La leptospirosis It has become one of those diseases that are almost always there, but that are rarely discussed until outbreaks occur after a period of heavy rains, river flooding, or inundationsRising temperatures and increased stagnant water create the perfect conditions for this bacteria to spread more easily between animals and people.
It is a zoonoses with a worldwide distributionwith health and economic impact. It affects livestock, other domestic and wild species, and also humans. Its silent nature, nonspecific symptoms, and certain lack of awareness among the population and some healthcare staff This means that many cases go undetected or are confused with other pathologies, making them difficult to control.
What is leptospirosis and how is it transmitted?
Leptospirosis is a infectious disease caused by bacteria of the genus Leptospira, Especially Leptospira questioningcapable of affecting almost all mammals. It is a classic zoonosis: It is transmitted from animals to people and direct human-to-human transmission rarely occurs.
The bacteria are primarily eliminated through the urine of infected animalswhich can contaminate soil, puddles, waterways, mud, damp pastures, and surfaces in stables or homes. Rodents, such as the rats, fundamental reservoirsalthough dogs, cattle, pigs, sheep, goats and other domestic or production animals may also be involved.
Human contagion occurs when the The bacteria enters the body through small wounds in the skin.or through the mucous membranes of the eyes, nose, or mouth, after contact with water, mud, or contaminated surfaces. This risk increases markedly in episodes of flooding, waterlogging or accumulation of stagnant waterwhere wastewater, mud, and animal urine are mixed.
In rural areas, agricultural workers, livestock farmers, veterinarians, and slaughterhouse or farm staff are frequently exposed to handling of potentially infected animals and humid environmentsBut the disease is not exclusive to rural areas: in urban areas, the presence of rodents and sanitation problems They also favor the appearance of cases, especially after heavy rains.
In production animals, such as cattle, the infection may go unnoticed for a while, but it has a significant impact on the reproduction and productivitySymptoms include miscarriages in late pregnancies, premature births, retained placenta, fertility problems, and decreased milk production. Leptospirosis is often only suspected once economic damage has already occurred.
Symptoms in people: from mild cases to Weil's syndrome
In humans, leptospirosis can present in a highly variable way, from mild infections similar to a severe flu to severe, potentially fatal forms. This range of clinical presentations is one of the reasons why many cases are confused with other diseases.
According to information from international organizations such as PAHO, the The incubation period usually ranges between 5 and 14 daysalthough in some cases it can last up to a month. Common initial symptoms include sudden fever, severe muscle pain (especially in the calves)Headache, general malaise, chills and, occasionally, nausea, vomiting, diarrhea and redness of the eyes.
This very nonspecific condition can be confused with the flu, dengue fever, hepatitis, or other common viral infectionsIt is not uncommon for the initial diagnosis to point to more "common" pathologies and leptospirosis not even be considered, which delays confirmation and the start of specific treatment.
A proportion of patients – it is estimated approximately one of every ten– can evolve into a severe form known as Weil's syndromeIn these cases, a combination of Acute renal failure, liver damage, marked jaundice, pulmonary hemorrhages, and, occasionally, meningitisWithout proper treatment, mortality from this severe form can reach around 50%.
The condition worsens if the infection is not recognized early or if access to medical care is limited. Hence the insistence of health authorities that, in the case of high fever, intense muscle pain, and a recent history of contact with stagnant water or unsanitary environmentsConsult a healthcare professional immediately to assess this possibility.
Why is leptospirosis so underdiagnosed and underreported?
Medical and veterinary professionals agree that leptospirosis remains a disease that is widely underreportedSeveral factors have been identified from academic circles and health organizations that explain this phenomenon.
One of the main problems is the clinical confusion with other pathologiesIn daily practice, when faced with a patient presenting with fever, headache, and muscle aches, the list of possible causes is long, and often the first suspicions are respiratory viruses, dengue fever, or other more common infections. Leptospirosis is not always among the initial diagnoses, and this delays the ordering of specific tests.
Added to this scenario is what some experts describe as the “silent cure"On many occasions, the infection self-limitsThe immune system itself resolves the condition without the person seeking medical help or undergoing tests to identify the bacteria. In other cases, the patient receives antibiotics for a suspected cold or other cause, and this treatment—unbeknownst to anyone—also eliminates the leptospiral bacteria.
This means that a significant number of cases are resolved outside the radar of surveillance systems. There is no diagnosis, no confirmation, and therefore, There is no official notificationThe disease exists, but it's not reflected in the statistics.
In veterinary medicine, diagnosis is not simple either. In cattle farms, for example, when “abortion stormsThe sample taken often comes from the expelled fetus, which is usually in poor condition due to decomposition, complicating the detection of the causative agent. Experts in the field recommend that, to improve diagnostic performance, priority be given to mother's urine sample collection and appropriate serological tests and laboratory investigations are used.
Laboratory methods also have their own limitations: dark-field microscopy can produce many false negativesBacterial culture requires several months to definitively rule out infection, making it impractical for rapid clinical decision-making. Therefore, serological techniques (such as MAT) are the usual basis for diagnosis, although they require expert interpretation of antibody titers.
In addition to all this, certain sociocultural mythsIn some settings, leptospirosis is mistakenly associated only with very poor neighborhoods or extremely degraded environments, when in reality it can also appear in middle and upper classesFor example, it is linked to recreational water activities or infected pets. In the production sector, the fear persists that reporting an outbreak will lead to the mandatory loss of animals, which leads some producers to avoid contact with health authorities, even though official services usually offer free diagnosis and advice on control without resorting to mass culling.
Impact on animal health and obligation to notify
Leptospirosis in farm animals is not only a welfare issue, but also a matter of public health and agricultural economicsIn many countries, including European ones, it is considered a notifiable disease in the veterinary fieldThis means that any suspicion on farms must be reported to the official services.
In cattle, the bacteria frequently settles chronically in the kidneys and reproductive system, facilitating continuous excretion of leptospires in the urine and transmission within the herd to other species. In pregnant cows, the infection results in abortions at term, premature births, births of weak calves, and decreased milk productionAll of this represents significant economic losses for the producers.
The disease is not limited to cattle either. Sheep, goats, pigs and dogs They can become infected and become additional sources of contagion for other animals and, indirectly, for the people who live or work with them. In the case of dogs, for example, walks in flooded areas or areas with rats increase the risk of exposure.
For these reasons, the authorities recommend that in the event of repeated abortions, reproductive failures, or compatible signs in a livestock establishmentThe official veterinary services should be notified. In Europe and Spain, this coordination between private veterinarians, producers, and health authorities is part of the "One Health" approach, which integrates animal, human, and environmental health.
Notifying not only allows us to support the producer with diagnosis and control guidelines, but also feeds into epidemiological surveillance systems, which help to to detect risk zones, changes in weather patterns associated with outbreaks, and possible emerging serovars of the bacteria.
Climate, floods and a surge in cases
The relationship between leptospirosis and climate is becoming increasingly evident. Periods of heat accompanied by frequent rain They favor the survival of the bacteria in the environment and increase the opportunities for contact between humans, animals, and contaminated water.
After storms, river flooding, overflowing sanitation systems, or failures in water networksIdeal conditions are created for the spread of leptospira. Wastewater can mix with rainwater, and in areas with a high rodent population, infected urine easily enters the water and mud system. People who walk barefoot or spend long periods with their legs submerged in such water are at greater risk of exposure.
In environments with damaged infrastructure or collapsed sewage systems, such as some coastal or riverine areas after extreme weather events, experts have pointed out the danger of an increase in diseases linked to contaminated waterThese include leptospirosis, viral hepatitis, and various types of gastroenteritis.
This climate and precarious sanitation context is not only associated with developing countries. It is also found in Europe, in certain rural or urban areas with aging networks. Torrential rains can overwhelm drainage systems and create environments with contaminated mud and puddles. Cleaning workers, utility personnel, farmers, and volunteers involved in emergency response then become at-risk groups.
Looking ahead, climate change, with Increasingly frequent episodes of heavy rainfall and heat wavesThis could favor an expansion of leptospirosis into areas where cases were previously scarce, which is why European authorities are maintaining surveillance of this zoonosis within their environmental health strategies.
Prevention measures in the countryside and in the city
The good news is that, although the risk cannot always be completely eliminated, There are numerous measures to significantly reduce the probability of infectionboth in rural and urban environments. The key is to combine actions concerning animals, the environment, and people.
In livestock farms, one of the central tools is the vaccination of animals against leptospirosisImmunization programs, combined with proper health management, help decrease the circulation of the bacteria in herds and reduce reproductive losses. When an outbreak is detected, veterinarians can also recommend specific antibiotic treatments to stop the infection in the affected animals.
Rodent control is another fundamental pillar. It is necessary. to minimize the conditions that favor their presenceThese measures include: accumulations of garbage, food scraps, and makeshift shelters in sheds, corrals, or around homes. Keeping feeders and waterers clean and in good condition, as well as sealing potential entry points to grain stores and other storage areas, are also part of these measures.
In the workplace, especially in high-risk areas, the systematic use of personal protective equipmentWaterproof gloves, high rubber boots, and, where appropriate, protective goggles to prevent splashes. This recommendation applies to rural workers, urban cleaning staff, emergency services personnel, and anyone who needs to operate in potentially contaminated waters.
For the general population, the authorities insist on avoiding, whenever possible, the direct contact with stagnant water, mud or puddlesEspecially after floods. If crossing flooded areas is unavoidable, it's best to wear appropriate footwear and protect your skin from cuts or open wounds. In homes and buildings, controlling rodents, sealing cracks, and storing food safely all help reduce the risk.
If you develop a fever, severe muscle pain, or general malaise after being in contact with humid, flooded environments or environments with the presence of rodentsIt is recommended to seek medical attention without delay and always mention this exposure, as this detail may be crucial for the professional to assess the possibility of leptospirosis.
The role of epidemiological surveillance and "One Health" coordination
Managing leptospirosis requires a a combined view of human medicine, veterinary medicine and the environmentThe "One Health" approach emphasizes that problems affecting people and animals in the same environment are linked and must be addressed in a coordinated manner.
Improving epidemiological surveillance This means not only detecting more cases, but also better understanding the patterns of bacterial circulation, the most vulnerable areas, and the environmental and social factors that contribute to outbreaks. In many countries, the increase in reported cases in recent years is attributed, in part, to a strengthening of clinical suspicion and reporting systems, rather than to uncontrolled growth of the disease.
Public health services insist that Any suspected case in humans should be evaluated with laboratory tests When clinical presentation and exposure suggest it, and that the results be included in epidemiological bulletins. At the same time, veterinarians are key to identifying problems on farms and in pets, taking samples correctly, and notifying the relevant authorities.
Continuing education for healthcare professionals helps ensure that, when faced with a compatible condition, Leptospirosis should not be ruled out due to lack of knowledge.Courses, updated clinical guidelines, and information campaigns allow for the dissemination of timely diagnostic and treatment criteria, as well as biosafety protocols for working with animals and potentially contaminated water.
Community involvement is also essential. Health education campaigns that explain, in accessible language, What is leptospirosis, how is it transmitted, and what are its symptoms? They encourage people to consult quickly and take simple steps in their daily lives: avoid bathing in dubious waters, strengthen cleanliness in yards and corrals, and collaborate in rodent control in neighborhoods and municipalities.
Leptospirosis remains a real but manageable threat Provided that human and animal health surveillance is combined, clinical suspicion is maintained in the face of compatible symptoms, and simple but constant prevention measures are applied, from rodent control and improved sanitation to livestock vaccination and the use of personal protection in risk activities, a shared effort can significantly reduce serious complications and deaths associated with this disease.
