Changes in phlebotomine sand fly species composition following insecticide thermal fogging in a rural setting of Western panamá

Chemical control of medically important arthropods in Panama: A systematic literature review of historical efforts

Vector-borne diseases are a major source of morbidity in Panama. Herein, we describe historical usage patterns of synthetic insecticides to control arthropod disease vectors in this country. We examine the influence of interventions by vector control programs on the emergence of insecticide resistance. Chemical control has traditionally focused on two mosquito species: Anopheles albimanus, a major regional malaria vector, and Aedes aegypti, a historical vector of yellow fever, and current vector of dengue, chikungunya, and Zika. Countrywide populations of An. albimanus depict hyperirritability to organochlorine insecticides administered by indoor residual spraying, although they appear susceptible to these insecticides in bioassays settings, as well as to organophosphate and carbamate insecticides in field tests. Populations of Ae. aegypti show resistance to pyrethroids, particularly in areas near Panama City, but the spread of resistance remains unknown in Ae. aegypti and Aedes albopictus. A One Health approach is needed in Panama to pinpoint the insecticide resistance mechanisms including the frequency of knockdown mutations and behavioral plasticity in populations of Anopheles and Aedes mosquitoes. This information is necessary to guide the sustainable implementation of chemical control strategies and the use of modern vector control technologies such as genetically modified mosquitoes, and endosymbiont Wolbachia-based biological control.

Qualitative behavior of a highly non-linear Cutaneous Leishmania epidemic model under convex incidence rate with real data

In the context of this investigation, we introduce an innovative mathematical model designed to elucidate the intricate dynamics underlying the transmission of Anthroponotic Cutaneous Leishmania. This model offers a comprehensive exploration of the qualitative characteristics associated with the transmission process. Employing the next-generation method, we deduce the threshold value $ R_0 $ for this model. We rigorously explore both local and global stability conditions in the disease-free scenario, contingent upon $ R_0 $ being less than unity. Furthermore, we elucidate the global stability at the disease-free equilibrium point by leveraging the Castillo-Chavez method. In contrast, at the endemic equilibrium point, we establish conditions for local and global stability, when $ R_0 $ exceeds unity. To achieve global stability at the endemic equilibrium, we employ a geometric approach, a Lyapunov theory extension, incorporating a secondary additive compound matrix. Additionally, we conduct sensitivity analysis to assess the impact of various parameters on the threshold number. Employing center manifold theory, we delve into bifurcation analysis. Estimation of parameter values is carried out using least squares curve fitting techniques. Finally, we present a comprehensive discussion with graphical representation of key parameters in the concluding section of the paper.

The bibliometric landscape of infectious disease research in Panama (1990-2019)

Background

This work aims to analyze the landscape of scientific publications on subjects related to One Health and infectious diseases in Panama. The research questions are: How does the One Health research landscape look like in Panama? Are historical research efforts aligned with the One Health concept? What infectious diseases have received more attention from the local scientific community since 1990?

Methods

Boolean searches on the Web of Science, SCOPUS and PubMed were undertaken to evaluate the main trends of publications related to One Health and infectious disease research in the country of Panama, between 1990 and 2019.

Results

4546 publications were identified since 1990, including 3564 peer-reviewed articles interconnected with One Health related descriptors, and 211 articles focused particularly on infectious diseases. A pattern of exponential growth in the number of publications with various contributions from Panamanian institutions was observed. The rate of multidisciplinary research was moderate, whereas those of interinstitutional and intersectoral research ranged from low to very low. Research efforts have centered largely on protozoan, neglected and arthropod-borne diseases with a strong emphasis on malaria, Chagas and leishmaniasis.

Conclusion

Panama has scientific capabilities on One Health to tackle future infectious disease threats, but the official collaboration schemes and strategic investment to develop further competencies need to be conciliated with modern times, aka the pandemics era. The main proposition here, addressed to the government of Panama, is to launch a One Health regional center to promote multidisciplinary, interinstitutional and intersectoral research activities in Panama and beyond.

Arthropod vectors of disease agents: their role in public and veterinary health in Turkiye and their control measures

Mosquitoes, sandflies, and ticks are hematophagous arthropods that pose a huge threat to public and veterinary health. They are capable of serving as vectors of disease agents that can and have caused explosive epidemics affecting millions of people and animals. Several factors like climate change, urbanization, and international travel contribute substantially to the persistence and dispersal of these vectors from their established areas to newly invaded areas. Once established in their new home, they can serve as vectors for disease transmission or increase the risk of disease emergence. Turkiye is vulnerable to climate change and has experienced upward trends in annual temperatures and rising sea levels, and greater fluctuations in precipitation rates. It is a potential hotspot for important vector species because the climate in various regions is conducive for several insect and acari species and serves as a conduit for refugees and immigrants fleeing areas troubled with armed conflicts and natural disasters, which have increased substantially in recent years. These people may serve as carriers of the vectors or be infected by disease agents that require arthropod vectors for transmission. Although it cannot be supposed that every arthropod species is a competent vector, this review aims to (1)illustrate the factors that contribute to the persistence and dispersal of arthropod vectors, (2)determine the status of the established arthropod vector species in Turkiye and their capability of serving as vectors of disease agents, and (3)assess the role of newly-introduced arthropod vectors into Turkiye and how they were introduced into the country. We also provide information on important disease incidence (if there's any) and control measures applied by public health officials from different provinces.

Effectiveness of insecticide thermal fogging in hyrax dens in the control of leishmaniasis vectors in rural Palestine: A prospective study

Background

Zoonotic cutaneous leishmaniasis (ZCL) is endemic in Palestine and transmitted by Phlebotomus sand flies. They inhabit dens of hyraxes, the reservoir animal. Control measures were implemented since 1996 but cases still occur. We estimated the effect of insecticide thermal fogging inside hyrax dens on sand fly density and leishmania infection.

Methodology/Principal findings

During July-September 2019, we conducted a 12-week controlled interrupted time series study in two control and one intervention sites containing three hyrax dens each. We implemented Permethrin thermal fogging in the intervention site at week 6. We measured weekly and 36hrs post-intervention sand fly abundance inside dens using CDC light traps. We performed Next-Generation Sequencing to identify sand fly Leishmania spp. infection. We calculated the abundance reduction (AR) using Mulla’s formula and negative binomial regression. Among 11427 collected sand flies, 7339 (64%) were females and 1786 (16%) were Phlebotomus spp. comprising ten species; P. sergenti was the dominant (n = 773, 43%). We report P. arabicus (n = 6) for the first time in Palestine. After fogging, Phlebotomus spp. AR was 93% at 36hrs, 18% and 38% at two and five weeks respectively and 41% during the complete post-intervention period. In the regression models, Phlebotomus spp. density in the intervention site decreased by 74% (IRR: 0.26, 95%CI: 0.11–0.57) at two weeks, 34% (IRR: 0.66, 95%CI: 0.48–0.90) at five weeks and 74% (IRR: 0.26, 95%CI: 0.12–0.59) during the complete period. The density of Leishmania infected sand flies decreased by 65% (IRR: 0.35, 95%CI: 0.26–0.48) at five weeks and 82% (IRR: 0.18, 95%CI: 0.07–0.42) for the complete period (zero infections until week two). Leishmania infection prevalence in the intervention site was 14% pre-intervention and 3.9% post-intervention.

Conclusions/Significance

Fogging hyrax dens reduced sand fly abundance and leishmania infection during the 5-week post-intervention period and especially the first two weeks suggesting it could be an effective source-reduction measure for ZCL vectors. Future randomized controlled trials are needed to confirm the effectiveness of fogging hyrax dens on decreasing ZCL incidence.

Diversity, Co-Occurrence, and Nestedness Patterns of Sand Fly Species (Diptera: Psychodidae) in Two Rural Areas of Western Panamá

Simple Summary

Sand flies are insects that can transmit the parasites causing leishmaniasis, a major neglected tropical disease. In the Americas, these insects are highly diverse, and unlike what is observed for other vector-borne diseases, many species co-occur in sites where this disease affects human populations. Here, we present results from a two-year-long study where we study how the number of species changes in two rural areas of Western Panamá with different land use cover and through the dry and wet seasons. We found that species number increased during the wet season and in plots with higher natural forest cover and that species number decreased in both areas in plots when the forest cover decreased, with some species changing through the seasons, and some species disappearing when comparing the sand fly faunas of the most forested with less forested plots. However, our results suggest that seasonality, or the change from a dry to rainy season, can be a more important driver of the number of species locally observed in the studied areas.

Abstract

Cutaneous Leishmaniasis transmission in the New World is observed in areas with rich sand fly species’ faunas. The diversity and composition of sand fly species can change in response to seasonal weather and land use changes. Here, we present results from a two-year-long study where we collected, using Centers for Disease Control (CDC) light traps, sand flies from two rural areas, Las Pavas (LP) and Trinidad de las Minas (T) in western Panamá. Over 710 trap-nights, we collected 16,156 sand flies from 15 genera and 35 species. We identified 34 species in T, and the most abundant species collected was Nyssomyia trapidoi (Fairchild and Hertig, 1952) (n = 2278, 37%), followed by Psychodopygus panamensis (Shannon, 1926) (n = 1112, 18%), and Trichopygomyia triramula (Fairchild and Hertig, 1952) (n = 1063, 17%). In LP, we identified 26 species, and the most abundant species collected were Ty. triramula (n = 4729, 48%), and Ps. panamensis (n = 3444, 35%). We estimated a higher species’ richness in T (Chao2 ± S.E.: 36.58 ± 3.84) than in LP (27.49 ± 2.28). In T, species’ richness was significantly higher in the rainy season, but no seasonal differences were observed in LP. Species’ assemblages were nested in the two areas. Phlebotomine sand fly species’ abundance increased at the two sites during the rainy season. Our data suggest that seasonality is more important than land use as a factor driving sand fly species’ diversity at the studied sites.

Leishmania spp. Infection Rate and Feeding Patterns of Sand Flies (Diptera: Psychodidae) from a Hyperendemic Cutaneous Leishmaniasis Community in Panamá

American cutaneous leishmaniasis (ACL) is a common and important vector-borne parasitic zoonosis in Panamá. Here, we study Leishmania spp. infection rates and blood-feeding patterns among common sand flies in Trinidad de Las Minas, a rural community with hyperendemic ACL transmission, and where a deltamethrin fogging trial was performed. Sand flies were collected from April 2010 to June 2011 with light traps installed inside and in the peridomicile of 24 houses. We restricted our analysis to the most abundant species at the study site: Lutzomyia trapidoi, Lutzomyia gomezi, Lutzomyia panamensis, Lutzomyia triramula, and Lutzomyia dysponeta. We detected Leishmania spp. infection in sand flies by polymerase chain reaction (PCR) amplification of the internal transcribed spacer region 1 (ITS-1) in pooled females (1-10 females per pool). Host species of engorged sand flies were identified using a cytochrome b PCR. From 455 sand fly pools analyzed, 255 pools were positive for Leishmania spp., with an estimated infection rate (confidence interval) of 0.096 [0.080-0.115] before the deltamethrin fogging which slightly, but not significantly (P > 0.05), increased to 0.116 [0.098-0.136] after the deltamethrin fogging. Blood meal analysis suggested that pigs, goats, and birds were the most common sand fly blood sources, followed by humans and domestic dogs. DNA sequencing from a subsample of ITS-1 positive pools suggests that Leishmania panamensis, Leishmania naiffi, and other Leishmania spp. were the parasite species infecting the most common vectors at the study site. Our data confirm an association between sand fly species, humans, domestic dogs, and pigs and Leishmania spp. parasites in rural Panamá.

Stability analysis of leishmania epidemic model with harmonic mean type incidence rate

We discussed anthroponotic cutaneous leishmania transmission in this article, due to its large effect on the community in the recent years. The mathematical model is developed for anthroponotic cutaneous leishmania transmission, and its qualitative behavior is taken under consideration. The threshold number R 0 of the model is derived using the next-generation method. In the disease-free case, local and global stability is carried out with the condition that R 0 will be less than one. The global stability at the disease-free equilibrium point has been derived by utilizing the Castillo-Chavez method. On the other hand, at the endemic equilibrium point, the local and global stability holds with some conditions, and R 0 is greater than unity. The global stability at the endemic equilibrium point is established with the help of a geometrical approach which is the generalization of Lyapunov theory, by using the third additive compound matrix. The sensitivity analysis of the threshold number with other parameters is also taken into account. Several graphs of important parameters are discussed in the last section.

Enzootic mosquito vector species at equine encephalitis transmission foci in the República de Panamá

The identification of mosquito vector species present at arboviral enzootic transmission foci is important to understand transmission eco-epidemiology and to propose and implement prevention and control strategies that reduce vector-borne equine encephalitis transmission. The goal of this study was to identify mosquito species potentially involved in the transmission of enzootic equine encephalitis, in relation to their abundance and diversity at three endemic regions in the República de Panamá. We sampled adult mosquitoes during the dry and rainy season of Panamá. We employed CDC light traps with octanol, EV traps with CO₂ and Trinidad 17 traps baited with live hamsters. Traps were deployed in the peridomicile and extradomicile of houses from 18:00 to 6:00 h. We estimated the abundance and diversity of sampled species. We collected a total of 4868 mosquitoes, belonging to 45 species and 11 genera, over 216 sampling nights. Culex (Melanoconion) pedroi, a major Venezuelan equine encephalitis vector was relatively rare (< 2.0% of all sampled mosquitoes). We also found Cx. (Mel) adamesi, Cx. (Mel) crybda, Cx. (Mel) ocossa, Cx. (Mel) spissipes, Cx. (Mel) taeniopus, Cx. (Mel) vomerifer, Aedes scapularis, Ae. angustivittatus, Coquillettidia venezuelensis, Cx. nigripalpus, Cx. declarator, Mansonia titillans, M. pseudotitillans and Psorophora ferox all species known to be vectorially competent for the transmission of arboviruses. Abundance and diversity of mosquitoes in the sampled locations was high, when compared with similar surveys in temperate areas. Information from previous reports about vectorial competence / capacity of the sampled mosquito species suggest that sampled locations have all the elements to support enzootic outbreaks of Venezuelan and Eastern equine encephalitides.

Synanthropic Mammals as Potential Hosts of Tick-Borne Pathogens in Panama

Synanthropic wild mammals can be important hosts for many vector-borne zoonotic pathogens. The aim of this study was determine the exposure of synanthropic mammals to two types of tick-borne pathogens in Panama, spotted fever group Rickettsia (SFGR) and Borrelia relapsing fever (RF) spirochetes. One hundred and thirty-one wild mammals were evaluated, including two gray foxes, two crab-eating foxes (from zoos), four coyotes, 62 opossum and 63 spiny rats captured close to rural towns. To evaluate exposure to SFGR, serum samples from the animals were tested by indirect immunofluorescence assay (IFA) using Rickettsia rickettsii and Candidatus Rickettsia amblyommii antigen. Immunoblotting was performed using Borrelia turicatae protein lysates and rGlpQ, to assess infection caused by RF spirochetes. One coyote (25%) and 27 (43%) opossums showed seroreactivity to SFGR. Of these opossums, 11 were seroreactive to C. R. amblyommii. Serological reactivity was not detected to B. turicatae in mammal samples. These findings may reflect a potential role of both mammals in the ecology of tick-borne pathogens in Panama.

Sensitivity Analysis and Optimal Control of Anthroponotic Cutaneous Leishmania

This paper is focused on the transmission dynamics and optimal control of Anthroponotic Cutaneous Leishmania. The threshold condition R0 for initial transmission of infection is obtained by next generation method. Biological sense of the threshold condition is investigated and discussed in detail. The sensitivity analysis of the reproduction number is presented and the most sensitive parameters are high lighted. On the basis of sensitivity analysis, some control strategies are introduced in the model. These strategies positively reduce the effect of the parameters with high sensitivity indices, on the initial transmission. Finally, an optimal control strategy is presented by taking into account the cost associated with control strategies. It is also shown that an optimal control exists for the proposed control problem. The goal of optimal control problem is to minimize, the cost associated with control strategies and the chances of infectious humans, exposed humans and vector population to become infected. Numerical simulations are carried out with the help of Runge-Kutta fourth order procedure.

Risk factors associated with Trypanosoma cruzi exposure in domestic dogs from a rural community in Panama

Chagas disease, caused by Trypanosoma cruzi infection, is a zoonosis of humans, wild and domestic mammals, including dogs. In Panama, the main T. cruzi vector is Rhodnius pallescens, a triatomine bug whose main natural habitat is the royal palm, Attalea butyracea. In this paper, we present results from three T. cruzi serological tests (immunochromatographic dipstick, indirect immunofluorescence and ELISA) performed in 51 dogs from 24 houses in Trinidad de Las Minas, western Panama. We found that nine dogs were seropositive (17.6% prevalence). Dogs were 1.6 times more likely to become T. cruzi seropositive with each year of age and 11.6 times if royal palms where present in the peridomiciliary area of the dog's household or its two nearest neighbours. Mouse-baited-adhesive traps were employed to evaluate 12 peridomestic royal palms. All palms were found infested with R. pallescens with an average of 25.50 triatomines captured per palm. Of 35 adult bugs analysed, 88.6% showed protozoa flagellates in their intestinal contents. In addition, dogs were five times more likely to be infected by the presence of an additional domestic animal species in the dog's peridomiciliary environment. Our results suggest that interventions focused on royal palms might reduce the exposure to T. cruzi infection.

SAND FLY SPECIES COMPOSITION (DIPTERA: PSYCHODIDAE: PHLEBOTOMINAE) IN THE MUNICIPALITY OF CANTAGALO , AN AREA WITH SPORADIC CASES OF HUMAN CUTANEOUS LEISHMANIASIS IN RIO DE JANEIRO STATE, BRAZIL

The municipality of Cantagalo is an area with sustained transmission of American Cutaneous Leishmaniasis (ACL). Monthly sand fly collections were performed for three years (June 2012 - May 2015) using a CDC light trap. A total of 3,310 specimens belonging to 12 species were trapped: Nyssomyia intermedia, Nyssomyia whitmani, Migonemyia migonei, Evandromyia lenti, Evandromyia cortelezzii, Micropygomyia quinquefer, Brumptomyia brumpti, Psathyromyia aragaoi, Micropygomyia schreiberi, Pintomyia fischeri, Sciopemyia sordellii, and Evandromyia edwardsi. The last seven species have not been previously recorded in this area. The highest abundance of species occurred between October and March. October was the month with the highest number of captured sand flies, one month before the peak in the summer rainfall. In October the highest number of Ny. intermedia, Ny. whitmani and Mg. migonei, were also collected, the three epidemiologically most important species. The high abundance of species with epidemiological importance for ACL transmission might explain the sporadic occurrence of the disease in the area.

Macroecological patterns of American Cutaneous Leishmaniasis transmission across the health areas of Panamá (1980-2012)

American Cutaneous Leishmaniasis (ACL) is a neglected vector-borne zoonosis that persists despite increasing socio-economic development and urbanization in Panamá. Here, we investigate the association between environmental changes and spatio-temporal ACL transmission in the Republic of Panamá (1980-2012). We employ a macroecological approach, where patterns of variation in ACL incidence at the spatially coarse-grained scale of health areas are studied considering factors linked to the ecology of ACL transmission. We specifically study impacts of climatic variability, measured by the different phases of El Niño Southern Oscillation (ENSO), within diverse ecosystems and sand fly (Diptera: Psychodidae) vector species, as well as heterogeneous local climatic patterns, deforestation, population growth rates, and changes in social marginalization. We found that over the study period, patterns of ACL incidence: (i) were asynchronous with clusters changing from east to west of the Panamá Canal, (ii) trends increased in the west, and decreased or remained nearly constant in the east, independent of human population growth, (iii) generally increased in years following El Niño, and (iv) decreased as forest cover increased. We found no significant association between changes in socio-economic indicators and ACL transmission. Regarding vector abundance and presence, we found that studies had been biased to locations east of the Panamá canal, and that, in general, the abundance of dominant vector species decreased during the cold phase of ENSO. Finally, our results indicate that a macroecological approach is useful to understand heterogeneities related to environmental change impacts on ACL transmission.

Sensitivity Analysis and Optimal Control of Anthroponotic Cutaneous Leishmania

This paper is focused on the transmission dynamics and optimal control of Anthroponotic Cutaneous Leishmania. The threshold condition R0 for initial transmission of infection is obtained by next generation method. Biological sense of the threshold condition is investigated and discussed in detail. The sensitivity analysis of the reproduction number is presented and the most sensitive parameters are high lighted. On the basis of sensitivity analysis, some control strategies are introduced in the model. These strategies positively reduce the effect of the parameters with high sensitivity indices, on the initial transmission. Finally, an optimal control strategy is presented by taking into account the cost associated with control strategies. It is also shown that an optimal control exists for the proposed control problem. The goal of optimal control problem is to minimize, the cost associated with control strategies and the chances of infectious humans, exposed humans and vector population to become infected. Numerical simulations are carried out with the help of Runge-Kutta fourth order procedure.

Nestedness patterns of sand fly (Diptera: Psychodidae) species in a neotropical semi-arid environment

A common pattern in neotropical Leishmania spp. transmission is the co-occurrence of several sand fly (SF) species at endemic foci. We collected 13 SF spp. by direct aspiration in natural resting places (NRP) and 10 SF spp. with Shannon traps (ST), totaling 15 spp. with both methods, at 6 locations within a semi-arid region with endemic visceral leishmaniasis transmission in Falcón State, Northwestern Venezuela. We used null model testing of species co-occurrence and nestedness metrics estimated with our field data to ask whether SF species composition was segregated/aggregated, and if aggregated whether there was nestedness, i.e., whether species composition across sampling locations could be described by ordered subsets of species from the most species rich location in a landscape. Results showed that SF species were aggregated (P<0.05), i.e., most species were present in species rich locations. Similarly, SF species were significantly nested (P<0.05). Differences in pairwise Sørensen and Simpson indices, estimated with the ST data and the combined ST and NRP data, were positively associated with the distance between sampling locations, suggesting that species nestedness might be partially shaped by dispersal limitation. Our data showed that three species of medical importance were common across the sampling locations: Lutzomyia gomezi, Lutzomyia panamensis and Lutzomyia evansi, suporting that vector species do not turnover in the studied setting.

Diversity and abundance of mosquitoes (Diptera:Culicidae) in an urban park: larval habitats and temporal variation

Urban parks are areas designated for human recreation but also serve as shelter and refuge for populations of several species of native fauna, both migratory and introduced. In Brazil, the effect of annual climate variations on Aedes aegypti and dengue epidemics in large cities like São Paulo is well known, but little is known about how such variations can affect the diversity of mosquito vectors in urban parks and the risk of disease transmission by these vectors. This study investigates the influence of larval habitats and seasonal factors on the diversity and abundance of Culicidae fauna in Anhanguera Park, one of the largest remaining green areas in the city of São Paulo. Species composition and richness and larval habitats were identified. Seasonality (cold-dry and hot-rainy periods) and year were considered as explanatory variables and the models selection approach was developed to investigate the relationship of these variables with mosquito diversity and abundance. A total of 11,036 specimens from 57 taxa distributed in 13 genera were collected. Culex nigripalpus, Cx. quinquefasciatus and Aedes albopictus were the most abundant species. Bamboo internodes and artificial breeding sites showed higher abundance, while ponds and puddles showed greater richness. Significant relationships were observed between abundance and seasonality, with a notable increase in the mosquitos abundance in the warm-rainy periods. The Shannon and Berger-Parker indices were related with interaction between seasonality and year, however separately these predictors showed no relationship with ones. The increased abundance of mosquitoes in warm-rainy months and the fact that some of the species are epidemiologically important increase not only the risk of pathogen transmission to people who frequent urban parks but also the nuisance represented by insect bites. The findings of this study highlight the importance of knowledge of culicid ecology in green areas in urban environments.

Species diversity of sand flies and ecological niche model of Phlebotomus papatasi in central Iran

Cutaneous leishmaniasis (CL) is the most important vector-borne disease in Iran. Qom Province is a very important area in the case of CL transmission, because of high traffic population from other parts of the country, or even other countries, as well as existence of confirmed foci of the disease. The aim of this study was to determine the ecology of sand flies in two different climates of this province and model the distribution of the main vector. Sand flies were collected monthly during April 2013-April 2014, at 22 urban/rural collection sites. Site selection was constrained by the geographical distribution of CL cases in recent years. Shannon-Weiner and Evenness indices were used to compare diversity in two studied climates. ArcGIS and MaxEnt were used to map and predict the appropriate ecological niches for sand flies. Totally, 5389 sand flies were collected and 12 species were identified. The most abundant species were Sergentomyia sintoni, P. papatasi, P. sergenti s.l. and Phlebotomus alexandri. Two peaks of activity were found in May and August in lowlands; while in mountainous areas they were observed in June and September. Species diversity in mountainous areas was found to be higher than in lowlands. The environmental variable with the highest gain in MaxEnt model was the monthly mean of (max temp-min temp). A big part of the lowland areas provides good ecological niches for P. papatasi and therefore higher transmission potential. These findings can be used in stratification of potential for CL transmission in Qom province.

Cutaneous Leishmaniasis in dogs: is high seroprevalence indicative of a reservoir role?

American cutaneous leishmaniasis (ACL) is a complex disease with a rich diversity of animal host species. This diversity imposes a challenge, since understanding ACL transmission requires the adequate identification of reservoir hosts, those species able to be a source of additional infections. In this study we present results from an ACL cross-sectional serological survey of 51 dogs (Canis familiaris), where we used diagnostic tests that measure dog's exposure to Leishmania spp. parasites. We did our research in Panamá, at a village that has undergone significant ecosystem level transformations. We found an ACL seroprevalence of 47% among dogs, and their exposure was positively associated with dog age and abundance of sand fly vectors in the houses of dog owners. Using mathematical models, which were fitted to data on the proportion of positive tests as function of dog age, we estimated a basic reproductive number (R 0 ± s.e.) of 1·22 ± 0·09 that indicates the disease is endemically established in the dogs. Nevertheless, this information by itself is insufficient to incriminate dogs as ACL reservoirs, given the inability to find parasites (or their DNA) in seropositive dogs and previously reported failures to experimentally infect vectors feeding on dogs with ACL parasites.

Survey of wild mammal hosts of cutaneous leishmaniasis parasites in panamá and costa rica

The eco-epidemiology of American cutaneous leishmaniasis (ACL) is driven by animal reservoir species that are a source of infection for sand flies that serve as vectors infecting humans with Leishmania spp parasites. The emergence and re-emergence of this disease across Latin America calls for further studies to identify reservoir species associated with enzootic transmission. Here, we present results from a survey of 52 individuals from 13 wild mammal species at endemic sites in Costa Rica and Panama where ACL mammal hosts have not been previously studied. For Leishmania spp. diagnostics we employed a novel PCR technique using blood samples collected on filter paper. We only found Leishmania spp parasites in one host, the two-toed sloth, Choloepus hoffmanni. Our findings add further support to the role of two-toed sloths as an important ACL reservoir in Central America.

Cutaneous leishmaniasis and sand fly fluctuations are associated with el niño in panamá

BACKGROUND

Cutaneous Leishmaniasis (CL) is a neglected tropical vector-borne disease. Sand fly vectors (SF) and Leishmania spp parasites are sensitive to changes in weather conditions, rendering disease transmission susceptible to changes in local and global scale climatic patterns. Nevertheless, it is unclear how SF abundance is impacted by El Niño Southern Oscillation (ENSO) and how these changes might relate to changes in CL transmission.

METHODOLOGY AND FINDINGS

We studied association patterns between monthly time series, from January 2000 to December 2010, of: CL cases, rainfall and temperature from Panamá, and an ENSO index. We employed autoregressive models and cross wavelet coherence, to quantify the seasonal and interannual impact of local climate and ENSO on CL dynamics. We employed Poisson Rate Generalized Linear Mixed Models to study SF abundance patterns across ENSO phases, seasons and eco-epidemiological settings, employing records from 640 night-trap sampling collections spanning 2000-2011. We found that ENSO, rainfall and temperature were associated with CL cycles at interannual scales, while seasonal patterns were mainly associated with rainfall and temperature. Sand fly (SF) vector abundance, on average, decreased during the hot and cold ENSO phases, when compared with the normal ENSO phase, yet variability in vector abundance was largest during the cold ENSO phase. Our results showed a three month lagged association between SF vector abundance and CL cases.

CONCLUSION

Association patterns of CL with ENSO and local climatic factors in Panamá indicate that interannual CL cycles might be driven by ENSO, while the CL seasonality was mainly associated with temperature and rainfall variability. CL cases and SF abundance were associated in a fashion suggesting that sudden extraordinary changes in vector abundance might increase the potential for CL epidemic outbreaks, given that CL epidemics occur during the cold ENSO phase, a time when SF abundance shows its highest fluctuations.

American Cutaneous Leishmaniasis in Panama: a historical review of entomological studies on anthropophilic Lutzomyia sand fly species

We review existing information on the epidemiology of American Cutaneous Leishmaniasis (ACL) in Panama, with emphasis on the bionomics of anthropophilic Lutzomyia sand fly species. Evidence from Panamanian studies suggests that there are six anthropophilic species in the country: Lutzomyia trapidoi, Lu. panamensis, Lu. gomezi, Lu. ylephiletor, Lu. sanguinaria and Lu. pessoana (Henceforth Lu. carrerai thula). In general, these taxa are abundant, widespread and feed opportunistically on their hosts, which make them potential transmitters of pathogens to a broad range of wildlife, domesticated animals and humans. Furthermore, nearly all man-biting species in Panama (with the exception of Lu. gomezi) expand demographically during the rainy season when transmission is likely higher due to elevated Leishmania infection rates in vector populations. Despite this, data on the distribution and prevalence of ACL suggest little influence of vector density on transmission intensity. Apart from Lu. trapidoi, anthropophilic species seem to be most active in the understory, but vertical stratification, as well as their opportunistic feeding behavior, could vary geographically. This in turn seems related to variation in host species composition and relative abundance across sites that have experienced different degrees of human alteration (e.g., deforestation) in leishmaniasis endemic regions of Panama.

Ecological interactions among phlebotomines (Diptera: Psychodidae) in an agroforestry environment of northeast Brazil

Phlebotomine vectors transmit parasites and can cause visceral leishmaniasis (VL) or cutaneous leishmaniasis (TL). Phlebotomine females are hematophagous but need to ingest carbohydrates, possibly promoting the development of protozoan parasites in their digestive tract. The present study evaluated the species composition and abundance across several habitats in a metropolitan landscape, as well as associations among phlebotomines, plants, and local climatic parameters. Three consecutive monthly collections were carried out in an Atlantic Forest fragment, using CDC light traps in peridomestic areas and cashew, coconut, and mango tree. plantations. Eight species of phlebotomine were captured: Evandromyia evandroi, Lutzomyia longipalpis, Psathyromyia shannoni, Sciopemyia sordellii, Evandromyia walkeri, Psychodopygus wellcomei, Nyssomyia whitmani, and Nyssomyia intermedia, primarily from the forest environment. L. longipalpis was confirmed as a species adapted to anthropic environments, while P. wellcomei was shown to be predominately forest-dwelling. Phlebotomines exhibited diversified food consumption patterns in relation to carbohydrate sources. They fed on both native and exotic species of arboreal and shrubby vegetables and gramineous plants.

Leishmaniasis sand fly vector density reduction is less marked in destitute housing after insecticide thermal fogging

BACKGROUND

Insecticide thermal fogging (ITF) is a tool to control vector borne diseases. Insecticide application success for vector control has been associated with housing materials and architecture. Vector abundance is correlated with weather changes. Nevertheless, housing quality and weather impacts on vector abundance have been unaccounted for in most New World insecticide control trials for leishmaniasis vectors.

METHODS

We conducted a 15 month insecticide control trial that included two deltamethrin [6 mg a.i.m-2] based ITF interventions in 12 of 24 monitored houses at Trinidad de Las Minas, a hyperendemic cutaneous leishmaniasis transmission village in western Panamá. During the study we followed sand fly (SF) abundance, keeping track of rainfall and quantified housing quality using an index based on architecture and construction materials.

RESULTS

We found a 50 to 80% reduction in SF density in the fogged houses when compared with control houses, while controlling for seasonal changes in SF abundance associated with rainfall. We found heterogeneities in the reductions, as abundance changed according to SF species: Lutzomyia gomezi, Lu. panamensis, Lu. dysponeta and Lu. triramula reduced in density between 40% and 90% after ITF. In contrast, Lu. trapidoi density increased 5% after ITF. Differences in the impact of ITF were associated with housing quality, the most destitute houses, i.e., those with features that ease insect entrance, had a disproportionally larger SF abundance, in some cases with increased domiciliary SF density following the ITF.

CONCLUSION

Our results suggest the potential of insecticide application to control SF density and leishmaniasis transmission could depend on housing quality beyond insecticide efficiency.