What causes leptospirosis?
Leptospira species are spirochetes which cause leptospirosis. They are found in soil, water, animals and human bodies. These organisms have been known to infect humans since ancient times. However, it was not until the 20th century that scientists discovered their ability to cause disease in humans.
The exact mechanism of how these bacteria cause disease remains unknown. It is believed that some individuals may have a natural immunity against the bacteria and are able to fight off the infection without any medical treatment. A number of factors increase the risk of developing disease after exposure to the bacteria. These factors include age, pregnancy, health status and the type of contact with soil or water.
Leptospirosis is a zoonotic disease which means it affects animals as well as humans. It is thought that most animals can carry the bacteria without any signs or symptoms of disease. Common animal carriers of the disease include livestock, rats, raccoons, pigs, dogs, and weasels. It is believed that most cases of leptospirosis occur from contact with an infected animal’s urine.
What are the signs and symptoms of leptospirosis?
Leptospirosis can progress through four distinct stages:
develops into a severe and sometimes life-threatening condition
can disappear completely or you may have long-term health problems
the final stage is called the chronic phase
In most cases the disease progresses through these stages within three weeks.
In the acute stage symptoms vary widely between individuals and may include:
high fever, chills and flu-like symptoms
These symptoms can last up to a week and affect between 20% and 50% of patients. More severe symptoms occur in 5% of patients and may include swelling of the brain, respiratory failure and shock. These symptoms can be fatal within 24 hours to a week.
In the second stage of leptospirosis the symptoms begin to disappear. Between 80% and 100% of patients experience complete recovery at this stage. If the disease is not fatal it enters a third stage of latency. In some patients the disease progresses to the final or chronic phase.
The final chronic phase of the disease can affect the central nervous system, liver, kidneys, heart or skin. These symptoms may develop months or even years after the original infection.
Some patients who experience the chronic phase of leptospirosis never have symptoms but remain carriers of the disease. They may experience complications in later life which are caused by the damage caused by the disease. Complications can also occur in patients who experience the acute stage.
What is the treatment for leptospirosis?
Antibiotics are usually given to treat leptospirosis. These may include doxycycline or penicillin. Supportive care may also be required. What this involves depends on the severity of your symptoms and the organs which are affected.
How is leptospirosis diagnosed?
If your doctor suspects you have leptospirosis they will examine you and ask you about your medical history and the activities you have recently undertaken. A blood test can confirm the presence and severity of infection. Urine tests may also be carried out to determine if you have an active infection.
What is the Public Health response to leptospirosis?
The Department of Health in conjunction with the National Institute for Communicable Diseases monitor the spread of diseases in South Africa. The Department also works with other government and non-government organisations to provide medication, vaccines and medical equipment to areas where these are needed most.
The Department has a campaign to advise the public on how to prevent infection. This consists of avoiding direct contact with rats or contaminated rat urine.
If you do become infected these measures should reduce the transmission of the disease and severity of your symptoms. If you are visiting an area with a higher risk of infection you can take extra precautions. These include:
keeping your arms and legs covered if you come into direct contact with rats or contaminated rat urine
washing your clothes and keeping your lawn clean to avoid tracking the rats’ urine into your home
washing your hands before eating or handling food
using gloves to prevent direct contact with rat urine or rats
You can also inform your family about the risk of infection and advise them to seek medical attention immediately should they experience the symptoms of leptospirosis.
How can I find out more?
Contact your local doctor or visit the Department of Health’s website.
Sources & references used in this article:
- Leptospira (RC Johnson, S Faine – Bergey’s manual of systematic bacteriology, 1984 – cidta.usal.es)
- Global morbidity and mortality of leptospirosis: a systematic review (F Costa, JE Hagan, J Calcagno, M Kane… – Plos negl trop …, 2015 – journals.plos.org)
- Orientia, rickettsia, and leptospira pathogens as causes of CNS infections in Laos: a prospective study (S Dittrich, S Rattanavong, SJ Lee, P Panyanivong… – The Lancet Global …, 2015 – Elsevier)
- Murine typhus and leptospirosis as causes of acute undifferentiated fever, Indonesia (MH Gasem, JFP Wagenaar, MGA Goris… – Emerging infectious …, 2009 – ncbi.nlm.nih.gov)
- Leptospirosis in humans (DA Haake, PN Levett – Leptospira and leptospirosis, 2015 – Springer)
- Leptospirosis in the Asia Pacific region (AFB Victoriano, LD Smythe… – BMC infectious …, 2009 – bmcinfectdis.biomedcentral.com)
- Reproductive losses caused by bovine viral diarrhea virus and leptospirosis (DL Grooms – Theriogenology, 2006 – Elsevier)
- Leptospirosis: an emerging disease in travellers (C Lau, L Smythe, P Weinstein – Travel medicine and infectious disease, 2010 – Elsevier)
- Ocular manifestations of leptospirosis (SR Rathinam – Journal of postgraduate medicine, 2005 – jpgmonline.com)