Leishmaniasis is a disease that is worth learning about. The contagious property has made it a major public health problem. This disease occurs regularly in 88 countries in the world. It affects 14 million globally with 2 million new cases each year.
First, many consider leishmaniasis to be one of the seven most important tropical diseases in the world. Despite this, this condition is quite neglected and forgotten. According to a study by Spain’s National Center of Epidemiology , to take Spain as an example, there were 1,359 autochthonous cases spread across 15 autonomous communities between 2014 and 2017.
Leishmaniasis: What exactly is it?
Leishmaniasis is a contagious infection produced by various species of protozoa of the genus Leishmania. These protozoa, also known as single-celled parasites, are microscopic organisms that need a vector to be transmitted.
A vector is an animal that transmits pathogens from an infected human or an animal to a healthy human. In other words, the disease does not spread through direct contact, it is another organism that is a carrier of the microorganism.
These vectors are usually invertebrates, such as mosquitoes, fleas, lice and ticks. In the case of the pathology we are talking about in this article, the Leishmania protozoan is transmitted by the bite of the sand fly.
The mosquito becomes infected when it ingests blood from an infected person or animal. When the parasite is inside the vector, it does not cause any symptoms, it just develops and divides.
When there are a sufficient number of parasites , they move towards the mouth and throat of the mosquito and are injected at the next bite. The infected sandfly bites another human or animal and injects them with the Leishmania protozoa, and this is how the spread occurs.
Despite the human body’s defense mechanisms, the pathogen does not die. Instead, it multiplies in the macrophages of the blood and tissues, which end up breaking down and releasing protozoa into the blood, where other macrophages become infected and the cycle continues.
Where do we find these vectors?
Sandflies love moisture and heat. For this reason, it is easy to find them in tropical and subtropical areas. However, they are also located on the Mediterranean.
According to the World Health Organization ( WHO ), leishmaniasis has everything to do with climate change. Let’s look at some risk factors.
- Socio-economic conditions: poverty means poor housing conditions and poor sanitation in the home. For this reason, this condition may increase the risk of leishmaniasis. This encourages breeding and resting development of the infectious mosquitoes.
- Malnutrition: Lack of proteins, vitamins, iron and minerals can cause a weakened immune system in individuals. This in turn will allow the disease to develop and spread.
- Population mobility : Settlement in previously forested areas (which is the mosquito’s habitat) leads to a rapid increase in cases.
- Environmental changes: deforestation, dams, irrigation systems and urbanization have led to mosquitoes having more contact with humans.
- Climate change: The Leishmania protozoan is very sensitive to changes in weather conditions. Variations in temperatures and humidity in different areas cause the mosquito to spread to places it did not live before.
What are the symptoms of leishmaniasis?
There are at least 20 species of protozoa of the genus Leishmania that can be transmitted via vectors. Depending on the nature and degree of invasion in the body, one may experience different symptoms. This pathology therefore has several degrees of severity.
The three most common variants are the following:
- Cutaneous leishmaniasis: Cutaneous leishmaniasis occurs when the infection only occurs at the bite site. Many individuals know it as botón del Oeste and it usually appears along the Mediterranean coast. At the bite site, a wound-forming protrusion appears which sometimes heals on its own, but leaves a scar.
- Mucocutaneous leishmaniasis: The parasite can spread from the skin to the mucous membranes, which especially affects the upper respiratory tract. Swelling, redness and ulceration occur in the mucous membranes.
- Visceral leishmaniasis: In addition to the type of infectious protozoa, it is also important to remember the immune system of the affected person. When their defenses fail , the parasite migrates to the intestines. The internal organs that are most exposed are the bone marrow, lymph nodes, liver and spleen.
How to avoid leishmaniasis?
Leishmaniasis is contagious as long as the vector exists. No one really knows if it can actually be transmitted from person to person, with the exception of specific cases that have been registered, where people, for example, have shared syringes to inject drugs. However, regular blood transfusions are completely safe since they undergo many checks.
However, it is true that there will be more mosquitoes in a place with infected people. This obviously increases the likelihood that the people around you will become infected. It is possible to talk about leishmaniasis as a contagious disease if one takes into account the participation of the vector.
Therefore, the main prevention begins with avoiding mosquito bites, especially in people who travel to countries where the disease is common. Let’s look at some good advice to avoid bites.
- Use insect repellent on exposed skin.
- Use mosquito nets at night and treat your clothes with medicines, such as permethrin.
- Wear socks, long-sleeved shirts and trousers to prevent mosquitoes from reaching the skin. You should also have the shirt down in your pants.
- Avoid outdoor activities from dusk to sunrise in tropical areas, as this is when mosquitoes are most active.