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1.
Rolão N  Melo C  Campino L 《Acta tropica》2004,90(1):123-126
Mice of the BALB/c strain are frequently used, due to their high susceptibility to Leishmania infection. Most of the studies in visceral leishmaniasis use the endovenous or the intraperitoneal routes to inoculate the parasites. In this study, the development of experimental visceral leishmaniasis infection was evaluated in BALB/c mice inoculated with Leishmania infantum parasites by endovenous (EV group) or intraperitoneal (IP group) routes. The results shows that both inoculation routes were able to produce progressive infection in mice. However, a higher dispersion of the values of parasite density was detected among the animals of the EV group than the IP group. Our results indicate that the intraperitoneal inoculation results in a higher homogeneity of infections, so we suggest that this route should be preferentially used in experimental infections in the mice model, particularly when pools of samples are required for immune cellular studies.  相似文献   

2.
Human visceral leishmaniasis is endemic in the Mediterranean basin. Since most infections are sub-clinical or asymptomatic, host genetics can provide concrete evidence in determining disease outcome. SLC11A1/NRAMP1 is a candidate gene that may be related to host susceptibility versus resistance to intracellular pathogens. This study aimed to determine possible association of SLC11A1 polymorphisms with visceral leishmaniasis among Moroccan children. A total of 106 children who developed visceral leishmaniasis due to Leishmania infantum were enrolled in this study. The control group was composed of 137 unrelated children, 97 asymptomatic subjects (DTH+) and 42 healthy individuals (DTH) who had no evidence of present or past infection. Four polymorphisms were studied by PCR–RFLP and sequencing: (GT)n microsatellite in the 5′ exon 1; silent substitutions 469 + 14G/C in intron 4; amino acid substitution D543N in exon 15 and 823C/T polymorphism in exon 8. Thereafter, the frequencies of genotypes, alleles and haplotypes were estimated. Two polymorphisms were each significantly associated in the genotypes with visceral leishmaniasis: 823C/T in exon 8 and D543N in exon 15 when comparing visceral leishmaniasis and DTH+ groups. The results of haplotype frequencies suggested an evidence of association with resistance to visceral leishmaniasis for the “286GTG” and “288GCA” haplotypes, whereas, the “286GCG” haplotype appears to increase the risk to visceral leishmaniasis susceptibility.Our data provide insights into the possible role of SLC11A1 variation in visceral leishmaniasis susceptibility. These results must be regarded as preliminary but suggestive that further study with larger populations is worthwhile.  相似文献   

3.
We investigated whether ELISA using crude antigens from insect and plant trypanosomatids, which are non-pathogenic and easily cultivated in large scale, has the same positivity data as Leishmania (Leishmania) chagasi, the etiological agent of human visceral leishmaniasis (VL) or canine leishmaniasis (CanL), or as Trypanosoma cruzi, the etiological agent of Chagas disease (CD). The antigens from Crithidia fasciculata, Crithidia luciliae, and Leptomonas seymouri showed 100% cross-reactivity with VL and CanL samples, with no statistically titers differences from L. (L.) chagasi, however, 34% (17/50) of VL samples revealed higher titers using the insect trypanosomatids than the homologous antigen. On the other hand, antigens from Strigomonas culicis, Angomonas deanei, and Phytomonas serpens showed low cross-reactivity with VL and CanL samples. The sera from patients with American tegumentary leishmaniasis showed low levels of cross-reactivity with all trypanosomatids investigated, even with L. (L) chagasi, without titers dissimilarity among them. These parasites were also worthless as antigen source for detection of CD cases, which required homologous antigens to reach 100% positivity. This study showed, by ELISA, that crude extract of Crithidia and Leptomonas have epitopes similar to L. (L.) chagasi, which supports the idea of using them as antigens source for the serodiagnosis of visceral leishmaniasis.  相似文献   

4.
Murray HW 《Acta tropica》2005,93(3):295-301
Interleukin 10 (IL-10), a suppressive Th2 cell-type cytokine, promotes disease progression in experimental visceral leishmaniasis. To extend testing the therapeutic effects of applying IL-10 receptor (IL-10R) blockade with antileishmanial chemotherapy, BALB/c mice with established intracellular Leishmania donovani infection were injected once with anti-IL-10R mAb at the time low-dose, daily pentavalent antimony (Sb) therapy was initiated. In this treatment model, simultaneous administration of anti-IL-10R enhanced overall antileishmanial activity in the liver in an interferon-gamma-dependent fashion, and accelerated the kinetics of Sb-associated killing, induced a >10-fold Sb dose-sparing effect and shortened the required duration of Sb treatment. These results suggest the possibility of using mAb-induced IL-10R blockade to develop low-dose and/or short-course immunochemotherapeutic regimens in visceral leishmaniasis.  相似文献   

5.
A study of the natural infection of phlebotomine sand flies by Leishmania (Leishmania) infantum was conducted in an area of visceral leishmaniasis in São Vicente Férrer, located in the northern part of the Atlantic rain forest region in the State of Pernambuco, Brazil. In a previous study, Migonemyia migonei have been found predominantly in peridomiciles and houses in this endemic area. The analysis of M. migonei, collected by CDC light trap, by multiplex PCR assay coupled to non-isotopic hybridization showed that 2 females out of 50 were infected by L. infantum. This is the first finding of natural infection of M. migonei by L. infantum suggesting that M. migonei may be the vector of L. infantum in areas of visceral leishmaniasis where Lutzomyia longipalpis, the usual vector, is absent.  相似文献   

6.
Leishmania are intracellular parasites that multiply as the amastigote form in the macrophages of their vertebrate hosts. Since vaccines against leishmaniases are still under development, the control of these diseases relies on prompt diagnosis and chemotherapy in infected humans as well as in dogs, which are the main reservoir of Leishmania infantum, in Mediterranean countries. To establish the macrophage type to be used as an in vitro model for antileishmanial chemotherapeutic studies, we analysed the susceptibility of human peripheral blood derived macrophages, macrophages derived from mouse bone marrow, mouse peritoneal macrophages and macrophages differentiated from cell lines U-937 and DH82 to infection by two L. infantum strains, one obtained from a human leishmanial infection and other from a canine infection. Both strains displayed comparable behaviour in their capacity of infecting the different macrophage types. Human peripheral blood macrophages and DH82 cells were less infectable by both strains. U-937, mouse peritoneal macrophages and mouse bone marrow derived macrophages are the most active cells to phagocytose the parasites. However, U-937 cell line appears to be the most useful as Leishmania infection model providing an unlimited source of homogeneous host cells with reproducibility of the results, is less time consuming, less expensive and tolerate high doses of first line drugs for human and canine visceral leishmaniasis treatment.  相似文献   

7.
Visceral leishmaniasis is associated with the reduced survival of erythrocytes, the cause of which remains to be fully explored. Here, we described the mechanism underlying the shortened lifespan of erythrocytes in visceral leishmaniasis and proposed a combination therapy with quercetin and hamster serum albumin towards its rectification. Decreased redox potential in erythrocytes followed by oxidative denaturation of hemoglobin and pathologic association of iron with the cell membrane facilitated premature hemolysis during leishmanial infection. Recently, we have reported the therapeutic efficacy of quercetin in arresting the enhanced destruction of erythrocytes in visceral leishmaniasis. Since serum albumin, the principal carrier protein for quercetin gets depleted in visceral leishmaniasis, the situation may compromise the efficacy of quercetin in this disease. We now report the use of quercetin-hamster serum albumin combination to increase the bioavailability of quercetin. The combination targeted hemoglobin oxidation and produced an effective attenuation of heme degradation. This led to decreased iron decompartmentalization, thereby increasing the life span of erythrocytes during leishmanial infection. Thus, we speculate that suppression of iron decompartmentalization, with the combination of quercetin and serum albumin might be a new approach in the prevention of reduced survival of erythrocytes in visceral leishmaniasis.  相似文献   

8.
In this study, we detected Leishmania spp. infection in R. sanguineus collected from dogs that were naturally infected with L. (L.) infantum. We examined 35 dogs of both sexes and unknown ages. The infected dogs were serologically positive by the immunofluorescence antibody test (IFAT), enzyme-linked immunosorbent assay (ELISA), and Quick Test-DPP (Dual Path Platform), as well as parasitological examination of a positive skin biopsy or sternal bone marrow aspiration. Ten negative dogs were included as controls. The ticks that infested these dogs were collected in pools of 10 adult females per animal. The PCR was performed with specific primers for Leishmania spp., which amplified a 720-bp fragment. Of the 35 analyzed samples, a product was observed in eight samples (8/35; 22.9%). We conclude that the presence of parasite DNA suggests that ticks participate in the zoonotic cycle of canine visceral leishmaniasis, in the city of Teresina, Piauí.  相似文献   

9.
The phlebotomine sand fly Lutzomyia longipalpis takes blood from a variety of wild and domestic animals and transmits Leishmania (Leishmania) infantum chagasi, etiological agent of American visceral leishmaniasis. Blood meal identification in sand flies has depended largely on serological methods but a new protocol described here uses filter-based technology to stabilise and store blood meal DNA, allowing subsequent PCR identification of blood meal sources, as well as parasite detection, in blood-fed sand flies. This technique revealed that 53.6% of field-collected sand flies captured in the back yards of houses in Teresina (Brazil) had fed on chickens. The potential applications of this technique in epidemiological studies and strategic planning for leishmaniasis control programmes are discussed.  相似文献   

10.
Clinically infected dogs have been identified as the main reservoir hosts of visceral leishmaniasis (VL) caused by Leishmania infantum in the Mediterranean region. The objective of this study was to determine the potential of asymptomatic infected dogs compared with symptomatic ones as a source of L. infantum infection to golden hamster.For this purpose, anti-Leishmania antibodies were detected with direct agglutination test (DAT) in 13 symptomatic (7 seropositive = ≥1:320) and 53 asymptomatic (9 seropositive = ≥1:320 and 44 seronegative =  <1:320) ownership dogs. DNA of Leishmania sp. was extracted from skin and peripheral blood tissues of each dog and tested by PCR. Sixty-six Syrian golden hamsters (Mesocricetus auratus) were used for the determination of infectivity and pathogenicity of L. infantum, isolated from the dogs. We used the internal transcribed spacer 2 (ITS 2) rDNA sequence analysis. The results showed that 22 and 11 out of 66 inoculated golden hamsters were positive by PCR and parasitological examinations, respectively. From 22 PCR positive hamsters, 17 were related to asymptomatic dogs and 5 were from symptomatic ones. There was no significant difference between symptomatic and asymptomatic dogs in producing Leishmania infection in the susceptible animal model (P = 0.66). Smears and cultures of 5 dogs from 13 symptomatic dogs (38.5%) and 6 dogs from 53 asymptomatic ones (11.3%) were found to be positive at parasitological examination.All the L. infantum isolates from symptomatic and asymptomatic dogs were similar in sequencing.In conclusion, asymptomatic infected dogs as well as symptomatic ones can harbor L. infantum in their blood and skins which are virulent and infectious for inoculated golden hamster.  相似文献   

11.
Human visceral (VL, also known as Kala-azar) and cutaneous (CL) leishmaniasis are important infectious diseases affecting countries in East Africa that remain endemic in several regions of Ethiopia. The transmission and epidemiology of the disease is complicated due to the complex life cycle of the parasites and the involvement of various Leishmania spp., sand fly vectors, and reservoir animals besides human hosts. Particularly in East Africa, the role of animals as reservoirs for human VL remains unclear. Isolation of Leishmania donovani parasites from naturally infected rodents has been reported in several endemic countries; however, the status of rodents as reservoirs in Ethiopia remains unclear. Here, we demonstrated natural Leishmania infections in rodents. Animals were trapped in 41 localities of endemic and non-endemic areas in eight geographical regions of Ethiopia and DNA was isolated from spleens of 586 rodents belonging to 21 genera and 38 species. Leishmania infection was evaluated by real-time PCR of kinetoplast (k)DNA and confirmed by sequencing of the PCR products. Subsequently, parasite species identification was confirmed by PCR and DNA sequencing of the 18S ribosomal RNA internal transcribed spacer one (ITS1) gene. Out of fifty (8.2%) rodent specimens positive for Leishmania kDNA-PCR and sequencing, 10 were subsequently identified by sequencing of the ITS1 showing that five belonged to the L. donovani complex and five to L. tropica. Forty nine kDNA-positive rodents were found in the endemic localities of southern and eastern Ethiopia while only one was identified from northwestern Ethiopia. Moreover, all the ten ITS1-positive rodents were captured in areas where human leishmaniasis cases have been reported and potential sand fly vectors occur. Our findings suggest the eco-epidemiological importance of rodents in these foci of leishmaniasis and indicate that rodents are likely to play a role in the transmission of leishmaniasis in Ethiopia, possibly as reservoir hosts.  相似文献   

12.
Visceral leishmaniasis (VL) is a neglected disease and is fatal if untreated. Dogs serve as reservoirs for Leishmania infantum (syn. L. chagasi) due to their susceptibility to infection and high skin parasitism. Therefore, VL control in Brazil involves the elimination of seropositive dogs, among other actions. However, the most frequently used serological tests have limitations regarding sensitivity and specificity. In this study, we have selected three Leishmania antigens (C1, C8 and C9) and have produced them as recombinant proteins using pET-28a-TEV vector and Escherichia coli BL-21 as expression system. When tested in ELISA with human samples, the C9 antigen was the one showing the most promising results, with 68% sensitivity and 78% specificity. When testing canine samples, the C1, C8 and C9 antigens showed a sensitivity range from 70% to 80% and specificity range from 60% to 90%. The C1 antigen presented higher sensitivity (80%) and the C8 antigen presented higher specificity (90%). Due to it, we decided to mix and test C1 and C8 antigens together, resulting in the C18 antigen. The mix also yielded high percentages of detected symptomatic and asymptomatic dogs however it did not improve the performance of the diagnostic. Comparison of our tests with the tests recommended by the Brazilian Ministry of Health revealed that our antigens’ sensitivities and the percentage of detected asymptomatic dogs were much higher. Our results suggest that the C1, C8, C18 and C9 recombinant proteins are good antigens to diagnose canine visceral leishmaniasis and could potentially be used in screening tests. To diagnose human visceral leishmaniasis, the C9 antigen presented reasonable results, but more optimization must be performed for this antigen to provide better performance.  相似文献   

13.
Intracardiac transfusion of plasma, mononuclear cell fraction and blood of infected hamster donors induced visceral leishmaniasis in normal hamster receptors. At the moment of transfusion, the donors already showed all the typical signs of the disease: ascites, cachexia, as well as splenomegaly and a high parasite load in the spleen and liver. All transfused hamsters developed typical visceral leishmaniasis between 90 and 120 days, indicating that all blood products were infectious. Transfusion of the mononuclear cell fraction induced the highest values of parasitic load (spleen, 766 Leishman Donovan Units (LDU); liver, 2650 LDU), splenomegaly and hepatomegaly (spleen-liver/body relative weight: 1.130 and 6.870, respectively). Animals that received the plasma fraction also developed visceral leishmaniasis, showing similar parasitic load (spleen, 107 LDU; liver, 220 LDU) and spleen-liver/body relative weight (1.005 and 6.35, respectively) than those transfused with whole blood. The finding of typical Leishmania donovani infection in animals transfused with plasma demonstrates the possibility of the extracellular location of parasites, free in this blood fraction deprived of red and white blood cells. Fluorescence-assisted cell sorter analysis (FACS) of plasma showed the presence of particles corresponding in size to amastigotes, which fluoresced strongly with the serum of a patient with Kala-azar (73%), but not with normal serum.  相似文献   

14.
The identification and characterization of Leishmania are relevant to diagnosis, treatment, eco-epidemiology studies, prophylactic measures and control of the disease. Two strains of Leishmania (MHOM/BR/1971/BH49 and MHOM/BR/1971/BH121), isolated from human cutaneous leishmaniasis, were studied using biological and molecular characteristics, in comparison with WHO reference strains. These studies are important because both strains were incorporated in a vaccine against American cutaneous leishmaniasis, and one of these strains has been used to prepare specific and sensitive antigen for serodiagnosis of visceral leishmaniasis in Brazil. Studies were made on the growth rates of promastigotes in Grace's insect medium, infectivity to C57BL/6 and BALB/c mice, electrophoresic mobility patterns of isoenzymes, random amplification of polymorphic DNA (RAPD), simple sequence repeat-anchored PCR amplification (SSR-PCR) and DNA fingerprinting profiles, infectivity to murine macrophages and cellular immune response. Infections of mice and macrophages were significantly different among the strains studied. Attempts to infect mice with culture promastigotes were unsuccessful with BH121, but BH49 infected BALB/c and C57BL/6 mice. Isoenzyme electrophoretic mobility patterns, RAPD and SSR-PCR using DNA amplified by polymerase chain reaction (PCR) with nine arbitrary primers, as well as DNA fingerprinting studies with a biotin-labeled 33.15 fingerprinting probe showed similar profiles to those of the Leishmania major WHO reference strain.  相似文献   

15.
Epidemiological surveillance of leishmaniasis was conducted in a northern Amazonian region of Ecuador, in which cutaneous leishmaniasis cases were recently reported. Sand flies were captured in the military training camp, and the natural infection of sand flies by Leishmania species was examined. Out of 334 female sand flies dissected, the natural infection by flagellates was microscopically detected in 3.9% of Lutzomyia yuilli yuilli and 3.7% of Lutzomyia tortura, and the parasite species were identified as Endotrypanum and Leishmania (Viannia) naiffi, respectively. After the sand fly surveillance, specimens from cutaneous leishmaniasis (CL) patients considered to have acquired the infection in the training camp area were obtained, and the infected parasite species were identified as L. (V.) naiffi. The present study reported first cases of CL caused by L. (V.) naiffi infection in Ecuador. In addition, a high ratio of infection of Lu. tortura by L. (V.) naiffi in the same area strongly suggested that Lu. tortura is responsible for the transmission of L. (V.) naiffi in this area.  相似文献   

16.
Visceral leishmaniasis is a life-threatening human disease commonly known as kala-azar. Leishmania donovani is the causative agent of this parasitic disease transmitted by the sand fly vector to infect hosts. Triphenyl tin salicylanilide thiosemicarbazone [Ph(3)Sn(OSal.TSCZH)] (TTST) which is an organometallic complex of triphenyl tin has been evaluated to explore possibility to develop a potent chemotherapeutic agent against visceral leishmaniasis. Effect of triphenyl tin complex on growth inhibition and host--parasite interaction were examined both in vitro and in vivo. Release of toxic superoxide radical was measured spectrophotometrically through the formation of blue formazan derived from reduced nitrobluetetrazolium. To understand mode of action of Ph(3)Sn(OSal.TSCZH), superoxide dismutase activity was determined spectrophotometrically by measuring ability of this enzyme to inhibit pyrogallol autoxidation and also by activity staining of the non-denaturing polyacrylamide gels after separating superoxide dismutase. Antileishmanial activity of triphenyl tin complex were found to be effective both in vitro and in vivo at lower concentrations compared to the existing toxic drugs available. IC(50) of Ph(3)Sn(OSal.TSCZH) was calculated as 0.05+/-0.01mg/L. Intracellular survival of the parasite in host macrophages was inhibited by TTST in a dose dependent manner. Parasite burden in spleen was reduced to 87% under TTST treatment (10mg/kg body weight) and under sodium antimony gluconate (20mg/kg body weight) reduced nearly to 65%. Its action as a chemotherapeutic agent is found to be mediated through inhibition of superoxide dismutase and simultaneous release of toxic superoxide radical. We propose that Ph(3) Sn(OSal.TSCZH) may be considered as a prospective candidate to establish a better line of therapeutic process against experimental visceral leishmaniasis.  相似文献   

17.

SUMMARY

The clinical outcome of infection with Leishmania species of the subgenus Viannia in hamster model (Mesocricetus auratus) has shown to be different depending on experimental protocol. Body weight has been a relevant determinant of the clinical outcome of the infection in hamsters with visceral leishmaniasis but its importance as a clinical parameter in hamsters with cutaneous leishmaniasis is not known. In this study, the clinical evolution of infection with L. (V) panamensis was evaluated in juvenile and adult male hamsters during 11 weeks by comparing clinical parameters such as attitude, temperature, respiratory rate, appearance of the stool, and body weight between infected and non-infected groups. Results showed that body weight decreased in adult hamsters after infection by L. (V) panamensis; this observation supports the use of body weight as an additional parameter to define the management or treatment of cutaneous leishmaniasis in infected adult hamsters used as an animal experimental model for leishmaniasis.  相似文献   

18.
The natural infection of Lutzomyia neivai with Leishmania in the endemic area of American cutaneous leishmaniasis (ACL) in northwestern Argentina was analyzed by the polymerase chain reaction (PCR)-hybridization technique. Phlebotominae sand flies were captured in the provinces of Tucumán and Salta between 1999 and 2003. From a sample of 440 Lu. neivai females analysed for the detection of the Leishmania (Viannia) and Leishmania (Leishmania) subgenera, 9.1% of the samples resulted infected with a parasite of the subgenus Viannia and none with the Leishmania. This is the first report of naturally infected sand flies in Argentina besides the first report of infected Lu. neivai sensu strictu. Our results contributed to further incrimination of this specie as vector of leishmaniasis in the area and the identification of the main circulating parasite as belonging to the Leishmania (Viannia) subgenera.  相似文献   

19.
In the present study, we aimed to carry out an epidemiological and entomological survey on a visceral leishmaniasis (VL) focus located on the northern central part of Anatolia, Turkey. Five villages of Corum province, where five confirmed cases of human visceral leishmaniasis (HVL) (one patient/village) were reported between June 1998 and August 2001 were included in the study. A total of 625 children and 131 dogs were sampled and the physical examination was carried out by authorized physicians and veterinarians. An indirect fluorescent antibody test (IFAT) was performed by standard procedures for human and dog sera, while the direct agglutination test (DAT) was only performed for dog sera. Sand fly collection was performed in three villages by CDC miniature light traps. Hepatosplenomegaly and hepatomegaly were detected in two and eight children, respectively. The seropositivity rate among children was found to be 0.16% (1/625) in the region. The seroprevalence of canine infection in these five villages ranged between 0.0% and 28.26%. In two villages, named Ahlatcik and Asagifindikli, no seropositive dogs were found. A total of 1218 sand flies were collected throughout the study. Six species of Phlebotomus were identified: P. transcaucasicus, P. neglectus, P. halepensis, P. tobbi, P. papatasi, and P. jacusieli. P. transcaucasicus was found to be the predominant species in Cevizli (47.44%; 343/723) and Ucoluk (79.95%; 351/439) villages, while P. tobbi was abundant in Kucukerikli (42.85%; 24/56).  相似文献   

20.
Current visceral leishmaniasis (VL) control programs in Brazil include the infected dog elimination but, despite this strategy, the incidence of human VL is still increasing. One of the reasons is the long delay between sample collection, analysis, control implementation and the low sensitivity of diagnostic tests. Due to the high prevalence of asymptomatic dogs, the diagnosis of these animals is important considering their vector infection capacity. Hence, a rapid and accurate diagnosis of canine visceral leishmaniasis is essential for an efficient surveillance program. In this study we evaluated the performance of rK39 antigen in an immunochromatographic format to detect symptomatic and asymptomatic Leishmania chagasi infection in dogs and compared the results with those using a crude antigen ELISA. The sensitivity of rK39 dipstick and ELISA were 83% vs. 95%, respectively, while the specificity was both 100%. Our results also demonstrated that the dipstick test was able to detect infected dogs presenting different clinical forms.  相似文献   

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