Etiology of cutaneous leishmaniasis and anthropophilic vectors in Juruti, Pará State, Brazil

First Report of Canine Infection by Leishmania (Viannia) guyanensis in the Brazilian Amazon

The American cutaneous (CL) and visceral leishmaniasis (VL) are zooanthroponoses transmitted by sand flies. Brazil records thousands of human leishmaniasis cases annually. Dogs are reservoirs of Leishmania infantum, which causes VL, but their role in the transmission cycle of CL is debatable. Wild mammals are considered reservoirs of the aetiological agents of CL (Leishmania spp.).

OBJECTIVE

To describe the aetiology of leishmaniasis in dogs in an endemic area for CL and VL in the Amazon, Brazil.

METHODS

Clinical evaluation and blood collection of 40 dogs from the villages Ubim (20) and Socorro (20), city of Tomé-Açu, state of Pará, were carried out. The DNA extracted from the blood was used for PCR with Leishmania-specific primers targeting the hsp70-234 gene sequence. Products were sequenced (ABI3500XL), and the sequences were aligned, edited (BioEdit), and analyzed (Blastn).

RESULTS

Of the 34 amplified samples, 21 were sequenced, namely Leishmania infantum (12), L. guyanensis (5), L. braziliensis (3), and Leishmania sp. (01).

CONCLUSION

Given the diversity of circulating pathogens, elucidation of the role of the dog in the Leishmania spp. cycle in Amazonian villages is imperative to the surveillance of CL in the region. We present the first report in Brazil, confirmed by sequencing, of canine infection by L. guyanensis, a species highly resistant to treatment in humans, with the drug of first choice (Glucantime^®).

Identification of Leishmania species by high-resolution DNA dissociation in cases of American cutaneous leishmaniasis

Background

American cutaneous leishmaniasis is an infectious dermatosis caused by protozoa of the genus Leishmania, which comprises a broad spectrum of clinical manifestations depending on the parasite species involved in the infections and the immunogenetic response of the host. The use of techniques for amplification of the parasites DNA based on polymerase chain reaction polymerase chain reaction and the recent application of combined techniques, such as high-resolution DNA dissociation, have been described as a viable alternative for the detection and identification of Leishmania spp. in biological samples.

Objectives

To identify the Leishmania species using the polymerase chain reaction high-resolution DNA dissociation technique in skin biopsies of hospital-treated patients, and compare with results obtained by other molecular identification techniques.

Methods

A retrospective study assessing patients with suspected American cutaneous leishmaniasis seen at a hospital in São Paulo/Brazil was conducted. The paraffin blocks of 22 patients were analyzed by polymerase chain reaction high-resolution DNA dissociation to confirm the diagnosis and identify the species.

Results

Of the 22 patients with suspected American cutaneous leishmaniasis, the parasite was identified in 14, comprising five cases (35.6%) of infection by L. amazonensis, four (28.5%) by L. braziliensis, two (14.4%) by L. amazonensis + L. infantum chagasi, two (14.4%) by L. guyanensis, and one (7.1%) by Leishmania infantum chagasi. In one of the samples, in which the presence of amastigotes was confirmed on histopathological examination, the polymerase chain reaction high-resolution DNA dissociation technique failed to detect the DNA of the parasite.

Study limitations

The retrospective nature of the study and small number of patients.

Conclusions

The method detected and identified Leishmania species in paraffin-embedded skin biopsies with a sensitivity of 96.4% and could be routinely used in the public health system.

The impact of industrial activities on vector-borne disease transmission

Industrial activities have produced profound changes in the natural environment, including the mass removal of trees, fragmentation of habitats, and creation of larval mosquito breeding sites, that have allowed the vectors of disease pathogens to thrive. We conducted a review of the literature to assess the impact of industrial activities on vector-borne disease transmission. Our study shows that industrial activities may be coupled with significant changes to human demographics that can potentially increase contact between pathogens, vectors and hosts, and produce a shift of parasites and susceptible populations between low and high disease endemic areas. Indeed, where vector-borne diseases and industrial activities intersect, large numbers of potentially immunologically naïve people may be exposed to infection and lack the knowledge and means to protect themselves from infection. Such areas are typically associated with inadequate access to quality health care, thus allowing industrial development and production sites to become important foci of transmission. The altered local vector ecologies, and the changes in disease dynamics that changes affect, create challenges for under-resourced health care and vector-control systems.

Aspects on the Ecology of Phlebotomine Sand Flies (Diptera: Psychodidae) From Guaraí, State of Tocantins, Brazil, Endemic Area for American Cutaneous Leishmaniasis

In Brazil, American cutaneous leishmaniasis (ACL) ecology involves a diversity of Leishmania species transmitted by different sand fly species. Workers involved in agricultural activities are those mainly affected by ACL in some regions from Tocantins State (TO), Brazil, where the disease can be established in new settlements. The objective of this study was to examine the seasonal and hourly frequency of sand fly species, focusing on the potential vectors of ACL, in a settlement in Guaraí (TO), an ACL transmission area. Sand flies were captured in forested area close to Pedra Branca Agricultural Project settlement, from March 2006 until December 2007, using Shannon trap. Monthly captures were made from 06:00 p.m. to 10:00 p.m., and 24-h captures were done twice per semester, from 06:00 a.m. to 06:00 a.m. A total of 10,089 specimens from 30 species were identified. Psychodopygus complexus Mangabeira, Psychodopygus llanosmartinsi Fraiha & Ward, and Nyssomyia antunesi Coutinho were the most abundant species. Nyssomyia antunesi was more frequent during the dry period, whereas Ps. complexus and Ps. llanosmartinsi had high frequencies during the rainy season. Precipitation was positively correlated with Ps. complexus and Ps. llanosmartinsi abundance, and negatively correlated with Ny. antunesi During 24-h captures, the majority of specimens were captured during the night followed by a decrease at dawn. The behavior and previous finding of natural infection by Leishmania (Viannia) braziliensis of Ps. complexus led us to the conclusion that this species can be a potential vector of L. (V.) braziliensis during the rainy season in Guaraí.

The phlebotomine fauna (Diptera: Psychodidae) of Guaraí, state of Tocantins, with an emphasis on the putative vectors of American cutaneous leishmaniasis in rural settlement and periurban areas

Phlebotomine sandflies were captured in rural settlement and periurban areas of the municipality of Guaraí in the state of Tocantins (TO), an endemic area of American cutaneous leishmaniasis (ACL). Forty-three phlebotomine species were identified, nine of which have already been recognised as ACL vectors. Eleven species were recorded for the first time in TO. Nyssomyia whitmani was the most abundant species, followed by Evandromyia bourrouli, Nyssomyia antunesi and Psychodopygus complexus. The Shannon-Wiener diversity index and the evenness index were higher in the rural settlement area than in the periurban area. The evaluation of different ecotopes within the rural area showed the highest frequencies of Ev. bourrouli and Ny. antunesi in chicken coops, whereas Ny. whitmani predominated in this ecotope in the periurban area. In the rural settlement area, Ev. bourrouli was the most frequently captured species in automatic light traps and Ps. complexus was the most prevalent in Shannon trap captures. The rural settlement environment exhibited greater phlebotomine biodiversity than the periurban area. Ps. complexus and Psychodopygus ayrozai naturally infected with Leishmania (Viannia) braziliensis were identified. The data identified Ny. whitmani as a potential ACL vector in the periurban area, whereas Ps. complexus was more prevalent in the rural environment associated with settlements.