Vector Infection Research Articles

Construction of a new emergency management system for potentially viral/viral municipal solid waste in China: Based on the "Beam-Column Structure" framework model

Emergency management of municipal solid waste during public health emergencies is crucial for curbing the spread of viruses and controlling environmental pollution. Most existing solid waste management systems, are designed with a top-down approach, covering multiple industries and sectors. However, these systems often fail to effectively manage potentially viral solid waste in household waste, which impedes effective solid waste management during public health emergencies and increases the risk of viral outbreaks. For example, during the COVID-19 outbreak, negligent management of potentially viral solid waste may result in the formation of a potential transmission chain of COVID-19 virus. Improper waste management may contaminate natural vectors such as water, soil and air, thereby increasing the pathways of human contact with infected vectors and promoting the risk of transmission of viral diseases such as dengue, Zika and hepatitis A. In this study, the applicability and limitations of the Chinese public emergency management system in the disposal of Potentially Viral/Viral Municipal Solid Waste (PVMSW) were analyzed in the breakout of public health crises. To address the need for precise risk control, efficient collaboration among key stakeholders, functional integration crossing multiple management organizations and flexible responses to complex situations, we proposed a PVMSW emergency management system based on a “Beam-Column Structure” model. This system consists of four modules: main traction, organizational leadership, functional articulation and demand matching. Each module is supported by the corresponding safeguards, including multi-level subject responsibilities, multi-scenario organization and implementation, multi-chain process connection and multi-demand control methods. The PVMSW emergency management system proposed in this study contributes to extending the framework of existing waste management protocols and enhancing the timely collection, transportation and disposal of PVMSW in public health crises. It offers valuable insights and guidance on the practices for improving risk awareness and management capacity in China's solid waste emergency response.

Revisiting the epidemiological role of a native vector in Northern California vineyards

Abstract Effective disease management hinges on an accurate understanding of the ecological and epidemiological underpinnings of the pathosystem. New epidemics may prompt consideration of whether knowledge gaps or changes to the pathosystem warrant revision of management strategies. Pierce’s disease of grapevines is highly episodic in coastal Northern California vineyards, with modest incidence in most years punctuated by occasionally severe epidemics. To better understand what was driving a developing epidemic in the region, we revaluated what is known about the ecology and epidemiological role of the dominant vector, the blue-green sharpshooter Graphocephala atropunctata. We monitored vector spatiotemporal dynamics at 32 vineyards over three years, surveyed plant community composition in the adjacent habitat to understand its link to vector recruitment, and quantified patterns of natural infectivity for the pathogen Xylella fastidiosa. Overall, the results were consistent with past studies of G. atropunctata ecology. For example, the scale of dispersal from source habitat and seasonal patterns in activity were generally similar to those documented in prior studies. The results also confirmed the influence of adjacent plant community composition on G. atropunctata activity in vineyards, and the role of riparian habitat and select plant taxa as vector sources. Nonetheless, further consideration of the epidemiological significance of certain features of the pathosystem may be warranted, especially those related to seasonality in X. fastidiosa infection in vectors. A marked increase in infected G. atropunctata late in the season likely reflects pathogen acquisition from infected grapevines, which may have implications for disease management strategies.

Analysis of a vector-borne disease model with vector-bias mechanism in advective heterogeneous environment

Abstract This study proposed and analyzed a vector-borne reaction–diffusion–advection model with vector-bias mechanism and heterogeneous parameters in one-dimensional habitat. The basic reproduction number R 0 {{\mathfrak{R}}}_{0} in connection with principal eigenvalue of elliptic eigenvalue problem is characterized as the role of determining the threshold dynamics of the system. The main objective of this study is to investigate the asymptotic profiles and monotonicity of R 0 {{\mathfrak{R}}}_{0} with respect to diffusion rates and advection rates under certain conditions. Through exploring the level set of R 0 {{\mathfrak{R}}}_{0} , we also find that there exists a unique surface separating the dynamics. Our results also reveal that the infected hosts and vectors will aggregate at the downstream end if the ratio of advection rates and diffusion rates is sufficiently large.

Epidemiology and Ecology of Usutu Virus Infection and Its Global Risk Distribution.

Usutu virus (USUV) is an emerging mosquito-transmitted flavivirus with increasing incidence of human infection and geographic expansion, thus posing a potential threat to public health. In this study, we established a comprehensive spatiotemporal database encompassing USUV infections in vectors, animals, and humans worldwide by an extensive literature search. Based on this database, we characterized the geographic distribution and epidemiological features of USUV infections. By employing boosted regression tree (BRT) models, we projected the distributions of three main vectors (Culex pipiens, Aedes albopictus, and Culiseta longiareolata) and three main hosts (Turdus merula, Passer domesticus, and Ardea cinerea) to obtain the mosquito index and bird index. These indices were further incorporated as predictors into the USUV infection models. Through an ensemble learning model, we achieved a decent model performance, with an area under the curve (AUC) of 0.992. The mosquito index contributed significantly, with relative contributions estimated at 25.51%. Our estimations revealed a potential exposure area for USUV spanning 1.80 million km2 globally with approximately 1.04 billion people at risk. This can guide future surveillance efforts for USUV infections, especially for countries located within high-risk areas and those that have not yet conducted surveillance activities.

TBC1D15-regulated mitochondria–lysosome membrane contact exerts neuroprotective effects by alleviating mitochondrial calcium overload in seizure

Mitochondrial calcium overload plays an important role in the neurological insults in seizure. The Rab7 GTPase-activating protein, Tre-2/Bub2/Cdc16 domain family member 15 (TBC1D15), is involved in the regulation of mitochondrial calcium dynamics by mediating mitochondria–lysosome membrane contact. However, whether TBC1D15-regulated mitochondria–lysosome membrane contact and mitochondrial calcium participate in neuronal injury in seizure is unclear. We aimed to investigate the effect of TBC1D15-regulated mitochondria–lysosome membrane contact on epileptiform discharge-induced neuronal damage and further explore the underlying mechanism. Lentiviral vectors (Lv) infection and stereotaxic adeno-associated virus (AAV) injection were used to regulate TBC1D15 expression before establishing in vitro epileptiform discharge and in vivo status epilepticus (SE) models. TBC1D15’s effect on inter-organellar interactions, mitochondrial calcium levels and neuronal injury in seizure was evaluated. The results showed that abnormalities in mitochondria–lysosome membrane contact, mitochondrial calcium overload, mitochondrial dysfunction, increased levels of reactive oxygen species, and prominent neuronal damage were partly relieved by TBC1D15 overexpression, whereas TBC1D15 knockdown markedly deteriorated these phenomena. Further examination revealed that epileptiform discharge-induced mitochondrial calcium overload in primary hippocampal neurons was closely associated with abnormal mitochondria–lysosome membrane contact. This study highlights the crucial role played by TBC1D15-regulated mitochondria–lysosome membrane contact in epileptiform discharge-induced neuronal injury by alleviating mitochondrial calcium overload.

EPO modified MSCs protects SH-SY5Y cells against ischemia/hypoxia-induced apoptosis via REST-dependent epigenetic remodeling

Hypoxic-ischemic encephalopathy (HIE) is a diffuse brain tissue injury caused by acute ischemia and hypoxia, and it is most commonly found in newborn infants but can also occur in adults. Mesenchymal stem cell (MSC) therapies have showed improved outcomes for treating HIE-induced neuronal defects. However, many key issues associated with poor cell viability and tolerance of grafted MSCs after HIE remain to be resolved. Genetic engineering could endow MSCs with more robust regenerative capacities. Our research, along with that of other scientists, has found that the expression of intracellular erythropoietin (EPO) in human umbilical cord MSCs (hUC-MSCs) increases proportionally with the duration of hypoxia exposure. Furthermore, we observed that EPO, when introduced into the EPO gene-modified hUC-MSCs, can be secreted into the extracellular space. However, the underlying mechanisms that support the neuroprotective effects of EPO-MSCs remain unclear. EPO-MSCs, hUC-MSCs, and NC-MSCs were identified by flow cytometry, osteogenic, and adipogenic differentiation assays. The oxygen-glucose deprivation (OGD)-induced SH-SY5Y cell-line was established, and five groups were set up: control, 24-h ischemia-hypoxia, co-cultured with hUC-MSCs, NC-MSCs, and EPO-MSCs after hypoxia. LEGENDplex™ multi-factor flow cytometry was used to detect the secretion of inflammatory factors in cell supernatants and cerebrospinal fluid. Chromosome-targeted excision and tagging (CUT&Tag) sequencing was applied to detect genomic H3K4me2 modifications, and conjoint analysis with transcriptome sequencing (RNA-seq) was performed. Lentiviral vector infection was used to construct SH-SY5Y cells with stable knockdown of RE1-silencing transcription factor (REST), and flow cytometry was used to detect alterations in apoptosis. Finally, the molecular mechanism underlying the neuroprotective and anti-apoptotic effects of EPO-MSCs was investigated using RNA sequencing, qRT-PCR, and western blot assays. Our results suggest that EPO-MSCs are genetically engineered to secrete significantly more EPO. EPO-MSCs treatment has anti-apoptotic properties and offers neuronal protection during ischemic-hypoxic injury. Furthermore, RNA-seq results suggest that multiple inflammation-related genes were down-regulated after EPO-MSCs treatment. Application of RNA-seq and CUT&Tag combined analysis found that the expressions of REST were significantly up-regulated. Lentiviral vector infection to construct REST knockdown SH-SY5Y failed to rescue apoptosis after hypoxia and co-culture with EPO-MSCs, and SETD2-mediated H3K36me3 protein level expression was reduced. EPO-MSCs may promote neuronal survival by affecting H3K4me2 and thus activating the expression of REST and TET3. EPO-MSCs also upregulated the modification level of SETD2-mediated H3K36me3 and regulated the expression of inflammation-related genes such as PLCG2, as well as apoptosis genes BCL2A1. To investigate the neuroprotective effects of EPO-modified hUC-MSCs and the underlying epigenetic regulatory mechanisms, this study aims to provide a theoretical foundation for the potential application of EPO gene-modified hUC-MSCs in the treatment of HIE.

Seroprevalence of Rickettsia Spp. and Orientia tsutsugamushi in Indigenous Populations from the Sierra Nevada de Santa Marta, Colombia.

Background: Rickettsia spp. are vector-borne zoonotic pathogens that cause febrile illness in humans. Rickettsioses is not included in the Colombian national surveillance system and is subsequently expected to be underreported. This cross-sectional study aimed to determine the seroprevalence of Rickettsia spp. and the closely related Orientia tsutsugamushi in two indigenous populations residing in the Sierra Nevada de Santa Marta, Colombia. Materials and Methods: Serum samples (n = 539) were collected from the Wiwa and Koguis people between 2021 and 2022. Serum samples were screened for spotted fever group (SFG) and typhus group (TG) Rickettsia spp. using the Fuller laboratories Rickettsia IgG IFA kit and for O. tsutsugamushi with the Scrub Typhus Detect™ IgG ELISA. Results: We observed an overall seroprevalence of 26.2% (95% confidence interval [CI] 22.5-30.1] for Rickettsia spp. of the SFG, 5.4% (95% CI 3.6-7.6) for Rickettsia spp. of the TG and 4.3% (95% CI 2.7-6.3) for O. tsutsugamushi. Common risk factors for zoonotic disease infections were assessed for 147 of the Wiwa participants. Increased odds of seropositivity for SFG Rickettsia spp. were observed for Wiwa participants who cared for livestock, including assisting with the birth of cattle (odds ratio [OR] = 8.85; 95% CI 1.54-50.90; p = 0.015) and goats (OR = 7.60; 95% CI 1.70-33.90; p = 0.008). Conclusions: These results highlight a notable exposure to Rickettsia spp., especially the SFG, in rural Colombia. Together with recent reports of high mortality for Rocky Mountain Spotted Fever in nearby regions of South America, more detailed investigations focusing on improving knowledge and awareness as well as "One Health" and "causes-of-fever" studies are needed. The characterization of Rickettsia spp. infections in humans, livestock, and tick vectors with their potential transmission routes could make a high impact on these easily treatable diseases.

Nosocomial Outbreak of SARS-CoV-2 in a Hospital Ward during the Omicron Variant-Dominant Wave with a Review of the Relevant Literature.

Clusters of nosocomial coronavirus disease 2019 (COVID-19) have been reported globally during the recent pandemic. Unfortunately, these clusters negatively affect inpatient morbidity, mortality, and hospital functioning. Using epidemiological data and whole-genome sequencing (WGS) of SARS-CoV-2, this study investigated the outbreak of COVID-19 at a university hospital. Eight inpatients and 13 healthcare workers tested positive for SARS-CoV-2 during a 1-month period. WGS of the virus in 11 patients revealed that the two variants of concern belonging to the Omicron sublineages, BA.2.3 and BA1.1.2, caused an outbreak when the proportion of the Omicron lineage in the community changed. When variants of concern undergo mutation, a response to the outbreak should be made with multiple variants in mind, even in the absence of epidemiological data showing close contact or other potential vectors of infection. Awareness of infection prevention and control should be raised to safeguard patient safety.

NUMERICAL ASSESSMENT OF SOME SEMI-ANALYTICAL TECHNIQUES FOR SOLVING A FRACTIONAL-ORDER LEPTOSPIROSIS MODEL

This research aims to apply and compare two semi-analytical techniques, the Variational Iterative Method (VIM) and the New Iterative Method (NIM), for solving a pre-formulated mathematical model of Fractional-order Leptospirosis. Leptospirosis is a significant bacterial infection affecting humans and animals. By implementing the VIM and NIM algorithms, numerical experiments are conducted to solve the leptospirosis model. Comparing the obtained findings demonstrates that VIM and NIM are effective semi-analytical methods for solving systems of fractional differential equations. Notably, our study unveils a crucial dynamic in the disease's spread. The application of VIM and NIM offers a refined depiction of the biological dynamics, highlighting that the susceptible human population gradually decreases, the infectious human population declines, the recovered human population increases, and a significant rise in the infected vector population is observed over time. This nuanced portrayal of the disease's dynamics is crucial for understanding the intricate interplay of Leptospirosis among human and vector populations. The study's outcomes contribute valuable insights into the applicability and performance of the methods in solving the Fractional Leptospirosis model. Results indicate rapid convergence and comparable outcomes for both methods.

Ecological and faunistic features of fleas in the Transcaucasian mounthill natural plague foci in Azerbaijan

Among all vectors of natural focal infections, fleas are the most active. In this respect, entomological and epizootological monitoring has always been of great importance. This article, based on the material collected from the Transcaucasian foothill natural plague focus, presents the results of a study of flea species diversity, the landscape and geographical area of their distribution. The goal of this work was to determine the diversity of flea species, their distribution and abundance based on the results of epizootological studies conducted in areas with different landscapes in the Transcaucasian foothill natural plague focus of Azerbaijan. The material for the study was obtained during epizootological studies and observations conducted in the spring and autumn seasons of 2020–2023. in the Transcaucasian foothill natural plague focus of Azerbaijan (Bozchol, Mil-Mugan, Eastern and Western Jeyranchel, Gobustan, Absheron, semi-deserts of Kilazi, Sitalchay). Collection, packaging, transportation, and marketing of the material were carried out on the basis of relevant biosafety rules and delivered for further study to the Special Dangerous İnfections Control Center. In total, 61,087 nest tracks were examined, and 7,939 fleas were collected and delivered. The material was processed and identified in the laboratory in accordance with the current regulatory and methodological document on the safety of working with pathogenic biological agents (PBA) of pathogenicity groups I–IV. As a result of sample identification, the species composition of fleas was determined and grouped by geographical areas and landscapes. Research was also carried out (using the PCR method) for the presence of the plague causative agent - Yersinia pestis. According to the results of the study, it was found that, regardless of the biocenotic and climatic characteristics of individual sectors of the Transcaucasian foothill natural plague focus of Azerbaijan, there may be enough carriers of infectious diseases and their growth increases over the years. The frequency of occurrence of the prevailing genera of fleas - Xenopsylla and Nosopsyllus- depends on the natural and climatic conditions of the focus being studied. The analysis for the presence of the plague causative agent among all fleas caught and studied did not give positive results. For the timely detection of epizootics among wild rodents and bloodsuckers, it is important to conduct regular epizootic surveys in enzootic areas for plague.

Immune targets for schistosomiasis control identified by a genome-wide association study of East African snail vectors.

Schistosomiasis, afflicting >260 million people worldwide, could be controlled by preventing infection of freshwater snail vectors. Intestinal schistosomiasis, caused by Schistosoma mansoni, occurs predominantly in Sub-Saharan Africa and is vectored by Biomphalaria sudanica and related Biomphalaria species. Despite their importance in transmission, very little genomic work has been initiated in African snails, thus hindering development of novel control strategies. To identify genetic factors influencing snail resistance to schistosomes, we performed a pooled genome-wide association study (pooled-GWAS) on the offspring of B. sudanica collected from a persistent hotspot of schistosomiasis in Lake Victoria, Kenya, and exposed to sympatric S. mansoni. Results of the pooled-GWAS were used to develop an amplicon panel to validate candidate loci by genotyping individual snails. This validation revealed two previously uncharacterized, evolutionarily dynamic regions, SudRes1 and SudRes2, that were significantly associated with resistance. SudRes1 includes receptor-like protein tyrosine phosphatases and SudRes2 includes a class of leucine-rich repeat-containing G-protein coupled receptors, both comprising diverse extracellular binding domains, suggesting roles in pathogen recognition. No loci previously tied to schistosome resistance in other snail species showed any association with compatibility suggesting that loci involved in the resistance of African vectors differ from those of neotropical vectors. Beyond these two loci, snail ancestry was strongly correlated with schistosome compatibility, indicating the importance of population structure on transmission dynamics and infection risk. These results provide the first detail of the innate immune system of the major schistosome vector, B. sudanica, informing future studies aimed at predicting and manipulating vector competence.

Evaluation of the Blood Feeding Preference of Aedes aegypti (Diptera: Culicidae) when Offered Diabetic and Non-Diabetic Blood.

Aedes aegypti (L.,1762) is a primary vector of arboviral infections like dengue, yellow fever, Zika. Female mosquitoes are influenced by various physical and chemical cues from host when blood feeding, e.g., they find some individuals with certain blood types or certain conditions more attractive than others. This study determined whether Ae. aegypti shows a preference when offered blood from a patient with diabetes mellitus (DM), an endocrine disorder associated with abnormal glucose metabolism, compared to healthy blood from non-DMs. In the dual feeding experiments, forty newly emerged female mosquitoes were provided with two blood feeding systems with blood from a non-diabetic (healthy) and diabetic patient using artificial feeders. Blood from 12 diabetic and 12 non-diabetic patients was matched by ABO blood type (e.g., diabetic type O blood was compared with non-diabetic type O blood). The number of mosquitoes that landed and fed from each membrane was counted every 2min for thirty minutes. Ae. aegypti species significantly preferred for blood from non-diabetic individuals (50-65% among the different blood type groups) compared to blood from diabetic individuals. Using multiplex allele-specific PCR it was also determined that, Ae. aegypti significantly preferred the O blood group regardless of blood sugar level compared to others. Ae. aegypti has less preference for diabetic blood to non-diabetics. Regardless people affected with this condition need to take preventive measures to reduce mosquito bites as they tend to have weaker immune systems and can experience more severe cases of dengue.

Moving population is a challenge for malaria elimination in India: A cross-sectional study to assess malaria parasite infections in walking pilgrims in western Rajasthan, India

ObjectivesIndia is vigorously pursuing malaria elimination by 2030 and one of the key challenges is how to prevent the malaria risk associated with long-distance migrations of populations from endemic to non-endemic areas. Millions of pilgrims walking to the holy Ramdevra temple stay in temporary shelters along the route in district of Jaisalmer, Rajasthan state in western India. The main pilgrimage period coincides with the post-monsoon period with elevated vector densities. We investigated this situation to assess the potential risk posed by migrant pilgrims along the four highways in the temple district in disseminating malaria infections associated with their annual movements. MethodsA cross-sectional study was conducted for screening malaria in walking pilgrims from neighboring states at selected sites and a follow-up study for screening residents in Rajasthan from 2021 to 2023. The study comprises state entry routes, Ramdevra shrine, and pilgrimage route villages situated in western Rajasthan. Epidemiologic and entomologic surveillance was conducted during the “fair” period (August-September) and in pilgrimage route villages in three different seasons of the year to assess malaria in humans and the vector's infectivity. ResultsOf the 5251 individuals tested for malaria, a total of 76 (1.4%) tested positive for malaria, of whom 40.7% were infected with Plasmodium vivax (n = 31), 36.8% with P. falciparum (n = 28), and 22.3% with P. vivax and P. falciparum (n = 17). Anopheles density was highest during the fair season, peaking in August. An. stephensi exhibited a higher human blood index (0.65) than An. culicifacies (0.50). No mosquitoes were found positive for parasites. ConclusionsUp to 1.5% of pilgrims carried malaria parasites, posing a risk of spreading malaria to surrounding communities that otherwise would have low or no malaria burden. Moving populations pose the risk of local malaria transmission and reintroduction to the areas undergoing elimination. Sentinel point surveillance at the border of states will be helpful for states to share information on malaria and subsequently for the prevention of malaria transmission.

Molecular and serological investigations of Batai virus in cattle and goats in the border area of Yunnan, China (2021-2022).

Batai virus (BATV), a zoonotic pathogen transmitted by mosquitoes, infects vertebrates, including livestock, birds, and humans. Although BATV has been detected and isolated in mosquitoes in Yunnan Province, China, there have been no reports of livestock infection. Thus, we conducted a molecular and serological investigation of BATV in cattle and goat sera collected in spring and autumn from 2021 to 2022 in Honghe Prefecture, Yunnan Province, on the China-Vietnam border. We used indirect enzyme-linked immunosorbent assays and reverse transcription real-time PCR (RT-qPCR) to test 929 cattle and 973 goat serum samples. BATV antibodies were detected in 262/929 (28.2%) cattle and 263/973 (27.0%) goat serum samples. RT-qPCR did not detect BATV RNA. The positive rate of BATV serum antibodies in cattle and goats in Luxi County was higher compared with other areas, and it was also higher in autumn compared with spring, which may be related to climate, temperature, and mosquito density. Although our findings indicated the presence of BATV infection in livestock in the region, RT-qPCR did not detect BATV RNA. Therefore, BATV monitoring in cattle and goats should be heightened in autumn, and the scope of host monitoring should be expanded to clarify the hosts and vectors of BATV infection.

The Activin Branch Ligand Daw Regulates the Drosophila melanogaster Immune Response and Lipid Metabolism against the Heterorhabditis bacteriophora Serine Carboxypeptidase.

Despite impressive advances in the broad field of innate immunity, our understanding of the molecules and signaling pathways that control the host immune response to nematode infection remains incomplete. We have shown recently that Transforming Growth Factor-β (TGF-β) signaling in the fruit fly Drosophila melanogaster is activated by nematode infection and certain TGF-β superfamily members regulate the D. melanogaster anti-nematode immune response. Here, we investigate the effect of an entomopathogenic nematode infection factor on host TGF-β pathway regulation and immune function. We find that Heterorhabditis bacteriophora serine carboxypeptidase activates the Activin branch in D. melanogaster adults and the immune deficiency pathway in Activin-deficient flies, it affects hemocyte numbers and survival in flies deficient for Activin signaling, and causes increased intestinal steatosis in Activin-deficient flies. Thus, insights into the D. melanogaster signaling pathways and metabolic processes interacting with H. bacteriophora pathogenicity factors will be applicable to entomopathogenic nematode infection of important agricultural insect pests and vectors of disease.

Analysis of Amblyomma americanum microRNAs in response to Ehrlichia chaffeensis infection and their potential role in vectorial capacity.

MicroRNAs (miRNAs) represent a subset of small noncoding RNAs and carry tremendous potential for regulating gene expression at the post-transcriptional level. They play pivotal roles in distinct cellular mechanisms including inhibition of bacterial, parasitic, and viral infections via immune response pathways. Intriguingly, pathogens have developed strategies to manipulate the host's miRNA profile, fostering environments conducive to successful infection. Therefore, changes in an arthropod host's miRNA profile in response to pathogen invasion could be critical in understanding host-pathogen dynamics. Additionally, this area of study could provide insights into discovering new targets for disease control and prevention. The main objective of the present study is to investigate the functional role of differentially expressed miRNAs upon Ehrlichia chaffeensis, a tick-borne pathogen, infection in tick vector, Amblyomma americanum. Small RNA libraries from uninfected and E. chaffeensis-infected Am. americanum midgut and salivary gland tissues were prepared using the Illumina Truseq kit. Small RNA sequencing data was analyzed using miRDeep2 and sRNAtoolbox to identify novel and known miRNAs. The differentially expressed miRNAs were validated using a quantitative PCR assay. Furthermore, a miRNA inhibitor approach was used to determine the functional role of selected miRNA candidates. The sequencing of small RNA libraries generated >147 million raw reads in all four libraries and identified a total of >250 miRNAs across the four libraries. We identified 23 and 14 differentially expressed miRNAs in salivary glands, and midgut tissues infected with E. chaffeensis, respectively. Three differentially expressed miRNAs (miR-87, miR-750, and miR-275) were further characterized to determine their roles in pathogen infection. Inhibition of target miRNAs significantly decreased the E. chaffeensis load in tick tissues, which warrants more in-depth mechanistic studies. The current study identified known and novel miRNAs and suggests that interfering with these miRNAs may impact the vectorial capacity of ticks to harbor Ehrlichia. This study identified several new miRNAs for future analysis of their functions in tick biology and tick-pathogen interaction studies.

Dynamical analysis of a stochastic maize streak virus epidemic model with logarithmic Ornstein-Uhlenbeck process.

To describe the transmission dynamics of maize streak virus infection, in the paper, we first formulate a stochastic maize streak virus infection model, in which the stochastic fluctuations are depicted by a logarithmic Ornstein-Uhlenbeck process. This approach is reasonable to simulate the random impacts of main parameters both from the biological significance and the mathematical perspective. Then we investigate the detailed dynamics of the stochastic system, including the existence and uniqueness of the global solution, the existence of a stationary distribution, the exponential extinction of the infected maize and infected leafhopper vector. Especially, by solving the five-dimensional algebraic equations corresponding to the stochastic system, we obtain the specific expression of the probability density function near the quasi-endemic equilibrium of the stochastic system, which provides valuable insights into the stationary distribution. Finally, the model is discretized using the Milstein higher-order numerical method to illustrate our theoretical results numerically. Our findings provide a groundwork for better methods of preventing the spread of this type of virus.

Malaria prevalence and transmission in the Zakpota sub-district of central Benin: baseline characteristics for a community randomised trial of a new insecticide for indoor residual spraying

BackgroundMalaria transmission is known to be perennial and heterogeneous in Benin. Studies assessing local malaria prevalence, transmission levels and vector characteristics are critical for designing, monitoring and evaluating new vector control interventions in community trials. We conducted a study in the Zakpota sub-district of central Benin to collect baseline data on household characteristics, malaria prevalence, vector characteristics and transmission dynamics in preparation for a randomised controlled trial to evaluate the community impact of VECTRON™ T500, a new broflanilide indoor residual spraying (IRS) product.MethodsA total of 480 children under 5 years of age from the 15 villages of the sub-district were tested for malaria by rapid diagnostic tests (RDTs). Mosquitoes were collected by human landing catches (HLCs), pyrethrum spray catches (PSCs) and Centers for Disease Control and Prevention miniature light traps (CDC-LTs) in selected houses in each village to assess vector density, composition, vector infectivity and prevalence of insecticide resistance markers. Bioassays were performed to detect vector susceptibility to pyrethroids, broflanilide (6 µg/bottle) and clothianidin (90 µg/bottle).ResultsA total of 9080 households were enumerated in the 15 study villages. Insecticide-treated net (ITN) usage was > 90%, with 1–2 ITNs owned per household. Houses were constructed mainly with cement (44%) and mud (38%) substrates or a mixture of cement and mud (18%), and 60% of them had open eaves. The overall prevalence of P. falciparum infection was 19% among surveyed children: 20% among females and 18% among males. The haemoglobin rate showed an anaemia (< 11 g/dl) prevalence of 66%. Anopheles coluzzii and An. gambiae sensu stricto (s.s.) were the two vector species present at an overall proportion of 46% versus 54%, respectively. The human biting rate was 2.3 bites per person per night (b/p/n) and biting occurred mostly indoors compared with outdoors (IRR = 0.776; P = 0.001). The overall proportion of outdoor biting was 44% and exceeded indoor biting in three villages. The sporozoite rate was 2% with a combined yearly entomological inoculation rate (EIR) of 16.1 infected bites per person per year (ib/p/y). There was great variability in malaria transmission risk across the villages, with EIR ranging from 0 to 29.3 ib/p/y. The vector population showed a high intensity of resistance to pyrethroids across the study villages but was largely susceptible to broflanilide and clothianidin.ConclusionsThis study found high levels of malaria prevalence, vector density and transmission in the Zakpota sub-district despite the wide use of insecticide-treated nets. The vector population was mostly indoor resting and showed a high intensity of pyrethroid resistance but was generally fully susceptible to broflanilide. These findings demonstrated the suitability of the study area for the assessment of VECTRON™ T500 in a community randomised trial.Graphical

Molecular characterization of Armigeres Subalbatus from Hyderabad region of Telangana state, India.

The mosquito Armigeres subalbatus (Coquillett, 1898) is a significant vector for Japanese encephalitis infection, and breeds in high organic polluted water. Understanding mosquito diversity and there abundance in relation to mosquito-borne diseases is an important component for public health managers. Though the conventional methods for systematic position of mosquito species by using morphological characteristics is a classical method, but it requires perfect expertise and well preserved specimen. Conversely, the molecular analysis of mitochondrial cytochrome C oxidase subunit I (COI) serves as a gene-centric DNA barcoding approach and offers a promising alternative method for mosquito species identification. The study at hand delves into the morphological characteristics of Armigeres subalbatus were compared with COI- gene to ensure a more dependable verification for identification of mosquito species found in Hyderabad region of Telangana. The 489 base pair amplicons were acquired and deposited into the NCBI Gene Bank nucleotide database under the accession number MG686500. The maximum likelihood tree infers that, the Hyderabad species was diverged from USA and Japan species but had ancestral relationship with Tamil Nadu, Karnataka, Maharastra, Kerala and Goa species. Mitochondrial gene (COI) based DNA barcoding is the most reliable and potential alternative technique to identify the mosquito species.

Seasonal variability and stochastic branching process in malaria outbreak probability

Background: Malaria is the world’s most fatal and challenging parasitic disease, caused by the Plasmodium parasite, which is transmitted to humans by the bites of infected female mosquitoes. Bangladesh is the most vulnerable region to spread malaria because of its geographic position. In this paper, we have considered the dynamics of vector-host models and observed the stochastic behavior. This study elaborates on the seasonal variability and calculates the probability of disease outbreaks. Methods: We present a model for malaria disease transmission and develop its corresponding continuous-time Markov chain (CTMC) representation. The proposed vector-host models illustrate the malaria transmission model along with sensitivity analysis. The deterministic model with CTMC curves is depicted to show the randomness in real scenarios. Sequentially, we expand these studies to a time-varying stochastic vector-host model that incorporates seasonal variability. Phase plane analysis is conducted to explore the characteristics of the disease, examine interactions among various compartments, and evaluate the impact of key parameters. The branching process approximation is developed for the corresponding vector-host model to calculate the probability outbreak. Numerous numerical results are accomplished to observe the analytical investigation. Results: Seasonality and contact patterns affect the dynamics of disease outbreaks. The numerical illustration provides that the probability of a disease outbreak depends on the infected host or vector. Additionally, periodic transmission rates have a great influence on the probability outbreak. The basic reproduction number (R0) is derived, which is the main justification for studying the dynamical behavior of epidemic models. Conclusions: Seasonal variability significantly impacts malaria transmission, and the probability of disease outbreaks is influenced by time and the initial number of infected individuals. Moreover, the branching process approximation is applicable when the population size is large enough and the basic reproduction number is less than 1. In the future, such analysis can help decision-makers understand the impact of various parameters and their stochastic behavior in the vector-host model to prevent such types of disease outbreaks.