Surveillance of sand flies (Psychodidae, Phlebotominae) from Mexico: altitudinal and climatic patterns after historical and new geographic records in endemic areas of leishmaniasis.

This study updates knowledge on historical geographic distribution of sand fly species through identifying altitudinal and bioclimatic patterns in leishmaniasis endemic areas in Mexico. We analyze and identify sand fly specimens obtained through national efforts by the Instituto de Diagnóstico y Referencia Epidemiológicos (InDRE, Mexico), collected between 1995-2001, 2008-2012, and 2017-2023, and add bibliographic information (427 additional records). After a principal components analysis of WorldClim variables and altitudinal ranges, variables that better explain the distribution of sand fly species were chosen (BIO6, BIO12, and BIO16, explaining 72% of variation). A total of 1,187 specimens of 22 species were retrieved from eight states, providing 29 new municipalities and 48 new localities, being Lutzomyia cruciata, Micropygomyia chiapanensis, and Psathyromyia shannoni the most common species. We presented new historical records of distribution for sand fly species from Morelos (3), Oaxaca (7) and Tabasco (1). The 82.7% of sand fly species analyzed were distributed in areas with altitudinal ranges below 420 m. The anthropophilic species Psathyromyia shannoni, and Lutzomyia cruciata showed the greatest variability regarding altitudinal range, and climatic preferences, while several wild species showed abiotic preferences. It is likely that the effect of urbanization and climate change generate new beneficial biotopes for the proliferation of the vector sand fly species. Complementary studies that consider seasonality, vegetation types, and change in land use could provide new information to better understand the spread of vector-borne diseases.

New records of Rhipicephalus linnaei infected by Rickettsia massiliae from Central Mexico.

BACKGROUND: On the American continent, Rhipicephalus sanguineus s.l. comprises two species: Rhipicephalus linnaei and R. sanguineus s.s. Each species has been identified as a potential vector of at least one of five species of pathogenic bacteria of the genus Rickettsia. In particular, Rickettsia massiliae is one of three species with the greatest importance in public health at the continental level. In Mexico, this species is reported exclusively in the Nearctic states of Baja California and Chihuahua. AIM: For this reason, the aim of this work was to provide new records of R. massiliae for the centre of the country derived from active acarological surveillance. MATERIALS AND METHODS: During the period of February-October 2019, 29 dogs from six municipalities in the state of Morelos were sampled. Hosts were visually inspected, and ticks were recovered and identified morphologically and molecularly by amplification of the 16S rDNA gene. Subsequently, five genes from members of the genus Rickettsia were amplified and sequenced. RESULTS: A total of 229 (117♀, 98♂ and 14 N) ticks identified as R. linnaei were recovered, two of which were positive for R. massiliae strains related to those recovered from Argentina and the United States. CONCLUSIONS: This work provides the second record of R. massiliae infecting R. linnaei in Mexico and the Americas, increasing the geographic distribution of this Rickettsia species in the Neotropical region, and providing information on the possible role of R. linnaei as a potential vector of this microorganism.

Design and Evaluation of a Sticky Attractant Trap for Intra-Domiciliary Surveillance of Aedes aegypti Populations in Mexico.

Surveillance consists of systematic data collection, analysis, and interpretation and is essential for planning and implementing control activities. The lack of success in the control and surveillance of the Ae. aegypti mosquito elsewhere demands the development of new accessible and effective strategies. This work aimed to develop and evaluate an adhesive lure trap for household indoor surveillance of Ae. aegypti. Based on a bibliographic review, four compounds that have significant attraction percentages for Ae. aegypti were considered. Our more effective blend was determined through preliminary bioassays using the high-throughput screening system (HITSS) and 90 × 90 cm mosquito cages. We designed a low-cost, pyramid-shaped, sticky cardboard trap to incorporate the selected blend. Semi-field 2 × 2 m cages and field tests were utilized to evaluate its effectiveness through mosquito capture percentages. In laboratory tests, blend number 2 presented an attraction percentage of 47.5 ± 4.8%; meanwhile, in semi-field cages, a 4-inch, 110 v powered fan was used to disperse the attractants, and then a similar capture percentage of 43.2 ± 4.0% was recorded. Results were recorded during the field evaluation of the at-house indoor environment and were compared with those recorded with the golden-standard BG-Sentinel trap, i.e., our prototype trapped an average of 6.0 ± 1.5 mosquitoes versus 10.0 ± 2.6. In most Latin American countries, there is a lack of formal and accessible strategies for monitoring adult populations of Ae. Aegypti; therefore, we must develop tools that reinforce entomological surveillance methods.

Updated checklist of the mosquitoes (Diptera: Culicidae) of Mexico.

Based on historical and recent records, an updated list of 244 nominal species and three undescribed mosquitoes from Mexico is presented. Since 1990, 15 species have been recorded for the first time in Mexico: Aedes guatemala, Ae. brelandi, Ae. insolitus, Ae. melanimon, Ae. albopictus, Culex daumastocampa, Cx. metempsytus, Cx. erethyzonfer, Culiseta melanura, Limatus asulleptus, Sabethes gymnothorax, Trichoprosopon pallidiventer, Toxorhynchites moctezuma, Uranotaenia socialis, and Wyeomyia chalcocephala. Five species were discovered and described: Ae. amaterui, Ae. lewnielseni, Cx. diamphidius, Shannoniana huasteca, and Tr. mixtli. Three species were discovered without yet describing or naming them: Ae. (Protomacleaya) sp. 1, Ae. (Ochlerotatus) sp. 2, and Wyeomyia sp. 3. Five species had been removed from the Mexican mosquito fauna: Ae. stigmaticus, Cx. imitator, Onirion personatum, Sa. tarsopus, and Tx. theobaldi. With the intention of updating the checklist of the mosquito species in Mexico, historical and recent species records were reviewed, as well as the review of entomological collections, resulting in the confirmation of the presence in Mexico of Ae. thelcter, Cs. impatiens, and Orthopodomyia alba. Morphological and molecular evidence confirms the presence of Wy. jocosa, while Anopheles atropos, Psorophora confinnis, Cx. jenningsi, Mansonia indubitans, Tr. pallidiventer, and Tr. soaresi are removed from the Mexican mosquito fauna.

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 ß-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.

Is Psathyromyia shannoni (Diptera: Psychodidae: Phlebotominae) a species complex? Retrospective study of genetic diversity of COI gene, pathogens and geographic distribution.

The sand fly Psathyromyia shannoni is a broadly distributed species that is relevant for the transmission of pathogens such as Leishmania, Bartonella and viruses in several countries of America. This species belongs to the Shannoni complex. Yet its identification is difficult due to morphologic intraspecific polymorphisms that make it difficult to distinguish between species, and could therefore lead to misidentification and overestimation of its distribution. The aim of this study was to perform a retrospective study on the genetic diversity of Pa. shannoni based on the Cytochrome Oxidase subunit 1 gene and considering its geographic distribution to achieve a better identification and differentiation from other species of the Shannoni complex. According to the Maximum Likelihood analysis and the data on the genetic structure, we propose a modified delimitation of Pa. shannoni species by classifying it into at least three genetic lineages, based on genetic variability and distribution. However, more genetic information on the COI gene, mainly from countries where this species has been reported, is needed to strengthen this proposal.

Detection of Wolbachia and Leishmania DNA in sand flies (Diptera: Psychodidae, Phlebotominae) from a focus of cutaneous leishmaniasis in Tabasco, Mexico.

Phlebotomine sand flies are the main vectors of Leishmania genus species worldwide; therefore, the detection of some reproductive parasites, such as Wolbachia, has been considered a possible strategy for biological control. In Mexico, leishmaniasis cases have been recorded in 25 states, yet only two sand fly species have been related to Wolbachia spp. Although the state of Tabasco has a high number of leishmaniasis cases, only few studies have been done on sand fly species. The aim of this study was to analyze the diversity of sand fly species and to detect Wolbachia spp. and/or Leishmania spp. in the captured specimens. Sand flies were collected at the locality of Huimango, Tabasco, Mexico, during October 2019, using nine light traps (CDC) and two Shannon traps per night. The specimens were identified and females were analyzed by PCR for the DNA detection for pathogens. A total of 193 sand fly specimens belonging to five species were morphologically identified. Pintomyia ovallesi was the most abundant species (76.84%), followed by Micropygomyia cayennensis (6.40%). Furthermore, first records of four sand fly species were established for the state of Tabasco, thereby increasing the species richness in the state from four to eight. We observed a natural infection rate of 9.7% (10/103) for Leishmania and 0.91% (1/103) for Wolbachia. The importance of conducting entomological surveys in endemic areas of leishmaniasis in Mexico is highlighted, to determine whether other sand fly species may be potential vectors of Leishmania spp., and if some Wolbachia strains could be relevant for the control of leishmaniasis.

Species diversity and blood meal sources of phlebotomine sand flies (Diptera: Psychodidae) from Los Tuxtlas, Veracruz, Mexico.

Phlebotomine sand flies can transmit several species of the genus Leishmania, that cause leishmaniasis, a serious neglected tropical disease worldwide. Although Mexico is an endemic country for the disease, studies on the biology, ecology, and the identification of blood meal sources of phlebotomine sand flies in some states remain unexplored. For this reason, this study aimed to evaluate the species diversity of sand flies, and identify their blood meal sources in the Biosphere Reserve Los Tuxtlas, Veracruz, an area with a high prevalence of Leishmania infantum. The cumulative sampling effort of sand flies covered 300 trap-nights between March 2011 and May 2013. For estimating species diversity, we calculated the species richness (q = 0), the diversity of the species (q = 1) and the dominant species (q = 2). To identify the blood meal sources, we amplified and sequenced a fragment of ≈400 bp of the vertebrate Cytb gene. A total of 951 specimens belonging to 15 species were collected. Psathyromyia aclydifera and Psychodopygus panamensis were the most abundant species. We were able to identify seven terrestrial vertebrate species, among which human beings were the most common source of the blood meal. In this study, relevant information on the structure of sand fly populations and their blood meal sources was obtained, providing basic and important information about the interactions between sand flies, hosts and Leishmania species.

Temporal Viability of Aedes aegypti and Aedes albopictus Eggs Using Two Hygroscopic Substances as Preservatives under a Sterile Insect Technique (SIT) Program in Southern Mexico.

Dengue and other Aedes-borne diseases have dramatically increased over the last decades. The Sterile Insect Technique (SIT) has been successfully used as part of integrated pest strategies to control populations of insect-plant and livestock pests and is currently being tested as a potential method to reduce mosquito populations in an environmentally friendly approach. However, during the mass rearing steps needed to produce millions of mosquitoes, egg storage and preservation are essential for a certain amount of time. Eggs of Aedes aegypti have a chorionic pad that functions as a sticky substance to glue them onto the inner walls of larval breeding sites. The chorionic pad is chemically made of hyaluronic acid, a hygroscopic compound, responsible to protect them from desiccation over time. Two commercial products with hygroscopic properties, hydrolyzed collagen, and Hyalurosmooth®, both were tested to assess their ability to prolong egg life storage for A. aegypti and A. albopictus. Results showed that 85-95% of Ae. aegypti eggs were able to hatch up to week 8 after being treated with both hydrophilic compounds, compared with the control 66.3%. These two substances showed promising effects for keeping Ae. aegypti eggs viable during prolonged storage in mass rearing insect production focused on vector control SIT programs.

Pediculosis Affects Mexican Children from Different Socioeconomic Status Equally: A Cross-Sectional Study.

The prevalence of pediculosis in Mexican children was studied in San Nicolas and Tapachula, Mexico. A cross-sectional study included 888 students between six and 12 years old from two urban communities with an unequal socioeconomic status between September 2015 and March 2016. A Pearson χ2 and multivariate logistic analysis were carried out to associate risk factors to pediculosis. The overall prevalence of pediculosis from both localities was 23.9%. The female gender; long and medium hair; living with someone infested; previously infested by head lice and curling hair were variables linked to a significantly higher prevalence of pediculosis (p < 0.01). Nevertheless, no significant differences were observed in the age groups, localities and socioeconomic status for human lice infection. Socioeconomic variables such as numbers of inhabitants, floors of house, beds and rooms; and parents' qualification did not show a significative association for pediculosis. Health education in schools is needed for pediculosis prevention and remove the stigmatization of this disease related to poverty.

Molecular Detection of Leptospira interrogans and Borrelia burgdorferi in Wild Rodents from Mexico.

Leptospirosis and Lyme borreliosis are zoonotic emerging diseases of global importance and wide distribution. The aim of this study was to detect by molecular testing to Leptospira interrogans and Borrelia burgdorferi sensu lato in wild rodents from Nuevo Leon, Quintana Roo, and Campeche, Mexico. This study is the first in report to Chaetodipus nelsoni, Dipodomys merriami, and Peromyscus eremicus infected with L. interrogans in Mexico. Besides, Chaetodipus hispidus, Heteromys gaumeri, Heteromys irroratus, Neotoma micropus, Peromyscus leucopus, Peromyscus maniculatus, and Sigmodon hispidus infected with B. burgdorferi s.l. in Mexico. Also, is the first report in identify coinfection of L. interrogans and B. burgdorferi s.l. in wild rodents such as H. irroratus and S. hispidus in Nuevo Leon, and H. gaumeri in Quintana Roo, Mexico. These wild rodent species infected represent a risk factor for the exposed population in these sylvatic and rural areas of Mexico.

Identification of phlebotomine sand flies (Diptera: Psychodidae) from leishmaniasis endemic areas in southeastern Mexico using DNA barcoding.

Leishmaniasis, a vector-borne disease transmitted to humans through the bite of phlebotomine sand flies, is of public health significance in southeastern Mexico. Active and continuous monitoring of vectors is an important aspect of disease control for the prediction of potential outbreaks. Thus, the correct identification of vectors is paramount in this regard. In this study, we employed DNA barcoding as a tool for identifying phlebotomine sand flies collected in localized cutaneous leishmaniasis endemic areas of Quintana Roo, Mexico. Specimens were collected using CDC light and Shannon traps as part of the Mexican Ministry of Health surveillance program. DNA extraction was carried out using a nondestructive protocol, and morphological identification based on taxonomic keys was conducted on slide-mounted specimens. Molecular taxonomic resolution using the 658-bp fragment of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene was 100% congruent with the morphological identification. Seven species were identified: Lutzomyia cruciata (Coquillett 1907), Lutzomyia longipalpis (Lutz & Neiva 1912), Psathyromyia shannoni (Dyar 1929), Dampfomyia deleoni (Fairchild & Hertig 1947), Dampfomyia beltrani/steatopyga (Vargas & Díaz-Nájera 1951), Bichromomyia olmeca olmeca (Vargas & Díaz-Nájera, 1959), and Brumptomyia mesai (Sherlock 1962). Mean intraspecific divergence ranged from 0.12% to 1.22%, while interspecific distances ranged from 11.59% to 19.29%. Neighbor-joining (NJ) analysis using the Kimura 2-parameter model also showed specimens of the same species to be clustered together. The study provides the first cox1 sequences for three species of sand flies and indicates the utility of DNA barcoding for phlebotomine sand flies species identification in southeastern Mexico.

Ecology of phlebotomine sandflies and putative reservoir hosts of leishmaniasis in a border area in Northeastern Mexico: implications for the risk of transmission of Leishmania mexicana in Mexico and the USA.

Leishmaniases are a group of important diseases transmitted to humans through the bite of sandfly vectors. Several forms of leishmaniases are endemic in Mexico and especially in the Southeast region. In the Northeastern region, however, there have only been isolated reports of cases and scanty records of sandfly vectors. The main objective of this study was to analyze the diversity of sandflies and potential reservoir hosts of Leishmania spp. in the states of Nuevo León and Tamaulipas. Species richness and abundances of sandflies and rodents were recorded. A fraction of the caught sandflies was analyzed by PCR to detect Leishmania spp. Tissues from captured rodents were also screened for infection. Ecological Niche Models (ENMs) were computed for species of rodent and their association with crop-growing areas. We found 13 species of sandflies, several of which are first records for this region. Medically important species such as Lutzomyia anthophora, Lutzomyia diabolica, Lutzomyia cruciata, and Lutzomyia shannoni were documented. Leishmania spp. infection was not detected in sandflies. Nine species of rodents were recorded, and Leishmania (Leishmania) mexicana infection was found in four species of Peromyscus and Sigmodon. ENMs showed that potential distribution of rodent pest species overlaps with allocated crop areas. This shows that Leishmania (L.) mexicana infection is present in the Northeastern region of Mexico, and that previously unrecorded sandfly species occur in the same areas. These findings suggest a potential risk of transmission of Leishmania (L.) mexicana.

Comparative Field Evaluation of Different Traps for Collecting Adult Phlebotomine Sand Flies (Diptera: Psychodidae) in an Endemic Area of Cutaneous Leishmaniasis in Quintana Roo, Mexico.

Phlebotominae are the vectors of Leishmania parasites. It is important to have available surveillance and collection methods for the sand fly vectors. The objectives of the present study were to evaluate and compare traps for the collection of sand fly species and to analyze trap catches along months and transects. Field evaluations over a year were conducted in an endemic area of leishmaniasis in the state of Quintana Roo, Mexico. A randomized-block design was implemented in study area with tropical rainforest vegetation. The study design utilized 4 transects with 11 trap types: 1) Centers for Disease Control and Prevention (CDC) light trap with incandescent bulb (CDC-I), 2) CDC light trap with blue light-emitting diodes (LEDs) (CDC-B), 3) CDC light trap with white LEDs (CDC-W), 4) CDC light trap with red LEDs (CDC-R), 5) CDC light trap with green LEDs (CDC-G), 6) Disney trap, 7) Disney trap with white LEDs, 8) sticky panels, 9) sticky panels with white LEDs, 10) delta-like trap, and 11) delta-like trap with white LEDs. A total of 1,014 specimens of 13 species and 2 genera (Lutzomyia and Brumptomyia) were collected. There were significant differences in the mean number of sand flies caught with the 11 traps; CDC-I was (P  =  0.0000) more effective than the other traps. Other traps exhibited the following results: CDC-W (17.46%), CDC-B (15.68%), CDC-G (14.89%), and CDC-R (14.30%). The relative abundance of different species varied according to trap types used, and the CDC-I trap attracted more specimens of the known vectors of Leishmania spp., such as like Lutzomyia cruciata, Lu. shannoni, and Lu. ovallesi. Disney trap captured more specimens of Lu. olmeca olmeca. Based on abundance and number of species, CDC light traps and Disney traps appeared to be good candidates for use in vector surveillance programs in this endemic area of Mexico.