First Report of Bartonella SP. In Sand Flies (Diptera: Psychodidae: Phlebotominae) From Southern Mexico

Field evaluation of a new suction light trap for the capture of phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae), vectors of leishmaniasis

Phlebotomine sand flies are crepuscular and nocturnal small dipteran insects in the family Psychodidae. Several disease agents, including Leishmania parasites, are transmitted to humans and other vertebrate hosts by the bite of an infected female sand fly. As part of leishmaniasis surveillance programs, light traps have been routinely used in sand fly collections. In this context, new trapping devices are always being required to improve vector monitoring. Here, the efficiency of a new suction light trap, named Silva suction trap or SS trap, was field evaluated in collecting sand flies. Two SS traps, one with green (520 nm, 15,000 mcd) and the other with white (wide spectrum, 18,000 mcd) LEDs, and one CDC-type trap were deployed in a rural forested environment. A total of 4686 phlebotomine sand flies were captured. The most frequent species were females of the Ps. Chagasi series (77.8%) followed by males of Ps. wellcomei (11.6%), Nyssomyia whitmani (3.3%), and Bichromomyia flaviscutellata (2.4%). The CDC-type light trap collected 101.9 ± 20.89 sand flies and 14 species, followed by the white-baited SS trap (87.78 ± 16.36, 14), and the green-baited SS trap (70.61 ± 14.75, 15), but there were no statistically significant differences among traps. A discussion on the considerable advantages of the use of SS traps over CDC traps is included. In this study, the Silva suction trap proved to be efficient and can be an alternative to CDC traps for monitoring adult phlebotomine sand fly populations.

Species diversity and detection of pathogens in phlebotomine sand flies collected from forest management areas of Quintana Roo, Mexico

Sand flies have expanded their areas of distribution, thereby increasing the risk of pathogen transmission in non-endemic areas. To establish efficient prevention and control strategies for the transmission of vector-borne pathogens, it is important to understand seasonal dynamics of their vectors. In Mexico, there are several areas where the contact between sand flies, hosts and reservoirs favours the transmission of the pathogen. We compared sand fly communities in a forest management area and a conserved area in Noh-Bec, Quintana Roo, Mexico. The analysis included species diversity, activity peaks and molecular detection of pathogens. Sand flies were collected from November to December 2021 and April to May 2022, during 84 night-traps. The conserved area showed higher numbers and greater species heterogeneity of sand flies as compared with the other sites. The β-diversity analysis revealed that sites disturbed by logging (S1, S2, S3) had greater similarity (90%) in their sand fly species composition than a conserved area (S4) (similarity = 36%). Although none of the specimens were infected with Leishmania, we detected Wolbachia (19.4%) in all four sites, as well as Bartonella (3.25%) only in the disturbed sites. Further studies on the dynamics of sand fly populations and their association with pathogens are necessary.

Entomological Survey and Leishmania (Leishmania) mexicana Prevalence in Sand Fly Species during an Outbreak of Cutaneous Leishmaniasis in Quintana Roo State, Mexico

(1) Background: Localized cutaneous leishmaniasis is a neglected vector-borne disease that has become a serious public health problem in the Yucatan Peninsula. Although more than 60% of cases originate from the state of Quintana Roo, it is one of the least explored areas in terms of incriminating vectors of the Leishmania parasite. Additionally, cases of leishmaniasis have increased substantially in that region in recent years. For this reason, we explored and provided primary evidence of Leishmania DNA in sand fly species from four localities during outbreaks of leishmaniasis in Quintana Roo. We also contributed information on the regional genetic diversity of Leishmania parasites. (2) Methods: Sand flies were collected during several periods from November 2022 to April 2023 using Mosquito Light Circle and Shannon traps, as well as an active entomological search in refuges. For Leishmania detection, we amplified a fragment of 300-350 bp of the internal transcribed spacer subunit 1 (ITS-1). (3) Results: Of the 242 females collected, we detected Leishmania DNA in 25 specimens represented by Bichromomyia olmeca (1), Psathyromyia shannoni (17), Lutzomyia cruciata (4), Psathyromyia undulata (2), and Dampfomyia deleoni (1). The detection of Leishmania in these last two species represents new records for the Yucatan Peninsula and for Mexico. Leishmania (Leishmania) mexicana was the only species detected in the Phlebotominae species, with prevalence values that ranked between 7.41% and 33.33% from specimens collected in the sylvatic areas of Cozumel Island and Petcacab. (4) Conclusions: This study provides the first evidence of infection of Da. deleoni and Pa. undulata by L. (L.) Mexicana. In addition, the presence of three dominant haplotypes in all the evaluated localities was evidenced using the analysis of genetic diversity, and the locality of Petcacab was the one with the circulation of two new haplotypes not previously described in Mexico or neighboring countries. These results highlight the importance of intensive epidemiological surveillance due to the dynamics of transmission of Leishmania between different species.

Molecular detection of Wolbachia and Bartonella as part of the microbiome of phlebotomine sand flies from Chiapas, Mexico

Phlebotomine sand flies are dipterans of relevance due to their role as vectors of several pathogens worldwide. Bacteria in the gut of sand flies possibly affect their vectorial capacity and competence to transmit parasites. A retrospective study was performed in sand fly specimens that had previously been collected in four localities of the state of Chiapas during the period 2009-2011 to detect Wolbachia and Bartonella and their possible coinfection with Leishmania. For the molecular detection of bacteria, we used primers and conditions that had previously been reported. A total of 531 sand fly specimens of 10 species were analyzed. Four Wolbachia strains were detected in five sand fly species, showing a prevalence of 8.6%. All the Wolbachia strains had previously been reported in other taxa. In one sand fly species, we also detected a new lineage of Bartonella evidenced by a phylogenetic analysis. No sand fly specimens showed coinfections of these bacteria and Leishmania. The bacteria found in the phlebotomine sand flies are possibly transmitted by plant-mediated horizontal transmission and during blood meal feeding.

Molecular phylogeny of heritable symbionts and microbiota diversity analysis in phlebotominae sand flies and Culex nigripalpus from Colombia

Background

Secondary symbionts of insects include a range of bacteria and fungi that perform various functional roles on their hosts, such as fitness, tolerance to heat stress, susceptibility to insecticides and effects on reproduction. These endosymbionts could have the potential to shape microbial communites and high potential to develop strategies for mosquito-borne disease control.

Methodology/Principal findings

The relative frequency and molecular phylogeny of Wolbachia, Microsporidia and Cardinium were determined of phlebotomine sand flies and mosquitoes in two regions from Colombia. Illumina Miseq using the 16S rRNA gene as a biomarker was conducted to examine the microbiota. Different percentages of natural infection by Wolbachia, Cardinium, and Microsporidia in phlebotomines and mosquitoes were detected. Phylogenetic analysis of Wolbachia shows putative new strains of Lutzomyia gomezi (wLgom), Brumptomyia hamata (wBrham), and a putative new group associated with Culex nigripalpus (Cnig) from the Andean region, located in Supergroup A and Supergroup B, respectively. The sequences of Microsporidia were obtained of Pi. pia and Cx. nigripalpus, which are located on phylogeny in the IV clade (terrestrial origin). The Cardinium of Tr. triramula and Ps. shannoni were located in group C next to Culicoides sequences while Cardinium of Mi. cayennensis formed two putative new subgroups of Cardinium in group A. In total were obtained 550 bacterial amplicon sequence variants (ASVs) and 189 taxa to the genus level. The microbiota profiles of Sand flies and mosquitoes showed mainly at the phylum level to Proteobacteria (67.6%), Firmicutes (17.9%) and Actinobacteria (7.4%). High percentages of relative abundance for Wolbachia (30%-83%) in Lu. gomezi, Ev. dubitans, Mi. micropyga, Br. hamata, and Cx. nigripalpus were found. ASVs assigned as Microsporidia were found in greater abundance in Pi. pia (23%) and Cx. nigripalpus (11%). An important finding is the detection of Rickettsia in Pi. pia (58,8%) and Bartonella sp. in Cx. nigripalpus.

Conclusions/Significance

We found that Wolbachia infection significantly decreased the alpha diversity and negatively impacts the number of taxa on sand flies and Culex nigripalpus. The Principal Coordinate Analysis (PCoA) is consistent, which showed statistically significant differences (PERMANOVA, F = 2.4744; R2 = 0.18363; p-value = 0.007) between the microbiota of sand flies and mosquitoes depending on its origin, host and possibly for the abundance of some endosymbionts (Wolbachia, Rickettsia).

The secondary endosymbionts can positively influence the metabolism of many compounds essential for the survival of the insect vectors, provide resistance to pathogens and impact susceptibility to insecticides, as also the tolerance to heat stress. We provide information from new records of natural infection of secondary endosymbionts, such as Wolbachia, Cardinium, Microsporidia, Flavobacterium, and Rickettsia in phlebotomine sand flies and mosquitoes from Colombia. An important finding is the detection of Bartonella sp. in Cx. nigripalpus. Clear differences were found in the composition and diversity of microbiota at the intra-specific and interspecific levels in sand flies and Cx. nigripalpus, which may depend in the of the load of natural infection of endosymbionts (as Wolbachia), the geographical distribution and host.

Molecular Detection of Bartonella sp. in Psathyromyia shannoni and Lutzomyia cruciata From Northeastern Mexico

Phlebotomine sand flies are vectors of Leishmania spp., Bartonella bacilliformis, and several arboviruses worldwide. In Mexico, the presence of Bartonella species is associated sporadically with arthropods and little is known on the diversity of insects that could be incriminated with its transmission. The aim of this study was to perform a molecular detection of Bartonella DNA in sand fly species collected in northeastern Mexico. Sand flies were collected at the states of Nuevo Leon and Tamaulipas from June to August 2010, using 16 light traps per night. Sand fly species were morphologically identified, and for Bartonella detection, we amplified ~378 bp of the citrate synthase gene (gltA). DNA sequences were compared in a phylogenetic reconstruction based on maximum likelihood. A total of 532 specimens from seven sand fly species were morphologically identified, where 11 specimens from Tamaulipas tested positive for the presence of a new lineage of Bartonella sp. associated with Psathyromyia shannoni and Lutzomyia cruciata. This work represents the second record of Bartonella-associated with sand flies outside of the endemic area of Carrion’s disease. More studies are necessary to understand their life cycle, transmission dynamics, and their relationship with sand fly species.

Detection of Changuinola virus (Reoviridae: Orbivirus) in field-caught sand flies in southern Thailand

BACKGROUND

Phlebotomine sand flies are vectors for several pathogenic bacteria, parasites and viruses that have significant impacts on public health. Sand fly-associated viruses that cause diseases in humans and animals have recently received more attention. This study aimed to detect pathogenic viruses belonging to the Orbivirus genus, Phlebovirus genus, Flavivirus genus and family Rhabdoviridae in several field-caught sand fly species in southern Thailand.

METHODS

Sand flies were collected in southern Thailand using CDC light traps. Each sample was processed individually for virus screening using RT-PCR and sequencing.

RESULTS

Seven out of 60 sand fly samples (two samples of Idiophlebotomus spp., three of Phlebotomus papatasi and two of Sergentomyia khawi) were positive for the Orbivirus genus, which is closely related to Changuinola virus (CGLV). Phlebovirus genus, Flavivirus genus and family Rhabdoviridae were negative in all samples.

CONCLUSIONS

CGLV causes Changuinola virus disease or Changuinola fever, a febrile illness in Central and South America. The virus has never been reported in Thailand. This study is the first report of the detection of CGLV in sand flies from Thailand. An extensive study of sand flies from other regions of the country and the associations between sand flies, viruses and vertebrate hosts in Thailand should be undertaken.