Experimental Infection of Lutzomyia (Nyssomyia) whitmani (Diptera: Psychodidae: Phlebotominae) With Leishmania (Viannia) braziliensis and Leishmania (L.) amazonensis, Etiological Agents of American Tugumentary Leishmaniasis

Oral and Intragastric: New Routes of Infection by Leishmania braziliensis and Leishmania infantum?

Although Leishmania transmission in nature is associated with the bite of an infected sandfly vector, other possible transmission routes are speculated to occur, such as the oral route. We evaluated the possibility of infection by this route in golden hamsters (Mesocricetus auratus) using Leishmania braziliensis (Lb) and Leishmania infantum (Li). Hamsters were exposed to experimental oral or intragastrical infection with axenic promastigotes, besides oral ingestion of a suspension of cultivated macrophages infected with amastigotes, lesion-fed Lutzomyia longipalpis, skin lesion or infective spleen fragment. The parasite's isolation, besides a positive PCR and IFAT, confirmed the intragastric infection by promastigote parasites. The oral ingestion of macrophages infected with L. braziliensis amastigotes was also infective. These results confirmed that Leishmania parasites could infect mammals by the intragastric route through the ingestion of promastigote forms (what can happen after a sandfly ingestion) and by the oral ingestion of infected macrophages (what can happen in nature in a predator-prey interaction). The better understanding of these alternative routes is essential to understand their transmission dynamics in nature. As far as we know, this is the first time that oral and intragastric Leishmania transmission has been experimentally demonstrated, constituting new infection routes, at least for L. infantum and L. braziliensis.

Predictive modeling of sand fly distribution incriminated in the transmission of Leishmania (Viannia) braziliensis and the incidence of Cutaneous Leishmaniasis in the state of Paraná, Brazil

Southern Brazil concentrates a considerable number of cases of cutaneous leishmaniasis reported since 1980, and Paraná is the state that most records CL cases in the region. The main sand fly species incriminated as vectors of Leishmania (Viannia) braziliensis (Vianna,1911) are Migonemyia (Migonemyia) migonei (França, 1920), Nyssomyia (Nyssomyia) neivai (Pinto, 1926) and Nyssomyia (Nyssomyia) whitmani (Antunes & Coutinho, 1936). In this study, we evaluated areas with climatic suitability for the distribution of these vectors and correlated these data with CL incidence in the state. The occurrence points of Mg. migonei, Ny. neivai, and Ny. whitmani were extracted from a literature review and field data. For CL analysis in the state of Paraná, data were obtained from the Informatics Department of the Unified Health System of Brazil (DATASUS), covering the period from 2001 to 2019. The layers of bioclimatic variables from the WorldClim database were used in the study. Species distribution modeling was developed using the MaxEnt Software version 3.4.4. ArcGIS software version 10.5 was used to develop suitability maps and the graphical representation of disease incidence. The AUC values were acceptable for all models (> 0,8). Bioclimatic variables BIO13 and BIO14 were the most influential in the distribution of Mg. migonei, while BIO19 and BIO6 were the variables that most influenced the distribution of Ny. neivai, and Ny. whitmani was most influenced by variables BIO5 and BIO9. During 19 years, 4992 cases of CL were reported in the state by 286 municipalities (71,6%). Northern Paraná showed the highest number of areas with very high and high climatic suitability for the occurrence of these species, coinciding with the highest number of CL cases. The modeling tools allowed analyzing the association between climatic variables and the geographical distribution of CL in the state. Moreover, they provided a better understanding of the climatic conditions related to the distribution of different species, favoring the monitoring of risk areas, the implementation of preventive measures, risk awareness, early and accurate diagnosis, and consequent timely treatment.

Diversity of phlebotomine sand flies and molecular detection of trypanosomatids in Brumadinho, Minas Gerais, Brazil

This study aimed to describe the sand fly fauna and detect trypanosomatids in these insects from Casa Branca, state of Minas Gerais, Brazil, an endemic area of both visceral (VL) and tegumentary leishmaniasis (TL). Sand flies were collected bimonthly from May 2013 to July 2014, using automatic light traps exposed for three consecutive nights in peridomiciliary areas of nine houses with previous reports of VL and TL. ITS1-PCR and DNA sequencing were performed for trypanosomatids identification. A total of 16,771 sand flies were collected belonging to 23 species. The most abundant species was Nyssomyia whitmani (Antunes & Coutinho, 1939) (70.9%), followed by Lutzomyia longipalpis (Lutz & Neiva, 1912) (15.2%) and Migonemyia migonei (França, 1920) (9.1%). Leishmania amazonensis DNA was detected in Ny. whitmani (four pools) and Le. braziliensis DNA was detected in Psychodopygus lloydi (one pool). In seven pools of Ny. whitmani and in one pool of Lu. longipalpis positive for Leishmania DNA, the parasite species was not determined due to the low quality of the sequences. Moreover, DNA of Herpetomonas spp. was detected in Ny. whitmani (two pools) and Cortelezzii complex (one pool). DNA of Crithidia spp. was detected in Ny. whitmani and Ps. lloydi (both one pool). Our results suggest that Ny. whitmani may be involved in the transmission of Le. amazonensis in the study area. The molecular detection of Le. amazonensis suggests the presence of this species in a sylvatic cycle between vertebrate and invertebrate hosts in the region of Casa Branca. Our data also reveal the occurrence of other non-Leishmania trypanosomatids in sand flies in Casa Branca District.

Molecular Identification of Leishmania spp. in Sand Flies (Diptera: Psychodidae: Phlebotominae) in the Lençóis Maranhenses National Park, Brazil

Sand flies are very common in the region of Lençóis Maranhenses National Park, an important tourist attraction in Brazil. However, the role of some species and their relative importance locally in Leishmania Ross 1903 transmission is unclear. The objective of this study was to identify Leishmania infection in phlebotomine sand flies collected around the Lençóis Maranhenses National Park, an important conservation area and popular international/national tourist destination with a high incidence of leishmaniasis. Sand flies were collected in peridomiciliary areas on the tourist route from September 2012 to August 2013. The captured females were subjected to molecular analyses for the detection of Leishmania DNA. Sand flies were infected with four Leishmania species: Leishmania (Viannia) braziliensis (Vianna, 1911) was found in Lutzomyia whitmani (Antunes and Coutinho, 1939) (2.1%) and Lutzomyia longipalpis (Lutz and Neiva, 1912) (1.7%); Leishmania (Leishmania) infantum (Nicole, 1908) infected Lutzomyia wellcomei (Fraiha, Shaw, and Lainson, 1971) (20%), Lutzomyia sordellii (Shannon and Del Ponte, 1927) (4.3%), Lu. longipalpis (3.7%), and Lu. whitmani (0.8%); Leishmania (Leishmania) amazonensis (Lainson & Shaw, 1972) was found in Lu. whitmani (0.58%), while Leishmania (Viannia) lainsoni infected Lutzomyia evandroi (Costa Lima and Antunes, 1936) (3.4%), Lu. longipalpis (1.06%), and Lu. whitmani (0.29%). The occurrence of these parasites requires control measures to reduce the incidence of cutaneous leishmaniasis and to contain a possible epidemic of visceral leishmaniasis, the most severe form of the disease.

The role of gallery forests in maintaining Phlebotominae populations: potential Leishmania spp. vectors in the Brazilian savanna

BACKGROUND

Knowledge on synanthropic phlebotomines and their natural infection by Leishmania is necessary for the identification of potential areas for leishmaniasis occurrence.

OBJECTIVE

To analyse the occurrence of Phlebotominae in gallery forests and household units (HUs) in the city of Palmas and to determine the rate of natural infection by trypanosomatids.

METHODS

Gallery forests and adjacent household areas were sampled on July (dry season) and November (rainy season) in 2014. The total sampling effort was 960 HP light traps and eight Shannon traps. Trypanosomatids were detected in Phlebotominae females through the amplification of the SSU rDNA region, and the positive samples were used in ITS1-PCR. Trypanosomatid species were identified using sequencing.

FINDINGS

A total of 1,527 sand flies representing 30 species were captured in which 949 (28 spp.) and 578 (22 spp.) were registered in July and November, respectively. In July, more specimens were captured in the gallery forests than in the HUs, and Nyssomyia whitmani was particularly frequent. In November, most of the specimens were found in the HUs, and again, Ny. whitmani was the predominant species. Lutzomyia longipalpis was commonly found in domestic areas, while Bichromomyia flaviscutellata was most frequent in gallery forests. Molecular analysis of 154 pools of females (752 specimens) identified Leishmania amazonensis, L. infantum, and Crithidia fasciculata in Ny. whitmani, as well as L. amazonensis in Lu. longipalpis, Trypanosoma sp. and L. amazonensis in Pintomyia christenseni, and L. amazonensis in both Psathyromyia hermanlenti and Evandromyia walkeri.

MAIN CONCLUSIONS

These results show the importance of gallery forests in maintaining Phlebotominae populations in the dry month, as well as their frequent occurrence in household units in the rainy month. This is the first study to identify Leishmania, Trypanosoma, and Crithidia species in Phlebotominae collected in Palmas, Tocantins, Brazil.

Sandfly fauna (Diptera: Psychodidae) in an urban area, Central-West of Brazil

Biological and ecological relations among vectors and their pathogens are important to understand the epidemiology of vector-borne diseases. Camapuã is an endemic area for visceral and tegumentary leishmaniasis. The aim of this study was to characterize the sandfly fauna present in Camapuã , MS, Brazil. Sand flies were collected every fortnight from May 2014 to April 2015 using automatic light traps in the domicile and peridomicile of twelve neighborhoods and forest. The collected specimens were identified based on morphology according to the valid identification keys. In total, 2005 sandflies of five genera and nine species were collected. Nyssomyia whitmani and Lutzomyia cruzi were the most abundant species. Males were more abundant, with a male-to-female ratio of 2.14. The highest diversity was observed in peripheral neighborhood, with abundant plant cover. The peridomicile presented greater abundance of sandflies, with the predominance of Ny. whitmani . No significant correlation between the absolute frequencies of the most abundant species and the precipitation variable was observed; however, there was a predominance of Lu. cruzi in the rainy season. We observed a high frequency of sandflies in urban area, especially vector species. The presence of Nyssomyia whitmani and Lutzomyia cruzi indicate the necessity for health surveillance in the municipality. Additional method of collection such as sticky trap is also recommended for appropriate faunestic study.