Distribution Of Vector-borne Diseases Research Articles

Impacts of Climate Change on Vector-Borne Diseases of Animals and Humans with Special Emphasis on Afghanistan

Vectors are organisms that transmit pathogenic microorganisms among animals and humans. Infections transmitted by the bites of blood-sucking arthropods are called vector-borne diseases (VBDs). This review highlights the impacts of climate change on the distribution, seasonal variation, and socioeconomic effects of VBDs in affected countries, especially Afghanistan. There is good enough evidence indicating that recent climate change has affected the interaction of the vector-pathogen-host cycle in many parts of the world. The emergence and re-emergence of bluetongue virus (BTV), Rift Valley Fever (RVF), lumpy skin disease (LSD), West Nile Virus (WNV), and malaria in new areas previously considered free of the diseases, and shift of seasonal occurrence of many VBDs in endemic areas, are the clear examples of climate change impacts on VDBs. Although significant progress has been made regarding VBD surveillance systems, diagnostic capacity, vaccine development, and vector control programs in resource-rich countries, failure in adaptation programs and ineffective mitigation strategies against VBDs in developing countries, especially in low and middle-income countries (LMICs), including Afghanistan facilitate widespread distribution of VBDs in these regions. Furthermore, developing drug resistance among the pathogens and their vectors makes the conditions more suitable for VBDs wide dispersion. Such situations cause severe health and socio-economic burdens to affected countries. Developing early-warning systems for detecting VBDs, identifying and developing resistant livestock species and breeds, and applying interceptive measures based on integrated research programs are crucial to effectively reduce the harmful impacts of VBDs on human and animal populations.

The influence of environmental factors on the historical distribution of Biomphalaria pfeifferi in the Tshwane Metropolitan Municipality

Abstract. Schistosomiasis remains the most endemic disease in tropical regions. Transmission rates and prevalence of schistosomiasis in Africa are relatively high compared to other regions. This is mostly associated with the lack of clean water and sanitation as necessities to curbing the spread of the disease. Over 90% of people in sub-Saharan Africa (SSA) are deprived of clean water and sanitation. 60-80% of the children in South African communities are infected. Climate variability plays a role in the distribution of vector-borne diseases by affecting intermediate host reproduction and changing their habitats thereby decreasing or increasing host survival and disease transmission ability. This study aims to determine the influence of environmental factors on the spatial distribution of Biomphalaria pfeifferi in the Tshwane Metropolitan Municipality. The use of species distribution models (SDMs) to model the intermediate snail hosts habitats in South Africa is uncommon, compared to other African countries. To our knowledge no modelling study has been done in South Africa particularly in the Tshwane Municipality, and this has therefore, paved a way for this study. A systematic literature review was conducted to identify all the important climatic variables that impact on the distribution of bilharzia-transmitting snails. Biomphalaria pfeifferi occurrence data was accessed from the National Freshwater Snails Collection, and the climate data was extracted from the ERA5 website respectively. The principal component analysis was used to reduce the multidimensionality of the dataset, with this framework tool, Pearson's correlations helped identify the variables showing a high correlation with the snail datasets and these were included in the ecological niche model. The following climatic variables: temperature, rainfall, water temperature, and other climate-related phenomena such as droughts and flooding influence the distribution patterns of intermediate snail hosts. The model showed high species presence along the central parts of Tshwane, mostly in the following areas Roodeplaat, Mamelodi, Winterveldt, and Refilwe. However, the south-eastern parts of the municipality did not indicate any species occurrence. The findings confirm that environmental factors impact on the historical distribution of Biomphalaria pfeifferi in the Tshwane Metropolitan Municipality. The response curves from the MaxEnt model depict the relationship between habitat suitability and environmental factors.

Potential Influence of Climate Change on the Occurrence and Distribution of Vector-Borne Diseases among Animal Populations

Potential Influence of Climate Change on the Occurrence and Distribution of Vector-Borne Diseases among Animal Populations

Development of environmental loop-mediated isothermal amplification (eLAMP) diagnostic tool for Bulinus truncatus field detection

BackgroundGlobal changes are reshaping the distribution of vector-borne diseases by spreading vectors to previously non-endemic areas. Since 2013, urogenital schistosomiasis has emerged in Corsica and threatens European countries. Gastropod vectors release schistosome larvae that can infect humans who come into contact with freshwater bodies. Monitoring schistosomiasis host vectors is a prerequisite to understand and subsequently to control this pathogen transmission. Because malacological surveys are time consuming and require special expertise, the use of a simple molecular method is desirable.MethodsThe aim of this study is to develop a ready-to-use protocol using the LAMP (loop-mediated isothermal amplification) method to detect environmental DNA of Bulinus truncatus, vector of Schistosoma haematobium. Interestingly, LAMP method possesses all the characteristics required for adaptability to field conditions particularly in low-income countries: speed, simplicity, lyophilized reagents, low cost and robustness against DNA amplification inhibitors. We have tested this new method on Corsican water samples previously analysed by qPCR and ddPCR.ResultsWe demonstrate that our diagnostic tool B. truncatus eLAMP (Bt-eLAMP) can detect the eDNA of Bulinus truncatus as effectively as the two other methods. Bt-eLAMP can even detect 1/4 of positive samples not detectable by qPCR. Moreover, the complete Bt-eLAMP protocol (sampling, sample pre-process, amplification and revelation) does not require sophisticated equipment and can be done in 1 ½ h.ConclusionsLAMP detection of environmental DNA provides large-scale sensitive surveillance of urogenital schistosomiasis possible by identifying potentially threatened areas. More generally, eLAMP method has great potential in vector-borne diseases and ecology.Graphical

Comparing Vector-Borne Disease Surveillance and Response in Beijing and the Netherlands

Background:Climate change, environmental change, and globalization affect the geographical distribution of vector-borne diseases. Temperate regions should be prepared for emerging diseases and learn from each other’s experiences.Objective(s):The vector-borne disease preparedness in two regions, Beijing and the Netherlands, were compared in order understand their similarities and differences leading to learning points on this complex topic.Methods:A comparative study was performed using interviews with vector-borne disease experts from Beijing and the Netherlands and supplemented by literature.Findings:In Beijing, syndromic surveillance is a priority for the identification of suspected vector-borne disease cases. In the Netherlands, the main surveillance emphasis is on laboratory confirmed vector-borne disease cases. Vector-surveillance at potential points of entry and other high-risk locations is performed according to the International Health Regulation (2005) in both settings. Beijing controls invasive and native mosquitos, which is not the case in the Netherlands. In Beijing, vector surveillance is performed to measure mosquito density around hospitals, this is not observed in the Dutch setting. Health risks posed by ticks are a priority in urban areas in the Netherlands, and the public is educated in self-protection. In contrast, ticks seem to occur less often in Beijing’s urban areas.Conclusions:The vector-borne disease context framework allowed us to compare the vector-borne disease preparedness between Beijing and the Netherlands, despite differences in vector-borne disease challenges. We can learn valuable lessons concerning surveillance and early detection of emerging vector-borne diseases when comparing the preparedness between different regions.

Retrospective study on dengue transmission

Weather variables, mainly temperature and humidity, influence vectors, viruses, human biology, ecology and consequently the intensity and distribution of vector-borne diseases . The climatic factors connected with Dengue fever happening in Chennai were investigated. The factors accountable for Dengue fever have been recognized and mapped to dengue cases in Chennai city. This work studies the association between yearly climate patterns between 2016 and 2017 and the spread of Dengue fever in Chennai. Monthly rainfall and temperature is taken as the factors of study. The study develops a statistical analysis to quantitatively assess the relationship between climate and Dengue fever. The correlation technique was used to fit the statistical model. The Inverse Distance Weighted (IDW) interpolation and Geographic Information System (GIS) techniques were used in mapping the spatial diffusion of Dengue fever risk zones. The results show that there is a significant correlation between Dengue fever and climate factors for the majority of the study area. Statistical analysis was conducted for comparison of model outputs and predictions.

Burden of malaria, impact of interventions and climate variability in Western Ethiopia: an area with large irrigation based farming

BackgroundLand use change has increasingly been expanding throughout the world in the past decades. It can have profound effects on the spatial and temporal distribution of vector borne diseases like malaria through ecological and habitat change. Understanding malaria disease occurrence and the impact of prevention interventions under this intense environmental modification is important for effective and efficient malaria control strategy.MethodsA descriptive ecological study was conducted by reviewing health service records at Abobo district health office. The records were reviewed to extract data on malaria morbidity, mortality, and prevention and control methods. Moreover, Meteorological data were obtained from Gambella region Meteorology Service Center and National Meteorology Authority head office. Univariate, bivariate and multivariate analysis techniques were used to analyze the data.ResultsFor the twelve-year time period, the mean annual total malaria case count in the district was 7369.58. The peak monthly malaria incidence was about 57 cases per 1000 people. Only in 2009 and 2015 that zero death due to malaria was recorded over the past 12 years. Fluctuating pattern of impatient malaria cases occurrence was seen over the past twelve years with an average number of 225.5 inpatient cases. The data showed that there is a high burden of malaria in the district. Plasmodium falciparum (Pf) was a predominant parasite species in the district with the maximum percentage of about 90. There was no statistically significant association between season and total malaria case number (F3,8: 1.982, P:0.195). However, the inter-annual total case count difference was statistically significant (F11,132: 36.305, p < 0001). Total malaria case count had shown two months lagged carry on effect. Moreover, 3 months lagged humidity had significant positive effect on total malaria cases. Malaria prevention interventions and meteorological factors showed statistically significant association with total malaria cases.ConclusionMalaria was and will remain to be a major public health problem in the area. The social and economic impact of the disease on the local community is clearly pronounced as it is the leading cause of health facility visit and admission including the mortality associated with it. Scale up of effective interventions is quite important. Continuous monitoring of the performance of the vector control tools needs to be done.

Spatio-temporal distribution of vector borne diseases in Australia and Papua New Guinea vis-à-vis climatic factors.

Weather and climate are directly linked to human health including the distribution and occurrence of vector-borne diseases which are of significant concern for public health. In this review, studies on spatiotemporal distribution of dengue, Barmah Forest Virus (BFV) and Ross River Virus (RRV) in Australia and malaria in Papua New Guinea (PNG) under the influence of climate change and/ or human society conducted in the past two decades were analysed and summarised. Environmental factors such as temperature, rainfall, relative humidity and tides were the main contributors from climate. The Socio-Economic Indexes for Areas (SEIFA) index (a product from the Australian Bureau of Statistics that ranks areas in Australia according to relative socio-economic advantage and disadvantage) was important in evaluating contribution from human society. For future studies, more emphasis on evaluation of impact of the El Niño-Southern Oscillation (ENSO) and human society on spatio-temporal distribution of vector borne diseases is recommended to highlight importance of the environmental factors in spreading mosquito-borne diseases in Australia and PNG.

Potential adverse health consequences of climate change related to rheumatic diseases

There is a growing body of literature regarding the health implications of climate change for the general population, but a scarcity of data specific to patients with rheumatic diseases. Human health will be affected by extreme weather events, heat waves, increased wildfires and a spread in the distribution of vector-borne diseases. Patients with underlying pulmonary, cardiac and renal disease are at high risk for adverse health outcomes related to these events. Many patients with rheumatic diseases share these comorbidities, which would presumably also put them at high risk for poor outcomes. There is research on ambient air pollution that indicates disease flares in patients with systemic lupus erythematosus are linked to elevated particulate matter. These patients are probably also at risk from increased particulate matter emanating from major wildfires. More research is needed on the specific adverse health impacts of climate change on patients with rheumatic diseases in order to guide policy decisions to mitigate the adverse impacts.

PNS6 Saving Lives or the Environment - How about Both? the Role of Health Technology Assessment (HTA) Bodies in Creating Sustainable Healthcare Systems

The natural environment is widely accepted as a determinant of global health; clean air, safe water, and the distribution of vector-borne diseases are some examples. Yet, if healthcare were a country, it would rank fifth on greenhouse gas emissions, largely offsetting environmental-related health benefits. By focusing on immediate needs of individual populations, healthcare systems around the world may compromise their long-term mandate of meeting future generations’ health needs too.

Analysis of climate factors and dengue incidence in the metropolitan region of Rio de Janeiro, Brazil.

Dengue is a re-emerging disease, currently considered the most important mosquito-borne arbovirus infection affecting humankind, taking into account both its morbidity and mortality. Brazil is considered an endemic country for dengue, such that more than 1,544,987 confirmed cases were notified in 2019, which means an incidence rate of 735 for every 100 thousand inhabitants. Climate is an important factor in the temporal and spatial distribution of vector-borne diseases, such as dengue. Thus, rainfall and temperature are considered macro-factors determinants for dengue, since they directly influence the population density of Aedes aegypti, which is subject to seasonal fluctuations, mainly due to these variables. This study examined the incidence of dengue fever related to the climate influence by using temperature and rainfall variables data obtained from remote sensing via artificial satellites in the metropolitan region of Rio de Janeiro, Brazil. The mathematical model that best fits the data is based on an auto-regressive moving average with exogenous inputs (ARMAX). It reproduced the values of incidence rates in the study period and managed to predict with good precision in a one-year horizon. The approach described in present work may be replicated in cities around the world by the public health managers, to build auxiliary operational tools for control and prevention tasks of dengue, as well of other arbovirus diseases.

Vector-borne diseases in Brazil: climate change and future warming scenarios

Climate change affects human health either directly or indirectly, and related impacts are complex, non-linear, and depend on several variables. The various climate change impacts on health include a change in the spatial distribution of vector-borne diseases. In this regard, this study presents and discusses changes in the spatial distribution of climate suitability for visceral leishmaniasis, yellow fever and malaria in Brazil, in different global warming scenarios. Maximum entropy (MaxEnt) was used to construct climate suitability models in warming scenarios. Models were based in climate variables generated by the Eta-HadGEM2 ES regional model, in the baseline period 1965-2005 and RCP8.5 scenario, representing global warming levels of 1,5ºC (2011-2040), 2,0ºC (2041-2070) and 4,0ºC (2071-2099). The three diseases studied are largely influenced by climate and showed different distribution patterns within the country. In global warming scenarios, visceral leishmaniasis found more favorable climate conditions in the Southeastern and Southern regions of Brazil, while climate in the Northern and Center-West regions gradually became more favorable to yellow fever. In malaria scenarios, an increase in favorable climate conditions to its high incidence was observed in the Atlantic Forest, where currently extra-Amazonian cases occur. The scenarios presented herein represent different possible consequences for the health sector in terms of adopting (or not) different measures to mitigate climate change in Brazil, such as reducing the emission of greenhouse gases.

Spatial and Temporal Epidemiology of Vector-borne Diseases in Punjab province of Pakistan-2018

Background: Vector-borne diseases are major public health problem worldwide. Dengue Fever (DF), Dengue Hemorrhagic Fever (DHF), and Malaria are endemic in Pakistan. The current study is aimed to find out temporal and spatial distribution of vector-borne diseases in Punjab province of Pakistan. Materials & Methods: The data of temporal, spatial and personal characteristics were collected from the health department of Punjab from July 1, 2016 to June 30, 2017 after taking departmental approval. The collected data was analyzed using Microsoft Excel and SPSS version 24.0. Frequencies and rates were calculated and graphically presented. Results: A total of 2,640 cases of malaria were reported during from July 1, 2016 to June 30, 2017 and with 1415(53%) male cases and male to female ratio of 1.3:1. A total of 2,520 cases of dengue fever were reported with 1829 (72%) male cases with male to female ratio of 2.6:1. Mean age was 17 years and 32 years for malaria and dengue fever cases respectively. For malaria, most affected age group was 5-9 years while for dengue fever 20-24 years. The highest number (n= 821) of malaria cases reported from Muzaffargarh (southern Punjab) and 1139 dengue cases reported from Rawalpindi (northern Punjab). Temporal characteristics of dengue indicated the highest frequency during September to November while malaria from August to October. Conclusion: Social, temporal and spatial distribution is suggestive of targeted interventions for both diseases yet integrated with their respective vector control measures. Dengue fever time trend is more demands robust outdoor preventive activities in north of Pakistan

Climate change and vector-borne diseases

Vector-borne diseases (VBD), such as Zika, dengue, chikungunya, yellow fever, leishmaniasis, malaria, Rift Valley Fever, Lyme disease and bluetongue are transmitted by exothermic arthropod vectors such as mosquitoes, flies, midges and ticks that do not regulate their internal temperature. Precipitation provides breeding sites for the early larval stages of the vectors, while temperature modulates their development, mortality rate and the time required for the pathogen to replicate in their body. As a consequence, climate change in addition to an ever-increasing mobility of goods and people and other socio-economic risk factors, will very likely affect the distribution of vector-borne diseases in future. Coupling mathematical disease models with climate observations and ensemble of future climate change scenarios, allow to explore potential future changes in VBD distribution and assess related uncertainties. This presentation will review research carried out at the University of Liverpool in collaboration with several international partners over the past decade. Our work confirmed the impact of the 2006 heatwave on the emergence of bluetongue, a midge-borne disease affecting ruminants, into northern Europe. In 2011 another publication anticipated the northward spread of Aedes albopictus, the Asian tiger mosquito, in Europe and into southern UK. In a study published in 2014 we showed that malaria risk could increase over tropical altitude regions while it could decrease over the warmer regions during the 2080s under the most extreme RCP8.5 scenario. In 2017, a study showed that the climatic conditions related to the 2015 El Niño event favoured the Zika outbreak that had a large impact on Latin America that year. Many other research groups anticipated the spread of vectors and the diseases they can transmit worldwide. This fact demonstrates the value and usefulness of such predictive risk models; and importantly that we need to take urgent measures to tackle anthropogenic climate change.

Large-scale disease patterns explained by climatic seasonality and host traits.

Understanding factors affecting the distribution of vector-borne diseases in space and across species is of prime importance to conservation ecologists. Identifying the underlying patterns of disease requires a perspective encompassing large spatial scales. However, few studies have investigated disease ecology from a macroecological perspective. Hence, we use a global disease database to uncover worldwide infection patterns using avian malaria (Plasmodium) as a model for vector-borne disease transmission. Using data on 678 bird species from 442 locations, we show that environmental variables likely to synchronize bird and vector abundance are the key factors dictating infection risk for birds. Moreover, direct effects of host traits on exposure risk as well as potential trade-offs in resource allocation were also shown to affect disease susceptibility, with larger bird species being more prone to infection. Our results suggest that considering evolutionary strategies and factors influencing spatial overlap between hosts and vectors is crucial for understanding worldwide patterns of disease transmission success.

Vector-borne disease distributions and risks to the UK

In the recent decades, the geographic distribution of vector-borne diseases (VBDs) of dogs and cats has changed for intrinsic and extrinsic reasons. Therefore some infections/infestations, some of zoonotic concern, have been recorded in geographic areas where they were unexpected. In Europe, arthropods (e.g. ticks, fleas, mosquitoes and sand flies) and the pathogens that they transmit are in general considered to be more frequent in the Mediterranean Basin. Nonetheless, a possible occurrence in other regions should not be a priori excluded, given that travels of animals (to or imported from endemic areas), movements of goods and global warming all may foster the introduction of vectors and/or transmitted pathogens in previously free areas. This could also be the case in the UK, which, because of its territorial characteristics as an island area in north-western Europe, is traditionally considered at minor risk of VBDs. Given the growing increase of movements and travels of pets, and changes in the phenology of many arthropod vectors, it is crucial that veterinary practitioners are aware of and prepared to diagnose, treat and control a series of unexpected diseases.

Evaluación de enfermedades transmitidas por vectores en perros de un área de clima sub-frío de México

La distribución geográfica de las enfermedades transmitidas por vectores está influenciada por una dinámica compleja de factores ambientales, sociales y el impacto cambiante de la transmisión de sus vectores, huéspedes intermedios y reservorios. El objetivo del presente estudio fue evaluar la seropositividad a anticuerpos anti-Ehrlichia canis, Anaplasma phagocytophilum, Borrelia burgdorferia y la seropositividad a antígenos de Dirofilaria immitis en perros de un área de México con un clima semifrío. Se tomaron 100 muestras de sangre de caninos de hogares privados y en clínicas veterinarias del estado de Amecameca de Juárez, Estado de México. El análisis de las muestras se llevó a cabo mediante un kit comercial de ELISA (Test SNAP® 4Dx® Plus Canine IDEXX®). A los resultados se observó una seropositividad a anticuerpos anti-E. canis del 30 %, 9 % para A. phagocytophilum, 4 % para B. burgdorferi y 16 % para antígenos de D. immitis. Así mismo, se halló una relación estadísticamente significativa entre la seropositividad a anticuerpos anti-E. canis y perros mayores a un año y de raza. Por otra parte se reportaron resultados similares en perros machos y mayores de un año con seropositividad a D. immitis. Con los resultados obtenidos, se concluye que existe una mayor seropositividad para la infección por E. canis y D. immitis y una asociación significativa en perros mayores de un año. Es de gran relevancia conocer la epidemiología de patógenos transmitidos por garrapatas debido al impacto zoonotico que implican. Se recomiendan investigaciones adicionales, así como medidas preventivas de salud animal y salud pública para reducir el riesgo de infección en perros.

Vector-borne disease distributions and risks to the UK

In the recent decades, the geographic distribution of vector-borne diseases (VBDs) of dogs and cats has changed for intrinsic and extrinsic reasons. Therefore some infections/infestations, some of zoonotic concern, have been recorded in geographic areas where they were unexpected. In Europe, arthropods (e.g. ticks, fleas, mosquitoes and sand flies) and the pathogens that they transmit are in general considered to be more frequent in the Mediterranean Basin. Nonetheless, a possible occurrence in other regions should not be a priori excluded, given that travels of animals (to or imported from endemic areas), movements of goods and global warming all may foster the introduction of vectors and/or transmitted pathogens in previously free areas. This could also be the case in the UK, which, because of its territorial characteristics as an island area in north-western Europe, is traditionally considered at minor risk of VBDs. Given the growing increase of movements and travels of pets, and changes in the phenology of many arthropod vectors, it is crucial that veterinary practitioners are aware of and prepared to diagnose, treat and control a series of unexpected diseases.

Zoonotic Babesia: A scoping review of the global evidence.

BackgroundBabesiosis is a parasitic vector-borne disease of increasing public health importance. Since the first human case was reported in 1957, zoonotic species have been reported on nearly every continent. Zoonotic Babesia is vectored by Ixodes ticks and is commonly transmitted in North America by Ixodes scapularis, the tick species responsible for transmitting the pathogens that also cause Lyme disease, Powassan virus, and anaplasmosis in humans. Predicted climate change is expected to impact the spread of vectors, which is likely to affect the distribution of vector-borne diseases including human babesiosis.MethodsA scoping review has been executed to characterize the global evidence on zoonotic babesiosis. Articles were compiled through a comprehensive search of relevant bibliographic databases and targeted government websites. Two reviewers screened titles and abstracts for relevance and characterized full-text articles using a relevance screening and data characterization tool developed a priori.ResultsThis review included 1394 articles relevant to human babesiosis and/or zoonotic Babesia species. The main zoonotic species were B. microti, B. divergens, B. duncani and B. venatorum. Articles described a variety of study designs used to study babesiosis in humans and/or zoonotic Babesia species in vectors, animal hosts, and in vitro cell cultures. Topics of study included: pathogenesis (680 articles), epidemiology (480), parasite characterization (243), diagnostic test accuracy (98), mitigation (94), treatment (65), transmission (54), surveillance (29), economic analysis (7), and societal knowledge (1). No articles reported predictive models investigating the impact of climate change on Babesia species.ConclusionKnowledge gaps in the current evidence include research on the economic burden associated with babesiosis, societal knowledge studies, surveillance of Babesia species in vectors and animal hosts, and predictive models on the impact of climate change. The scoping review results describe the current knowledge and knowledge gaps on zoonotic Babesia which can be used to inform future policy and decision making.

Exotic threats to UK equines

Historically, veterinary surgeons in the UK have had little cause to consider many vector-borne infections that are of great significance elsewhere in the world. Primarily this has reflected the combination of a lack of the required vectors and climate conditions for disease transmission, combined with the geographical barrier to disease entry that being a small island provides. In recent years there have been significant changes in the global distribution of vector-borne diseases, and it has been suggested that these are associated with climate change and the increasing international movement of animals and animal products. Veterinary surgeons attending cases with clinical findings consistent with exotic disease, in particular in any equids that have travelled or are housed with equids that have travelled, must remain vigilant to the possibility of the disease occurring in areas currently considered disease-free. This article focuses on three such diseases that increasingly threaten the UK equine population: African horse sickness, piroplasmosis and West Nile virus infection.