Visceral leishmaniasis in Tunisia: result of the isoenzymatic characterization of 65 Leishmania infantum strains

The Sporadic cutaneous leishmaniasis due to Leishmania infantum in Morocco: A presumably trend towards endemicity

In Morocco, cutaneous leishmaniasis (CL) is an endemic disease; it is considered a major public health problem caused by three species Leishmaniamajor, Leishmaniatropica, and the dermotropic variant MON-24 of Leishmaniainfantum. This species has three incriminated vectors named; Phlebotomus ariasi, Phlebotomus longicuspis and Phlebotomus perniciosus, with the dog as reservoir.The main aim of this review is to elucidate the current epidemiological pattern of CL due to L.infantum and to investigate the factors facilitating its propagation throughout the country. Therefore, the number of CL cases due to L.infantum, their repartition; the distribution of L.infantum vectors, as well as the factors affecting their abundance and spread were investigated. We showed a wide extension of this form of CL, from the north of Morocco to the Saharan areas, as well as an increase of reported cases. This extension of the disease has been accompanied by a juxtaposed spread and a high abundance of confirmed vectors of L. infantum, which are present in almost all bioclimatic zones. In this review, we have highlighted the impact of climate: temperature, humidity, precipitation; vegetation and human activities on the geographical expansion of L. infantum vectors. These abiotic and biotic factors constitute favorable conditions for the increase of vector populations, and their introduction into areas where they did not exist before, and subsequently raise the risk of introduction of this form of cutaneous leishmaniasis into previously free areas. To conclude, CL by L.infantum, traditionally evolving as a sporadic form, is changing to an endemic mode, which seeks more epidemiological studies, and more attention from the health authorities when implementing control programs.

Canine leishmaniosis in Tunisia: Growing prevalence, larger zones of infection

Background

Discovered by Nicolle and Comte in 1908 in Tunisia, Leishmania infantum is an intracellular protozoan responsible for zoonotic canine leishmaniosis (CanL) and zoonotic human visceral leishmaniasis (HVL). It is endemic in several regions of the world, including Tunisia, with dogs considered as the main domestic reservoir. The geographic expansion of canine leishmaniosis (CanL) has been linked to global environmental changes that have affected the density and the distribution of its sand fly vectors.

Methodology/Principal findings

In this study, a cross-sectional epidemiological survey on CanL was carried out in 8 localities in 8 bioclimatic areas of Tunisia. Blood samples were taken from 317 dogs after clinical examination. Collected sera were tested by indirect fluorescent antibody test (IFAT; 1:80) for the presence of anti-Leishmania infantum antibodies. The overall seroprevalence was 58.3% (185/317). Among positive dogs, only 16.7% showed clinical signs suggestive of leishmaniosis. Seroprevalence rates varied from 6.8% to 84.6% and from 28% to 66% by bioclimatic zone and age group, respectively. Serological positivity was not statistically associated with gender. The presence of Leishmania DNA in blood, using PCR, revealed 21.2% (64/302) prevalence in dogs, which varied by bioclimatic zone (7.3% to 31%) and age group (7% to 25%). The entomological survey carried out in the studied localities showed 16 species of the two genera (Phlebotomus and Sergentomyia). P. perniciosus, P. papatasi, and P. perfiliewi were the most dominant species with relative abundances of 34.7%, 25% and 20.4%, respectively.

Conclusions/Significance

The present report suggests a significant increase of CanL in all bioclimatic areas in Tunisia and confirms the ongoing spread of the infection of dogs to the country’s arid zone. Such an expansion of infection in dog population could be attributed to ecological, agronomic, social and climatic factors that affect the presence and density of the phlebotomine vectors.

Visceral leishmaniasis caused by Leishmania infantum is an endemic disease in several regions of the world, especially, in the Mediterranean basin, where dogs constitute the main domestic reservoir for humans. This zoonotic vector-borne disease is closely associated with the environment.

We carried out studies in 8 different regions of Tunisia, collecting and testing blood samples from 317 dogs. Out of which, more than half (58.3%) tested positive for L. infantum (IFAT+), although, only one-third of these displayed clinical signs. However, the detection of Leishmania DNA by blood PCR revealed a global prevalence in dogs of 21.2% (64/302) with a variation between bioclimatic zones. Our entomological survey revealed 16 sand fly species, dominated by the Phlebotomus and Sergentomyia genera, of which the most dominant were P. perniciosus, P. perfiliewi and P. papatasi. The first two of these are recognized vectors of L. infantum. Canine leishmaniosis continues to spread across Tunisia, moving southward, to arid zones because of global warming and agronomic and social factors affecting the presence and density of the phlebotomine vectors.

Macrophage ghost entrapped amphotericin B: a novel delivery strategy towards experimental visceral leishmaniasis

Leishmania donovani, an intracellular parasite, poses many challenges against attempted chemotherapy. After the resistance towards the first-line antileishmanial drug, amphotericin B has become the treatment of choice against visceral leishmaniasis, a fatal tropical disease. However, unfavorable toxicity profile, severe side effects, and prolonged parenteral administration limit its use. Lack of available specific delivery system also makes this drug unsafe for long-term use. In the current study, a "ghost cell" strategy based on macrophage membrane-derived nanovesicle has been introduced as a specific carriage for amphotericin B. Membrane proteins of macrophage ghost play a crucial role in the dissemination of infection in host by communicating between infected neutrophil-macrophage system and non-infected macrophages. These membrane proteins are the basis of specificity of the drug delivery to the infected tissues in this current macrophage ghost cell carrier. This cheap and biocompatible delivery vehicle has significantly improved the toxicity profile and lowered LD50 value of the drug compared to traditional way of its direct administration and widely accepted antileishmanial therapy, AmBisome.

Modeling and comparative study of the spread of zoonotic visceral leishmaniasis from Northern to Central Tunisia

During the last twenty years, zoonotic visceral leishmaniasis (ZVL) spread from the north characterized by humid, sub-humid, and semi-arid bio-climates to the arid areas located in Central Tunisia. In order to understand the eco-epidemiological factors involved in the distribution of ZVL, both a sero-epidemiological and an entomological investigation were performed in two governorates situated in two different bio-geographical areas: Bizerte in the north and Kairouan in the center. A mathematical model for transmission of ZVL was built, describing the disease dynamic in these areas. Among 108 sera collected from clinically healthy owned dogs used for guarding houses in the governorate of Bizerte and tested for anti-L. infantum antibodies by indirect immune-fluorescence antibody test (IFAT), 8.3% were positive. From a total of 191 serum samples collected from clinically healthy owned dogs used for guarding houses in the governorate of Kairouan and tested for anti-L. infantum antibodies by IFAT, 26.7% were sero-positive. The cumulative incidences of ZVL in humans in the governorates of Bizerte and Kairouan were 39.17/100,000 and 0.2/100,000 inhabitants, respectively. The infection rates of sand flies with Leishmania DNA in the governorate of Bizerte and Kairouan were 3.8% and 9.4%, respectively. It is important to point out that ZVL epidemic in humans is preceded or concomitant to a high prevalence of Leishmania infantum in dogs and in sand flies. The model showed also a non-linear relationship between dog infection and ZVL in humans. These results suggest an important force of infection (R0) in emerging foci such as the governorate of Kairouan leading to an increased incidence of ZCL in humans. A high prevalence of L. infantum in dogs will result in high prevalence in the vector and obviously high probability to infect human; that it is a key factor for triggering transmission to humans, and subsequently it is an important parameter in the control of ZVL transmission.

Risk factors for mortality of children with zoonotic visceral leishmaniasis in Central Tunisia

BACKGROUND

Zoonotic visceral leishmaniasis (ZVL) caused by Leishmania infantum is endemic with an epidemiological profile of a paediatric disease in Tunisia. In the context of a high fatality rate, identifying risk factors for in-hospital mortality in children treated for ZVL is of major epidemiological importance.

DESIGN

A retrospective (case-control) study included 230 immuno-competent children diagnosed and confirmed with primary ZVL in the paediatric department of the University Hospital of Kairouan between 2004 and 2014. Forty-seven per cent (47%) were children under 18 months of age, and with a male ⁄ female ratio of 1.01:1.

RESULTS

The overall case-fatality was 6% (n = 14). The risk factors for in-hospital death identified by a multivariate analysis were: bleeding at admission (OR = 25.5, 95% CI: 2.26-287.4; p = 0.009), white cell count less than 4000/mm3 (OR = 5.66, 95% CI: 1.16-27.6; p = 0.032), cytolysis (OR = 28.13, 95% CI: 4.55-173.6; p < 0.001), and delay between onset of symptoms and admission ≥ 15 days (OR = 11, 95% CI: 1.68-72; p = 0.012).

CONCLUSION

The results strongly suggest that paediatric patients admitted 15 days after onset of symptoms, with bleeding, white cell counts below 4,000/mm3, and cytolysis at admission should be considered severe cases and subsequently, they are at high risk of mortality. A better understanding of factors associated with death of children from ZVL may contribute to decrease mortality.

The Montpellier Leishmania Collection, from a Laboratory Collection to a Biological Resource Center: A 39-Year-Long Story

We report the development of a laboratory collection of Leishmania that was initiated in 1975 and, after 39 years, has become an international Biological Resource Center (BRC-Leish, Montpellier, France, BioBank No. BB-0033-00052), which includes 6353 strains belonging to 36 Leishmania taxa. This is a retrospective analysis of the technical and organizational changes that have been adopted over time to take into account the technological advances and related modifications in the collection management and quality system. The technical improvements concerned the culture and cryopreservation techniques, strain identification by isoenzymatic and molecular techniques, data computerization and quality management to meet the changes in international standards, and in the cryogenic and microbiological safety procedures. The BRC is working toward obtaining the NF-S 96-900 certification in the coming years. Our long-term expertise in Leishmania storage and typing and collection maintenance should encourage field epidemiologists and clinical practitioners in endemic countries to secure their own strain collection with the help of the French BRC-Leish.

The site of the bite: Leishmania interaction with macrophages, neutrophils and the extracellular matrix in the dermis

Leishmania spp., the causative agents of leishmaniasis, are intracellular parasites, transmitted to humans via the bite of their sand fly vectors. Once inoculated, the promastigotes are exposed to the dermis, which is composed of extracellular matrix (ECM), growth factors and its resident cells. Promastigote forms are phagocytosed by macrophages recruited to the site of the sand fly bite, either directly or after interaction with neutrophils. Since Leishmania is an intracellular parasite, its interaction with the host ECM has been neglected as well as the immediate steps after the sand fly bite. However, promastigotes must overcome the obstacles presented by the dermis ECM in order to establish the infection. Thus, the study of the interaction between Leishmania promastigotes and ECM components as well as the earliest stages of infection are important steps to understand the establishment of the disease, and could contribute in the future to new drug developments towards leishmaniasis.

An investigation on vertical transmission of Leishmania infantum in experimentally infected dogs and assessment of offspring's infectiousness potential by xenodiagnosis

Dogs are the main reservoir host of Leishmania infantum, etiologic agent of human visceral leishmaniasis (HVL) and canine visceral leishmaniasis (CVL). Transmission of L. infantum to humans and dogs is mainly through the bite of infected sand flies. In the Western Mediterranean basin, Phlebotomus perniciosus is the main vector of L. infantum. However, occasional vertical transmission of L. infantum has been reported. This study investigated L. infantum vertical transmission in offspring of experimentally infected dogs. Among 14 surviving puppies from three female beagle dogs that developed CVL following an experimental infection with L. infantum, one was tested positive by indirect immunofluorescence antibody test, by PCR and by xenodiagnosis with a high parasite burden in the spleen at 14 months old. None of the remaining puppies were tested positive for L. infantum. These findings strongly suggest that infected puppies following vertical transmission can sustain infection and contribute in infecting sand flies with L. infantum. Any strategy for controlling CVL should take into consideration the vertical transmission of L. infantum.

Interaction between canine and human visceral leishmaniases in a holoendemic focus of Central Tunisia

Canine visceral leishmaniasis (CVL) is endemic in the Mediterranean basin. In Tunisia, CVL is spatially associated with human visceral leishmaniasis (HVL) affecting mostly children younger than 5 years old. In this study, seroprevalence of Leishmania infantum infection in dogs was assessed in highly endemic districts of the governorate of Kairouan where more than 50% of HVL cases in Tunisia were reported. An entomological investigation was also carried out in two endemic districts (Bouhajla and Haffouz) to assess sand fly fauna and infection status of sand flies with Leishmania. A total of 191 serum samples were collected from healthy dogs and tested for anti-L. infantum antibodies by indirect immunofluorescence antibody test (IFAT). Overall seroprevalence for L. infantum was 26.7% being highest among dogs in the district of Bouhajla (52.7%) and the lowest in the district of Chbika (5.2%). In dogs, seroprevalence did not differ significantly based on gender or age, with dogs younger than 1 year showing a higher seroprevalence compared to older dogs. These findings suggest strong force of infection in naïve animals in holoendemic regions leading to emerging high incidence of HVL. Concomitant to the high CVL prevalence observed in the Bouhajla district, a significantly high cumulative HVL incidence also was observed in this district. Phlebotomus perniciosus and Phlebotomus longicuspis were the most abundant sand fly species in Bouhajla and Haffouz districts. The rate of Leishmania-DNA infection in sand flies was 9.4%. This finding points to spatial correlation between the occurrence of disease in humans, a high rate of infection in dogs and a high abundance of P. pernicious and P. longicuspis. Thus, CVL is the main risk factor for transmission to humans and subsequently, it is an important parameter for controlling transmission to humans.

Leishmaniases in Maghreb: an endemic neglected disease

Maghreb is known to be one of the most endemic areas of leishmaniases where both visceral and cutaneous forms are reported. Cutaneous leishmaniasis (CL) is older and has a higher prevalence than visceral one (VL). It is caused by four taxa (Leishmania (L.) major, L. infantum, L. tropica and L. killicki) which are responsible for a large clinical spectrum of lesions. Most transmission cycles of these taxa are known and many phlebotomine sandflies vectors and reservoir hosts are identified. The zoonotic transmission is well established for L. major. However, for L. infantum and L. killicki it needs more investigations to be proven. Regarding L. tropica, studies suggest it to be of both zoonotic and anthroponotic types. The isoenzymatic characterization of these four taxa showed a large enzymatic polymorphism varying from two zymodemes for L. major to 10 zymodemes for L. tropica. Cutaneous leishmaniasis is widely distributed and covers all bioclimatic stages with the coexistence of more than one taxon in the same foci. Visceral leishmaniasis is the second form of leishmaniases in Maghreb. Only L. infantum is known to cause this disease. The transmission cycle of this parasite is zoonotic but still not well known. The isoenzymatic identification of L. infantum causing VL showed the presence of six zymodemes. Geographically, VL is distributed in all bioclimatic stages of Maghreb countries. Despite all the previous studies realized on leishmaniases in Maghreb, they are still considered as neglected diseases because of the rarity or the absence of efficient control strategies.

Geographical distribution updating of Tunisian leishmaniasis foci: about the isoenzymatic analysis of 694 strains

Over a period of ten years, a series of 694 Leishmania strains from Tunisian leishmaniasis foci were isolated and identified by isoenzymatic analysis. Strains were obtained from human cutaneous and visceral leishmaniasis in immunocompetent subjects, visceral leishmaniasis in imunocompromised individuals and from dogs with visceral leishmaniasis. Two classically dermotropic species, Leishmania (L.) major and Leishmania killicki were found. L. major with the single zymodeme MON-25 was the most isolated in cutaneous leishmaniasis foci of the Centre and South of Tunisia with a recent northern extension. L. killicki zymodeme MON-8 was sporadically found both in its classical microfocus of Tataouine in southeastern Tunisia as well as in some new foci in Southwestern, Central and Northern Tunisia. Leishmania infantum with its three zymodemes MON-1, MON-24 and MON-80 was isolated from both visceral and cutaneous human cases. The majority of L. infantum strains were found in the Northern part of the country; however, some strains were reported for the first time in the Southern part. L. infantum MON-1 was the only zymodeme isolated from canine leishmaniasis.

Geographical distribution and epidemiological features of Old World Leishmania infantum and Leishmania donovani foci, based on the isoenzyme analysis of 2277 strains

A series of 2277 Leishmania strains from Old World visceral leishmaniasis foci, isolated between 1973 and 2008, were studied by isoenzyme analysis. The strains were obtained from humans, domestic and wild carnivores, rodents and phlebotomine sandflies, and came from 36 countries. In all, 60 different zymodemes were identified and clustered by a phenetic analysis into 3 different groups corresponding to the typically visceralizing species L. donovani (20 zymodemes, 169 strains), L. archibaldi (3 zymodemes, 46 strains) and L. infantum (37 zymodemes, 2,062 strains). The taxonomic position of these isoenzymatic groups is discussed in view of contradictory results obtained from recent molecular studies.

[Visceral leishmaniasis in immunocompetent adults. About six cases]

OBJECTIVE

Studying the epidemiological variations of visceral leishmaniasis in Tunisia and proving the importance of parasitological investigations to raise the diagnosis.

PATIENTS AND METHODS

Six patients hospitalised during the period between January 1998 and January 2009 at Fattouma Bourguiba Teaching Hospital in Monastir, five men and an only one woman, aged from 26 to 70 years old, originating from the central and eastern regions of the country. Epidemiological, clinical, biological and therapeutic data were obtained from the patient's medical files.

RESULTS

The major clinical symptoms were fever, weakness and spleen enlargement. Biological data revealed the presence of anaemia in every case and leucopoenia associated or not associated with thrombopenia in four cases. The diagnosis of visceral leishmaniasis was confirmed by the identification of the parasite in the blood or in the bone marrow. All patients were treated with two courses of antimoniate of meglumine separated by a 6-week interval. The outcome was positive and the patients were cured.

CONCLUSION

Visceral leishmaniasis is increasing among adults in Tunisia. Moreover, it is spreading outside its epidemiological area in the north to reach the central and southern regions. It should be raised when fever and spleen enlargement occur. Biological data are hardly specific. Diagnosis is based on finding the parasite in human fluids, mainly by molecular techniques. The rapid establishment of a specific treatment is vital.

Isoenzymatic variability of Leishmania infantum in Tunisia concerning 254 human strains

The different clinical forms of leishmaniasis are the result of both the immunological status of individuals and the species of the parasite causing the infection. In Mediterranean countries, the Leishmania infantum complex groups zymodemes which are responsible for visceral, cutaneous and exceptionally cutaneomucosal or mucosal leishmaniasis. We report in this study a synthesis concerning 254 cases of L. infantum that have been characterized at the "Laboratoire de Parasitologie" of the Rabta Hospital. The strains were isolated from human cases of visceral leishmaniasis (VL) and cutaneous leishmaniasis (CL) by culture on NNN medium: 156 VL cases and 98 CL cases. The isoenzymatic characterization revealed three zymodemes of L. infantum. * L. infantum MON 1, a common zymodeme of VL,occurred in 154 cases (61%): 147 VL (95%) and 7 CL (5%). All CL cases were from the northern provinces, six of them occurring during an epidemic disease in 2001. * L. infantum MON 24, a common zymodeme of CL in the north, occurred in 98 cases (38.5%): 91 CL (93%) and 7 VL (7%). The seven VL cases were immunocompetent children aged from 8 months to 9 years and native of northern Tunisia. Two of the CL cases were from central regions of the country. This is the first time that cases from these regions are reported. * L. infantum MON 80, an uncommon zymodeme in Tunisia, occurred in two VL cases (0.5%): two children aged 7 and 5. The small number of strains of this zymodeme does not allow understanding of its epidemiological role. The results of this study indicate a low enzymatic variability of L. infantum in the country. However, our study includes only human strains and should be extended to animal ones (dogs, rodents and sand flies). This would lead to a better understanding of the epidemiology of leishmaniasis in Tunisia.

Portage asymptomatique de Leishmania infantum chez des malades tunisiens infectés par le VIH

The number of visceral leishmaniasis (VL) cases is in continuous growth in Mediterranean countries. In Tunisia, in addition to the traditional infantile form, more and more cases in immunocompetent or immunocompromised adults have been reported. However, co-infection VL-HIV remains rare in Tunisia and diagnosis of all the cases up till now has been done using traditional techniques (serology, direct examination and culture of bone marrow). However, the last years, several studies proved the greatest sensitivity of PCR in VL diagnosis. We carried out a systematic detection of Leishmania in peripheral blood for 25 HIV infected patients (10 were asymptomatic, 6 presented a fever and/or a paleness and/or an asthenia, and 9 had an opportunist infection other than VL). In all cases, the culture on Novy-Nicolle-McNeal (NNN) medium was negative by the end of the month. Serology carried out for 22 patients was negative in IFI in 17 cases, positive at the 1/20 for four others and positive at the 1/40 for one patient (confirmed by Western Blot technique). A PCR using the primers Lei70L-Lei70R, specific of the gene of Leishmania infantum, allowed the display of the specific band of 345 bp for 17 samples. The higher sensitivity of PCR compared to conventional methods is subject to the difficulty of result interpretation in PCR positive testing among patients not having any other marker of the disease which raises the question of significance for this asymptomatic bearing.

First detection and genetic typing of Leishmania infantum MON-24 in a dog from the Moroccan Mediterranean coast: genetic diversity of MON-24

As in the countries edging the Mediterranean basin, Leishmania infantum zymodeme MON-1 is the main causative agent of visceral leishmaniasis in Morocco, where visceral leishmaniasis is most active in the North-Eastern slopes of the Rif mountains. The dog was confirmed to be the main reservoir of L. infantum MON-1, while the reservoir of L. infantum MON-24 causative agent of both infantile visceral leishmaniasis and cutaneous leishmaniasis has not yet been identified. Here we report the first detection of this last zymodeme in a dog in Morocco. The isolated strain was first identified by the use of genotyping markers and confirmed by isoenzyme analysis. Phylogenetic analysis with the use of concatenated sequences from 26 Leishmania donovani complex strains revealed strong geographical correlation with the MON-24 strain from Morocco clustering with other East African strains whereas two other MON-24 strains clustered with L. infantum strains. Interestingly, the two distinct populations of MON-24 identified with the use of genotyping markers cannot be distinguished by multilocus enzyme electrophoresis.

Natural infection of Phlebotomus (Larroussius) langeroni (Diptera: Psychodidae) with Leishmania infantum in Tunisia

Phlebotomine sand flies were captured from an active transmission focus of sporadic cutaneous leishmaniasis, caused by Leishmania infantum, in El Kef region, northern Tunisia. Both Phlebotomus perniciosus and P. langeroni were found. Phlebotomus langeroni females showed a statistically significant intradomiciliary dominance (P<0.01 for the 2003 and 2004 seasons) when compared to animal shelters. During the 2003 season, dissection of collected female specimens showed the presence of flagellates within the digestive tracts of two P. perniciosus among 1086 observed, but none in 232 P. langeroni. Amplification of kinetoplast minicircles of Leishmania parasites was applied to DNA samples extracted from 298 frozen females including 249 P. perniciosus, 36 P. langeroni, 5 P. longicuspis and 8 P. perfiliewi and revealed by radioactive probe hybridization. Two P. langeroni females showed a signal of the size expected for L. infantum (800bp) indicating infection with these parasites. However, this PCR-hybridization method failed to identify any positive P. perniciosus females in pools of specimens. These results show for the first time the natural infection of P. langeroni with L. infantum in Tunisia, and support the existence of different L. infantum transmission cycles in Tunisia, with a potential role for P. langeroni as a vector.

Leishmaniasis in Portugal: enzyme polymorphism of Leishmania infantum based on the identification of 213 strains

This study reports isoenzyme polymorphism of Leishmania strains isolated in different regions of Portugal between 1982 and 2005. A total of 213 strains were obtained from cases of visceral and cutaneous leishmaniasis isolated from immunocompetent patients (adults and children) and immunocompromised adults, as well as from dogs and sandflies. Four zymodemes were identified: MON-1, MON-24, MON-29 and MON-80. Zymodeme MON-1 was identified in 96.7% of the strains, predominating in both immunocompetent and immunocompromised human patients, and it was the only zymodeme isolated from dogs. Isoenzyme diversity in HIV-infected patients was higher than in the immunocompetent group, in which all the strains from visceral leishmaniasis were MON-1. The domestic dog was confirmed as the reservoir host of zoonotic leishmaniasis in Portugal and Phlebotomus perniciosus and Phlebotomus ariasi as vectors. The overall low enzyme polymorphism observed in the Portuguese foci contrasts with the neighbouring foci in Spain.

Intra-specific variability of virulence in Leishmania infantum zymodeme MON-1 strains

This study aims to characterize the intra-specific variability of virulence in Leishmania infantum zymodeme MON-1 strains isolated from dogs and immunocompetent and immunosuppressed patients through the evaluation of growth pattern, infective ability and immunopathogenicity. Two of the strains, classified as the most virulent, presented higher levels of macrophage infection, increased promastigote replication in culture medium and as well as amastigote multiplication within macrophages. These strains caused the most pathogenic infection inducing splenomegalia and maximum parasite loads in spleen and liver of BALB/c mice. The other strains exhibited either low virulence, with reduced infective capability and low replication levels, or an intermediate virulent phenotype showing mixed features similar to low and high virulent phenotypes. A correlation between the infectivity, growth dynamics and pathogenicity of each strain and the humoral and cellular immune response was demonstrated. Strains with accentuated virulent phenotype induced higher levels of anti-Leishmania IgG1 antibodies and TGF-beta but reduced production of IFN-gamma. Virulence phenotype seems to be a characteristic of each strain regardless of the host (dog or human) from which it was firstly isolated.

Leishmania infection impairs beta 1-integrin function and chemokine receptor expression in mononuclear phagocytes

Leishmania spp. are intracellular parasites that cause lesions in the skin, mucosa, and viscera. We have previously shown that Leishmania infection reduces mononuclear phagocyte adhesion to inflamed connective tissue. In this study, we examined the role of adhesion molecules and chemokines in this process. Infection rate (r = -0.826, P = 0.003) and parasite burden (r = -0.917, P = 0.028) negatively correlated to mouse phagocyte adhesion. The decrease (58.7 to 75.0% inhibition, P = 0.005) in phagocyte adhesion to connective tissue, induced by Leishmania, occurred as early as 2 h after infection and was maintained for at least 24 h. Interestingly, impairment of cell adhesion was sustained by phagocyte infection, since it was not observed following phagocytosis of killed parasites (cell adhesion varied from 15.2% below to 24.0% above control levels, P > 0.05). In addition, Leishmania infection diminished cell adhesion to fibronectin (54.1 to 96.2%, P < 0.01), collagen (15.7 to 83.7%, P < 0.05), and laminin (59.1 to 82.2%, P < 0.05). The CD11b(hi) subpopulation was highly infected (49.6 to 97.3%). Calcium and Mg(2+) replacement by Mn(2+), a treatment that is known to induce integrins to a high state of affinity for their receptors, reverted the inhibition in adhesion caused by Leishmania. This reversion was completely blocked by anti-VLA4 antibodies. Furthermore, expression of CCR4 and CCR5, two chemokine receptors implicated in cell adhesion, was found to be downregulated 16 h after infection (2.8 to 4.1 times and 1.9 to 2.8 times, respectively). Together, these results suggest that mechanisms regulating integrin function are implicated in the change of macrophage adhesion in leishmaniasis.

Occurrence of Leishmania infantum cutaneous leishmaniasis in central Tunisia

Cutaneous leishmaniasis (CL) due to Leishmania infantum occurs sporadically in Tunisia where its distribution is confined to the northern parts of the country. However, during the past decade there have been occasional repeated reports of cases from areas in central Tunisia, known to be free of CL. Epidemiological, clinical and parasitological data regarding these patients were collected and analysed. Data were very suggestive of the sporadic form of CL due to L. infantum. The parasites contained within the lesions of some of the patients were characterised by two different previously described PCR assays, each having different resolutive powers. The first assay, which amplified complete kDNA minicircles, showed a fragment size characteristic of the L. donovani complex; whilst the second consisted of a PCR-RFLP analysis targeting the gp63 coding sequences that confirmed assignment of the parasites to L. infantum species while illustrating its differences from the reference isolate. These findings confirm the aetiology of CL in the concerned areas in central Tunisia and suggest that L. infantum CL might be more prevalent and widespread than previously thought, or possibly emerging in these areas.

Isoenzymatic analysis of 712 strains of Leishmania infantum in the south of France and relationship of enzymatic polymorphism to clinical and epidemiological features

In the south of France, leishmaniasis due to Leishmania infantum occurs in the following five foci of endemicity (from west to east): Pyrénées-Orientales, Cévennes, Provence, Côte d'Azur, and Corsica. Between 1981 and 2002, 712 Leishmania strains obtained from humans, dogs, cats, and sand flies were studied by isoenzyme analysis. In total, seven zymodemes were identified: MON-1, MON-11, MON-24, MON-29, MON-33, MON-34, and MON-108. The Pyrénées-Orientales focus is characterized by a predominance of human cutaneous leishmaniasis and a high enzymatic polymorphism (five zymodemes). In the other foci, where human visceral leishmaniasis is predominant, only two zymodemes are present. L. infantum MON-1 is the parasite most frequently found, in patients both with and without concomitant human immunodeficiency virus infection. MON-1 is the only zymodeme present in dogs, which act as the reservoir host in all of the foci. In Cévennes, where the complete life cycle of zymodeme MON-1 has been identified, Phlebotomus perniciosus and Phlebotomus ariasi are vectors. The enzymatic polymorphism is compared to that of neighboring countries (Spain and Italy). In Pyrénées-Orientales, small variant zymodemes with electromorphs of heterozygote-like and homozygotic patterns can be explained by different genetic hypotheses.