In recent decades, rising cases of vector-borne tropical diseases such as dengue fever, malaria and chikungunya have raised fears that these types of diseases will spread throughout Europe. Climatic factors directly influence the distribution and distribution of insect pathogen vectors as their life cycle and survival are related to temperature and humidity.
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A disease with many faces
Among the tropical diseases whose incidence has increased due to global warming is leishmaniasis, which is included in the World Health Organization’s list of neglected tropical diseases. In fact, it is a complex of ailments caused by a parasite. Leishmania, transmitted through the bite of insects called mosquitoes. They are smaller and hairier than mosquitoes, and their wings are V-shaped when at rest.
Leishmaniasis has a variety of clinical manifestations. While the cutaneous form causes skin ulcers that can develop into painful ulcers, the mucocutaneous variant affects the lining of the nose, mouth and throat, causing sores that can disfigure the patient. But the most serious form is visceral, which affects internal organs such as the liver and spleen, causing fever, weight loss and anemia, and if not treated promptly, death.
Unlike other tropical infections, in southern European countries it is present as zoonotic leishmaniasis, that is, it is transmitted from animals to humans. Caused by the view Leishmania childhoodits main domestic reservoir is dogs.
It spreads in outbreaks, areas in which environmental and epidemiological conditions exist for transmission of the parasite, with the presence of mosquitoes and a high prevalence in dogs. The main victims are young children and immunocompromised adults.
Alarming expansion across Europe
In recent years, an increase in incidence has been observed in endemic areas of Europe, such as Portugal, northern Italy, Greece and the Balkans. However, a recent study by the European Center for Disease Prevention and Control (ECDC) found that leishmaniasis is not reportable in all countries with local cases and that few track and control infections in both animals and humans.
This lack of preparedness and a more reactive rather than preventive attitude on the part of European governments contributed significantly to the spread of the disease.
The increase in the number of cases is directly related to global warming: an average increase in air temperature of one degree is estimated to lead to a significant increase in incidence. Warmer conditions favor mosquito survival and activity, population density, biting rates, and the maturation of the parasite within. A long summer prolongs the period of transmission and the risk of infection in hosts, humans or dogs.
Global warming is also facilitating the northward movement of vector populations, allowing for local transmission from imported cases in previously non-endemic areas. Currently, mosquitoes have already spread throughout the Iberian Peninsula, northern Italy and the Balkans, reaching Germany. Its expansion is expected to continue in the coming years.
Mobility makes the problem worse
Along with climate change, another aggravating factor is the increasing mobility of people and pets, including travel and forced migration. Although it has been suggested that the arrival of refugees in Europe may pose a risk of introducing new species Leishmania (How L. tropicalis And L. Donovani), these species are already sporadically present in Greece and Cyprus.
The biggest risk is the movement of millions of tourists from the north to the Mediterranean coast. This movement affects not only people, but also domestic animals: large numbers of infected dogs live in non-endemic areas and can become a source of the parasite, establishing a local focus of transmission.
Another factor associated with the rising incidence of leishmaniasis in Europe is the increasing number of immunocompromised people. Like in the 90s, when HIV co-infectionLeishmania has led to a resurgence of leishmaniasis in southern Europe, with many of the new cases reported in people who have undergone solid organ transplantation or are on immunosuppressive treatment. These circumstances increase your susceptibility to developing the disease if you become infected.
Thus, an outbreak of leishmaniasis identified in Gothenburg (Sweden) among people on immunosuppressive treatment who were on holiday on the Mediterranean coast highlights the high level of transmission. This might have gone unnoticed if not for the greater sensitivity of these patients.
An additional threat is the emergence of parasite resistance to the few available drugs. In Europe, dogs are routinely treated for canine leishmaniasis, but treatment is not always effective and animals relapse. This causes the parasite to accumulate resistance over time and also affects treatment in humans.
It is also possible that parasites are spreading resistance to mosquitoes. This process can occur without direct pharmacological intervention, since susceptible parasites can become resistant when exposed to other resistant parasites from animals or humans treated during their cycle within the vector.
You need to change your attitude
Leishmaniasis should be understood as a growing public health problem in Europe. It is essential to take measures to reduce and control it, such as monitoring human and dog cases, the spread of mosquitoes, drug sensitivity of parasites, and the emergence of leishmaniasis in previously non-endemic regions.
Ultimately, governments have the opportunity to take a proactive rather than a reactive stance. This will allow them to anticipate and be better prepared to deal with the problems associated with this disease.