weil's disease. The symptoms of Leptospira infection occur after an incubation period of 7 to 10 days.

The common clinical features include the following:

  • High-grade fever is associated with rigor and chills.

  • Severe headaches and retro-orbital pain.

  • Extreme muscle pain and tenderness, particularly in the calf and lower back.

  • Red eyes, nausea, vomiting, and extreme exhaustion.

  • Severe leptospirosis or Weil's disease starts after three to ten days of infection.

Weil's Disease:

Weil's disease is a rapidly progressing form of leptospirosis which can be fatal unless proper treatment is given. It is characterized by a combination of bleeding manifestation, jaundice, hypotension, and acute renal failure. It can also affect the brain and mimic symptoms of meningitis like nausea, vomiting, neck rigidity, and altered mental states. If left untreated, it can cause fatal complications and may result in death.

What Are the Phases of Leptospirosis?

The disease can be divided into two phases.

1. Leptospiremic Phase

  • Acute phase or also called the septicemic phase.

  • Sudden onset of flu-like symptoms, which starts 2 to 14 days after infection.

  • This phase lasts 3 to ten days.

  • Bacterial presence in blood and moving to organs. Blood tests show signs of infection.

2. Immune Phase

  • Bacteria present in the bloodstream have moved to organs.

  • The concentration of bacteria occurs in the kidney. Urine tests show signs of bacteria and antibodies against leptospira in the bloodstream.

  • People with Weil's syndrome show internal bleeding, kidney damage, and severe yellowing of the skin and eyes.

Who Is at Risk of Developing Leptospirosis?

Although leptospirosis is more prevalent in tropical regions, it can also arise in impoverished neighborhoods of major cities in developing countries that are not near tropical regions.

The WHO states that periods of heavy rain and flooding increase the risk. It is more common for leptospirosis to occur in Asia, Central America, and Africa's East Sub-Saharan region.

How Is Leptospirosis Diagnosed?

  • The suspected cases of leptospirosis should be evaluated by a physician at the earliest because early treatment significantly reduces the chances of complications.

  • During the initial stages, the symptoms are nonspecific, and it might cause initial misdiagnosis because many diseases have similar symptoms to leptospirosis.

  • Biochemical and hematological tests are non-specific in the early stages, and many diseases show a similar pattern.

  • Chest X-rays and Electrocardiogram ( ECG) should be taken to rule out cardiac and pulmonary involvement respectively.

  • Serological assays are the mainstays of diagnosing leptospirosis. Leptospirosis can be confirmed by detecting the presence of IgM antibodies against Leptospira bacteria by ELISA (enzyme-linked immunosorbent assay) or agglutination tests.

  • MAT (microscopic agglutination test) is the most distinct among the investigations.

What Is the Differential Diagnosis for Leptospirosis?

Due to diverse clinical manifestations and wide geographical distribution, many clinical conditions have to be ruled out before making a diagnosis. The following are the possible differential diagnosis.

  • Malaria.

  • Rickettsial diseases like scrub typhus and spotted fever.

  • Viral hepatitis.

  • Chikungunya.

  • Viral hemorrhagic fever.

  • Dengue.

  • Typhoid fever.

How Is Leptospirosis Treated?

  • Highly efficient antibiotics are available against Leptospira. Penicillins and tetracyclines are used as first-line drugs.

  • Cephalosporins like Ceftriaxone and Cefotaxime are also used. Antibiotics are effective in the early stages of the disease and in later stages their role is controversial.

  • In the advanced stages of the disease and Weil's disease, the patient might require intensive treatment.

  • The patient has to be hospitalized and might need intravenous antibiotics. Fluid and electrolyte balance has to be well maintained. Bleeding manifestations and shock have to be managed accordingly.

  • Cardiac monitoring in the form of continuous ECG monitoring may be needed in case of complications like myocarditis.

  • Patients with renal failure might require dialysis.

What Is the Prognosis of Leptospirosis?

The majority of the patients infected with Leptospira experience a complete recovery. The severity of the illness regarding renal and pulmonary dysfunctions are the most important determinants of prognosis. The extremes of age, evident pulmonary involvement, bleeding manifestations, renal failure, and thrombocytopenia are associated with poor outcomes. The common causes of death in leptospirosis patients are renal failure, shock, and myocarditis.

How Is Leptospirosis Prevented?

  • No effective vaccine is available for human leptospirosis. Some research is undergoing, but the clinical results are unsatisfactory.

  • Antibiotic prophylaxis is moderately effective and is the method used for prevention. Doxycycline is used for chemoprophylaxis in extremely high-risk individuals such as manual laborers exposed to contaminated surface running water.

  • Rodent control with pesticides and proper disposal of sewage are useful methods to prevent outbreaks.


Leptospirosis is an uncommon disease that shows mild to severe symptoms. Prevention of diseases is more important than treating the condition. Contact with contaminated water should be avoided. If there are some cuts or wounds present, a person should avoid contact with contaminated water. People at high risk like sewage cleaning workers should be taught about the diseases and tips to prevent them. If there are any symptoms, stop working and consult a doctor immediately

Frequently Asked Questions


How Can You Avoid Leptospirosis?

Leptospirosis can be avoided if you take certain precautions, such as -
- Avoiding touching water or soil contaminated with animal urine.
- Avoiding contacting things that might be contaminated with animal urine,  animal bedding, etc.
- Avoid any contact with fresh water after a flood or heavy rain.
- Do not swim in lakes, rivers, or swamps, especially after a flood.
- Drink water only after boiling or after chemical treatment.
- Travelers can take certain medications before traveling to prevent leptospirosis.


How Do Humans Get Infected by Leptospirosis?

Humans can get leptospirosis infection -
- Coming in contact with urine or other bodily fluids except for an infected animal's saliva.
- Coming in contact with contaminated water, soil, or food with the urine of infected animals.
- Drinking contaminated water.
- The bacteria enter the body through broken or cut skin or mucous membranes of the eyes or the mouth


How Long Does Leptospirosis Bacteria Survive?

The leptospirosis bacteria can survive in damp and moist conditions outside the host body for several days or weeks. Then, it spreads through the contaminated urine of the infected animals and survives there for weeks or months.


Can Leptospirosis Transmit From Human to Human?

Leptospirosis infects humans through direct contact with the contaminated urine of the infected animals. However, human-to-human transmission happens very rarely.


Who Is at Risk of Contacting Leptospirosis?

Leptospirosis is common in temperate or tropical climatic conditions. People working outdoors directly or indirectly with animals are at higher risk, such as -
- Veterinarians.
- Farmers.
- Sewer workers.
- Mineworkers.
- Slaughterhouse workers.
- Fishermen and fish vendors.
- Dairy farmers.
- Military personnel.
- Swimmers.
- Children.


How to Disinfect Leptospirosis?

Surfaces that might be contaminated with leptospirosis, or have urine from an infected animal, can be disinfected with an antibacterial cleansing solution or a solution made with one part household bleach mixed with ten parts of water. Also, the infected animal should be made to take the medications prescribed by the veterinarian.


Can Leptospirosis Be Cured?

Leptospirosis can be cured with the help of antibiotics, such as Doxycycline or Penicillin. These antibiotics should be administered in the early course of the disease. For people with severe symptoms, an intravenous antibiotic administration might be required. Suspected individuals should contact a healthcare provider.


Can Cooking Kill Leptospirosis Bacteria?

The leptospirosis bacteria get killed by heat, drying, disinfectants, acids, and alkalis. For example, heating up to 50 degrees celsius for five minutes kills the bacteria immediately. Therefore, customarily cooked food and boiled water are safe to consume.


Where Is Leptospirosis Bacteria Found in the Body?

Leptospirosis is caused by the bacteria leptospira interrogans. The bacteria are mainly found in the kidneys of people. Thus it enters the soil and water through the contaminated urine.


Is Vaccination Available for Leptospirosis?

Vaccines are generally given to healthy individuals to make them resistant to a specific disease. A vaccine is currently being tested in Cuba, and the results look promising. However, it has not been licensed to use in humans as there are not sufficient long-term studies to prove its efficacy.


How Is Leptospirosis Diagnosed in Humans?

It is difficult to differentiate the symptoms in the early stages of the infection. Several test help in diagnosing the disease -
- Urine Test - To detect the Leptospire DNA.
- Blood Test - To look for signs of anemia to evaluate the kidneys and liver health.
- Chest X-ray - To evaluate lung health.
- Serology - Serology tests are used frequently for diagnosing the infection. Leptospirosis can be diagnosed based on the presence of IgM antibodies by (ELISA) test when the sample is collected during the acute infection.


Is Leptospirosis Infectious?

Yes, leptospirosis is an infectious disease caused by the bacteria leptospira interrogans. It spreads by contaminated water and soil. It is generally a mild infection but can turn fatal if not treated promptly. The infection is transmitted from animals to humans.


How Do the Kidneys Get Affected With Leptospirosis

The kidneys are the main target organ of leptospira. Acute kidney injury is an early manifestation of leptospirosis. In chronic infection, leptospira colonizes the kidney tubules leading to chronic tubulointerstitial nephritis and fibrosis.


How Long Can Leptospirosis Survive in Water?

Leptospirosis can survive up to 152 days in freshwater via cellular aggregation. As a result, the levels of leptospira bacteria found in underground water, streams, and open gutters are higher than that of the bacteria found in rural water sources.


How Can You Prevent Developing Leptospirosis Infection?

- The risk of getting the leptospirosis infection can be prevented by abstaining from swimming in water that might be contaminated with animal urine and not coming in contact with infected animals directly or indirectly.
  - Wearing protective clothing and footwear by those working on contaminated water or soil can also help prevent infection.
Dr. Shinas Hussain A. P
Dr. Shinas Hussain A. P

General Practitioner


chemoprophylaxisweil's diseaseleptospirosis
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