August 1, 2024 Author : Saraiva da Cunha Leptospirosis is a zoonosis , that is, an infectious disease that is transmitted from animals to humans. It exists throughout the world but is more prevalent in tropical areas. In Europe it is more common in the Mediterranean area and in countries in the European Eastern region. It is due to bacteria of the genus Leptospira, which are eliminated in the urine of infected animals . Human infection occurs through direct or indirect exposure to this urine. The animal species that are at the origin of the infection are mammals , most frequently: Rats , which become infected in the mother's womb or at birth, are the main reservoir of Leptospira, and are asymptomatic carriers that spread the bacteria throughout their lives. Domestic species such as cattle, pigs, sheep, goats, horses and dogs : They may just be carriers, or they may manifest the disease and it may become fatal; In livestock species, leptospirosis is an important cause of spontaneous abortion, with significant economic losses for farmers; In dogs, leptospirosis has an associated mortality of around 10%. More than 160 animal species , domestic and non-domestic, that may be hosts for Leptospira have been identified. In animals, Leptospira goes to kidneys and is eliminated through urine, contaminating the environment. Leptospira shed in the urine of infected animals can survive up to 16 days in fresh water and almost 24 days in soil, particularly in hot and humid conditions. Infection and presentation of the disease Human infection can originate from: Contact with water or soil contaminated by urine from infected animals; Ingestion of food or water contaminated by urine from infected animals; Direct contact with urine or reproductive fluids from infected animals Leptospira enters the human body through mucous membranes (e.g. ocular, oral) or non-integral skin (wounds or wounds) and is also possible via the respiratory route . The spread of leptospirosis between people is very rare , but it has been identified through sexual intercourse and breastfeeding. Transmission through the placenta is also possible in pregnant women, but the complications for fetuses and the frequency with which they occur are not known. Once in the body, Leptospira tends to settle in the liver and kidneys , although it can also spread to other places. The following are known risk groups for leptospirosis: Occupational/work context : farmers, notably those cultivating rice crops, slaughterhouse workers, workers in basic sanitation structures (e.g. sewage, wastewater treatment), pest control workers, gardeners, veterinarians, among others; Inhabitants of areas with high population density and precarious basic sanitation conditions ; Practitioners of water activities in freshwater courses , lakes and reservoirs and others; Travelers to areas where the disease is more prevalent. Outbreaks of leptospirosis are more common in tropical areas, where the disease is endemic, following heavy rains and floods, particularly when basic sanitation conditions are poor. Other outbreaks have been known around the world following freshwater sporting competitions. In humans, leptospirosis can have two forms of clinical presentation , one that is milder and self-limited and another that can be severe and associated with mortality. Anicteric leptospirosis This is the most common form, representing around 90% of cases . It is less serious. It begins suddenly, on average 7-10 days (limits 2-30 days) after infection, with symptoms similar to flu , the main ones occurring in more than 75% of cases: Fever; Goosebumps; Chills; Muscle pain; Headaches. Other symptoms, more rarer, may be nausea, vomiting, cough, joint pain, bone pain, sore throat and abdominal pain. Symptoms may persist for a few days, usually 2-9, and are self-limiting. A new episode may occur again later, sometimes with aseptic meningitis and eye changes (uveitis). Although in most cases recovery from anicteric leptospirosis is complete, some people still continue having headache problems, with recurrent and chronic episodes and sometimes also with vision problems and other neurological problems. Icteric leptospirosis This form of presentation is also called Weil's disease and involves multiple body systems . It is much more serious. The main symptoms include fever, kidney failure, jaundice and difficulty breathing. There may be muscular and central nervous system involvement. Symptoms may continue for several weeks. Icteric leptospirosis has a high mortality rate. Diagnosis and treatment In addition to the personal history, especially the most recent context, and the results of the physical examination, results of other diagnostic tests may be necessary for diagnosis, depending on the symptoms present. Sometimes it may even be necessary to perform a lumbar puncture. The definitive diagnosis of leptospirosis implies a positive result in a specific test carried out on a urine or blood sample by polymerase chain reaction (PCR) or by microbiological culture; serological diagnostic techniques are also available. Treatment is with medicines, including antibiotics to eliminate bacteria and other medications to control symptoms that are present. Many people with the most severe form of leptospirosis require hospitalization in intensive care and, often, hemodialysis sessions. Prevent leptospirosis Reducing the likelihood of having leptospirosis is based on care to avoid contact with animal urine and water, soil or materials that may be contaminated . In places where the presence of rats is more likely (for example, warehouses, garages, gardens and backyards, among others), provide adequate control. Store food and drinks where there is no contact with animals. Avoid contact with untreated, stagnant or visibly dirty water reservoirs or water close to livestock farms, particularly in rainy seasons. Take special care when you have risky professional occupations. Some data The World Health Organization estimates that around 873 thousand cases of leptospirosis occur annually across the world, which are responsible for more than 40 thousand deaths. In 2022, 765 cases of leptospirosis were diagnosed in the 28 countries of the European Union / European Economic Area that reported information, of which 65 in Portugal. Between 2010 and 2021, 713 cases of leptospirosis were reported in Portugal , 328 (46%) from the Azores. In recent years, our country has always been among the five countries with the highest number of cases, only being systematically surpassed by France, Germany and the Netherlands. Since 2021 there have been no cases of death in Portugal, but in the previous 10 years people almost always died from leptospirosis in the country. Souces Day NP. Leptospirosis: Epidemiology, microbiology, clinical manifestations, and diagnosis. www.uptodate.com European Center for Disease Prevention and Control. Surveillance Atlas of Infectious Diseases . European Center for Disease Prevention and Control. Leptospirosis . Julien B, et al. Epidemiology of reported cases of leptospirosis in the EU/EEA, 2010 to 2021. Euro Surveill 2024;29:2300266. Wang S, Stobart Gallagher MA, Dunn N. Leptospirosis 2022. Treasure Island: StatPearls Publishing; 2024. Meet the Infectious Diseases clinical team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
