Occurrence Of Vector Borne Diseases Research Articles

Relationship between climatic factors and the flea index of two plague hosts in Xilingol League, Inner Mongolia Autonomous Region

Climatic factors are closely associated with the occurrence of vector-borne diseases, and they also influence the distribution of vectors. The occurrence of plague is closely related to the population dynamics of fleas and their host animals, as well as climatic conditions. This study focuses on Xilingol League, utilizing climatic and flea index data from 2012 to 2021. Spearman correlation and "Boruta" importance analysis are conducted to screen for climatic variables. A generalized additive model (GAM) is employed to investigate the influence of climatic factors and rodent density on the flea index. GAM analysis reveals distinct trends in flea index among different rodent hosts. For Meriones unguiculatus, the flea index declines with increased density and with higher humidity, yet rises with greater lagged sunshine duration. For Spermophilus dauricus, an initial increase in flea index with density is observed, followed by a decrease, and a rise in the index is noted when ground temperatures are low. This study reveals the nonlinear interactions and lag effects among climatic factors, density, and flea index. Climatic factors and density variably influence the flea index of two Yersinia pestis hosts. This research advances the prediction and early warning efforts for plague control, providing a theoretical basis for rodent and flea eradication strategies.

Impacts of Changing Climate on Arthropod Vectors and Diseases Transmission

Climate change stands as a burgeoning global concern with profound implications. The present review seeks to present the projected impacts of climate change on disease vectors and their transmission of various human and animal diseases. The impact of climate on the prevalence of vector-borne diseases (VBDs), which significantly affect human and animal populations, is notable. The occurrence of VBDs, influenced by local epidemiological and ecological factors alongside specific climatic conditions, may exhibit fluctuations due to climate change. Particularly affected are exothermic arthropod vectors, responsible for transmitting most vectorborne diseases. The intricate interplay of temperature, precipitation, humidity, and other environmental factors significantly shapes the reproduction, development, behavior, and population dynamics of arthropod disease vectors. Also, climate change can alter the spread of pathogens within vectors, influence population dynamics, and impact the range of nonhuman vertebrate reservoirs for numerous vector-borne diseases. Predicting the precise impact of sustained climate change on these diseases poses a considerable challenge, necessitating comprehensive long-term research. These researches must encompass the effects of climate change while considering the contributions of other global change agents, including increased trade and travel, demographic shifts, civil unrests, alterations in land use, water availability, and related factors. The association between climate change and the emergence of specific diseases has been established. However, for certain diseases, the risk of local transmission is significant, while for others, pinpointing the exact influence remains elusive. Therefore, strategic adaptation and preparedness for the shifting distribution patterns of VBDs are imperative, especially in the context of Nigeria and Africa as a whole.

Climate variability and occurrence of vector borne diseases: evidence from National Capital Region of Delhi, India

Climate variability and occurrence of vector borne diseases: evidence from National Capital Region of Delhi, India

Under-diagnosis of vector-borne diseases among individuals suspected of having Scrub Typhus in South Korea.

Due to environmental and ecological changes and suitable habitats, the occurrence of vector-borne diseases is increasing. We investigated the seroprevalence of four major vector-borne pathogens in human patients with febrile illness who were clinically suspected of having Scrub Typhus (ST) caused by Orientia tsutsugamushi. A total of 187 samples (182 patient whole blood and sera samples, including 5 follow-up) were collected. Antibodies to Anaplasma phagocytophilum, Ehrlichia chaffeensis, Borrelia burgdorferi, and Bartonella henselae were tested by using indirect immunofluorescence assays. Molecular diagnoses were performed using real-time PCR. Of the 182 cases, 37 (20.3%) cases were designated as confirmed cases of ST, and the remaining 145 (79.7%) cases as other febrile diseases (OFDs). The seroprevalence of A. phagocytophilum, E. chaffeensis, B. burgdorferi, and B. henselae was 51.4% (19/37), 10.8% (4/37), 86.5% (32/37), and 10.8% (4/37) among the ST group, and 42.8% (62/145), 10.4% (19/145), 57.7% (105/145), and 15.9% (29/145) among the OFD group, respectively. There were no significant differences in the seroprevalence between the ST and the OFD groups. Considering the co-occurrence, 89.0% (162/182) had at least one antibody to tick-borne pathogens, 37.0% (60/162) were positive for two pathogens, 17.3% (28/162) for three pathogens, and 6.2% (10/162) for four pathogens. In real-time PCR, O. tsutsugamushi was positive in 16 cases [15 (40.5%) in ST group and 1 (2.2%) in OFD group], and the four other pathogens were negative in all cases except one confirmed as anaplasmosis. In evaluating the five follow-up samples, the appearance of new antibodies or an increase in the pre-existing antibody titers was detected. Our data highlighted that acute febrile illness and manifestations suggestive of a vector-borne infection must be recognized and further considered for coinfections in clinical practice and the laboratory.

First molecular confirmation of multiple zoonotic vector-borne diseases in pet dogs and cats of Hong Kong SAR

In recent years, the incidence of vector-borne diseases (VBDs) has increased throughout the globe. In particular, tick-borne diseases (e.g., caused by Ehrlichia canis, E. ewingii, Anaplasma phagocytophilum, A. platys, Borrelia burgdorferi sensu stricto (s.s.) and Babesia gibsoni) and mosquito-borne diseases (e.g., caused by Dirofilaria immitis) diseases pose a burden on animal health. Nevertheless, there have been no studies undertaken on the occurrence of VBDs in pet dogs and cats in Hong Kong SAR. This study fills this gap, and is the first to determine the seroprevalence of major VBDs, such as those caused by D. immitis, E. canis, E. ewingii, A. phagocytophilum, A. platys and B. burgdorferi s.s, in dogs and cats through commercially available SNAP 4Dx plus testing. Infection by all these pathogens and Babesia sp. was further assessed through PCR and DNA sequencing. A total of 224 blood samples were collected from domestic dogs (n = 159) and cats (n = 65) in Hong Kong SAR during summer 2022. Hematocrit and platelet counts were determined in each blood sample and other hematological parameters were assessed using an automatic hematology analyzer and vortex the specimen for one to two minutes at or near the highest setting to minimize the clumping. All cat sera samples were negative for tested pathogens, but antibodies against some of the pathogens were detected in dog sera samples. Here, the highest figures were recorded for seroprevalence of E. canis/E. ewingii (10.7%), followed by D. immitis (5.7%), and A. phagocytophilum/A. platys (2.5%). No B. burgdorferi s.s. antibodies were detected in any of the dogs tested. Through molecular diagnostics, we detected the presence of B. gibsoni (3.7%), E. canis (3.1%), D. immitis (5.7%), and A. phagocytophilum (1.3%). Neighbor-Joining phylogenetic trees for vector-borne pathogens (i.e., genus Anaplasma sp.) showed 100% clustering to Japan, the USA and Germany, whereas genus Ehrlichia sp. showed 100% clustering to China, Turkey, Cuba, and Greece. Similarly, genus Babesia sp. clustered 100% to India, Sri Lanka and Austria, while D. immitis clustered in Iraq, South Korea, Portugal, France, the USA and Italy. This study provides the first evidence on the occurrence of tick-borne pathogens in pet dogs in Hong Kong SAR. Based on these findings, it is recommended that appropriate screening should be undertaken in domestic dogs to evaluate the prevalence of these pathogens and promote the timely control of VBDs.

Impact of COVID-19 lockdown during 2020 on the occurrence of vector-borne diseases in India.

India imposed one of the world's largest nationwide lockdown in the aftermath of COVID-19 pandemic in March 2020 which was partly extended up to December. Some of the impacts of the COVID-19 lockdown on the economy, research, travel, education, and sports were readily apparent; the same was less obvious in the occurrence of vector-borne diseases (VBDs). The objective of this study was to statistically determine the impact of the COVID-19 lockdown on the occurrence of VBDs in India. The reported incidence of VBDs such as malaria, dengue, Chikungunya, Japanese encephalitis, and kala-azar in India during the years 2015-2019 was analyzed by fitting Poisson and negative binomial (NB) models for each VBDs separately. The number of cases reported was compared with the number of cases predicted for each year from 2015 to 2020 for all the VBDs under study to infer whether or not the lockdown had any impact on their prevalence in India. The percentage of the actual case was lower by 46, 75, 49, 72, and 38 respectively for malaria, dengue, Chikungunya, Japanese encephalitis, and kala-azar when comparing the lockdown period and the year before lockdown (2020 vs. 2019). The number of cases predicted for the year 2020 based on the trend of the five preceding years (2015-2019) also showed a great variation between actual and predicted cases. The differences in cases were considered as the cases missed in 2020 were largely due to the lockdown. The analysis showed that the lockdown had a considerable impact on the occurrence of VBDs.

Study of mosquito (Culicidae) larvae and characterisation of water bodies in urban and periurban areas

Abstract Urbanisation has modified the distribution and community composition of mosquito species (Culicidae). Habitat disturbance may increase the risk of loss of species diversity and the occurrence of vector-borne diseases. Studies on the presence of larvae and the eco-physicochemical characteristics of water bodies near urban areas provide information on the risk of these diseases. In this study, the presence of larvae in different types of urban and periurban water bodies in Villahermosa City, Tabasco, Mexico was analysed. The eco-physicochemical characteristics of each collecting site were measured. A total of 67 528 larvae were collected, 1366 were identified to species, and 15 species were observed. Although Culex spp. were the most dominant species, Anopheles albimanus was the only species present in all habitats. Despite the large variability in the parameters measured (especially in physicochemical parameters; e.g., pH, electrical conductivity, total dissolved solids), differences were observed among the breeding sites. Weak correlations were found between eco-physicochemical parameters and species presence. Predators may have a major role in determining community processes in the region. Habitat disturbance may be responsible for eco-physicochemical variations altering mosquito community composition, resulting in the loss of endemic mosquito species and increasing the risk of vector-borne diseases in Villahermosa.

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.

Major climate change-induced risks to human health in South Africa

There are many climatic changes facing South Africa which already have, or are projected to have, a detrimental impact on human health. Here the risks to health due to several alterations in the climate of South Africa are considered in turn. These include an increase in ambient temperature, causing, for example, a significant rise in morbidity and mortality; heavy rainfall leading to changes in the prevalence and occurrence of vector-borne diseases; drought-associated malnutrition; and exposure to dust storms and air pollution leading to the potential exacerbation of respiratory diseases. Existing initiatives and strategies to prevent or reduce these adverse health impacts are outlined, together with suggestions of what might be required in the future to safeguard the health of the nation. Potential roles for the health and non-health sectors as well as preparedness and capacity development with respect to climate change and health adaptation are considered.

Health of Farming Communities Prior to Modification of the Occupational Environment through a Watershed Development Project in Kolar, India.

Background:Watershed development (WSD) projects, aimed primarily at enhancing soil and water conservation and supporting livelihoods in semi-arid areas, have the potential to impact health by modifying the occupational and household environments in agrarian communities. To identify and address potential health concerns arising from a planned WSD project in Kolar district, India, a health impact assessment (HIA) was conducted. This necessitated understanding the health status and concerns in the project villages.Objective:To characterize the health of farmers and their household members in close proximity of the planned WSD project.Methods:We carried out a cross-sectional survey between April and July 2019. The study comprised: (i) a household survey covering the four project villages and two comparison villages (e.g. socio-demographic characteristics, occurrence of vector-borne diseases (VBDs), access to safe water, sanitation and hygiene, and utilization of healthcare); and (ii) an anthropometric survey for children under the age of 5 years in the four project villages and four comparison villages.Results:Respondents (n = 333) reported household-level occurrences of VBDs (chikungunya, 3.3%; and dengue, 1.5%), consuming unsafe water (54.5%) and frequent pesticide application in fields (26.7%). The prevalence of child underweight was 23.8%.Conclusions:VBDs, poor water quality and child undernutrition were found to be important local health concerns, amenable for preventive and promotive measures through the planned WSD project. Occupational environments in agricultural settings affect the workers and their households, and comprehensive projects such as WSD can seize the opportunity for improving health of farming and other rural households.

Introduction to Modern Climate Change. Andrew E. Dessler: Cambridge University Press, 2011, 252 pp, ISBN-10: 0521173159

Climate change is the variability of the climate system that includes the atmosphere, the biogeochemical cycles (Carbon cycle, Nitrogen cycle and Hydrological cycle), the land surface, ice and the biotic and abiotic components of the planet earth. Significant impact of climate change is seen in the form of rise in temperature called as global warming. Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are the primary greenhouse gases (GHGs) mainly responsible for the global warming and climate change. These GHGs have drawn lot of attention due to their significant role in the global warming potential. Intergovernmental Panel on Climate Change (IPCC) suggested to stop global warming at 1.5oC above preindustrial levels as warming beyond this level might lead to heat extremes, alter insect and plant phenology (Phenological shifts) and more occurrence of vector borne diseases. Climate change is the topic of interest in all fields of life starting from social science and going to the applied science. Global climate cycles and world food production systems are under threat due to the recent climate extreme events. These events include heat waves and change in the rainfall patterns. Thus, risk reduction intervention in the form of mitigation and adaptation is required to minimize the impacts of climate change. Mitigation option includes understanding the present and future components of the climate system and interaction among them through coupled modeling system i.e. Global Circulation Model (GCM). Finally, global issue of climate change could be addressed by taking worldwide cooperation and action and adopting sustainable measures like use of alternative energy sources. The visible benefit on recovery of climate has been seen recently through global lockdown against coronavirus disease 2019 (COVID-19) pandemic.

Vector-borne diseases in waste pickers in Brasilia, Brazil

Solid waste management is a challenge in developing countries. The Structural dump in Brasilia, Brazil, was the largest Latin American open-air dump until its closure in 2018. Thus, this study sought to investigate the prevalence of self-reported dengue, Zika and Chikungunya arbovirus infections in waste pickers who worked at the dumpsite and assess its association with the sanitary conditions in their residences and workplaces. This research used a mixed methods study using a questionnaire for the quantitative method and semi-structured interviews for the qualitative portion. A cross-sectional, observational, epidemiological study along with a phenomenological study were carried out to characterize socio environmental, occupational and health-related aspects to vector-borne diseases in Structural dumpsite in Brazil. Of the 1,025 respondents, 301 (29.2%) reported to have gotten sick from dengue, Zika or chikungunya fevers. We found significant associations between place of residence of waste pickers (p = 0,003) and the work conditions, use of personal protective equipment (p < 0.001) and weekly workload (p = 0.04) and occurrence of vector-borne disease. Results were confirmed by qualitative data and geo-referencing, in relation to location of their homes and proximity to the dumpsite, as well as through the vulnerability due to their working conditions. This research confirms that waste pickers are highly susceptible to vector-borne diseases; this situation that needs to be immediately addressed by interdisciplinary and intersectoral approaches in waste management and public health. This information confirms vulnerability of waste pickers to diseases transmitted by Ae. aegypti mosquito as a result of sanitary conditions at their residence and workplace.

Assessment of relation of land use characteristics with vector-borne diseases in tropical areas

Land use and land cover changes play an important role in the occurrence of vector-borne diseases. It is highly essential to identify the prominent changes responsible for its occurrence so that suitable measures can be adopted. An attempt was made to identify the prominent land use and land cover changes responsible for the spread of chikungunya, malaria, and dengue fever in the State of Kerala, India, using hierarchical cluster analysis and multiple regression analysis. Large extent of water bodies, low land and agricultural land played a significant role on the incidence of chikungunya and malaria. High population density, built-up area and agricultural area favoured dengue fever. Vector-borne diseases were found to be the lowest in places where there is no low land and with higher forest area. Inappropriate disposal of wastes generated in the built-up area might be the reason for the spread of dengue fever. Freshwater in drains of these areas is polluted and form breeding grounds for mosquitoes. Hence much attention is to be paid to provide appropriate treatment and disposal of wastes generated in the built-up area of the State In an evolving urban policy, priority is to be given to the installation of safe treatment and disposal facility of wastes especially, sewage, sullage, and solid waste. The protection of forest land also plays an important role. Economic policy instruments such as Payment for Environment Services (PES) schemes, may constitute a useful tool to encourage an improved land use management through appropriate price signals, such as, for instance, for the preservation of forested areas especially in proximity of highly populated urban environments.

OPTIMAL CONTROL OF VECTOR-BORNE DISEASE WITH DIRECT TRANSMISSION

This paper introduces the usage of three controls as a way to reduce the occurrence of vector-borne disease. The governing equation of the dynamical system used in this paper describes both direct and indirect transmission mode of vector-borne disease. This means that the disease can be transmitted in two different ways. First, it can be transmitted through mosquito bites and the other is through human blood transfusion. The three controls that are incorporated in the dynamical system include a measurement of basic practice for blood donation procedure, self-prevention effort and vector control strategy by health authority. The optimality system of the three controls is characterized using optimal control theory and the existence and uniqueness of the optimal control are established. Then, the effect of the incorporation of the three controls is investigated by performing numerical simulation.

Mosquitoes (Diptera: Culicidae) and their relevance as disease vectors in the city of Vienna, Austria.

Mosquitoes (Diptera: Culicidae) are important vectors for a wide range of pathogenic organisms. As large parts of the human population in developed countries live in cities, the occurrence of vector-borne diseases in urban areas is of particular interest for epidemiologists and public health authorities. In this study, we investigated the mosquito occurrence in the city of Vienna, Austria, in order to estimate the risk of transmission of mosquito-borne diseases. Mosquitoes were captured using different sampling techniques at 17 sites in the city of Vienna. Species belonging to the Culex pipiens complex (78.8 %) were most abundant, followed by Coquillettidia richiardii (10.2 %), Anopheles plumbeus (5.4 %), Aedes vexans (3.8 %), and Ochlerotatus sticticus (0.7 %). Individuals of the Cx. pipiens complex were found at 80.2 % of the trap sites, while 58.8 % of the trap sites were positive for Cq. richiardii and Ae. vexans. Oc. sticticus was captured at 35.3 % of the sites, and An. plumbeus only at 23.5 % of the trap sites. Cx. pipiens complex is known to be a potent vector and pathogens like West Nile virus (WNV), Usutu virus (USUV), Tahyna virus (TAHV), Sindbis virus (SINV), Plasmodium sp., and Dirofilaria repens can be transmitted by this species. Cq. richiardii is a known vector species for Batai virus (BATV), SINV, TAHV, and WNV, while Ae. vexans can transmit TAHV, USUV, WNV, and Dirofilaria repens. An. plumbeus and Oc. sticticus seem to play only a minor role in the transmission of vector-borne diseases in Vienna. WNV, which is already wide-spread in Europe, is likely to be the highest threat in Vienna as it can be transmitted by several of the most common species, has already been shown to pose a higher risk in cities, and has the possibility to cause severe illness.

Assessment of changes of vector borne diseases with wetland characteristics using multivariate analysis.

Vector borne diseases are a threat to human health. Little attention has been paid to the prevention of these diseases. We attempted to identify the significant wetland characteristics associated with the spread of chikungunya, dengue fever and malaria in Kerala, a tropical region of South West India using multivariate analyses (hierarchical cluster analysis, factor analysis and multiple regression). High/medium turbid coastal lagoons and inland water-logged wetlands with aquatic vegetation have significant effect on the incidence of chikungunya while dengue influenced by high turbid coastal beaches and malaria by medium turbid coastal beaches. The high turbidity in water is due to the urban waste discharge namely sewage, sullage and garbage from the densely populated cities and towns. The large extent of wetland is low land area favours the occurrence of vector borne diseases. Hence the provision of pollution control measures at source including soil erosion control measures is vital. The identification of vulnerable zones favouring the vector borne diseases will help the authorities to control pollution especially from urban areas and prevent these vector borne diseases. Future research should cover land use cover changes, climatic factors, seasonal variations in weather and pollution factors favouring the occurrence of vector borne diseases.

Solid-waste management in Jalandhar city and its impact on community health

In this study, solid-waste management practices were evaluated in order to find out its link with occurrence of vector-borne disease. Strategies for solid-waste management were employed as practical model to solve the problems regarding pollution which is originated by solid-waste.

Food Webs and Disease: Is Pathogen Diversity Limited by Vector Diversity?

Classical predator–prey and host–parasite systems have been extensively studied in a food web context. Less attention has been paid to communities that include pathogens and their vectors. We present a coarse-grained, pan-African analysis of the relationships between the abiotic environment (location, precipitation, temperature), the species richness and community composition of ixodid ticks, and the species richness and community composition of pathogens that ticks transmit to humans. We found strong correlations between the abiotic environment and tick species richness, and a weak but significant correlation between the abiotic environment and pathogen species richness. A substantial amount of variation in community composition of parasites and pathogens was not explained by the variables that we considered. A structural equation model that compensated for the indirect effects of climate on the pathogen community via tick community composition suggested that while the environment strongly regulates tick community composition and tick community composition strongly regulates pathogen community composition, abiotic influences on pathogen species richness and community composition are weak. Our results support the view that changes in the broader environment will influence tick-borne pathogens primarily via the influence of the environment on ticks. The interactions that regulate host–vector–pathogen dynamics are of particular relevance in understanding the relationships between environmental change and health concerns, such as the impact of climate change on the occurrence of vector-borne diseases.

Data collection techniques : R. F. Hahn. Proceedings 1972 Annual Reliability and Maintainability Symposium, San Francisco. IEEE Cat. No. 72CH0577-7R. 25–27 January (1972), p. 38

Climate change is the variability of the climate system that includes the atmosphere, the biogeochemical cycles (Carbon cycle, Nitrogen cycle and Hydrological cycle), the land surface, ice and the biotic and abiotic components of the planet earth. Significant impact of climate change is seen in the form of rise in temperature called as global warming. Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are the primary greenhouse gases (GHGs) mainly responsible for the global warming and climate change. These GHGs have drawn lot of attention due to their significant role in the global warming potential. Intergovernmental Panel on Climate Change (IPCC) suggested to stop global warming at 1.5oC above preindustrial levels as warming beyond this level might lead to heat extremes, alter insect and plant phenology (Phenological shifts) and more occurrence of vector borne diseases. Climate change is the topic of interest in all fields of life starting from social science and going to the applied science. Global climate cycles and world food production systems are under threat due to the recent climate extreme events. These events include heat waves and change in the rainfall patterns. Thus, risk reduction intervention in the form of mitigation and adaptation is required to minimize the impacts of climate change. Mitigation option includes understanding the present and future components of the climate system and interaction among them through coupled modeling system i.e. Global Circulation Model (GCM). Finally, global issue of climate change could be addressed by taking worldwide cooperation and action and adopting sustainable measures like use of alternative energy sources. The visible benefit on recovery of climate has been seen recently through global lockdown against coronavirus disease 2019 (COVID-19) pandemic.