Leptospirosis is a zoonotic disease that develops due to an infection caused by a bacterium called Leptospira. While many may not have heard of the disease yet, it is not a rare disease at all, as, according to data published by the Pan American Health Organization (PAHO), for example, there are about half a million cases of the disease in the world each year.
Human-to-human transmission of leptospirosis is rare; usually the bacterium enters the human body when a person has been in contact with the urine of infected animals or its contaminated environment. In this article, we will explain in more detail what kind of pathogen this disease is about and what risks it poses to human health.
Knowledge of the pathogen causing leptospirosis
First, it is important to first know the function of the microorganism that causes this disease. The bacterium that causes leptospirosis is known as Leptospira interrogans and belongs to the class of spirochete bacteria.
Due to its long helical shape and the lines at both ends, Leptospira interrogans may give the false impression that it is a microscopic worm.
However, this bacterium is a prokaryotic organism. In other words, it has only one cell, so its structural complexity is less than that of any other arthropod.
A complex life cycle
The main stores of Leptospira are wild mammals such as beavers, foxes or raccoons. Infection from animal to human is simple, as it is sufficient for the wound or mucosa of a healthy human to come into contact with the urine of an infected animal.
In this way, man inadvertently becomes the host for these parasitic bacteria; the infection does not fall within the life cycle of the bacterium, but it causes clinical symptoms in the host organism.
How does leptospirosis begin?
As we have already mentioned above, the spread of leptospirosis in infected areas is high because the bacterium spreads through the urine and can remain active in water or land for up to more than four weeks.
According to the U.S. National Library of Medicine, people can get the disease when they come in contact with water or soil contaminated with the urine of an infected animal. Direct contact with a sick animal can also pose a risk of spreading the infection.
When it enters the body through mucous membranes or superficial wounds, it multiplies temporarily in different parts of the body until it eventually settles in the kidneys and liver.
Leptospirosis: clinical picture
The germination period of the bacterium usually lasts from about a week to 12 days, and in this first stage, the patient may experience symptoms similar to those seen with the common flu. Depending on the severity and serotype of the bacterium, the disease may be prolonged over time, causing the patient to develop more severe symptoms. These symptoms may include:
- Stiff neck
- Kidney deficiency
- Difficulty breathing
The illness lasts from a few days to a week depending on the severity of the case. However, it is far from always a serious disease, as in the majority of patients diagnosed, this disease does not go beyond the first stage; that is, it causes only mild flu-like symptoms or some patients may even be completely asymptomatic.
At the same time, however, the elderly population, the pathologies associated with aging, and a weakened immune system are factors that tend to expose you more to this infection, as they allow for a wider proliferation of bacteria in the body, which in turn makes their elimination difficult.
Based on all this information, we can form superficial perceptions of which Groups of People are more vulnerable to this infection: communities in low-income countries that have access to water contaminated by a sick animal.
- As simple as the entry of urine from an infected wild mammal into the well is a sufficient cause of endemic infection in the population using this water (disease events in small areas).
- Floods also contribute to the spread of this bacterium, as they can produce mixtures of different water bodies and thus increase the contact of water streams with contaminated soil.
Should we be worried about this disease?
Yes and no. While it is true that it is the most widespread animal-to-human disease in the world and can occur in both developed and developing countries, the prevalence of leptospirosis is higher in tropical areas where water resources are not adequately managed.
At the individual level, people working with livestock or wildlife in particular, including farmers, are at risk. However, with the right precautions, the onset and spread of the disease can be effectively prevented, as in the end, bacteria cannot enter the body unless contaminated hands come in contact with mucous membranes or water contaminated with the bacterium is consumed.
Although leptospirosis occurs in many of Finland’s neighboring countries, such as the Baltic countries and Russia, it is relatively rare in Finland and is not normally found in humans. The spread of the bacterium is monitored through studies and vaccinations of animals if the animal travels to an area where the infection is common. Although leptospirosis is not currently a legally contagious animal disease, infections should be reported immediately to a municipal veterinarian or regional government agency.