Leptospirosis
Leptospirosis
Disease History, Characteristics, and Transmission
Introduction
Leptospirosis is a disease that is caused by bacteria from the genus Leptospira. It is considered an emerging disease and is found worldwide. Leptospirosis often goes undiagnosed, since the symptoms of this disease are similar to those of a number of other diseases, including influenza. For this reason, the prevalence of the disease is unknown.
Infection occurs when humans come in contact with freshwater, soil, or vegetation that is contaminated with the urine of an infected animal. The bacteria pass from the urine into the human body via mucosal linings, such as the linings of the eyes, nose, or mouth; through broken skin; or orally, when food or water is ingested. Illness develops, usually within 10 days, and is characterized by fever, aches, vomiting, diarrhea, and jaundice. Treatment with antibiotics leads to successful recovery, although, in some cases, a second phase can occur with more severe symptoms. During this second phase, known as Weil's disease, patients suffer more severe symptoms that may include kidney failure, liver failure, or meningitis. Weil's disease occurs in around 10% of cases.
Leptospirosis occurs mainly in the tropics, although it is a worldwide disease found both in rural and urban regions of developed and developing countries. There is no vaccine for this disease, and prevention efforts focus on avoiding contact with anything that may have been contaminated with the bacteria. Risk is highest for people who work or spend time outdoors, in freshwater, or with animals.
Disease History, Characteristics, and Transmission
Leptospirosis was first recognized in 1886 by the German scientist Adolf Weil (1848–1916). The cause of the disease was not identified until about 40 years later, during the 1920s, when both Japanese and German scientists discovered that bacteria were responsible. Leptospirosis is caused by leptospires, which are diseasecausing bacteria in the genus Leptospira. The primary agent causing leptospirosis is Leptospira interrogans.
Scope and Distribution
Leptospirosis most commonly occurs in the tropics, although it is present in temperate regions. Leptospires thrive best in warm temperatures and moist conditions. They are transmitted by wild and domestic animals including rodents, dogs, cattle, horses, and pigs. Therefore, people who spend a great deal of time outdoors, or with animals, are more likely to contract leptospirosis. This includes veterinarians, military personnel, farmers, and sewer workers. In addition, people taking part in outdoor recreational activities, such as camping or water sports, are also at higher risk, since they are more likely to come in contact with urine-contaminated water.
Leptospirosis occurs worldwide but tends to be underreported in most countries, since it is often overlooked during diagnosis. This is due to the similarities between symptoms of leptospirosis and those of other tropical diseases. As a result, the global prevalence of this disease is unknown. However, increases in the occurrence of this disease were observed in Germany between 1962 and 2003. These increases are thought to be a result of more frequent travel, increases in freshwater recreational activities, and higher rat populations in cities.
WORDS TO KNOW
JAUNDICE: Jaundice is a condition in which a person's skin and the whites of the eyes are discolored a shade of yellow due to an increased level of bile pigments in the blood resulting from liver disease. Jaundice is sometimes called icterus, from a Greek word for the condition.
LEPTOSPIRE: Also called a leptospira, a leptospire is any bacterial species of the genus Leptospira. Infection with leptospires causes leptospirosis.
WEIL'S DISEASE: Weil's disease, named after German doctor Adolf Weil (1848–1916), is a severe form of leptospirosis or seven-day fever, a disease caused by infection with the corkscrew-shaped bacillus Leptospira interrogans.
Treatment and Prevention
Patients with leptospirosis can recover without treatment, although recovery may take several months, and lack of treatment may lead to complications. Treatment is usually administered as soon as possible and involves a course of antibiotics. A range of antibiotics can be used, including doxycycline, penicillin, ampicillin, and amoxicillin. Recovery can take from three days to several weeks. However, in most cases recovery is complete. More severe complications arise when the patient does not receive antibiotics or if the patient develops the second phase of the illness.
There is no vaccine for leptospirosis, so prevention is best achieved by avoiding contaminated water, soil, or vegetation, particularly in areas with infected or potentially infected animals. Clothing, such as boots or waders, will provide protection during recreational activities, and gloves will provide protection when handling animals. Taking antibiotics while traveling through infected areas may also help prevent severe infections from developing, if people become contaminated.
Impacts and Issues
Leptospirosis is becoming more common and has been recognized as an emerging infectious disease by the United States Directors of Health Promotion and Education. Since this disease occurs in both developed and developing countries and in both urban and rural areas, it has become globally important.
Despite the high likelihood of recovery following treatment, there is still a significant mortality rate for leptospirosis. This is largely due to delayed diagnosis, since the disease is hard to recognize. In addition, due to the lack of a vaccine, avoidance of the bacteria remains the best prevention method. This avoidance depends on the maintenance of rigorous sanitation methods, which is not always possible in developing countries or in countries experiencing war or other social upheavals. Therefore, contamination still occurs frequently.
The chance of exposure to contaminated sources is exacerbated during floods, outdoor activity, or in animal-populated regions. In 1995, widespread flooding in Nicaragua spread the bacteria, and more than 2,000 people contracted leptospirosis. At least 13 of those with the disease died. Two years later, nine Americans became infected while white-water rafting in Costa Rica. In addition, growing rat populations, especially in inner cities, increase public exposure to leptospirosis when water systems and sewers become contaminated. This has been suggested as one cause of the higher levels of leptospirosis seen in Germany during 1962–2003.
IN CONTEXT: PERSONAL RESPONSIBILITY AND PROTECTION
As of April 2007, the CDC states that “No vaccine is available to prevent leptospirosis in the United States. Travelers who might be at an increased risk for the disease should be advised to consider preventive measures such as wearing protective clothing and minimizing contact with potentially contaminated water. Such travelers also might benefit from chemoprophylaxis (a course of treatment prior to exposure that reduces risk or impact of disease). Until further data become available, CDC recommends that travelers who might be at increased risk for leptospirosis be advised to consider chemoprophylaxis begun 1 to 2 days before exposure and continuing through the period of exposure.”
Individuals should always seek advice from their personal physician with regard to specific medications and doses.
SOURCE: Centers for Disease Control and Prevention. Health Information for International Travel 2005–2006. Atlanta: US Department of Health and Human Services, Public Health Service, 2005.
See AlsoBacterial Disease; Emerging Infectious Diseases; Meningitis, Bacterial; Personal Protective Equipment; Travel and Infectious Disease; War and Infectious Disease; Water-borne Disease.
BIBLIOGRAPHY
Books
Mandell, G. L., J. E. Bennett, and R. Dolin. Principles and Practice of Infectious Diseases. 6th ed. Philadelphia: Elsevier, 2004.
World Health Organization. Human Leptospirosis: Guidance for Diagnosis, Surveillance and Control. Malta: World Health Organization, 2003.
Periodicals
Jansen, A., et al. “Leptospirosis in Germany, 1962–2003.” Emerging Infectious Diseases 11 (2005): 1048–1054.
Web Sites
Directors of Health Promotion and Education. “Leptospirosis.” <http://www.dhpe.org/infect/Lepto.html> (accessed March 1, 2007).
Centers for Disease Control and Prevention. “Leptospirosis.” October 12, 2005. <http://www.cdc.gov/ncidod/dbmd/diseaseinfo/leptospirosis_g.htm> (accessed March 1, 2007).