[show abstract][hide abstract] ABSTRACT: Leishmania species of the subgenus Leishmania and especially L. donovani are responsible for a large proportion of visceral leishmaniasis cases. The debate on the mode of reproduction and population structure of Leishmania parasites remains opened. It has been suggested that Leishmania parasites could alternate different modes of reproduction, more particularly clonality and frequent recombinations either between related individuals (endogamy) or between unrelated individuals (outcrossing) within strongly isolated subpopulations. To determine whether this assumption is generalized to other species, a population genetics analysis within Leishmania donovani complex strains was conducted within a single village. The results suggest that a mixed-mating reproduction system exists, an important heterogeneity of subsamples and the coexistence of several genetic entities in Sudanese L. donovani. Indeed, results showed significant genetic differentiation between the three taxa (L. donovani, L. infantum and L. archibaldi) and between the human or canine strains of such taxa, suggesting that there may be different imbricated transmission cycles involving either dogs or humans. Results also are in agreement with an almost strict specificity of L. donovani stricto sensu to human hosts. This empirical study demonstrates the complexity of population structure in the genus Leishmania and the need to pursue such kind of analyses at the smallest possible spatio-temporal and ecological scales.
[show abstract][hide abstract] ABSTRACT: Recent studies have suggested that host genetics may be useful for predicting drug response and have supported the recommendation that single polynucleotide polymorphisms (SNPs) of IL28B should be investigated when treating hepatitis C virus (HCV)-1 infected patients. The aim of this study was to determine whether a single IL-28B genotype SNP rs8099917 or rs12979860 determination is sufficient to predict treatment failure in patients with chronic HCV.
A total of 198 patients were included; mean (±standard deviation) age was 47±12 years and 140 (71%) were men. One hundred and fifty-six (79%) patients were infected with HCV genotype 1 and 42 (21%) with HCV genotypes 2 or 3. One hundred and eight (55%) patients had sustained virologic response (SVR). Two SNPs in the IL-28B were analyzed (rs8099917 and rs12979860).
A total of 115 (58%) patients had rs8099917 TT genotype and 61 (31%) had rs12979860 CC genotype. Rs8099917 TT and rs12979860 CC genotypes were associated with SVR in HCV genotype 1 patients [odds ratio=2.60 (1.36-5.00), P=0.004 and odds ratio=3.30 (1.58-6.90), P=0.03 respectively]. No association was found between SNPs and SVR in HCV genotype 2 or 3 patients.
This study confirms that SNPs rs8099917 and rs12979860 used alone may be useful for predicting the outcome of HCV treatment. In a rational and cost-effective approach, determination of only one of these two SNPs is sufficient for predicting SVR. Because of the highest predictive SVR associated with rs12979860 CC compared with the rs8099917 TT (respective positive predictive value: 72% vs. 63%, P=ns), rs12979860 determination alone is sufficient for predicting interferon response.
European journal of gastroenterology & hepatology 10/2011; 23(10):931-5. · 1.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: Abnormal fibrosis occurs during chronic hepatic inflammations and is the principal cause of death in hepatitis C virus and schistosome infections. Hepatic fibrosis (HF) may develop either slowly or rapidly in schistosome-infected subjects. This depends, in part, on a major genetic control exerted by genes of chromosome 6q23. A gene (connective tissue growth factor [CTGF]) is located in that region that encodes a strongly fibrogenic molecule. We show that the single nucleotide polymorphism (SNP) rs9402373 that lies close to CTGF is associated with severe HF (P = 2 x 10(-6); odds ratio [OR] = 2.01; confidence interval of OR [CI] = 1.51-2.7) in two Chinese samples, in Sudanese, and in Brazilians infected with either Schistosoma japonicum or S. mansoni. Furthermore, SNP rs12526196, also located close to CTGF, is independently associated with severe fibrosis (P = 6 x 10(-4); OR = 1.94; CI = 1.32-2.82) in the Chinese and Sudanese subjects. Both variants affect nuclear factor binding and may alter gene transcription or transcript stability. The identified variants may be valuable markers for the prediction of disease progression, and identify a critical step in the development of HF that could be a target for chemotherapy.
Journal of Experimental Medicine 10/2009; 206(11):2321-8. · 13.21 Impact Factor
[show abstract][hide abstract] ABSTRACT: IL-17 and IL-22 have been shown to increase protection against certain bacteria and fungal pathogens in experimental models. However, no human studies have demonstrated a crucial role of IL-17 and IL-22 in protection against infections. We show here that Leishmania donovani, which can cause the lethal visceral disease Kala Azar (KA), stimulates the differentiation of Th17 cells, which produce IL-17, IL-22, and IFN-gamma. Analysis of Th1, Th2, and Th17 cytokine responses by cultured PBMCs from individuals in a cohort of subjects who developed KA or were protected against KA during a severe outbreak showed that IL-17 and IL-22 were strongly and independently associated with protection against KA. Our results suggest that, along with Th1 cytokines, IL-17 and IL-22 play complementary roles in human protection against KA, and that a defect in Th17 induction may increase the risk of KA.
The Journal of clinical investigation 09/2009; 119(8):2379-87. · 15.39 Impact Factor
[show abstract][hide abstract] ABSTRACT: In leishmaniasis, Th1-related cytokines production seems to be crucial for host control of parasite burden and clinical cure. Visceral and diffuse cutaneous leishmaniasis are characterized by negative skin test for parasite antigens and failure to produce Th1 cytokines, whereas tegumentary leishmaniasis is characterized by positive skin test and the ability of peripheral blood mononuclear cells (PBMCs) to produce Th1 cytokines. In this study, specific antibody plasma levels and cytokine production in PBMC culture supernatants were evaluated by enzyme-linked immunoabsorbent assay in patients with active or cured cutaneous leishmanial lesions and in subjects without disease history living in the same endemic area. Higher tumor necrosis factor-alpha, interferon (IFN)-gamma, interleukin (IL)-12, IL-4, and IL-10 levels were observed in patients with active lesions, whereas cured subjects produced only IFN-gamma at elevated levels. Analysis of specific antibody isotypes correlate with cellular immune response observed in vitro, as the production of IgG1 and IgG3 was higher in patients with active lesions. Our results suggest the presence of a mixed Th1/Th2 response during active disease and that clinical cure is associated with a sustained Th1 response characterized by elevated IFN-gamma levels and down-modulation of IL-4 and IL-10 production.
Human immunology 07/2009; 70(6):383-90. · 2.55 Impact Factor
[show abstract][hide abstract] ABSTRACT: Schistosoma japonicum is the most pathogenic agent of hepatosplenic schistosomiasis. It causes fibrosis of the central (CentF) and peripheral (PerF) portal areas. We investigated whether CentF and PerF in Chinese fishermen infected with S. japonicum were associated with an abnormal production of cytokines and chemokines that, in experimental models, have been implicated in the regulation of fibrosis.
Cytokines were measured by enzyme-linked immunosorbent assay in cultures of peripheral blood mononuclear cells from 127 patients, after stimulation with S. japonicum egg antigens. Data were analyzed by logistic regression that included age, sex, number of treatment episodes, alcohol use, and exposure as covariates.
CentF was associated with low levels of interleukin (IL)-10 (P= .0004), regulated on activation normally T cell expressed and secreted (P= .0004), and macrophage inflammatory protein-1alpha (P= .007). In a multivariate analysis, only IL-10 was associated with CentF (odds ratio [OR], 10.8; 95% confidence interval [CI], 3.2-38; P= .0004). Splenomegaly was also associated with low IL-10 production and, independently, with CentF. In multivariate analysis, PerF was associated with low production of interferon (IFN)-gamma (OR, 8.2; 95% CI, 2-33; P= .0035) but not with production of IL-10.
IL-10 is associated with protection against central fibrosis, because of its anti-inflammatory and antifibrosis effects. IFN-gamma is associated with protection against PerF, which depends more on egg load and egg-associated toxicity.
The Journal of Infectious Diseases 09/2008; 198(3):418-26. · 5.85 Impact Factor
[show abstract][hide abstract] ABSTRACT: In populations exposed to Leishmania braziliensis, certain subjects develop skin ulcers, whereas others are naturally protected against cutaneous leishmaniasis. We have evaluated which cytokines are most crucial in the development of skin lesions. We found that active lesions occur in subjects with polarized Th2 or mixed Th1/Th2 responses, both associated with elevated IL-10 production. IL-10 was strongly associated (p = 0.004, odd ratio (OR) = 6.8, confidence interval = 1.9-25) with lesions, excluding IFN-gamma, IL-12, TNF, IL-13, and IL-4 from the regression model. IL-10 was produced by blood monocytes and CD4(+)CD25(+) T lymphocytes (mostly Foxp3(+)). However, we did not observe any difference between the number of these cells present in the blood of subjects with active lesions and those present in resistant subjects. Genetic analysis of the IL10-819C/T polymorphism, located in the IL10 promoter, showed that the C allele increased the risk of lesions (OR = 2.5 (1.12-5.7), p = 0.003). Functional analysis of these variants showed allele-specific binding of nuclear factors. The IL10-819C/C genotype was associated with higher levels of IL-10 than C/T and T/T genotypes. These observations demonstrate an important role for IL-10 in skin lesions in humans infected with L. braziliensis, and identify circulating monocytes and Tregs as principal sources of IL-10 in these patients.
The Journal of Immunology 06/2008; 180(9):6139-48. · 5.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: Kala azar (KA) is a lethal disease caused by Leishmania parasites (Leishmania donovani s.l.) that multiply in large numbers in deep organs such as spleen and liver. The host immunological response to these organisms is complex and experimental studies in animals have detected a large number of genetic loci involved in the control of infection and disease. We report here on a study in a human population of Sudan carried out during an outbreak of KA. The following conclusions are presented: (1) environmental factors that could have affected the distribution of the insect vector, influenced progression of KA in the initial phase of the epidemics - but they became less important later at the peak of transmission, probably after infected phlebotomies had spread to all parts of the village -; (2) Leishmania population during the epidemics was heterogeneous, suggesting a possible parasite evolution during the outbreak; (3) the incidence of KA varied markedly among age groups, families and ethnic groups. Susceptibility to KA was shown to depend on a locus on chromosomes 22q12 and on NRAMP1 on chromosome 2q35; the data also suggested a third locus in the region 2q23-q24. Overall, this study indicates complex interactions between host genes and environment in the spreading of KA in that population. It is also suspected that the large parasite diversity observed in the outbreak has contributed to disease spreading across host genetic barriers.
[show abstract][hide abstract] ABSTRACT: To investigate the influence of genetic variability on the phenotypic expression of systemic sclerosis (SSc), by testing possible associations between single nucleotide polymorphisms (SNP) in IL13RA1 and IL13RA2 genes and SSc in a Caucasian population.
As IL13RA1 and IL13RA2 are located on the X chromosome and SSc occurs far more frequently in women than in men, only women were genotyped. The study group comprised 97 women with SSc, 36 with diffuse (dcSSc) and 61 with limited (lcSSc) cutaneous forms of disease, and 109 healthy controls. Patients and controls were Caucasian. We investigated 4 SNP in IL13RA1 and 3 in IL13RA2 by polymerase chain reaction amplifications and enzymatic digestion or primer extension reactions and denaturing high-performance liquid chromatography.
We detected an association between IL13RA2 rs638376 and patients with SSc [p = 0.004, odds ratio (OR) = 1.85, confidence interval (CI) 1.22-2.74, p corr = 0.02], as well as with dcSSc in that subgroup of patients (p = 0.01, OR 2.22, 95% CI 1.27-3.89, p corr = 0.05). The IL13RA2 rs638376G allele frequency was higher in patients with SSc (51.6%) than in controls (36.4%, p = 0.003, OR 1.86, 95% CI 1.24-2.79, p corr = 0.015) and in the subgroup with dcSSc (57.6%) than in controls (36.4%, p = 0.003, OR 2.37, 95% CI 1.35-4.15, p corr = 0.015). One other IL13RA2 SNP was only associated with the dcSSc subgroup: the IL13RA2 rs5946040G allele was more common in patients with dcSSc (33.8%) than in controls (17%, p = 0.004, OR 2.5, 95% CI 1.36-4.60, p corr = 0.02).
Our data suggest that IL13RA2 gene polymorphisms may be involved in susceptibility to SSc. Further studies are under way to show that they contribute to disease.
The Journal of Rheumatology 11/2006; 33(10):2015-9. · 3.26 Impact Factor
[show abstract][hide abstract] ABSTRACT: Systemic sclerosis (SSc) is a multisystem disease of unknown etiology. It is characterized by excessive cutaneous and visceral fibrosis, damage to small blood vessels, and production of autoantibodies. Interleukin-13 (IL-13) has been shown to be involved in abnormal fibrosis in other diseases. Therefore, we have evaluated its possible involvement in SSc. We analyzed four IL13 gene polymorphisms, rs1800925 (IL13-1055), rs20541 (Arg130Gln), rs847, and rs2243204 in 107 unrelated SSc patients (40 patients having diffuse cutaneous form and 67 patients having limited cutaneous form) and in 170 controls. All subjects were Caucasians. In the total patient population and in the diffuse cutaneous subset, we observed an association between two IL13 polymorphisms, IL13 rs1800925 (IL13-1055), and IL13 rs2243204, and disease (p=0.03-0.04). The IL13 rs2243204T allele was more common in SSc patients (p=0.01, OR=2.3 CI 1.21-4.38) and in the diffuse cutaneous form (p=0.01, OR=2.95, CI 1.35-6.49) than in control subjects. Our result supports the suggestion that polymorphisms in IL13 are associated to SSc and skin fibrosis process. However, further studies on larger and independent population and functional analyses are needed to confirm these findings.
[show abstract][hide abstract] ABSTRACT: This study aimed to determine whether single nucleotide polymorphisms (SNPs) within tumour necrosis factor-alpha (TNF) and interleukin-10 (IL10) promoters and genes are associated with human African trypanosomiasis (HAT). The polymorphisms used in the analysis were TNF(-308G/A), TNF(-238G/A), TNF(-1031T/C), TNF(+488G/A), IL10(-1082G/A) and IL10(-592C/A). A familial case-control sample of 277 individuals (102 cases and 175 parents) and a matched case-control group of 225 subjects (88 cases and 137 unrelated controls) were gathered together in this study. A conditional logistic regression was used to test for association. We carried out this analysis in the overall population and after stratification by time of exposure, age and ethnic group. Our results show that in the overall population, and after stratification by time of exposure, the IL10(-592A) allele is associated with a lower risk of disease, suggesting the possibility of a protective effect. After stratification by time of exposure, individuals homozygous for the SNP located in the TNF(-308) promoter were shown to present a higher risk of developing the disease early after exposure. Our study shows that TNF(-308G/A) and IL10(-592C/A) SNPs are polymorphisms of interest in the investigation of the genetic susceptibility to human African trypanosomiasis. Larger studies are currently underway to confirm these results.
Infection Genetics and Evolution 04/2006; 6(2):123-9. · 2.77 Impact Factor
[show abstract][hide abstract] ABSTRACT: Millions of humans are exposed to schistosome infections, which cause severe kidney and liver disease and 280,000 deaths annually. Th2-mediated immunity is critical to human defenses against this pathogen and susceptibility to infection is controlled by a major genetic locus that includes IL4, IL5, and IL13 genes. These observations led us to evaluate whether certain polymorphisms in IL4, IL5, or IL13 determine schistosome infection. The study was performed in two Dogon villages where Schistosoma haematobium is endemic. Schistosome infections were evaluated by counting eggs and measuring worm Ags in urine. Genetic polymorphisms were determined by restriction enzyme analysis or by primer extension and denaturing high-performance liquid chromatography analysis. Associations were tested using family-based association tests and logistical regression analysis. The alleles IL13-1055C (p = 0.05) and IL13-591A (p = 0.01) are shown, by family-based association test, to be preferentially transmitted to children with the 10% highest infections. A logistic regression analysis that included IL13-1055 G/G, G/T and T/T genotypes, age, gender, and village of residency, applied to the whole study population, showed that subjects bearing the IL13-1055T/T genotype were on average much less infected than individuals with other genotypes. Previous studies on asthma indicated that the IL13-1055T allele increased gene transcription, which is in agreement with the fact that this cytokine enhances resistance to infection by schistosome in humans.
The Journal of Immunology 06/2005; 174(10):6274-81. · 5.52 Impact Factor
[show abstract][hide abstract] ABSTRACT: This study aimed to determine whether single nucleotide polymorphisms (SNPs) within tumour necrosis factor-alpha (TNF) and interleukin-10 (IL10) promoters and genes are associated with human African trypanosomiasis (HAT). of 277 individuals (102 cases and 175 parents) and a matched case-control group of 225 subjects (88 cases and 137 unrelated controls) were gathered together in this study. A conditional logistic regression was used to test for association. We carried out this analysis in the overall population and after stratification by time of exposure, age and ethnic group. Our results show that in the overall population, and after stratification by time of exposure, the IL10 À592 A allele is associated with a lower risk of disease, suggesting the possibility of a protective effect. After stratification by time of exposure, individuals homozygous for the SNP located in the TNF À308 promoter were shown to present a higher risk of developing the disease early after exposure. Our study shows that TNF À308 G/A and IL10 À592 C/A SNPs are polymorphisms of interest in the investigation of the genetic susceptibility to human African trypanosomiasis. Larger studies are currently underway to confirm these results. # 2005 Elsevier B.V. All rights reserved.
[show abstract][hide abstract] ABSTRACT: Immunity against schistosomes includes anti-infection immunity, which is mainly active against invading larvae in the skin, and anti-disease immunity, which controls abnormal fibrosis in tissues invaded by schistosome eggs. Anti-infection immunity is T-helper 2 (Th2) cell-dependent and is controlled by a major genetic locus that is located near the Th2 cytokine locus on chromosome 5q31-q33. Mutations in the gene encoding interleukin (IL)-13 that decrease or increase IL-13 production account, at least in part, for that genetic control. In contrast, protection against hepatic fibrosis is dependent on interferon (IFN)- and is controlled by a major genetic locus that is located on 6q23, near the gene encoding the IFN- receptor β chain. Mutations that modulate IFN- gene transcription are associated with different susceptibility to disease. These data indicate that IL-13 in the skin and IFN- in the liver are key players in protective immunity against schistosomes. These roles relate to the high anti-fibrogenic activities of IFN- and to the unique ability of IL-13 in Th2 priming in the skin and in the mobilization of eosinophils in tissues. The coexistence of strong IFN- and IL-13-mediated immune responses in the same subject may involve the compartmentalization of the anti-schistosome immune response between the skin and the liver.
[show abstract][hide abstract] ABSTRACT: The aim of this case-control study was to identify epidemiological risk factors for severe malaria among children living in Bamako, a malaria-endemic area. For this, 260 healthy community controls were matched to 130 patients with severe malaria. Conditional multiple logistic regression analysis indicated that all examined independent factors associated with severe malaria are directly related to characteristics of the child's mother, with the exception of the child's own yellow fever vaccination history (odds ratio (OR): 1.93, 95% confidence intervals (CI(95%)) [1.10-3.37]). The following characteristics were all associated with a decreased risk of severe malaria in the child: maternal education (OR: 0.52, CI(95%) [0.31-0.86]), the mother's adequate knowledge about malaria (OR: 0.46, 95% CI(95%) [0.25-0.86]), her use of mosquito bed nets (OR: 0.53, CI(95%) [0.30-0.92]) and breast-feeding for at least 2 years (OR: 0.57, CI(95%) [0.33-0.94]). Conversely, chronic maternal disease (OR: ?3.16, CI(95%) [1.31-7.61]) was associated with an increased risk of severe malaria. These findings strongly support the hypothesis that maternal factors are central to the development of severe malaria in children. Programmes aiming to improve both maternal health and maternal education may reduce the incidence of severe malaria in children and should therefore be advocated in Bamako and in areas with similar epidemiological patterns for malaria.
Microbes and Infection 06/2004; 6(6):572-8. · 2.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: Vanin-1 is a membrane-anchored pantetheinase highly expressed in the gut and liver. It hydrolyzes pantetheine to pantothenic acid (vitamin B5) and the low-molecular-weight thiol cysteamine. The latter is believed to be a key regulating factor of several essential metabolic pathways, acting through sulfhydryl-disulfide exchange reactions between sulfhydryl groups of the enzymes and the oxidized form, cystamine. Its physiological importance remains to be elucidated, however. To explore this point, we developed Vanin-1-deficient mice that lack free cysteamine. We examined the susceptibility of deficient mice to intestinal inflammation, either acute (NSAID administration) or chronic (Schistosoma infection). We found that Vanin-1(-/-) mice better controlled inflammatory reaction and intestinal injury in both experiments. This protection was associated with increased gamma-glutamylcysteine synthetase activity and increased stores of reduced glutathione, as well as reduced inflammatory cell activation in inflamed tissues. Oral administration of cystamine reversed all aspects of the deficient phenotype. These findings suggest that one cysteamine function is to upregulate inflammation. Consequently, the pantetheinase activity of Vanin-1 molecule could be a target for a new anti-inflammatory strategy.
Journal of Clinical Investigation 03/2004; 113(4):591-7. · 12.81 Impact Factor
[show abstract][hide abstract] ABSTRACT: In 1996, an epidemic outbreak of visceral leishmaniasis (VL) started in Barbar el Fugara, a village in Gedarif State (eastern Sudan). From 1997 to 2000, regular epidemiological studies were carried out in the human population, as well as in mammals and sand flies. In symptomatic patients, 46/69 lymph node, 6/20 post kala-azar dermal leishmaniasis (PKDL) and 1/4 cutaneous cultures in NNN medium were positive. In 69 dogs, 23/79 lymph node cultures were positive. In other mammals (47 rodents, five donkeys, one mongoose and one monkey) spleen and/or blood cultures were negative. Characterization of isolated strains (by starch gel electrophoresis and isoelectrofocusing) identified three zymodemes of Leishmania donovani, two of L. infantum and two of L. archibaldi complexes from patient samples and three zymodemes of L. donovani, three of L. infantum and two of L. archibaldi complexes from dog samples. Five of them were present in both man and dog. For the first time, a strain from a PKDL case was identified as L. infantum, and a child had the same L. infantum zymodeme in VL and in subsequent PKDL. Blood samples from dogs were studied by immunofluorescent antibody test (IFAT). The seroprevalence in dogs was 72.5%, 74.3% and 42.9% in 1998, 1999 and 2000, respectively. By using CDC miniature light traps 12 745 sand flies were collected and then identified. Phlebotomus papatasi (7%) and P. orientalis (5%) were sympatric, mainly inside homes (85% and 75%, respectively). These results, the relative stability of seroprevalence in dogs and the intradomiciliar presence of P. orientalis, known as a vector of VL in Sudan, suggest several hypotheses: (i) man is responsible for the disease in dogs, (ii) the dog is the reservoir of VL, (iii) the dog is an intermediate host between a possible sylvatic cycle and the anthroponotic cycle. More extensive studies are needed to assess the transmission cycle of VL in this area of Sudan.
Microbes and Infection 11/2003; 5(12):1103-8. · 2.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: Parasitic diseases, including human visceral leishmaniasis, are multifactorial. Factors that are expected to play an important role in the parasite-human interaction are exposure, parasite "virulence" and host resistance factors. In populations exposed to Leishmania donovani most subjects do not allow the parasites to establish themselves or remain asymptomatic. Some individuals, however, fail to control parasite expansion and dissemination and develop a visceral disease. We report here the results of a longitudinal survey whose aims were to identify risk factors underlying visceral leishmaniasis (VL) susceptibility during an outbreak that occurred in a Sudanese village between 1995 and 1999. Most of the 660 subjects (90%) living in the central district were exposed to Leishmania and 20.9% (n = 138), mostly teenagers, developed VL. VL cases increased markedly in adults late in the outbreak, suggesting some changes in adult resistance status or in Leishmania "virulence" during the epidemic. Age and ethnic origin of the patients were the most important critical risk factors to account for the distribution of the VL cases that were recorded during the whole epidemic. This and the high frequency of VL in certain families suggest that host genetic factors played an important role in shaping the outbreak in this village. However, environmental factors (the presence of cows and neems in the households) that increase/decrease exposure to the parasite had significant effects on the distribution of VL cases in the village in the first phase of the outbreak.
Microbes and Infection 12/2002; 4(14):1449-57. · 2.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: An outbreak of visceral leishmaniasis (VL) started in 1995 in the Atbara River area in eastern Sudan. This article reports on this outbreak and on the clinical and immunological studies that were carried out in a village, with the highest incidence of VL cases, from 1996 to 1997. A significant increase in VL incidence was recorded in a dozen villages in this area; one village, Barbar El Fugara accounted for half of the total number of cases recorded at the regional hospital. A total of 152 VL and 61 post kala-azar dermal lesion (PKDL) cases were diagnosed and treated in Barbar. Household (n = 671) and school (n = 276) surveys were performed using the leishmanin skin test (LST) and the direct agglutination test (DAT). LST positivity was 23.1 and 15.7%, whereas DAT positivity was 8.9 and 26.4% in both surveys, respectively. No gender differences were observed in either test. Unlike DAT, LST positivity was predominant in the higher age groups that also exhibited lower prevalence of VL. Few individuals were positive by both tests (1.3%, 5.2%) while the majority (68.8%, 64.8%) had no evidence of acquired immune response, suggesting either a role of innate immunity in preventing parasite establishment or, unexpectedly, lack of exposure to Leishmania. Subclinical parasitism was also demonstrated, as evidence of both acquired humoral and cellular immune responses was observed in individuals with no past history of the disease. The wide spectrum of L. donovani/human interactions may be explained by differential exposure to environmental risk factors, parasite strain polymorphisms or host genetic makeup.
Microbes and Infection 12/2002; 4(14):1439-47. · 2.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: Une étude familiale effectuée dans une population exposée aux schistosomes montre que la résistance humaine à la bilharziose est sous le contrôle d'un gène majeur et qu'un polymorphisme au niveau de ce locus explique en grande partie les différences de susceptibilité à l'infection. Des études d'association effectuées sur des sujets exposés aux parasites à l'origine du paludisme et de la leishmaniose indiquent également un contrôle génétique de la susceptibilité humaine à ces infections et aux pathologies qui leur sont associées.
Annales de l'Institut Pasteur / Actualités. 08/1996; 7(1):59-62.