Vector-borne Disease Surveillance Research Articles

Gut Microbiome Characterisation of Chrysomya megacephala: Isolation, Identification, Antibiotic Profiling, and Initial Documentation of Leclercia adecarboxylata from the Fly

Chrysomya megacephala, known for its vector potential, harbors a diverse microbiota crucial in understanding disease transmission dynamics. Herein, we report the first documentation of Leclercia adecarboxylata isolated from C. megacephala. L. adecarboxylata is an Enterobacteriaceae, gram-negative bacillus that cause infections in human and animals. Additionally, we have reported the presence of Pseudomonas aeruginosa and Enterococcus faecalis from C. megacepahala. The study carried out the antibiotic profiling and hemolytic assays, which revealed distinct resistance patterns and virulence characteristics, shedding light on potential public health implications. L. adecarboxylata, Pseudomonas aeruginosa and Enterococcus faecalis showed positive result for hemolysis and in terms of antibiotic resistance P. aeruginosa strains showed resistance to Amoxicillin, Ampicillin and Tetracycline while, E. faecalis showed resistance towards Streptomycin and Tetracycline. However, L. adecarboxylata showed sensitivity to all antibiotics. This study was conducted from Kozhikode, Kerala, India, and this is the first of its kind of study from the region to analyse the vector potential of C. megacephala. These findings underscore the significance of comprehensive microbiological investigations in vector-borne disease surveillance and management strategies.

Bayesian group testing regression models for spatial data

Spatial patterns are common in infectious disease epidemiology. Disease mapping is essential to infectious disease surveillance. Under a group testing protocol, biomaterial from multiple individuals is physically combined into a pooled specimen, which is then tested for infection. If the pool tests negative, all contributing individuals are generally assumed to be uninfected. If the pool tests positive, the individuals are usually retested to determine who is infected. When the prevalence of infection is low, group testing provides significant cost savings over traditional individual testing by reducing the number of tests required. However, the lack of statistical methods capable of producing maps from group testing data has limited the use of group testing in disease mapping. We develop a Bayesian methodology that can simultaneously map disease prevalence using group testing data and identify risk factors for infection. We illustrate its real-world utility using two datasets from vector-borne disease surveillance.

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.

A Qualitative Analysis of the Perceptions of Stakeholders Involved in Vector Control and Vector-Borne Disease Research and Surveillance in Orinoquia, Colombia.

Colombia has a tropical climate and environmental conditions that favour the circulation of most of the known vector-borne diseases (VBDs). Protocols have been established and implemented to address the threats of these diseases, but they are for country-wide use and do not take into consideration the nuances of the different environments of the country. Almost the entire population is vulnerable to infection with one or more VBD. This study aims to characterise the perceptions and experiences of stakeholders involved in vector control and VBDs in the Orinoquia region in Colombia. Two panel discussions, and 12 semi-structured interviews, were conducted. Experts from the Colombian National Health Institute (INS), health secretaries from Meta, Guaviare and Vichada Departments, academic researchers, and individuals from private vector control companies participated. All sessions were recorded, transcribed, and translated, and then subject to thematic analysis. Three major themes emerged: involvement, limitations, and recommendations. Results showed that participants are engaged in vector surveillance activities, education, and vector control research. Participants focused on problems of disjointed efforts towards VBD control between health secretaries and the health ministry, as well as societal issues, such as socioeconomic, cultural, and political issues, which became the rationale for the lack of vector control resources. Responses in the panel discussions and interviews overlapped in opinions, and suggested that vector control could be improved through better communication between vector control bodies, strengthened engagement with vulnerable communities, more collaborative actions, and a more balanced distribution of resources.

Variable performance of DNA barcoding and morpholo­gical characteristics for the identification of Arctic black-legged Aedes (Diptera: Culicidae), with a focus on the Punctor subgroup

Abstract Arctic ecosystems face increasing risks from vector-borne diseases due to climate-driven shifts in disease patterns and vector distribution. However, species identification challenges impact vector-borne disease surveillance, necessitates accurate identification. Aedes species are predominant among Arctic mosquitoes and pose health risks, with some species potentially carrying Jamestown Canyon and Snowshoe hare viruses. However, identifying Aedes species is challenging, especially under Arctic conditions and with complex adult traits. This study assessed the suitability of DNA barcoding (COI and ITS2 regions) and morphological characteristics for the identification of Arctic black-legged Aedes. It also aimed to evaluate the reliability of publicly available sequences. Our analysis focused on Aedes impiger, Aedes nigripes, and two species from the Punctor subgroup – Aedes hexodontus and Aedes punctor. In our study, the COI barcoding region distinguished Ae. impiger and Ae. nigripes but not within the species of the Punctor subgroup. In addition, the ITS2 barcoding region did not differentiate the species. When we evaluated GenBank and BOLD sequences, we found issues of under-representation and misidentifications, particularly within the Punctor subgroup. Based on these results, we recommend addressing identification difficulties, particularly within the Punctor subgroup, and advocate for more comprehensive morphological and molecular identification strategies. Integrating morphology and DNA barcoding holds promise for robust disease surveillance in Arctic regions, yet challenges persist, especially in complex species groups like the Punctor subgroup. Tackling these issues is pivotal to ensuring accurate vector status determination and reliable disease risk assessments in a rapidly changing Arctic ecosystem.

In silico identification of multiple conserved motifs within the control region of Culicidae mitogenomes

Mosquitoes are important vectors for human and animal diseases. Genetic markers, like the mitochondrial COI gene, can facilitate the taxonomic classification of disease vectors, vector-borne disease surveillance, and prevention. Within the control region (CR) of the mitochondrial genome, there exists a highly variable and poorly studied non-coding AT-rich area that contains the origin of replication. Although the CR hypervariable region has been used for species differentiation of some animals, few studies have investigated the mosquito CR. In this study, we analyze the mosquito mitogenome CR sequences from 125 species and 17 genera. We discovered four conserved motifs located 80 to 230 bp upstream of the 12S rRNA gene. Two of these motifs were found within all 392 Anopheles (An.) CR sequences while the other two motifs were identified in all 37 Culex (Cx.) CR sequences. However, only 3 of the 304 non-Culicidae Dipteran mitogenome CR sequences contained these motifs. Interestingly, the short motif found in all 37 Culex sequences had poly-A and poly-T stretch of similar length that is predicted to form a stable hairpin. We show that supervised learning using the frequency chaos game representation of the CR can be used to differentiate mosquito genera from their dipteran relatives.

Collaboration is the key to resilience

Owing to the impact of the Covid pandemic that swept across Europe and the world since early 2020, never before has infectious diseases and their potential as a health and economic risk been so forefront in the minds of the European public, at least not in recent times. Those of us that been involved in medical and veterinary entomology or vector-borne disease related research and surveillance know only too well how quickly new and existing diseases can emerge to cause local and regional outbreaks. The outbreak of Zika in the Americas highlighted the prospect of global transmission of a vector-borne disease with outbreaks concerning the Americas, suddenly a concern for Europe.

A statistical calibration tool for methods used to sample outdoor-biting mosquitoes

BackgroundImproved methods for sampling outdoor-biting mosquitoes are urgently needed to improve surveillance of vector-borne diseases. Such tools could potentially replace the human landing catch (HLC), which, despite being the most direct option for measuring human exposures, raises significant ethical and logistical concerns. Several alternatives are under development, but detailed evaluation still requires common frameworks for calibration relative to HLC. The aim of this study was to develop and validate a statistical framework for predicting human-biting rates from different exposure-free alternatives.MethodsWe obtained mosquito abundance data (Anopheles arabiensis, Anopheles funestus and Culex spp.) from a year-long Tanzanian study comparing six outdoor traps [Suna Trap (SUN), BG Sentinel (BGS), M-Trap (MTR), M-Trap + CDC (MTRC), Ifakara Tent Trap-C (ITT-C) and Mosquito Magnet-X Trap (MMX)] and HLC. Generalised linear models were developed within a Bayesian framework to investigate associations between the traps and HLC, taking intra- and inter-specific density dependence into account. The best model was used to create a calibration tool for predicting HLC-equivalents.ResultsFor An. arabiensis, SUN catches had the strongest correlation with HLC (R2 = 19.4), followed by BGS (R2 = 17.2) and MTRC (R2 = 13.1) catches. The least correlated catch was MMX (R2 = 2.5). For An. funestus, BGS had the strongest correlation with the HLC (R2 = 53.4), followed by MTRC (R2 = 37.4) and MTR (R2 = 37.4). For Culex mosquitoes, the traps most highly correlated with the HLC were MTR (R2 = 45.4) and MTRC (R2 = 44.2). Density dependence, both between and within species, influenced the performance of only BGS traps. An interactive Shiny App calibration tool was developed for this and similar applications.ConclusionWe successfully developed a calibration tool to assess the performance of different traps for assessing outdoor-biting risk, and established a valuable framework for estimating human exposures based on the trap catches. The performance of candidate traps varied between mosquito taxa; thus, there was no single optimum. Although all the traps tested underestimated the HLC-derived exposures, it was possible to mathematically define their representativeness of the true biting risk, with or without density dependence. The results of this study emphasise the need to aim for a consistent and representative sampling approach, as opposed to simply seeking traps that catch the most mosquitoes.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.

All for One Health and One Health for All: Considerations for Successful Citizen Science Projects Conducting Vector Surveillance from Animal Hosts.

Simple SummaryVector-borne diseases are often zoonotic and so a One Health approach must be employed in order to investigate and control them. Therefore, surveillance of arthropod vectors and pathogens among animal populations should complement human disease surveillance. Since traditional surveillance methods to collect arthropod vectors and conduct pathogen testing from animals can be challenging, data collection can be supplemented with citizen science approaches, where the general public is actively involved in collecting animals and/or samples. In this review, we discuss considerations for researchers to create a successful vector surveillance program using citizen science approaches with different stakeholders who own, have interests in, or work with animals.Many vector-borne diseases that affect humans are zoonotic, often involving some animal host amplifying the pathogen and infecting an arthropod vector, followed by pathogen spillover into the human population via the bite of the infected vector. As urbanization, globalization, travel, and trade continue to increase, so does the risk posed by vector-borne diseases and spillover events. With the introduction of new vectors and potential pathogens as well as range expansions of native vectors, it is vital to conduct vector and vector-borne disease surveillance. Traditional surveillance methods can be time-consuming and labor-intensive, especially when surveillance involves sampling from animals. In order to monitor for potential vector-borne disease threats, researchers have turned to the public to help with data collection. To address vector-borne disease and animal conservation needs, we conducted a literature review of studies from the United States and Canada utilizing citizen science efforts to collect arthropods of public health and veterinary interest from animals. We identified common stakeholder groups, the types of surveillance that are common with each group, and the literature gaps on understudied vectors and populations. From this review, we synthesized considerations for future research projects involving citizen scientist collection of arthropods that affect humans and animals.

VectorNet: Putting Vectors on the Map.

Public and animal health authorities face many challenges in surveillance and control of vector-borne diseases. Those challenges are principally due to the multitude of interactions between vertebrate hosts, pathogens, and vectors in continuously changing environments. VectorNet, a joint project of the European Food Safety Authority (EFSA) and the European Centre for Disease Prevention and Control (ECDC) facilitates risk assessments of VBD threats through the collection, mapping and sharing of distribution data for ticks, mosquitoes, sand flies, and biting midges that are vectors of pathogens of importance to animal and/or human health in Europe. We describe the development and maintenance of this One Health network that celebrated its 10th anniversary in 2020 and the value of its most tangible outputs, the vector distribution maps, that are freely available online and its raw data on request. VectorNet encourages usage of these maps by health professionals and participation, sharing and usage of the raw data by the network and other experts in the science community. For the latter, a more complete technical description of the mapping procedure will be submitted elsewhere.

Predict the incidence of Guillain Barré Syndrome and arbovirus infection in Mexico, 2014-2019.

The Dengue (DENV), Zika (ZIKV), and Chikungunya (CHIKV) virus infections have been linked to Guillain-Barré syndrome (GBS). GBS has an estimated lethality of 4% to 8%, even with effective treatment. Mexico is considered a hyperendemic country for DENV due to the circulation of four serotypes, and the ZIKV and CHIKV viruses have also been circulating in the country. The objective of this study was to predict the number of GBS cases in relation to the cumulative incidence of ZIKV / DENV / CHIKV in Mexico from 2014 to 2019. A six-year time series ecological study was carried out from GBS cases registered in the Acute Flaccid Paralysis (AFP) Epidemiological Surveillance System (ESS), and DENV, ZIKV and CHIKV estimated cases from cases registered in the epidemiological vector-borne diseases surveillance system. The results shows that the incidence of GBS in Mexico is positively correlated with DENV and ZIKV. For every 1,000 estimated DENV cases, 1.45 GBS cases occurred on average, and for every 1,000 estimated ZIKV cases, 1.93 GBS cases occurred on average. A negative correlation between GBS and CHIKV estimated cases was found. The increase in the incidence of GBS cases in Mexico can be predicted by observing DENV and ZIKV cases through the epidemiological surveillance systems. These results can be useful in public health by providing the opportunity to improve capacities for the prevention of arbovirus diseases and for the timely procurement of supplies for the treatment of GBS.

Dengue Virus Infecting Mosquito Vectors and Non-recognized Vectors in Zoological Parks: a Call for Vector Borne Diseases Surveillance

Dengue Virus Infecting Mosquito Vectors and Non-recognized Vectors in Zoological Parks: a Call for Vector Borne Diseases Surveillance

Diversity and Seasonal Dynamics of Ticks on Ring-Tailed Coatis Nasua nasua (Carnivora: Procyonidae) in Two Urban Areas from Midwestern Brazil.

Simple SummaryThe knowledge of the dynamics of ticks in wild animals is essential for surveillance of tick-borne diseases. Coatis (Nasua nasua) are mammals that easily adapt to anthropized areas, favoring close contact with domestic animals and humans, favoring the exchange of ticks and tick-borne agents. The present study aimed to investigate the tick diversity on coatis from forest urban areas of midwestern Brazil, as well as the dynamics of ticks during the seasons of the year and the correlation between tick species and gender and age of the sampled coatis. Three tick species were identified parasitizing coatis from forested urban fragments, namely A. dubitatum nymphs, A. sculptum adults and nymphs, and A. ovale adults. After analyzing the obtained results, it is likely that coatis from anthropized areas present tick species diversity lower than those from natural landscapes. The mean intensity and prevalence of Amblyomma larvae and nymphs is similar among males and females as well as in immature and mature animals, which might reflect the gregarious behavior of coatis, since adult males live together with females and offspring outside and inside the mating season, forming large groups of individuals.Understanding the diversity and ecology of ectoparasites in wild animals is essential for surveillance of vector-borne diseases. Coatis (Nasua nasua) easily adapt to anthropized areas, favoring close contact with domestic animals and humans, with the possibility of exchange of ectoparasites and pathogens. The present study aimed to identify the diversity of ticks parasitizing coatis from forest urban areas of midwestern Brazil, to evaluate the seasonal dynamics of ticks during the seasons of the year, and to assess the correlation between tick species and gender and age of the sampled coatis. For this purpose, 103 coatis were captured in two Conservation areas, both located in Campo Grande city, Mato Grosso do Sul state, Midwestern Brazil. The animals’ entire body was inspected for the presence of ectoparasites, and ticks were removed for taxonomic identification. In total, 168 captures were performed in both areas during the observational study considering the first capture and recaptures. In total, 2242 ticks were collected: 838 Amblyomma larvae, 1241 A. sculptum nymphs, and 150 A. dubitatum nymphs. Thirteen adult ticks were identified as three males and five females of A. sculptum and two males and three females of A. ovale. While a quantity of Amblyomma larvae was observed in the first months of the year (January, April and May), Amblyomma nymphs showed a higher quantity during the months of July, August, October and November. No statistical difference was observed when comparing mean intensity and prevalence of Amblyomma larvae, nymphs of A. sculptum and A. dubitatum between the two sampled areas, males vs. females and immature vs. mature animals. In conclusion, three tick species were identified parasitizing coatis from forested urban fragments in midwestern Brazil, namely A. dubitatum nymphs, A. sculptum adults and nymphs, and A. ovale adults. Coatis from anthropized areas seem to present tick species diversity lower than those from natural areas. The lack of statistical difference regarding mean intensity and prevalence of Amblyomma larvae and nymphs between males vs. females and immature vs. mature animals might have reflected the gregarious behavior of coatis, since adult males live together with females and offspring outside and inside the mating season, forming large groups of individuals.

Riding the Wave: Reactive Vector-Borne Disease Policy Renders the United States Vulnerable to Outbreaks and Insecticide Resistance.

Funding for vector-borne disease surveillance, management, and research is cyclical and reactive in the United States. The subsequent effects have yielded gross inequities nationally that unintentionally support recurrent outbreaks. This policy forum is comprised of four primary subsections that collectively identify specific areas for improvement and offer innovative solutions to address national inadequacies in vector borne disease policy and infrastructure.

Scrub typhus in urban areas of Wardha district in central India.

Scrub typhus caused by Orientia tsutsugamushi presents as acute undifferentiated fever and can be confused with other infectious causes of fever. We studied scrub typhus as part of a study on hospital-based surveillance of zoonotic and vector-borne zoonotic diseases at a tertiary care hospital located in the Wardha district, Maharashtra, India. We report here descriptive epidemiology and climatic factors affecting scrub typhus. Patients of any age and sex with fever of ≥5 days were enrolled for this study. Data on sociodemographic variables were collected by personal interviews. Blood samples were tested by IgM ELISA to diagnose scrub typhus. Confirmation of scrub typhus was done by indirect immunofluorescence assay for IgM (IgM IFA). The climatic determinants were determined using time-series Poisson regression analysis. It was found that 15.9 per cent of the study participants were positive for scrub typhus by IgM ELISA and IgM IFA, both. Positivity was maximum (23.0%) in 41-60 yr of age and more females were affected than males (16.6 vs. 15.5%). Farmworkers were affected more (23.6%) than non-farm workers (12.9%). The disease positivity was found to be high in monsoon and post-monsoon seasons (22.9 and 19.4%) than in summer and winter. There were three hot spots of scrub typhus in urban areas of Wardha district. Rainfall and relative humidity in the previous month were the significant determinants of the disease.

Surveillance, prevention, and control of vector-borne diseases 2

Surveillance, prevention, and control of vector-borne diseases 2

Surveillance, prevention, and control of vector-borne diseases 1

Surveillance, prevention, and control of vector-borne diseases 1

A comparison of BG Sentinel and CDC trap attractants for mosquito surveillance in urban and suburban areas of Montgomery and Prince George's Counties, Maryland, U.S.A.

Monitoring mosquito populations is crucial for vector-borne disease surveillance. Routine mosquito surveillance in many regions of the United States is performed either by vector abatement districts or public health departments. These surveillance programs often use multiple trap types and attractants to target key mosquito species, however setting different traps with varying attractants can be expensive and labor intensive. Because funding for mosquito control is highly variable throughout the U.S., some programs may be limited in their surveillance capabilities. To determine whether a single trap-attractant combination could provide specificity for key vector and nuisance species, as well as sensitivity for rare species, we compared the BG-Sentinel 2 and CDC miniature light traps paired with CO2, UV-LED, BG Lure, BG Sweetscent, octenol, or chicken feathers. Trapping was conducted biweekly from June/July-October 2019 and 2020 in Montgomery and Prince George's County, MD. BG traps collected significantly more Aedes albopictus than CDC traps when paired with BG Lure, Sweetscent, or octenol. BG/CO2 traps collected both the greatest number of total mosquitoes and Culex pipiens. BG/CO2, CDC/CO2, and CDC/UV traps provided the most diverse collections. Trapping with the CO2-baited BG-Sentinel is recommended as an effective strategy for general mosquito surveillance when resources are limited.

Identification of Phasi Charoen-Like Phasivirus in Field Collected Aedes aegypti from Karnataka State, India

Background: A wide range of insect-specific viruses (ISVs) have been reported worldwide. There are no studies from India that have reported ISVs. The current study describes the identification of Phasi Charoen-like virus (PCLV) from Aedes aegypti mosquito-pools from six districts of Karnataka state, India. Materials and Methods: During the Chikungunya virus (CHIKV) outbreak in the Bangalore Urban district in 2019, using conventional PCR, it was found that both human and mosquito samples were positive for CHIKV. For retrieve the complete genome sequence, mosquito samples were subjected to next generation sequencing (NGS) analysis and PCLV was also found. During 2019, as part of a vector-borne disease surveillance, we received 50 mosquito pool samples from 6 districts of the state, all of them were subjected to NGS to identify PCLV. Results: The A. aegypti mosquito-pools samples were subjected to the NGS platform that led to identification of an ISV, PCLV. PCLV was identified in 26 A. aegypti mosquito-pools collected from 6 districts. We also found mixed infection of PCLV with the Dengue virus (DENV; genotypes 1 and 3) and CHIKV from five pools. The nucleotide identity for the L gene of Indian PCLV sequences ranged between 97.1% and 98.3% in comparison with the Thailand sequences. Conclusions: To the best of our knowledge, this is the first report of PCLV dual infection with DENV and CHIKV in India. The present study confirms the presence of PCLV in A. aegypti mosquitoes from Karnataka state. The study adds India in the global geographical distribution of PCLV.