| Abstract |
The aim of the current thesis was to study leishmaniasis in Greece, in man and in the dog:
the geographical distribution of the disease, the species and zymodemes of the parasite and
their resistance to drugs, as well as the geographic spread of vectors-hosts of the parasite.
Leishmaniasis is a parasitic disease that is endemic in tropical and subtropical areas such
as in southern European countries (including Greece). It constitutes the second disease of
protozoal origin worldwide, with a wide geographical spread. Until recently it was ranked among
the most "neglected" diseases. The disease is caused by the intracellular protozoan Leishmania
infantum and presents a wide range of clinical presentations, depending on the species of
protozoa and the immune status of the host. If is characterized by a variety of clinical
syndromes (visceral, cutaneous and mucocutaneous form), with the most severe being visceral
leishmaniasis.
The survey was designed and conducted in order to identify the areas with the highest
rates of seropositivity in dogs, that is the areas with the greatest risk for the transmission of
leishmaniasis in humans by: a) creating a network of physicians and veterinarians in the
country, b) sending questionnaires for the study of leishmaniasis in veterinary private and public
sector (840 questionnaires), c) the epidemiological study in dogs by examining 8316 samples
corresponding to 5772 animals from 13 regions of the country (almost all prefectures of the
country) and mapping the results using GIS, d) processing the results of the epidemiological
study in dogs and correlating to answers provided by veterinarians into the questionnaires e) the
study of the disease in the human population with laboratory testing of patient samples from
Crete and other regions of the country (153 patients) (and use of data from the Center for
Disease Control and Prevention, g) the isolation, cultivation and standardization of the
protozoan parasite Leishmania from dogs and patients, recording the species / strains of the
parasite detected in dogs and people in Greece and comparing with strains detected in the
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Mediterranean, i) creating a parasite bank and j) studying the resistance of Leishmania strains
isolated against antileishmanial drugs using flow cytometry and mapping the results using GIS.
A network was created consisting of doctors in government hospitals in the country,
notably Crete and Athens (where biological samples were obtained from 153 patients with
suspected leishmaniasis), and veterinarians from across the country (who collected 8316
received biological samples from 5772 randomly selected dogs). 840 questionnaires were sent
to veterinarians in the private and public sector. The analysis of the questionnaires showed that
the vast majority of veterinarians believe that an increase in incidence of the disease in dogs is
observed at their areas and that the measures taken to fight bites of sandflies have not been
successful in dogs. The correlation of the results of the questionnaires and of the
epidemiological study in 5772 randomly selected dogs from all regions of the country showed
that a) the questionnaire developed by the European project FP6 EDEN - Leish subgroup, is a
reliable epidemiological tool and when the results are analyzed and mapped using GIS system it
can be used to draw useful results in identifying high-risk areas and areas of new input of the
disease (Ntais et al., 2013 c).
The epidemiological study in dogs demonstrated the seropositivity rate of dogs all over the
country and the mapping results revealed the high risk areas for humans. The climatic and
geographical features of each area were associated with seropositivity rate of dogs, with the
presence of human cases and the presence of species midges playing the role of transmitter
host of the Leishmania parasite (Ntais et al., 2013 a).
The laboratory diagnosis and process of biological samples from patients and dogs
resulted in the isolation of 212 strains of the parasite that were typed with the gold standard
method of analysis of an enzyme profile of each strain. This analysis revealed that in Greece
the encountered species of the parasite are Leishmania infantum MON-1 and MON-98,
responsible for visceral leishmaniasis and L. tropica MON-300, MON-58, responsible for
cutaneous leishmaniasis (Ntais et al., 2013 a). Leishmania tropica MON-300 was recorded only
in Greece (Crete) and MON-58, although being an anthroponotic species, was recorded in man
and in a dog in Crete. This zymodeme was reported in only six patients in Afghanistan and the
identification of Crete in young refugee from Afghanistan (which plagued his country) and a dog
is an alarming fact towards the installation of a new pathogen in a local midge population and
development of new epidemiological cycle of the parasite in man and dog (Ntais et al., 2013 b).
Until today, L. tropica was considered a human disease in Greece.
A parasite bank was created to use in future studies from the laboratory of Parasitology
and in collaboration with other laboratories in Greece and abroad. The spread of strains in the
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country was mapped and they were correlated with the species of gnat-vector host found in the
respective areas. In the continuity, we compared the Greek strains with strains detected in other
Mediterranean regions.
The results of the study of the resistance of the parasite to antileishmanial drugs, which
had been conducted in the laboratory from previous studies, were mapped with a GIS system
and concluded in the regions of Greece with resistant parasites, which enhances the degree of
risk area to humans and enhances the need for action to combat the disease and the vector at
these areas. Of the 212 strains studied in the laboratory, only 11 strains (two from humans and
9 from dogs) revealed drug resistance.
The survey results are very important for understanding the magnitude in terms of public
health in Greece. Clearly leishmaniasis has spread across the country and drug-resistant
parasites have developed and spread all over the country. Greece is located at the crossroads
of Asia, Africa and Europe, while the changes arising from globalization and global warming,
favor the appearance of new species and strains o Leishmania in our country. The large number
of species of midges (13) occurring in Greece, enables the import, installation and dispersion of
these new pathogens with unknown implications on public health. This study provides data on
the basis of which the competent institutions need to intervene to combat the problem in the
high-risk areas for humans.
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