Leptospirosis: Causes, Symptoms, Diagnosis, Treatment & Prevention

Introduction

The monsoon may bring cooler weather and much-needed rain, but it also creates favourable conditions for certain diseases to spread. Walking through flooded streets, cleaning waterlogged homes, or coming into contact with contaminated water can expose people to infections that often begin with non-specific symptoms such as fever and body aches. While dengue and malaria often dominate conversations during the rainy season, leptospirosis is another important infection that should not be overlooked^1,2. 

Leptospirosis disease is estimated to cause nearly 58,900 deaths every year, with more than 75% of cases occurring in tropical regions, including South Asia³. This is why early recognition and timely leptospirosis treatment are important, as they can significantly help reduce the risk of severe complications.  

In this blog, we’ll discuss leptospirosis meaning, causes, symptoms, diagnosis, treatment, and practical ways to prevent leptospirosis, especially during the monsoons. 

What Is Leptospirosis?

Leptospirosis is a bacterial infection caused by spiral-shaped bacteria belonging to the Leptospira species. It is a zoonotic disease, meaning it spreads from animals to humans^2,4.  

People usually become infected after coming into contact with water or soil contaminated with the urine of infected animals, particularly rodents, cattle, pigs, and dogs^4,5.  

Types of Leptospirosis

Leptospirosis disease is broadly classified into two main types based on the severity of the infection, as follows: 

Mild Leptospirosis (Anicteric Leptospirosis)

This is the most common form, accounting for approximately 90% of leptospirosis cases. It usually causes a self-limiting illness, meaning most people recover completely with timely diagnosis and appropriate management with antibiotics (after being prescribed by a doctor)⁴.  

Severe Leptospirosis (Icteric Leptospirosis or Weil’s Disease) 

A small proportion (5 to 10%) of infected individuals develop severe leptospirosis, also known as Weil’s disease⁶. This form is much more serious because the infection spreads beyond the bloodstream and can damage multiple organs, including the liver, kidneys, lungs, heart, and brain. It may lead to life-threatening complications without prompt diagnosis and hospital-based leptospirosis treatment⁴. Therefore, early recognition and appropriate medical care are critical to improve the chances of recovery. 

Stages (Phases) of Leptospirosis

Leptospirosis often follows a biphasic course, meaning the illness progresses through two distinct phases. However, many people experience only the first phase, while others may develop the second phase after a brief period of recovery. Leptospirosis stages include: 

Acute (Leptospiremic or Septicemic) Phase

This is the first phase of the illness and usually begins 2 to 30 days after exposure, most commonly within 5 to 14 days⁶.During this phase^4,6: 

• The Leptospira bacteria circulate in the bloodstream and spread throughout the body. 
• The infection begins to affect different tissues and organs. 

This phase usually lasts about 4 to 7 days  

Immune (Leptospiruric) Phase

After a short period of improvement, some patients enter the second phase of the illness. During this phase^6,7,8:

• The body’s immune system starts producing antibodies (proteins to fight against the infection) against the bacteria. 
• The bacteria are usually cleared from the bloodstream but may continue to survive in the kidneys and be shed in the urine. 
• This phase may last several days to weeks, depending on the severity of the infection. 

Symptoms of Leptospirosis

Early symptoms of leptospirosis often resemble those of the flu. This can make the infection difficult to recognise. Common leptospirosis symptoms include^2,4,5:

• Sudden high fever 
• Chills 
• Headache 
• Muscle pain (especially calves and lower back) 
• Fatigue or extreme weakness 
• Red eyes (conjunctival suffusion) 
• Nausea and vomiting 
• Diarrhoea 
• Loss of appetite 
• Abdominal pain 

In severe cases, additional symptoms may develop as the infection affects multiple organs. Severe leptospirosis symptoms include^4,5,7:

• Yellowing of the skin and eyes (jaundice) 
• Chest pain 
• Reduction in urine output  
• Severe dehydration 
• Difficulty breathing 
• Coughing up blood 
• Altered mental status (changes in thinking or behaviour) 
• Low blood pressure (shock) 

Causes of Leptospirosis

The bacteria that cause leptospirosis are found in the urine of infected animals and can survive in fresh water and moist soil for weeks to months. People become infected when the bacteria enter their body through cuts or broken skin, or through the eyes, nose, or mouth. Common leptospirosis causes include^2,9: 

• Contact with water contaminated with infected animal urine, such as floodwater or stagnant water. 
• Contact with contaminated soil or mud where the bacteria can survive. 
• Direct contact with the urine, blood, or tissues of infected animals. 
• Eating food or drinking water contaminated with infected animal urine (less common). 
• Rare person-to-person transmission, such as through breastfeeding or sexual contact (although this is uncommon). 

Risk Factors of Leptospirosis

Certain activities, occupations, and environmental conditions can increase the likelihood of developing leptospirosis. Factors that increase the risk include^2,10: 

• Exposure to heavy rainfall, flooding, or waterlogged areas, especially during the monsoon season. 
• Working in occupations such as farming, livestock handling, sewage or sanitation work, and slaughterhouses. 
• Participating in freshwater recreational activities, including swimming, rafting, kayaking, fishing, or camping in potentially contaminated water. 
• Living in areas with poor sanitation, inadequate waste disposal, or high rodent population. 
• Having cuts, abrasions, or broken skin that then come into contact with contaminated water or soil. 
• Spending time outdoors or working barefoot in muddy or flooded environments. 

Complications of Leptospirosis

Most people with leptospirosis recover completely with timely diagnosis and appropriate treatment by a doctor. However, if the infection progresses or treatment is delayed, it can lead to the following complications and become life-threatening^4,6:

• Kidney damage or kidney failure 
• Jaundice or liver damage 
• Lung complications, such as pulmonary haemorrhage or acute respiratory distress syndrome (ARDS) 
• Meningitis, which is inflammation of the membranes surrounding the brain and spinal cord 
• Heart problems, including inflammation of the heart muscle (myocarditis)  
• Multiple organ failure, where two or more organs stop functioning properly 

Diagnosis of Leptospirosis

Your doctor will consider your leptospirosis signs and symptoms as well as recent exposure to contaminated water or animals and recommend one or more tests to confirm the diagnosis. Common tests for leptospirosis include⁴ 

• Medical history and physical examination to assess leptospirosis symptoms and identify possible exposure to contaminated water, soil, or animals. 
• Blood Tests to look for signs of infection and assess kidney and liver function. 
• Complete blood count (CBC) to check for changes in blood cells associated with infection. 
• Urine tests may be performed to evaluate kidney involvement. 
• Chest X-ray, if lung complications are suspected. 
• Lumbar puncture (spinal tap) may be recommended if meningitis is suspected. 
• Specialised laboratory tests, such as polymerase chain reaction (PCR), microscopic agglutination test (MAT), or ELISA antibody tests, may be used to confirm leptospirosis, depending on the stage of illness and the availability of testing. 

Treatment for Leptospirosis

The management of leptospirosis depends on the severity of the infection. Common leptospirosis treatment/management options may include^3,4:

• Antibiotics to address the bacterial infection. Your doctor may prescribe oral antibiotics for mild illness or intravenous (IV) antibiotics for more severe infections. Early treatment is generally associated with better outcomes. 
• Hospitalisation for people with severe leptospirosis, especially if multiple organs are affected. 
• Supportive care, such as dialysis for kidney failure or mechanical ventilation for severe lung involvement, depending on the complications. 

Prevention of Leptospirosis

Taking a few simple precautions can significantly reduce your risk of infection, especially during the monsoon season or after flooding. Some helpful tips include^2,9: 

• Avoid contact with potentially contaminated water, especially floodwater, stagnant water, rivers, or streams after heavy rainfall or flooding. 
• Avoid direct contact with urine or tissues of animals that may carry the Leptospira bacteria, particularly rodents, cattle, pigs, and dogs. 
• Cover cuts, scrapes, and open wounds with waterproof dressings before going outdoors or into potentially contaminated areas. 
• Wear protective clothing, such as waterproof boots, gloves, and long-sleeved clothing, when working or walking in flooded or muddy areas. 
• Drink only safe, clean water. If the safety of drinking water is uncertain, boil or appropriately disinfect it before use. 
• Practice good hand hygiene by washing your hands thoroughly with soap and water after handling animals, working outdoors, or coming into contact with potentially contaminated water or soil. 
• Clean and disinfect equipment and surfaces that may have been contaminated by animal urine, particularly on farms, in veterinary clinics, and at workplaces. 
• Take extra precautions during water-based recreational activities, such as swimming, boating, fishing, or kayaking. Check whether leptospirosis has been reported in the area and avoid entering contaminated water. 
• Ask your doctor about preventive antibiotics if you are at high risk of short-term exposure (for example, during disaster relief work or travel to high-risk areas).  

When to See a Doctor?

You should see a doctor if you experience the following leptospirosis symptoms, especially after exposure^2,5: 

• A high fever that develops after contact with floodwater, contaminated water, or animals. 
• Severe headache or muscle pain, particularly in the calves or lower back. 
• Red eyes along with fever or other flu-like symptoms. 
• Persistent nausea, vomiting, diarrhoea, or abdominal pain. 
• Leptospirosis Symptoms that persist, worsen, or new symptoms develop after a few days.  

You should seek emergency medical care if you have the following^4,5,7:

• Yellowing of the skin or eyes (jaundice) 
• Difficulty breathing or coughing up blood 
• Confusion, excessive drowsiness, or seizures 
• Severe dehydration or signs of shock, such as dizziness, fainting, or a rapid heartbeat 

Also Read: Influenza B: What is It, Causes, Symptoms, Treatment & Prevention

Conclusion

Leptospirosis is a potentially serious but manageable bacterial infection that becomes more common during the monsoon season, especially after heavy rainfall and flooding.  

Leptospirosis signs and symptoms often resemble those of other illnesses. That is why recognising the signs and seeking medical care promptly are essential for avoiding severe complications. In addition to this, taking simple precautions, such as avoiding contact with contaminated water, practicing good hygiene, protecting open wounds, and using appropriate protective gear when needed, can significantly reduce your risk of infection.  

Frequently Asked Questions (FAQs)

References

1. Infectious Diseases. In: From Monsoons to Microbes: Understanding the Ocean’s Role in Human Health. National Academies Press (US); 1999. Accessed July 13, 2026. Available from: https://www.ncbi.nlm.nih.gov/books/NBK230695/ 

2.  About Leptospirosis. Leptospirosis. February 10, 2026. Accessed July 13, 2026. Available from: https://www.cdc.gov/leptospirosis/about/index.html 

3. Gupta N, Wilson W, Ravindra P. Leptospirosis in India: a systematic review and meta-analysis of clinical profile, treatment and outcomes. Infez Med. 31(3):290-305. doi:10.53854/liim-3103-4  Available from: https://pubmed.ncbi.nlm.nih.gov/37701390/

4. Wang S, Dunn N. Leptospirosis. StatPearls; 2026. Accessed July 13, 2026. Available from: http://www.ncbi.nlm.nih.gov/books/NBK441858/ 

5. Haake DA, Levett PN. Leptospirosis in humans. Curr Top Microbiol Immunol. 2015;387:65-97. doi:10.1007/978-3-662-45059-8_5 Available from: https://pubmed.ncbi.nlm.nih.gov/25388133/

6. Day NPJ. Leptospirosis: Epidemiology, microbiology, clinical manifestations, and diagnosis. UpToDate. Accessed July 13, 2026. Available from: https://www.uptodate.com/contents/leptospirosis-epidemiology-microbiology-clinical-manifestations-and-diagnosis 

7. Rajapakse S. Leptospirosis: clinical aspects. Clin Med. 2022;22(1):14-17. doi:10.7861/clinmed.2021-0784 Available from: https://pubmed.ncbi.nlm.nih.gov/35078790/ 

8. Johnson RC. Leptospira. Medical Microbiology. 1996. Accessed July 15, 2026. Available from: http://www.ncbi.nlm.nih.gov/books/NBK8451/ 

9. Leptospirosis. CDC. Accessed July 13, 2026. Available from: https://www.cdc.gov/leptospirosis/pdf/fs-leptospirosis-clinicians-eng-508.pdf 

10. Kamath R, Swain S, Pattanshetty S, Nair NS. Studying Risk Factors Associated with Human Leptospirosis. J Glob Infect Dis. 2014;6(1):3-9. doi:10.4103/0974-777X.127941  Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC3982353/

11. Muñoz-Zanzi C, Dreyfus A, Limothai U, et al. Leptospirosis—Improving Healthcare Outcomes for a Neglected Tropical Disease. Open Forum Infect Dis. 2025;12(2):ofaf035. doi:10.1093/ofid/ofaf035  Available from: https://pubmed.ncbi.nlm.nih.gov/39963696/

12. About Hantavirus. CDC. May 9, 2026. Accessed July 13, 2026. Available from: https://www.cdc.gov/hantavirus/about/index.html 

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