Evidence for a major gene controlling susceptibility to tegumentary leishmaniasis in a recently exposed Bolivian population.

Tegumentary leishmaniasis due to Leishmania braziliensis is a parasitic disease that occurs in two stages after the infected sandfly bite: (1) a primary cutaneous lesion followed by (2) a secondary mucosal involvement generally resulting in severe facial deformities. In order to investigate the genetic and environmental factors involved in the development of the cutaneous lesion, a familial study was performed in a region of Bolivia in which the disease is endemic. Complete selection of 118 nuclear families (703 subjects, with 241 patients), each with at least one cutaneous affected subject, was achieved; 41 families were of native origin, and 77 (herein designated "migrant") recently had settled in the area. For the analysis, the trait under study was the time to onset of the primary cutaneous lesion. The start of the follow-up was birth, for native population, or date of arrival in the endemic area, for migrant population. Segregation analysis was performed by use of a model based on survival analysis methods that allows joint estimation of genetic and environmental effects and accounts for gene x covariate interactions. A significant effect of gender, home-forest distance, and forest-related activity was found. In the 77 migrant families there was evidence for a recessive major gene controlling the onset of the primary cutaneous lesion, with residual familial dependences and age x genotype interaction. Penetrance estimations show that young subjects are genetically more susceptible than older subjects, suggesting that this genetic component could concern mechanisms involved in the development of individual protection during childhood. There was also a significant genetic heterogeneity of the sample according to the native/migrant origin of the families, and no major-gene effect was found in the native subsample.

Risk factors for onset of cutaneous and mucocutaneous leishmaniasis in Bolivia.

A survival analysis was performed on data from an endemic area of Bolivia where two populations, natives and highland migrants, were living, to investigate risk factors for onset of cutaneous leishmaniasis (CL) and its mucosal form (MCL). In a first data set (703 subjects with 242 CL patients), significant risk factors for CL were gender, native/migrant status, activity, and home-forest distance. The instantaneous risk of CL increased until adolescence in both populations, and rapidly decreased thereafter. This risk was 3-10 times higher in migrants than in natives until 20 years of age, and became similar thereafter. Environmental and behavioral factors did not seem sufficient to explain this contrast between the two populations, and this evolution with age may suggest differences in the mechanisms involved in the development of individual protection during childhood. In a second data set (446 CL patients with 34 mucosal forms) the native/migrant status was the main factor associated with the onset of mucosal form.

Rural campaign to diagnose and treat mucocutaneous leishmaniasis in Bolivia.

Mucocutaneous leishmaniasis (MCL) is endemic in the tropical Amazonian lowlands of Bolivia, an area that regularly receives influxes of migratory populations. In these new agricultural development areas, a campaign to diagnose and treat the disease was carried out between 1989 and 1992, in order to provide direct access to MCL treatment in the endemic areas at a standard equivalent to that offered in the urban centres in Bolivia. The campaign led to the creation of decentralized local centres for diagnosis and treatment of the disease. A campaign to inform the population about leishmaniasis was also undertaken and courses were run to educate medical and paramedical personnel. As a result of the campaign, 3285 cases of leishmaniasis were diagnosed, including 2152 cutaneous and 326 mucosal forms. Also, a total of 1888 cases were treated, 1677 of which cutaneous and 211, mucosal.

[Wing morphology and species characterization of sandflies]. / Morphometrie alaire et caracterisation specifique des phlebotomes.

We study the information included in sandfly wings in order to test this organ as a source for the specific discrimination. The cartesian coordinates of the vein intersections are collected using a microscope and a graphic table. From these data a specifically developed software searches for discriminant characters. The present study on 32 New World species shows that, in addition to classical wing indices, discriminative characters are available for inter-specific discrimination.