First assessment for the presence of phlebotomine vectors in Bavaria, Southern Germany, by combined distribution modeling and field surveys

First Evidence of Leishmania infantum Antibodies in Sheep (Ovis aries) from Southern Germany

In Europe, Leishmania infantum is the most prevalent Leishmania species, and this protozoan is transmitted by phlebotomine sandflies. A recent publication has shown that sheep harbor L. infantum antibodies. This raises questions about the epidemiological role of small ruminants. Therefore, sera from small ruminants located in two southern German federal states, Baden-Wuerttemberg (BW) and Bavaria (BAV), were analyzed with an ELISA to determine the presence of L. infantum antibodies. The species, sex and age (gimmer vs. ewe) were recorded, and a univariate analysis was conducted to determine possible associations. In total, seven sheep flocks (274 sheep/10 goats) from BW and seven sheep flocks (277 sheep/78 goats) from BAV were examined. In BW, four sheep from three flocks tested positive for L. infantum antibodies. In BAV, the same number of positive sheep were detected but in four flocks. The total seropositivity rate in sheep was 1.45%. All goats tested negative. No significant association (p > 0.05) was detected between Leishmania seropositivity and the variables evaluated. Our study reveals the exposure of sheep to L. infantum in a non-endemic area. Further investigation is needed to determine whether sheep can be used as sentinels to identify new phlebotomine habitats and Leishmania risk areas.

Same parasite, different outcomes: unraveling the epidemiology of Leishmania infantum infection in Brazil and Spain

Human leishmaniosis caused by Leishmania infantum is an important health problem worldwide. One of the main aspects arousing interest is the epidemiological scenario surrounding Le. infantum infection in the New World (NW) and Old World (OW). This parasite was introduced to the Americas during European colonization leading to different epidemiology outcomes, even more enigmatic in the face of global changes. Thus, this review aims to highlight the differences and similarities between Le. infantum epidemiology between Brazil (NW) and Spain (OW), as both countries are leading the total number of leishmaniosis cases in their respective continents. Grounded on a systemic view, this article also draws attention to possible common innovative strategies to rethink ways of controlling infections caused by Le. infantum.

A Review on Climate, Air Pollution, and Health in North Africa

PURPOSE OF REVIEW

The aim of this review is to summarize and provide clear insights into studies that evaluate the interaction between air pollution, climate, and health in North Africa.

RECENT FINDINGS

Few studies have estimated the effects of climate and air pollution on health in North Africa. Most of the studies highlighted the evidence of the link between climate and air pollution as driving factors and increased mortality and morbidity as health outcomes. Each North African country prioritized research on a specific health factor. It was observed that the health outcome from each driving factor depends on the studied area and data availability. The latter is a major challenge in the region. As such, more studies should be led in the future to cover more areas in North Africa and when more data are available. Data availability will help to explore the applicability of different tools and techniques new to the region. This review explores studies related to climate and air pollution, and their possible impacts on health in North Africa. On one hand, air quality studies have focused mainly on particulate matter exceedance levels and their long-term exposure impacts, namely, morbidity and mortality. The observed differences between the various studies are mainly due to the used exposure-response function, the studied population, background emissions, and natural emission from the Sahara Desert that characterize the region. On the other hand, climate studies have focused primarily on the impact of heat waves, vector-borne disease, and mental disorders. More than half of these studies have been on leishmaniasis disease. The review revealed unbalanced and insufficient research on health impacts from air pollution episodes and climate extremes across the region.

Trends in the Epidemiology of Leishmaniasis in the City of Barcelona (1996-2019)

Background: Leishmaniasis is a neglected zoonosis produced by 20 different flagellated parasites of the Leishmania genus, a protozoan transmitted to humans and other vertebrates by the bite of dipteran insects of the Phlebotominae subfamily. It is endemic in Mediterranean countries and the number of cases is expected to increase due to climate change and migration. Prioritizing public health interventions for prevention and control is essential. The objective was to characterize the epidemiology and temporal trends in the incidence of human leishmaniasis in the city of Barcelona, between the years 1996 and 2019. Methods: A population-based, analytical observational study among residents in the city of Barcelona was conducted of all the cases of leishmaniasis reported between 1996 and 2019 to the Public Health Agency. The epidemiological survey contains clinical, diagnostic, and epidemiological data, including contact with suspicious mammals or insects. Annual incidence-rates were calculated by sex, age, and country of origin. Chi-square tests were used to assess association between studied risk factors, periods of time and type of leishmaniasis. Results: During the study period a total of 177 cases of leishmaniasis were reported in Barcelona, being 74.6% (n = 132) of the total cases in Spanish born, although within the foreign-born population the incidence was higher. Median age was 34 years (IQR = 10-48) and 121 (66.8%) were male. The main type was cutaneous (46%) followed by visceral (35.1%). The cumulative incidence was 0.47 per 100,000 inhabitants, with the highest incidence found in 2017 (1.60 per 100,000 inhabitants). A higher incidence was observed in the 0-4-year-old group (1.73 per 100,000 inhabitants), but increased during the study period for all age groups. There was an increase of foreign origin cases, and a decrease in the number of cases associated to any immunosuppression. Conclusion: In Barcelona, leishmaniasis incidence continues to be higher in people under 5 years of age, and 25-64 years old males, but it has also increased in population from foreign country of birth. There is an increase of the cases since 2016, probably due to the changes in the notification system, increasing the diagnosis of cutaneous leishmaniasis. Improvements in the current surveillance system are needed. Notification of the disease, vector, and reservoir control activities are also essential for the control of the disease.

Leishmaniasis Beyond East Africa

Climate change is having a substantial impact on our environment and ecosystems and has altered the way humans live, access, and utilize resources with increased risk of zoonotic infectious disease encounters. As global temperatures continue to increase, they impact on public health, migration, food security and land conflict, and as new environments become favorable, exposure to disease carrying vectors. Increased forests or natural habitat clearance for land repurposing, urbanization, road building, and water management are related to an increase in emerging vector borne parasitic diseases. The East African region remains one of the most impacted regions globally for leishmaniasis, a vector borne disease that impacts significantly on the health, wellbeing and livelihoods of affected communities and for which a lack of reporting and control interventions hinder progress toward elimination of this neglected tropical disease. As our world continues to transform, both politically and climatically, it is essential that measures are put in place to improve surveillance and disease management with implementation of control measures, including vector control, especially in low- and middle-income countries that are expected to be most impacted by changes in climate. Only through effective management, now, can we be sufficiently resilient to preventing the inevitable spread of vectors into suitable habitat and expansion of the geographical range of leishmaniasis. This review offers a current perspective on Leishmaniasis as an endemic disease in East Africa and examines the potential of the recent emergence of Leishmania infection in hitherto unaffected regions to become a public health concern if no disease management is achieved.

Modeling the climatic suitability of leishmaniasis vector species in Europe

Climate change will affect the geographical distribution of many species in the future. Phlebotomine sandflies are vector species for leishmaniasis, a tropical neglected disease. We applied an ensemble forecasting niche modeling approach to project future changes in climatic suitability for ten vector competent sandfly species in Europe. Whereas the main area of sandfly distribution currently lies in the Mediterranean region, models generally projected a northwards expansion of areas with suitable climatic conditions for most species (P. alexandri, P. neglectus, P. papatasi, P. perfiliewi, P. tobbi) in the future. The range of distribution for only two species (P. ariasi, P. mascittii) was projected to decline in the future. According to our results, a higher number of vector competent species in Central Europe can generally be expected, assuming no limitations to dispersal. We recommend monitoring for the establishment of vector species, especially in areas with projected climatic suitability for multiple vector species, as a precautious strategy. An increased number of vector species, or a higher abundance of a single species, might result in a higher transmission risk of leishmaniasis, provided that the pathogens follow the projected range shifts.

Evaluation of the impacts of climate change on disease vectors through ecological niche modelling

Vector-borne diseases are exceptionally sensitive to climate change. Predicting vector occurrence in specific regions is a challenge that disease control programs must meet in order to plan and execute control interventions and climate change adaptation measures. Recently, an increasing number of scientific articles have applied ecological niche modelling (ENM) to study medically important insects and ticks. With a myriad of available methods, it is challenging to interpret their results. Here we review the future projections of disease vectors produced by ENM, and assess their trends and limitations. Tropical regions are currently occupied by many vector species; but future projections indicate poleward expansions of suitable climates for their occurrence and, therefore, entomological surveillance must be continuously done in areas projected to become suitable. The most commonly applied methods were the maximum entropy algorithm, generalized linear models, the genetic algorithm for rule set prediction, and discriminant analysis. Lack of consideration of the full-known current distribution of the target species on models with future projections has led to questionable predictions. We conclude that there is no ideal 'gold standard' method to model vector distributions; researchers are encouraged to test different methods for the same data. Such practice is becoming common in the field of ENM, but still lags behind in studies of disease vectors.

Factors influencing the presence of sand flies in Majorca (Balearic Islands, Spain) with special reference to Phlebotomus pernicious, vector of Leishmania infantum

BACKGROUND

Although the Mediterranean island of Majorca is an endemic area of leishmaniosis, there is a lack of up-to-date data on its sand fly fauna, the last report dating from 1989. The aim of the present study was to provide information on the current sand fly distribution, the potential environmental factors favoring the presence of Phlebotomus perniciosus and which areas are at risk of leishmaniosis.

METHODS

In July 2008 sand fly captures were carried out in Majorca with sticky castor oil interception traps. The capture stations were distributed in 77 grids (5x5 km2) covering the entire island. A total of 1,882 sticky traps were set among 111 stations. The characteristics of the stations were recorded and maps were designed using ArcGIS 9.2 software. The statistical analysis was carried out using a bivariate and multivariate logistic regression model.

RESULTS

The sand fly fauna of Majorca is composed of 4 species: Phlebotomus perniciosus, P sergenti, P. papatasi and Sergentomyia minuta. P. perniciosus, responsible for Leishmania infantum transmission, was captured throughout the island (frequency 69.4 %), from 6 to 772 m above sea level. Through logistic regression we estimated the probability of P. perniciosus presence at each sampling site as a function of environmental and meteorological factors. Although in the initial univariate analyses the probability of P. perniciosus presence appeared to be associated with a wide variety of factors, in the multivariate logistic regression model only altitude, settlement, aspect, drainage hole construction, adjacent flora and the proximity of a sheep farm were retained as positive predictors of the distribution of this species.

CONCLUSIONS

P. perniciosus was present throughout the island, and thereby the risk of leishmaniosis transmission. The probability of finding P. perniciosus was higher at altitudes ranging from 51 to 150 m.a.s.l., with adjacent garrigue shrub vegetation, at the edge of or between settlements, and in proximity to a sheep farm.

Ecology of phlebotomine sand flies and Leishmania infantum infection in a rural area of southern Italy

Phlebotomine sand flies are insects of major medico-veterinary significance in the Mediterranean region, as they may transmit pathogens to animals and humans, including viruses and protozoa. The present study was conducted in southern Italy, in an area where visceral leishmaniasis caused by Leishmania infantum is endemic. Insects were collected monthly during two consecutive years using light traps set in five different ecologic contexts (i.e., a stonewall near a woodhouse, a tree near volcanic rocks in a high-altitude area, a tree trunk in a meadow habitat, a sheep stable, and a chicken coop) and weekly in one site (the garage of a private house). A total of 13,087 specimens were collected and six species identified (i.e., Phlebotomus perfiliewi, Phlebotomus perniciosus, Phlebotomus neglectus, Phlebotomus papatasi, Phlebotomus mascittii, and Sergentomyia minuta), representing 75% of the total number of phlebotomine species found in Italy. P. perfiliewi was the most abundant species, comprising 88.14% of the specimens identified. The greatest species diversity and abundance was recorded in human dwellings and in animal sheds. Sand flies were active from June to October, peaking in July-August in 2010 and July-September in 2011. Part of the females (n=8865) was grouped into 617 pools (range, 1-10 insects each) according to species, feeding status, day and site of collection. A total of four pools (10 non-engorged specimens each) and one engorged female of P. perfiliewi were positive for L. infantum. This study confirms that phlebotomine vectors in southern Italy are highly adapted to human-modified environments (e.g., animal sheds) and that P. perfiliewi is a major vector of L. infantum in some regions of southern Italy.

A global set of Fourier-transformed remotely sensed covariates for the description of abiotic niche in epidemiological studies of tick vector species

BACKGROUND

Correlative modelling combines observations of species occurrence with environmental variables to capture the niche of organisms. It has been argued for the use of predictors that are ecologically relevant to the target species, instead of the automatic selection of variables. Without such biological background, the forced inclusion of numerous variables can produce models that are highly inflated and biologically irrelevant. The tendency in correlative modelling is to use environmental variables that are interpolated from climate stations, or monthly estimates of remotely sensed features.

METHODS

We produced a global dataset of abiotic variables based on the transformation by harmonic regression (time series Fourier transform) of monthly data derived from the MODIS series of satellites at a nominal resolution of 0.1°. The dataset includes variables, such as day and night temperature or vegetation and water availability, which potentially could affect physiological processes and therefore are surrogates in tracking the abiotic niche. We tested the capacities of the dataset to describe the abiotic niche of parasitic organisms, applying it to discriminate five species of the globally distributed tick subgenus Boophilus and using more than 9,500 published records.

RESULTS

With an average reliability of 82%, the Fourier-transformed dataset outperformed the raw MODIS-derived monthly data for temperature and vegetation stress (62% of reliability) and other popular interpolated climate datasets, which had variable reliability (56%-65%). The transformed abiotic variables always had a collinearity of less than 3 (as measured by the variance inflation factor), in contrast with interpolated datasets, which had values as high as 300.

CONCLUSIONS

The new dataset of transformed covariates could address the tracking of abiotic niches without inflation of the models arising from internal issues with the descriptive variables, which appear when variance inflation is higher than 10. The coefficients of the harmonic regressions can also be used to reconstruct the complete original time series, being an adequate complement for ecological, epidemiological, or phylogenetic studies. We provide the dataset as a free download under the GNU general public license as well as the scripts necessary to integrate other time series of data into the calculations of the harmonic coefficients.

Hemophagocytic lymphohistiocytosis in imported pediatric visceral leishmaniasis in a nonendemic area

OBJECTIVES

To describe characteristics of visceral leishmaniasis-associated hemophagocytic lymphohistiocytosis (HLH) with focus on diagnostic clues and pitfalls, including the frequency of central nervous system (CNS) involvement, and to determine the efficacy of liposomal amphotericin B (L-AmB).

STUDY DESIGN

We retrospectively analyzed clinical and laboratory features, diagnostic procedures, and treatment of 13 patients with HLH with imported visceral leishmaniasis, reported to the German HLH reference center (1999-2012).

RESULTS

The spectrum of presentations was indistinguishable from patients with hereditary HLH or with acquired HLH because of infections with other pathogens. In 8 patients, disease onset occurred before the age of 2 years, coinciding with the typical age of manifestation of primary HLH. Two patients had mild nonspecific CNS findings. Misleading antiviral IgM (n = 6) and autoantibodies (n = 2) led to inaccurate interpretation of the etiology of HLH, sometimes with inappropriate therapeutic consequences. False negative results for Leishmania were obtained by initial bone marrow microscopy in 6/13, serology in 1/12, bone marrow culture in 2/5, and polymerase chain reaction of peripheral blood in 1/3 patients, and all bone marrow samples tested were Leishmania-positive by polymerase chain reaction (n = 7). L-AmB was administered to 12 patients, 5 of whom had no prior HLH-directed immunosuppressive therapy; sodium stibogluconate was administered to 1 patient. Persistent remission was achieved in 11 cases. Two patients required repeated or prolonged L-AmB therapy.

CONCLUSIONS

Awareness of diagnostic pitfalls may save patients from unnecessary toxic treatment. CNS involvement is rare. L-AmB shows efficacy in visceral leishmaniasis-associated HLH.

Implementing cargo movement into climate based risk assessment of vector-borne diseases

During the last decades the disease vector Aedes albopictus (Asian tiger mosquito) has rapidly spread around the globe. Global shipment of goods contributes to its permanent introduction. Invaded regions are facing novel and serious public health concerns, especially regarding the transmission of formerly non-endemic arboviruses such as dengue and chikungunya. The further development and potential spread to other regions depends largely on their climatic suitability. Here, we have developed a tool for identifying and prioritizing European areas at risk for the establishment of Aedes albopictus by taking into account, for the first time, the freight imports from this mosquito's endemic countries and the climate suitability at harbors and their surrounding regions. In a second step we consider the further transport of containers by train and inland waterways because these types of transport can be well controlled. We identify European regions at risk, where a huge amount of transported goods meet climatically suitable conditions for the disease vector. The current and future suitability of the climate for Aedes albopictus was modeled by a correlative niche model approach and the Regional Climate Model COSMO-CLM. This risk assessment combines impacts of globalization and global warming to improve effective and proactive interventions in disease vector surveillance and control actions.