Leptospirosis

Is Leptospirosis a global problem?


Even though Leptospirosis infections are seen worldwide, it is more common in the tropics and subtropics.  Each year an average of 1.03 million persons are infected and 58,900 deaths occur due to leptospirosis globally. Infections and deaths disproportionately occur among economically active young adult males between the ages of 20-49 years. Leptospirosis infection is categorized as a neglected tropical disease.



Figure 1 - Global Leptospirosis Incidence Per 100,000 Population Per Year
(Source: Paul R. Torgerson, José E. Hagan, Federico Costa, Juan Calcagno, Michael Kane, Martha S. Martinez-Silveira, Marga GA Goris, Claudia Stein, Albert I. Ko, and Bernadette Abela-Ridder (2015)


Is Leptospirosis a problem in Sri Lanka?

Infections are reported throughout the year and outbreaks commonly occur following rainfall due to the higher possibility of contamination of water by infected rodent urine. Seasonal variability is clearly seen in disease occurrence, as Leptospira infections peak following the two monsoons. A smaller peak in disease incidence is observed during March-May and a much higher peak is seen during October-December. These two peaks coincide with the two main paddy cultivation and harvesting seasons (especially if it rains during harvesting) of “Yala” and “Maha”. There are more leptospirosis infections following floods.

 

Who is more at risk for contracting Leptospirosis?

Leptospirosis is a disease associated with agriculture-related occupations such as paddy cultivation, Cattle farming and piggeries as well as occupations like Gem mining, sewage and canal work. People involved in recreational activities in marshy lands and water bodies could potentially be at risk of contracting this disease as well.


Figure 3 – Paddy workers and people displaced in flood at risk of Leptospirosis

What is Leptospirosis?

Leptospirosis is an infection in humans caused by a bacteria known as leptospira. These microorganisms are found in the natural environment in the kidneys of animals of reservoir hosts, such as rodents, ruminants, canines and wild animals. Water and soil are contaminated either by infected animal urine directly or by urine infected rain or flood water indirectly. The Leptospira bacteria can survive up to a few weeks in stagnant water or wet soil. Mixing of urine-contaminated soil and water into large freshwater bodies or fields creates conducive environments for disease transmission among humans.

 

How is man infected with leptospirosis?


Entry into the human body is an accidental event in the life cycle of this pathogen. Water or soil contaminated by the urine of affected animals is the most common exposure, which allows the bacteria to enter man. This is commonly seen following rainfall or flooding. The site of entry into the human body is through abraded/damaged skin or undamaged/damaged mucosa of the nasal and oral cavity or the mucus membranes of the eyes.

 

What are the symptoms of leptospirosis?

The clinical presentation of those infected varies widely. A majority of those who are exposed to this bacterium do not show any symptoms. On average symptoms appear within 5-14 days following the exposure (the range for the incubation period is 2-30 days). When symptomatic it commonly manifests as an undifferentiated febrile illness. Around 5-10% of those infected can develop severe forms of disease which may often lead to fatalities.

The diagnosis of leptospirosis is a possibility in any person presenting with acute febrile illness with chills and headache together with muscle pain/ tenderness, jaundice, conjunctival suffusion, cough, shortness of breath and gastro-intestinal symptoms. Some important causes of death in leptospirosis include renal heart or respiratory failure, widespread haemorrhage, or involvement of the central nervous system.

 

How is leptospirosis treated?

Leptospirosis is a serious but treatable disease. Early diagnosis and initiation of effective antibiotic medication at the earliest will prevent complications of disease and fatalities.

 

How can leptospirosis be Prevented?

Preventive measures are based on local epidemiological and behavioural practices of high-risk groups. As this disease is mainly related to occupations such as agriculture , farming, gem-mining, sewage and canal cleaning, raising awareness on precautions and availing the prophylactic medication under the guidance of Healthcare workers when indicated is important.

General preventive measures such as good hygiene and appropriate waste management practices especially around fields and waterbodies and farms, keeping animals away from children’s play areas such as gardens, playgrounds and sandboxes, avoiding potentially contaminated water for rinsing the mouth and washing face should be practiced. It is also advisable to avoid unnecessarily playing/wading in flood waters as it could be potentially contaminated. 

It is also important to cover all wounds/abrasions on the skin with a waterproof covering prior to contact with any potentially infected environmental sources. Whenever appropriate protective clothing including knee-high boots, gloves should be worn.

Currently, occupational groups at high-risk of leptospirosis as well as communities affected by floods and landslides are recommended for weekly antibiotic prophylaxis under the guidance of the area Medical Officer of Health (MOH) or Public Health Inspector (PHI). Intersectoral collaboration and networking between health, agriculture, and the veterinary sector are needed for the prevention of disease through vector control and environmental management.



Figure 5: Awareness campaign on high-risk areas for contracting Leptospirosis