Summary: Objectives  To test the non‐inferiority hypothesis that a vector control approach targeting only the most productive water container types gives the same or greater reduction of the vector population as a non‐targeted approach in different ecological settings and to analyse whether the targeted intervention is less costly.Methods  Cluster randomized trial in eight study sites (Venezuela, Mexico, Peru, Kenya, Thailand, Myanmar, Vietnam, Philippines), with each study area divided into 18–20 clusters (sectors or neighbourhoods) of approximately 50–100 households each. Using a baseline pupal‐demographic survey, the most productive container types were identified which produced ≥55% of all Ae. aegypti pupae. Clusters were then paired based on similar pupae per person indices. One cluster from each pair was randomly allocated to receive the targeted vector control intervention; the other received the ‘blanket’ (non‐targeted) intervention attempting to reach all water holding containers.Results  The pupal‐demographic baseline survey showed a large variation of productive container types across all study sites. In four sites the vector control interventions in both study arms were insecticidal and in the other four sites, non‐insecticidal (environmental management and/or biological control methods). Both approaches were associated with a reduction of outcome indicators in the targeted and non‐targeted intervention arm of the six study sites where the follow up study was conducted (PPI, Pupae per Person Index and BI, Breteau Index). Targeted interventions were as effective as non‐targeted ones in terms of PPI. The direct costs per house reached were lower in targeted intervention clusters than in non‐targeted intervention clusters with only one exception, where the targeted intervention was delivered through staff‐intensive social mobilization.Conclusions  Targeting only the most productive water container types (roughly half of all water holding container types) was as effective in lowering entomological indices as targeting all water holding containers at lower implementation costs. Further research is required to establish the most efficacious method or combination of methods for targeted dengue vector interventions.

Ecological niche models are useful tools to infer potential spatial and temporal distributions in vector species and to measure epidemiological risk for infectious diseases such as the Leishmaniases. The ecological niche of 28 North and Central American sand fly species, including those with epidemiological relevance, can be used to analyze the vector's ecology and its association with transmission risk, and plan integrated regional vector surveillance and control programs. In this study, we model the environmental requirements of the principal North and Central American phlebotomine species and analyze three niche characteristics over future climate change scenarios: i) potential change in niche breadth, ii) direction and magnitude of niche centroid shifts, iii) shifts in elevation range. Niche identity between confirmed or incriminated Leishmania vector sand flies in Mexico, and human cases were analyzed. Niche models were constructed using sand fly occurrence datapoints from Canada, USA, Mexico, Guatemala and Belize. Nine non-correlated bioclimatic and four topographic data layers were used as niche components using GARP in OpenModeller. Both B2 and A2 climate change scenarios were used with two general circulation models for each scenario (CSIRO and HadCM3), for 2020, 2050 and 2080. There was an increase in niche breadth to 2080 in both scenarios for all species with the exception of Lutzomyia vexator. The principal direction of niche centroid displacement was to the northwest (64%), while the elevation range decreased greatest for tropical, and least for broad-range species. Lutzomyia cruciata is the only epidemiologically important species with high niche identity with that of Leishmania spp. in Mexico. Continued landscape modification in future climate change will provide an increased opportunity for the geographic expansion of NCA sand flys' ENM and human exposure to vectors of Leishmaniases. The present study models the niche of the most abundant sand fly species in North and Central America, including all proven and incriminated vectors of Leishmaniases, an important neglected tropical disease of the region. The expansion and elevation or centroid shifts of the species' niche are modeled for extreme (A2) and conservative (B2) climate change scenarios to 2020, 2050 and 2080. In climate change scenarios, models predict significant niche breadth changes in geographic space, principally in temperate sand fly species, while elevation shifts occur principally in tropical, and greatest, in vector species. Niche centroid shifts for individual species were predominately to the northwest, and secondarily to the northeast. The highest proportion of human population at-risk for contact with a vector species was with Lutzomyia diabolica and Lutzomyia shannoni. Despite the fact that Lutzomyia olmeca olmeca is the only confirmed vector species in Mexico, the present study demonstrates a significant niche identity between Leishmania spp. and Lutzomyia cruciata.

Leishmaniases are a group of vector-borne diseases with different clinical manifestations caused by parasites transmitted by sand fly vectors. In Mexico, the sand fly Lutzomyia olmeca olmeca is the only vector proven to transmit the parasite Leishmania mexicana to humans, which causes leishmaniasis. Other vector species with potential medical importance have been obtained, but their geographic distributions and relation to transmission areas have never been assessed. We modeled the ecological niches of nine sand fly species and projected niches to estimate potential distributions by using known occurrences, environmental coverages, and the algorithms GARP and Maxent. All vector species were distributed in areas with known recurrent transmission, except for Lu. diabolica, which appeared to be related only to areas of occasional transmission in northern Mexico. The distribution of Lu. o. olmeca does not overlap with all reported cutaneous leishmaniasis cases, suggesting that Lu. cruciata and Lu. shannoni are likely also involved as primary vectors in those areas. Our study provides useful information of potential risk areas of leishmaniasis transmission in Mexico.

Leishmania (Leishmania) mexicana causes cutaneous leishmaniasis, an endemic zoonosis affecting a growing number of patients in the southeastern states of Mexico. Some foci are found in shade-grown cocoa and coffee plantations, or near perennial forests that provide rich breeding grounds for the sand fly vectors, but also harbor a variety of bat species that live off the abundant fruits provided by these shade-giving trees. The close proximity between sand flies and bats makes their interaction feasible, yet bats infected with Leishmania (L.) mexicana have not been reported. Here we analyzed 420 bats from six states of Mexico that had reported patients with leishmaniasis. Tissues of bats, including skin, heart, liver and/or spleen were screened by PCR for Leishmania (L.) mexicana DNA. We found that 41 bats (9.77%), belonging to 13 species, showed positive PCR results in various tissues. The infected tissues showed no evidence of macroscopic lesions. Of the infected bats, 12 species were frugivorous, insectivorous or nectarivorous, and only one species was sanguivorous (Desmodus rotundus), and most of them belonged to the family Phyllostomidae. The eco-region where most of the infected bats were caught is the Gulf Coastal Plain of Chiapas and Tabasco. Through experimental infections of two Tadarida brasiliensis bats in captivity, we show that this species can harbor viable, infective Leishmania (L.) mexicana parasites that are capable of infecting BALB/c mice. We conclude that various species of bats belonging to the family Phyllostomidae are possible reservoir hosts for Leishmania (L.) mexicana, if it can be shown that such bats are infective for the sand fly vector. Further studies are needed to determine how these bats become infected, how long the parasite remains viable inside these potential hosts and whether they are infective to sand flies to fully evaluate their impact on disease epidemiology. Leishmaniasis is endemic in southeastern Mexico, where Leishmania (L.) mexicana is the principle parasite species causing disease in humans. Previous studies using methodology for inferring potential biotic interactions between species had shown a high prevalence of bat species as potential hosts for Leishmania, yet bats have not been identified as hosts in Mexico. Motivated by these predictions, we currently analyze whether bats are infected with Leishmania (L.) mexicana and to what extent they serve as hosts for this parasite. We analyzed 420 bats from six states, and through PCR analysis of skin, heart, liver and/or spleen we found that 41 bats (9.77%) of 13 different bat species were infected. Most of the infected bats were netted in an eco-region characterized by plantations grown beneath shade-providing fruit trees that favors breeding conditions for the sand fly vectors and brings them in close proximity with frugivorous, insectivorous or nectarivorous bats. None of the infected bat tissues showed macroscopic lesions. Through artificial infections, we were also able to show that Leishmania (L.) mexicana remains viable and infective after passage through one species of bat. We conclude that various species of bats belonging to the family Phyllostomidae are possible reservoir hosts of Leishmania (L.) mexicana.

Cutaneous leishmaniasis (CL) is endemic to the Yucatan Peninsula of Mexico. The main causative agent is the parasite Leishmania mexicana (Biagi) (Kinetoplastida: Trypanosomatidae) and, based on the classic work of Dr Biagi's research team, it has been generally accepted and frequently reported that the only vector of L. mexicana in the region is the sandfly Lutzomyia olmeca olmeca (Vargas & Diáz‐Nájera) (Diptera: Psychodidae). Evidence gathered from recent entomological studies conducted mainly in Calakmul, Campeche, however, suggests that other species may also be vectors of L. mexicana . We conducted a field study in two villages in Calakmul, Campeche in the Yucatan Peninsula, where recent cases of CL have been reported, to document the species composition and relative abundances of the sandfly fauna and to identify which species are likely to be the main vectors by assessing the biting rates and parasite infection rates of the suspected vector species. Sandfly catches were conducted from November 2005 to February 2006 in Unión 20 de Junio and Dos Lagunas Sur. Sandflies were captured using Shannon (18.00–22.00 hours), Disney and CDC light traps (18.00–06.00 hours). Biting and infection rates were calculated for the four most abundant species: Lutzomyia cruciata (Coquillett), Lu. o. olmeca , Lutzomyia panamensis (Shannon) and Lutzomyia shannoni (Dyar). In Dos Lagunas Sur, Lu. panamensis and Lu. o. olmeca exhibited the highest biting rates throughout the sampling period. In Unión 20 de Junio, Lu. cruciata and Lu. o. olmeca had the highest biting rates over the same period. Regarding infection rates, we report herein the establishment of a polymerase chain reaction protocol and validation of IR1 and LM17 oligonucleotides to analyse the infection rates of sandflies. Out of 769 females analysed, the overall infection rates were 1.4% in Dos Lagunas Sur and 5.3% in Unión 20 de Junio. In Dos Lagunas Sur we found L. mexicana infections in two sandfly species, Lu. shannoni and Lutzomyia ylephiletor (Fairchild & Hertig), whereas in Unión 20 de Junio we found infections in Lu. shannoni , Lu. cruciata , Lu. o. olmeca and Lu. panamensis . The possible role of these four sandfly species in relation to L. mexicana transmission in Calakmul is discussed.

The surveillance of prevalent Leishmania sand fly vectors is an important issue for epidemiological studies in populated areas where leishmaniasis is endemic. In this study, we collected sand flies from a peri-urban area in the southeast of Mexico. Natural infection with Leishmania (L.) mexicana was studied by PCR using a Leishmania internal transcribed spacer of the ribosomal RNA gene for amplification. Infected Lutzomyia olmeca olmeca, Lu. shannoni and Lu. cruciata sand flies were collected mainly during the high transmission season (November to March), coinciding with the highest sand fly densities. Additionally, positive specimens of Lu. olmeca olmeca were also captured during July and August. The infected sand flies were from primary forest (subperennial forest) and secondary forest (18-25 years old and 10-15 years old respectively). Sand flies collected with Disney and Shannon traps were the ones found to be infected with L. (L.) mexicana. We conclude that the high-risk period in which L. (L.) mexicana is transmitted in the peri-urban area of Chetumal City is from July to March and that transmission is associated with both the subperennial forest and the secondary forest.