Gloria R. Monteiro

An Emerging Peri-Urban Pattern of Infection with Leishmania chagasi, the Protozoan Causing Visceral Leishmaniasis in Northeast Brazil

Peri-urban visceral leishmaniasis (VL) caused by Leishmania chagasi is emerging in a new epidemiologic pattern in Brazilian cities. We studied peri-urban VL in endemic neighborhoods surrounding Natal, Brazil, identified through hospitalized individuals with VL. Clinical and environmental information obtained for 1106 members of 216 families living in endemic neighborhoods enabled us to identify 4 groups: VL: individuals with current or prior symptomatic visceral leishmaniasis (n=135); DTH+: individuals with positive delayed-type hypersensitivity response with no history of VL (n=390); Ab+: individuals with negative DTH response and seropositive (n=21); DTH−: individuals with negative DTH and seronegative (n=560). The mean±SD age of VL was 9.3±12.3 y. The gender distribution was nearly equal below age 5, but skewed toward males at higher ages. Acutely infected VL subjects had significantly lower hematocrits, neutrophils, and eosinophils than other categories. AB+ subjects also had lower eosinophil counts than others, a possible immune marker of early infection. VL was not associated with ownership of dogs or other animals, raising the question whether the reservoir differs in peri-urban settings. This new pattern of L. chagasi infection enables us to identify epidemiological and host factors underlying this emerging infectious disease.

Common variants in the HLA-DRB1-HLA-DQA1 HLA class II region are associated with susceptibility to visceral leishmaniasis

To identify susceptibility loci for visceral leishmaniasis, we undertook genome-wide association studies in two populations: 989 cases and 1,089 controls from India and 357 cases in 308 Brazilian families (1,970 individuals). The HLA-DRB1–HLA-DQA1 locus was the only region to show strong evidence of association in both populations. Replication at this region was undertaken in a second Indian population comprising 941 cases and 990 controls, and combined analysis across the three cohorts for rs9271858 at this locus showed Pcombined = 2.76 × 10−17 and odds ratio (OR) = 1.41, 95% confidence interval (CI) = 1.30–1.52. A conditional analysis provided evidence for multiple associations within the HLA-DRB1–HLA-DQA1 region, and a model in which risk differed between three groups of haplotypes better explained the signal and was significant in the Indian discovery and replication cohorts. In conclusion, the HLA-DRB1–HLA-DQA1 HLA class II region contributes to visceral leishmaniasis susceptibility in India and Brazil, suggesting shared genetic risk factors for visceral leishmaniasis that cross the epidemiological divides of geography and parasite species.

Genetic predisposition to self-curing infection with the protozoan Leishmania chagasi : A genomewide scan

The protozoan Leishmania chagasi can cause disseminated, fatal visceral leishmaniasis (VL) or asymptomatic infection in humans. We hypothesized that host genetic factors contribute to this variable response to infection. A family study was performed in neighborhoods of endemicity for L. chagasi near Natal in northeastern Brazil. Study subjects were assessed for the presence of VL or asymptomatic infection, which was defined by a positive delayed-type hypersensitivity (DTH) skin test response to Leishmania antigen without disease symptoms. A genomewide panel of 385 autosomal microsatellite markers in 1254 subjects from 191 families was analyzed to identify regions of linkage. Regions with potential linkage to the DTH response on chromosomes 15 and 19, as well as a novel region on chromosome 9 with potential linkage to VL, were identified. Understanding the genetic factors that determine whether an individual will develop symptomatic or asymptomatic infection with L. chagasi may identify proteins essential for immune protection against this parasitic disease and reveal strategies for immunotherapy or prevention.

Canine visceral leishmaniasis in urban and rural areas of Northeast Brazil

The purpose of this study was to determine the clinical and laboratory profiles of canine leishmaniasis in two distinct areas. Dogs from urban and rural areas were examined. The population studied in the metropolitan area included 54 dogs. Of these, 20 (37%) animals did not present with any signs suggestive of visceral leishmaniasis (VL). Among these, only eight were confirmed negative by ELISA (rK39 and CE) and 12 dogs, clinically negative for leishmaniasis, were seropositive by ELISA (rK39 and CE). Thinness, conjunctivitis and onychogryphosis were the most frequent clinical signs in the urban areas, followed by crusty lesions, alopecia, ulcerated lesions, hyperkeratosis and exfoliation. In the metropolitan area human VL cases occurred mainly in 1991, 1992, 1999 and 2000. In the rural areas the ELISA rK39 test detected a seroprevalence of 11.3% and ELISA CE (Leishmania crude extract) of 20.6%. Thirty-nine dogs were examined 6 months after the first visit. Serological exams using rK39 antigen showed seroconversion of only one dog, whereas Leishmania CE showed seroconversion of 13 (33.4%) dogs. In this rural environment 83.3% of the positive dogs were asymptomatic. Lutzomyia intermedia and Lu. longipalpis were the most predominant sandfly vector species. Amastigotes were identified in spleen and liver fragments of symptomatic necropsied animals. PCR amplification of DNA isolated from promastigote culture indicated that the species was Leishmania chagasi. This finding suggests that delayed diagnosis and euthanasia of potentially infectious animals may occur with an increased transmission risk to sandflies and subsequently to humans.

Genes at human chromosome 5q31.1 regulate delayed-type hypersensitivity responses associated with Leishmania chagasi infection.

Visceral leishmaniasis (VL) caused by Leishmania chagasi is endemic to northeast Brazil. A positive delayed-type hypersensitivity skin test response (DTH+) is a marker for acquired resistance to disease, clusters in families and may be genetically controlled. Twenty-three single nucleotide polymorphisms (SNPs) were genotyped in the cytokine 5q23.3–q31.1 region IRF1-IL5-IL13-IL4-IL9-LECT2-TGFBI in 102 families (323 DTH+; 190 DTH−; 123 VL individuals) from a VL endemic region in northeast Brazil. Data from 20 SNPs were analyzed for association with DTH+/− status and VL using family-based, stepwise conditional logistic regression analysis. Independent associations were observed between the DTH+ phenotype and markers in separate linkage disequilibrium blocks in LECT2 (OR 2.25; P=0.005; 95% CI=1.28–3.97) and TGFBI (OR 1.94; P=0.003; 95% CI=1.24–3.03). VL child/parent trios gave no evidence of association, but the DTH− phenotype was associated with SNP rs2070874 at IL4 (OR 3.14; P=0.006; 95% CI=1.38–7.14), and SNP rs30740 between LECT2 and TGFBI (OR 3.00; P=0.042; 95% CI=1.04–8.65). These results indicate several genes in the immune response gene cluster at 5q23.3–q31.1 influence outcomes of L. chagasi infection in this region of Brazil.

Forum: geographic spread and urbanization of visceral leishmaniasis in Brazil. Postscript: new challenges in the epidemiology of Leishmania chagasi infection

as an example of this process in Brazil, was similar to that observed in the Northeast, with subsequent spread to other cities in the South-east and Central-West. It is worrisome that these endemic areas have a high population density, thus placing the population at increased risk of infection.Dogs have traditionally been considered the principal reservoirs of

Leptospirosis in a subsistence farming community in Brazil

Leptospirosis has been reported in rural areas of Brazil. However, there is limited information about the exposure risk or the risk of Leptospira infection for rural-based populations. A cross-sectional study was carried out in order to determine the prevalence and risk factors for prior Leptospira infection in a rural subsistence farming region of the state of Rio Grande do Norte, an area in which outbreaks of leptospirosis have occurred. Among 290 individuals enrolled, 44 (15.2%) had anti-Leptospira IgM antibodies as determined by IgM ELISA. Infection tended to occur with activities related to the rice fields (P=0.08). Our findings indicate that Leptospira infection occurs even in years of low rainfall, and may have an important impact among poor rural-based subsistence farmers in Brazil. Additional studies are needed to characterize the mode of transmission in this region.

Association of Pro-Inflammatory Cytokines and Iron Regulatory Protein 2 (IRP2) with Leishmania Burden in Canine Visceral Leishmaniasis

Leishmania infantum infection in humans and dogs can evolve with a wide range of clinical presentations, varying from asymptomatic infections to visceral leishmaniasis. We hypothesized that the immune response elicited by L. infantum infection could modulate whether the host will remain asymptomatic or progress to disease. A total of 44 dogs naturally infected with L. infantum were studied. Leishmania burden was estimated in the blood and spleen by qPCR. The expression of IFN-γ, TNF-α, IL-10 and Iron Regulatory Protein 2 (IRP2) were determined in the spleen by quantitative PCR. Sera cytokines were evaluated by ELISA. Dogs were grouped in quartiles according parasite burden. Increased expression of IFN-γ and TNF-α was associated with reduced Leishmania burden, whereas increased IL-10 and IRP2 expressions were associated with higher Leishmania load. Increased plasma albumin and IFN-γ expression explained 22.8% of the decrease in parasite burden in the spleen. These data confirm that lower IFN-γ response and higher IL-10 correlated with increased parasite load and severity of the visceral leishmaniasis in dogs. The balance between the branches of immune response and the intracellular iron availability could determine, in part, the course of Leishmania infection.

A multicentric evaluation of the recombinant Leishmania infantum antigen-based immunochromatographic assay for the serodiagnosis of canine visceral leishmaniasis

BackgroundVisceral leishmaniasis (VL) is a serious public health challenge in Brazil and dogs are considered to be the main urban reservoir of the causative agent. The culling of animals to control VL in some countries makes the accurate diagnosis of canine VL (CVL) essential. Recombinant antigens rLci1A and rLci2B were selected from a cDNA library of Leishmania infantum amastigotes due to their strong potential as candidates in diagnostic testing for CVL. The present multicentric study aimed to evaluate the sensitivity of a prototype test using these antigens (DPP rLci1A/rLci2B) against 154 sera obtained from symptomatic dogs within three endemic areas of VL in Brazil. The specificity was evaluated using 40 serum samples from negative dogs and dogs infected with other pathogens. Sensitivity and specificity rates of DPP rLci1A/rLci2B prototype were compared to rates from other diagnostic tests currently in use by the Brazilian Ministry of Health, including DPP®LVC, EIE®LVC.FindingsDPP rLci1A/rLci2B prototype offered similar performance to that offered by DPP®LVC rapid test, as follows: sensitivity of 87% (CI 81–91) and 88% (CI 82–93) and specificity of 100% (CI 91–100) and 97% (CI 87–100), respectively for DPP rLci1A/rLci2B and DPP®LVC. When results of these two tests were considered concomitantly, sensitivity increased to 93.5% (CI 89–96).ConclusionsThe recombinant antigens rLci1A and rLci2B represent promising candidates for use in a multi-antigen rapid test for CVL. The inclusion of novel antigens to the DPP rLci1A/rLci2B prototype model could offer additionally enhanced sensitivity to detect animals infected by L. infantum.

Identifying Leprosy and Those at Risk of Developing Leprosy by Detection of Antibodies against LID-1 and LID-NDO

Leprosy is caused by Mycobacterium leprae infection and remains a major public health problem in many areas of the world. Challenges to its timely diagnosis result in delay in treatment, which is usually associated with severe disability. Although phenolic glycolipid (PGL)-I has been reported as auxiliary diagnostic tool, currently there is no serological assay routinely used in leprosy diagnosis. The aim of this study was to evaluate the effectiveness of two related reagents, LID-1 and LID-NDO, for the detection of M. leprae infection. Sera from 98 leprosy patients, 365 household contacts (HHC) and 98 endemic controls from Rio Grande do Norte, Brazil, were evaluated. A subgroup of the HHC living in a hyperendemic area was followed for 7–10 years. Antigen-specific antibody responses were highest in multibacillary (MB) at the lepromatous pole (LL/BL) and lowest in paucibacillary (PB) at the tuberculoid pole (TT/BT). A positive correlation for both anti-LID-1 and anti-LID-NDO antibodies was found with bacterial burden (LID-1, r = 0.84, p<0.001; LID-NDO, r = 0.82, p<0.001), with higher sensitivity than bacilloscopy. According to Receiver Operating Curve, LID-1 and LID-NDO performed similarly. The sensitivity for MB cases was 89% for LID-1 and 95% for LID-NDO; the specificity was 96% for LID-1 and 88% for LID-NDO. Of the 332 HHC that were followed, 12 (3.6%) were diagnosed with leprosy in a median time of 31 (3–79) months after recruitment. A linear generalized model using LID-1 or LID-NDO as a predictor estimated that 8.3% and 10.4% of the HHC would become a leprosy case, respectively. Together, our findings support a role for the LID-1 and LID-NDO antigens in diagnosing MB leprosy and identifying people at greater risk of developing clinical disease. These assays have the potential to improve the diagnostic capacity at local health centers and aid development of strategies for the eventual control and elimination of leprosy from endemic areas.