Leptospirosis

Leptospirosis is a zoonotic disease and endemic in many countries, especially in tropical and subtropical areas with high rainfall. The disease is found mainly where humans come into contact with the urine of infected animals or a urine-polluted environment. Outbreaks of leptospirosis have been reported following natural disasters such as flooding or cyclones. The global burden of leptospirosis is expected to rise with demographic shifts that favour increases in the number of urban slum environments and due to climate change, increasing the number of flood disasters.

The following are standard case definitions to allow national health authorities to interpret data in an international context. However, during an outbreak case definitions may be adapted to the local context and the Red Cross Red Crescent should use those agreed/established by national health authorities. NB: Consider that during community surveillance, volunteers should use broad (simplified) case definitions to recognize most or all possible cases and encourage them to seek care. Other actors such as healthcare workers or investigators studying the cause of a disease, on the other hand, can use more specific case definitions that may require laboratory confirmation.

Recommended types of surveillance include immediate case-based surveillance to establish human health and veterinary response and control actions; in endemic areas, routine reporting of aggregated data of confirmed cases is also important. It is estimated that leptospirosis is under-reported in many countries due to the difficulties of clinical diagnosis and unavailability of diagnostic laboratory services.

Clinical description: The usual presentation is an acute febrile illness with headache, muscle pain (particularly calf muscle) and fatigue associated with any of the following symptoms/signs: red eyes, no or less urination,  jaundice, cough, coughing blood and breathlessness, haemorrhages (from the intestines; lung bleeding is notorious in some areas), meningeal irritation, cardiac arrhythmia or failure, skin rash. Other common symptoms include nausea, vomiting, abdominal pain, diarrhoea and joint pain. The clinical diagnosis is difficult where diseases with symptoms similar to those of leptospirosis occur frequently.

Case classification (humans)

Suspected: A case that is compatible with the clinical description and a presumptive laboratory diagnosis.

Confirmed: A suspect case with a confirmatory laboratory diagnosis.

WHO case definition source of information: https://www.who.int

• The disease occurs seasonally in countries with humid subtropical and tropical climates. In urban settings, epidemics are associated with high rainfall, while in rural areas epidemics are associated with harvest seasons.
• During a hurricane, flooding or heavy rain, animal urine in the soil or on other surfaces can run into floodwater, contaminating it. Streams and other natural water sources can also be contaminated. Cases of leptospirosis can increase during these disasters when people may have to wade through contaminated water or use it for drinking or bathing.
• Individuals living in urban slum environments characterized by inadequate sanitation and poor housing are at high risk of rat exposure infected by leptospira.
• Eating food that has been exposed to contaminated water or potentially urinated on by rodents.
• Drinking from potentially contaminated water sources, including floodwater, streams, rivers or unsafe tap water.

Occupational hazard for many people who work outdoors or with animals, such as:

• Farm and agricultural workers.
• Pet shop workers.
• Miners.
• Veterinarians.
• Sewer workers.
• Abattoir workers.
• Meat handlers.
• Military personnel.

Recreational hazard for those who participate in outdoor activities, such as:

• People engaging in recreational water sports (e.g, swimming, wading, kayaking).
• Campers.

Attack rates range from 5 per cent ( e.g. AR: 5.95 per cent Orissa, India in 2002) to up to 50 per cent (e.g., AR: 41.3 per cent Thailand 1999)  in past outbreaks.

• Mortality increases with age, particularly in patients older than 60 years of age.
• Pregnant women. people with chronic diseases such as renal disease, cancer, chronic lung or liver disease and diabetes.
• People with weakened immune systems such as those receiving chemotherapy, steroids, transplant recipients or HIV carriers.

Leptospira interrogans (bacterium).

Zoonotic disease: a variety of animals can spread leptospirosis, including rodents, dogs, cattle, buffaloes, horses, sheep, goat, pigs, dogs and wildlife.

Humans.

• Contact transmission: Through cuts and abrasions of the skin, or through the mucous membranes of the eyes, nose and mouth with water contaminated with the urine of infected animals. As animals are constantly in our environment, there is a particular danger of getting leptospirosis when flooding occurs, such as following a typhoon or very heavy seasonal rains, because of exposure to contaminated water when wading in floodwaters. Transmission can also occur by directly touching the urine from an infected animal .
• Vehicle-borne transmission: Leptospirosis can occasionally also be transmitted through the drinking of water or ingestion of food contaminated with urine of infected animals.
• Sexual transmission: Human-to-human transmission occurs only very rarely during sexual intercourse.
• Congenital transmission: Trans-placentally from the mother to the foetus and via breast milk to a child.

Typically, between 5 to 14 days (range of 2—30 days).

First seven to ten days of illness.

In general, the disease presents in four broad clinical categories:

• 90 per cent of the infected people present a mild, influenza-like illness: after around one week fever stops but then comes back for a second phase. Additional symptoms can be gastrointestinal pain, rash, redness of the conjunctiva. This category is often self-limited.
• A more severe illness affecting multiple organs: characterized by jaundice, renal failure, haemorrhage and infection of the heart muscle with arrhythmias (historically called Weil’s syndrome).
• Meningitis/meningoencephalitis.
• Pulmonary haemorrhage with respiratory failure.

Influenza, dengue fever, hantavirus pulmonary syndrome, yellow fever and other haemorrhagic fevers, malaria and typhoid fever.

The disease is usually diagnosed in the laboratory by detecting antibodies, (serodiagnosis), by culturing the bacteria from blood, urine or tissues, or by demonstrating the presence of leptospira in tissues using antibodies labelled with fluorescent markers.

Please refer to the appropriate local or international guidelines for clinical management. All clinical management including the administration of a treatment or vaccine should be conducted by a health professional.

• Leptospirosis can be treated with antibiotics that should be given as early in the course of illness as possible. No isolation is needed because there is almost no human-to-human transmission.
• Commercial human vaccines have been produced in certain countries providing a certain degree of protection. However, these vaccines have a high side-effect profile, do not induce long-term protection against infection and do not provide cross-protective immunity against the different types of leptospira. Until further studies are done, the human vaccine is not recommended by WHO.

The level and duration of immunity is unclear and can vary.