An historical review is given of American visceral leishmaniasis (AVL),

American cutaneous leishmaniasis (ACL) in Brazil is caused by a variety of dermotropic Leishmania species and the greatest diversity of these parasites is to be found in the Amazon Region.Transmission of the causal agents involves different species of phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae) in close relationship with the mammalian reservoir hosts of the parasites, with the consequent formation of a number of different transmission cycles throughout the country. The data from ecological and epidemiological studies on the different species of the subgenera Viannia and Leishmania, together with those from experimental laboratory transmissions, have either suggested or definitely indicated certain species of sand flies as being responsible for the transmission of ACL. Relatively few, however, have been considered as outstandingly important vectors.According to the taxonomic criteria proposed by Young and Duncan (1994), three genera of sand flies are recognized in the New World: Lutzomyia França & Parrot, 1924; Brumptomyia França &Parrot, 1921 and Warileya Hertig, 1940. The genus Psychodopygus Mangabeira, 1941 has been accepted by some (Fraiha et al. 1971, Fraiha & Ward 1974, Forattini 1973, Lainson et al. 1973 and modifications of the taxonomy have been suggested (Galati 2003). In this review, however, we propose to follow that of Young & Duncan (1994). Vectorial competence of some neotropical sand fliesLutzomyia (Nyssomyia) intermedia (Lutz & Neiva, 1912) -L. intermedia, described from specimens collected in the Fazenda Ouro Fino, in the state of Minas Gerais (MG), where it was found to be abundant in houses, was one of the first species of sand fly to be described in the Neotropical Region.In the 1940's, important studies on the biology of L. intermedia s.l. were made by Barretto (1943) in the state of São Paulo (SP), together with observations on the behaviour of some other species of sand fly. It is a species found in both primary and secondary forests and particularly in areas where deforestation has gradually modified the ecological profile -clearly seen in those parts of the country that underwent past colonization. As long ago as 1943, Barretto suggested that L. intermedia s.l. had, in fact, developed a preference for secondary forest or low, bushy vegetation located in areas suffering from such human impact and according to Tolezano et al. (1980), the environmental changes that took place in SP at the beginning of the 20th century certainly modified the composition of the phlebotomine fauna. While this caused other species of silvatic sand fly to disappear, or survive at low frequency, L. intermedia s.l. adapted so well to the peridomestic habitat that it actually has become the predominate species of sand fly in a new epidemiological profile for ACL in this region. These authors further suggested that the small numbers of this sand fly now captured in the remaining forest indicates that transmission of ACL by L. intermedia is now taking place solely outside of that habitat.Like most s...

Abstract

Since the description of Lutzomyia longipalpis by Lutz and Neiva more than 100 years ago, much has been written in the scientific literature about this phlebotomine species. Soares and Turco (2003) and Lainson and Rangel (2005) have written extensive reviews focused on vector-host-parasite interactions and American visceral leishmaniasis ecology. However, during the last two decades, the success of Lu. longipalpis in colonising urban environments and its simultaneous geographical spreading have led to new theoretical and operational questions. Therefore, this review updates the general information about this species and notes the more challenging topics regarding the new scenario of urbanisation-spreading and its control in America. Here, we summarise the literature on these issues and the remaining unsolved questions, which pose recommendations for operational research.

No abstract

In a focus of cutaneous leishmaniasis in Jacarepaguá, Rio de Janeiro, one specimen of Lutzomyia intermedia was found naturally infected with Leishmania braziliensis.

After outbreaks of cutaneous leishmaniasis in Solano State, Venezuela, 5% of the population had parasitized ulcers while after similar outbreaks in Mesquita, Rio de Janeiro State, Brazil, 9% had the disease. In these foci children, including some under six years of age, were affected. There was no significant difference in the occurrence of the disease according to sex or type of employment. In Solano, 3% of dogs and 28% of donkeys had parasitized lesions, while in Mesquita these indices were 19.8% and 30.8% respectively. The parasite from man, dogs and equines was identified as Leishmania (Viannia) braziliensis, by zymodeme and serodeme characterization. In these foci there is evidence suggesting that leishmaniasis is a zoonosis, possibly with equines and dogs as reservoirs, although both a wild enzootic cycle and the role of man as a source of infection can not be ruled out. Transmission is assumed to occur peridomestically by sandfly vectors such as Lutzomyia panamensis in Venezuela and Lutzomyia intermedia in Brazil. Information about the origin of these foci suggests that infected equines may be an important factor in the dissemination of the parasite in a peridomestic situation where these sandflies are abundant.

Vector borne diseases are susceptible to climate change because distributions and densities of many vectors are climate driven. The Amazon region is endemic for cutaneous leishmaniasis and is predicted to be severely impacted by climate change. Recent records suggest that the distributions of Lutzomyia (Nyssomyia) flaviscutellata and the parasite it transmits, Leishmania (Leishmania) amazonensis, are expanding southward, possibly due to climate change, and sometimes associated with new human infection cases. We define the vector’s climatic niche and explore future projections under climate change scenarios. Vector occurrence records were compiled from the literature, museum collections and Brazilian Health Departments. Six bioclimatic variables were used as predictors in six ecological niche model algorithms (BIOCLIM, DOMAIN, MaxEnt, GARP, logistic regression and Random Forest). Projections for 2050 used 17 general circulation models in two greenhouse gas representative concentration pathways: “stabilization” and “high increase”. Ensemble models and consensus maps were produced by overlapping binary predictions. Final model outputs showed good performance and significance. The use of species absence data substantially improved model performance. Currently, L. flaviscutellata is widely distributed in the Amazon region, with records in the Atlantic Forest and savannah regions of Central Brazil. Future projections indicate expansion of the climatically suitable area for the vector in both scenarios, towards higher latitudes and elevations. L. flaviscutellata is likely to find increasingly suitable conditions for its expansion into areas where human population size and density are much larger than they are in its current locations. If environmental conditions change as predicted, the range of the vector is likely to expand to southeastern and central-southern Brazil, eastern Paraguay and further into the Amazonian areas of Bolivia, Peru, Ecuador, Colombia and Venezuela. These areas will only become endemic for L. amazonensis, however, if they have competent reservoir hosts and transmission dynamics matching those in the Amazon region.