Leptospirosis

Overview

Leptospirosis is a zoonotic bacterial disease of variable clinical manifestations. Leptospira is a spiral organism and a member of the order Spirochaetales, found mainly in infected wild and domestic animals (e.g. rodents or dogs, horses, cattle, and pigs).

Pathogen

Spirochaete bacterium of Leptospira genus.

Transmission

Transmission occurs through direct contact with:

• Urine

• Fluids or tissues of infected animals

• Urine-contaminated environment (e.g. through swimming, wading in flood-waters, accidental immersion, occupation immersion, or contaminated moist soil or vegetation)

• Eating food or drinking water contaminated by urine

The bacteria enters the body through cuts or abrasions on the skin, or through the mucous membranes of the mouth, nose, and eyes.

Incubation period: Typically 5 to 14 days; range is 2 to 30 days.

Infectious period: Unknown, as human-to-human transmission is rare.

Clinical features

The clinical manifestations of leptospirosis are variable. In the majority of cases, infection is asymptomatic or presents as a mild flu-like illness. In some, the disease can be severe and even fatal.

The clinical course usually has two phases. In the initial phase, patients experience an acute onset of high fever, myalgias, and headache (retro-orbital and frontal). About a third of cases have conjunctival suffusion (presents as conjunctival redness), which is a frequently overlooked sign.

While some patients recover, others progress to a second, more severe phase which includes prolonged fever and systematic complications such as jaundice and renal failure (Weil’s disease), pulmonary haemorrhage with respiratory failure, and aseptic meningitis or meningoencephalitis.

Risk factors

Risk factors include:

• Living in or travelling to areas where infection is endemic in animal reservoirs

• People who work outdoors or with animals

• Campers or those who participate in outdoor activities (e.g. swimming or rafting in contaminated waters)

Diagnosis

Serological tests are most frequently used in the laboratory diagnosis of leptospirosis. PCR testing on blood or urine samples may also be helpful within the first week of illness.

Treatment and management

In mild cases, oral antibiotics can be given. Severe cases will require hospitalisation for intravenous antibiotics and management of complications.

Precautions, prevention, and control

Standard precautions apply in healthcare settings.

Epidemiological investigations should be performed to identify the source of infection and to implement control measures (e.g. rodent control).

The most important control measures for preventing human leptospirosis include:

• Avoiding potential sources of infection such as stagnant water and animal farm water runoff

• Implementing rodent control

• Protecting consumables from animal contamination

• Covering cuts or scratches with waterproof bandages or other coverings that seal out water

• Not getting into, bathing in, or swallowing floodwater or any fresh water source that may have animal urine in it

• Wearing waterproof protective clothing and shoes near water or soil that may be contaminated with animal urine

• Keeping rodents away by putting food, water, and trash in closed containers, and trapping rodents

Vaccines against leptospirosis are available for animals but human vaccines are not commercially available. However, if a definite exposure to leptospirosis has occurred, antibiotics such as doxycycline can be considered for post-exposure prevention and can be prescribed after medical consultation or with the advice of an infectious disease specialist.

Notification

Who should notify:

• Laboratories

When to notify:

• On laboratory confirmation

How to notify:

• Please refer to the Infectious Disease Notification for more information. 

Notification timeline:

• As soon as possible. No later than 24 hours from the time of diagnosis.

Resources

Please refer to the Weekly Infectious Diseases Bulletin for the number of leptospirosis cases in Singapore.