Leptospirosis Overview and Transmission

Leptospirosis Overview

• Leptospirosis is a zoonotic infectious disease, meaning it can spread from animals to humans
• It is also known as Weil's disease, Canicola fever, hemorrhagic jaundice, mud fever, and swine herd disease.
• The bacterium Leptospira interrogans is the causative agent.

Transmission

• Leptospirosis originates from both domestic and wild animals.

• The bacteria enter the human body via ingestion, abraded skin, or mucous membranes, often through contact with contaminated water or urine from infected animals.

Etiological Agent

• Leptospira interrogans is a spirochete, a type of bacteria

• It is primarily an aquatic organism found in rivers, lakes, sea water. It's also found in sewage.

• There are 150 serotypes divided into 18 serogroups; some species are pathogenic to humans and animals.

• The organism can survive in water for weeks to months.

Incubation Period

• The incubation period varies from 6 to 15 days.

Mode of Transmission

• Transmission occurs by ingestion or skin/mucous membrane contact with animal urine or carcasses of wild and domestic mammals.
• The pathogens also enter through the mucous membrane of eyes, nose and mouth, and through breaks in the skin.
• Leptospira enters the bloodstream and damages kidneys, liver, meninges, and conjunctiva.
• Person-to-person transmission is rare.

Sources of Infection

• Contaminated food and water are sources
• Urine of infected wildlife and domestic animals, particularly rodents.

Serogroups

• Leptospira icterohaemorrhagiae (rats) frequently causes Weil's disease in miners, abattoir workers, and sewer workers. Rats in farmlands transmit L. bataviae to rice field workers.
• Leptospira canicola affecting veterinarians, breeders, and dog owners.
• Leptospira grippotyphosa affecting farmers and flax workers.

Period of Communicability

• Leptospira can be detected in the urine for 10 to 20 days after onset of symptoms.

Risk Factors

• Leptospirosis is an occupational hazard for people who engage in outdoor pursuits, particularly in tropical regions.
• Linked to swimming, wading, and rafting in contaminated lakes and rivers.
• Specific risk groups include rice and crop farmers, dairy farmers, mine and sewer workers, veterinarians and animal caretakers, military personnel, and people in large cities prone to flooding.

Clinical Manifestations - Initial Phase

• Abrupt headache (usually frontal)

• Fever

• Severe muscle aches

• Cutaneous hyperesthesia (increased sensitivity to touch)

• Chills, and rapid rising temperature

• Anorexia

• Nausea and vomiting, lasting 4 to 9 days.

Clinical Manifestations - Physical Exam

• On examination, Patients are usually bradycardic (slow heart rate), but with normal blood pressure

• Conjunctival effusion (fluid in the eye), cutaneous hemorrhages, and skin rashes (petechiae and purpura) may be apparent on days 3 or 4

• Initial symptoms may resolve, but illness can recur.

Clinical Manifestations - Second Phase

• Symptoms are more varied, with a hallmark potentially being aseptic meningitis
• Fever is often milder
• Gastrointestinal and muscle symptoms may be less intense.

Clinical Manifestations - Icteric Type

• This is the more severe form
• Characterized by persistent high-grade fever, deterioration, development of jaundice, and hepatic dysfunction (liver problems)
• Myocarditis (heart inflammation) and decreased renal function can occur.
• Pulmonary complications (like cough, shortness of breath, or bloody sputum) and hemorrhage.

Clinical Manifestations - Renal Failure

• Renal failure is commonly due to acute tubular necrosis,
• But rarely requires dialysis.
• Complete absence of urine (anuria) is a poor prognostic sign.

Clinical Manifestations - Other Manifestations

• The septic stages involve a febrile state (fever) lasting 4 to 7 days
• Patients commonly exhibit symptoms of anorexia, abdominal pain, prostration (extreme physical weakness), and possible respiratory issues.
• Fever may resolve by lysis.
• The "immune/toxic" stage may last 4 to 30 days, occurring with or without jaundice, and commonly exhibiting symptoms such as iritis (eye inflammation) and headache.

Clinical Manifestations - Severe Manifestations

• Severe cases manifest shock, coma, and/or congestive heart failure.
• Death can occur between the 9th and 16th day.

Management

• A: Penicillin G Na 1.5 million units intravenously four times a day (QID) is often given.
• B: Tetracycline 10-20 mg/kg body weight/24 hours, divided into doses given four times a day (QID),
• C: Peritoneal dialysis
• D: Administration of fluids and electrolytes, with blood transfusions as needed.

Management - Without Treatment

• Leptospirosis may cause irreversible damages in the absence of treatment.
• These include kidney damage, meningitis, liver failure, respiratory issues, and even death.

Prevention and Control

• Prophylaxis with doxycycline 200 mg/week for at-risk individuals

• Excellent sanitation in homes, workplaces and farms

• Control of rodent populations (40-60% of rodents are commonly afflicted)

• Vaccination of animals, e.g., cattle, pigs, dogs, and cats.

• Treatment of infected people and pets

• Avoid swimming/wading/exposure in flooded areas

• Wear rubber boots in flooded regions, especially at affected sites on the feet and legs

• Thoroughly wash feet with soap and water after wading in water

• Monitor individuals for symptoms and consult a physician promptly.

This quiz covers key aspects of leptospirosis, a zoonotic infectious disease caused by the bacterium Leptospira interrogans. Learn about its modes of transmission, etiological agents, and incubation period. Test your knowledge on this important health topic.