Blood Meal Research Articles

Host Preferences and Impact of Climate on Blood Feeding in Anopheles funestus Group from South Africa.

Anopheles vaneedeni and Anopheles parensis (members of the An. funestus group) are generally not considered malaria vectors. However, both species were recently identified as potential vectors in South Africa. A critical factor needed to determine their role in malaria transmission is their preference for human blood. The human blood index of An. vaneedeni and An. parensis and their potential role in the ongoing residual malaria transmission in South Africa is unknown. This study aimed to identify host blood meals from the wild-caught An. funestus group in a longitudinal study, and to establish the relationship between temperature, relative humidity, and precipitation on host feeding preferences. Anopheles leesoni, An. parensis, An. vaneedeni, and Anopheles rivulorum were collected, and females mainly fed on cattle. Climatic parameters did not influence the host feeding preferences of these four members of the An. funestus group, but impacted the proportion of females that took a blood meal. Significant changes in feeding proportions were driven by relative humidity, temperature, and precipitation. The role of these species in the ongoing residual malaria transmission in South Africa needs further investigation, as no human blood meals were identified. It is recommended that vector surveillance teams incorporate climatic monitoring and host blood meal identification into their routine activities. This information could provide the malaria vector control programmes with scientific evidence to evaluate the importance of the An. funestus group in residual malaria transmission.

Multiple bloodmeals enhance dissemination of arboviruses in three medically relevant mosquito genera

BackgroundMosquitoes in nature may acquire multiple bloodmeals (BMs) over the course of their lifetime; however, incorporation of frequent feeding behavior in laboratory vector competence studies is rarely done. We have previously shown that acquisition of a second non-infectious BM can enhance early dissemination of Zika virus (ZIKV), dengue virus, and chikungunya virus in Aedes aegypti and ZIKV in Aedes albopictus mosquitoes, yet it is unknown if other taxonomically-diverse virus-vector pairings show a similar trend under a sequential feeding regimen.MethodsTo test this, we evaluated the impact of a second noninfectious BM on the vector competence of Aedes aegypti and Anopheles quadrimaculatus for Mayaro virus, Culex quinquefasciatus for West Nile virus, Aedes triseriatus for La Crosse virus, and Aedes aegypti for Oropouche virus (OROV). Female mosquitoes were fed BMs containing these viruses and half of them were given a second noninfectious BM at 3 or 4-days post infection. Mosquitoes were harvested at various time points and assayed for virus infection in bodies and disseminated infection in legs by performing reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assays.ResultsWe found that a second noninfectious BM had no impact on midgut infection rates but increased virus dissemination for all but one of the virus-vector pairings- Ae. aegypti and OROV. Unlike the other arboviruses under consideration, which are strictly mosquito-borne, biting midges (Culicoides spp.) serve as the main vector of OROV and this virus rarely disseminated to the mosquito leg tissue in our study.ConclusionsTaken together, our findings show that sequential blood feeding enhances virus dissemination across diverse arbovirus-vector pairings, representing three mosquito genera and virus families, but a second BM was insufficient to overcome a strong midgut virus escape barrier in a nonnatural virus–vector pairing.Graphical

Investigating undiagnosed Fabry disease in young adults with ischemic stroke: A multicenter cohort study.

The global prevalence of ischemic stroke in young adults is increasing, leading to a significant social impact. Fabry disease is a recognized cause of ischemic stroke in young patients, and although disease-modifying treatments are available, further evidence is needed to confirm their effectiveness in reducing the incidence of ischemic strokes. This study aimed to identify undiagnosed Fabry disease in young adult patients with ischemic stroke in a Taiwanese cohort. This multicenter, prospective cohort study enrolled patients aged 20-55 years who had experienced an ischemic stroke or transient ischemic attack (TIA) within 10 days, from 1 January 2016 to 31 December 2020. Screening for Fabry disease was performed using a dry blood test to measure α-galactosidase activity in male patients and blood globotriaosylsphingosine (lyso-Gb3) levels in female patients. For patients with positive screen results, genetic diagnosis of Fabry disease was pursued through Sanger sequencing of the GLA gene, covering all exons and a segment of intron 4. A total of 977 patients (659 male, 68%) were enrolled from seven hospitals across Taiwan. Four patients (0.4%, all male) had positive screening results, and two patients (0.2%) were genetically diagnosed with Fabry disease. Case 1 had the GLA c.658C>T mutation and experienced ischemic stroke in the bilateral occipital regions. Case 2 had the GLA c.640-801G>A mutation and experienced an ischemic stroke in the left superficial watershed area. The prevalence of undiagnosed Fabry disease in this cohort of Taiwanese young adults with ischemic stroke or TIA was 0.3% among the young male population. Understanding the prevalence of undiagnosed Fabry disease in young adults with ischemic stroke could help shape future Fabry disease screening policies. The collected data will be available upon reasonable request from the corresponding author.

The development of L. major, L. donovani and L. martiniquensis, Leishmania currently emerging in Europe, in the sand fly species Phlebotomus perniciosus and P. tobbi.

Several new species of Leishmania have recently emerged in Europe, probably as the result of global changes and increased human migration from endemic areas. In this study, we tested whether two sand fly species, the Western Mediterranean Phlebotomus perniciosus and the Eastern Mediterranean P. tobbi, are competent vectors of L. donovani, L. major and L. martiniquensis. Sand flies were infected through the chick skin membrane using Leishmania species and strains of various geographical origins. Leishmania infections were evaluated by light microscopy and qPCR, and the representation of morphological forms was assessed from Giemsa-stained gut smears. Neither P. perniciosus nor P. tobbi supported the development of L. martiniquensis, but L. major and L. donovani in both species survived defecation of blood meal remnants, colonized the stomodeal valve and produced metacyclic stages. The results with L donovani have shown that infection rates in sand flies can be strain-specific; therefore, to determine vector competence or refractoriness, it is optimal to test at least two strains of Leishmania. Both sand fly species tested are potential vectors of L. donovani and L. major in Mediterranean area. However, further studies will be needed to identify European vectors of L. martiniquensis and to test the ability of other European sand fly species to transmit L. major, L. donovani, L. tropica and L. infantum.

Blood-Feeding Patterns and Resting Behavior of Aedes aegypti from Three Health Districts of Ouagadougou City, Burkina Faso.

Recent dengue outbreaks have occurred in Ouagadougou and Bobo-Dioulasso, the two major cities of Burkina Faso. Dengue is a viral disease transmitted primarily by Aedes aegypti, a highly anthropophilic mosquito that thrives in human-transformed environments and breeds predominantly in artificial containers. In 2018, we investigated the resting and blood-feeding habits of Ae. aegypti in urban settings of Ouagadougou. In a 3-month cross-sectional study starting in August 2018, indoors and outdoors resting adult mosquitoes were collected using Prokopack aspirators in three health districts (HD). All mosquitoes were morphologically identified, and DNA was extracted from blood-fed Ae. aegypti females. A multiplex polymerase chain reaction with specific primers was used to identify the origin of the blood meal. A total of 4,256 adult Ae. aegypti mosquitoes, including 1,908 females, were collected. A preference for exophily was recorded in Bogodogo and Nongremassom, although an unexpectedly higher proportion of blood-fed females were found indoors than outdoors. Respectively, 96.09%, 91.03%, and 95.54% of the blood meals successfully analyzed in Baskuy, Bogodogo, and Nongremassom were from a single human host, with the remainder from domestic mammals as single or multiple hosts. Modeling total Ae. aegypti and blood-fed female counts showed that among other predictors, human density, outdoor environment, and house type affect their total densities. Our study revealed an exophilic tendency as well as a pronounced anthropophilic preference of Ae. aegypti adults, critical findings to consider when planning accurate entomological surveillance and effective interventions against Ae. aegypti in urban settings.

Bed bugs, Cimex lectularius: Undercover agents in forensic investigations.

Insects have long played a role in forensic investigations and can be used to estimate minimum time since death, corpse translocation, and link an individual to a crime scene. Bed bugs (Cimex lectularius) are wingless ectoparasitic insects of potential forensic utility, given that all mobile life stages feed on vertebrate blood. Successful profiling of autosomal short tandem repeats (STRs) from human DNA isolated from bed bugs has been previously reported. This proof-of-concept study looked to expand this work and determine any possible limitations of using bed bugs for both rapid stain identification (RSID™) for human blood and Y-STR profiling. To achieve this, bed bugs were fed either human male only or human pooled (female:male) blood for 30 min and subsequently collected at 12-h intervals up to 108 h post-blood meal (PBM). RSID™ blood testing was successful from the bed bug carcass remaining after DNA isolation, regardless of blood meal type and time of collection PBM. Complete Y-STR profiles were generated from bed bugs <60 h PBM. As the time PBM increased, DNA quantity decreased, while the degradation index increased. Collection of bed bugs at a crime scene could provide a valuable source of human blood for Y STR profiling and be used to link an individual to a crime scene or for potential male suspect exclusion. Future studies should look to replicate the results of this proof-of-concept study with larger numbers of bed bugs, more diverse blood donors, and additional STR profiling kits.

Evidence of Limited Laboratory Infection of Culex Tarsalis (Diptera: Culicidae) by Usutu Virus.

Background: Usutu virus (USUV) is an emerging flavivirus, closely related to West Nile virus (WNV), that has spread into Europe from Africa. Since Culex tarsalis Coquillett is an important vector for WNV transmission in the United States, we tested the ability of USUV to replicate in and be transmitted by these mosquitoes. Materials and Methods: USUV was used to infect 3-4 day-old Cx. tarsalis with 5.6 to 7.5 log10 pfu/ml in goose bloodmeals. Saliva, heads, and bodies were collected on day 13 or 14 and analyzed by RT-qPCR for detection for USUV vRNA. Blotting paper punches were also collected daily to assess viral transmissibility. Results: The low and high dose blood meal resulted in 0% and 19.6% of the mosquitoes having established infections, respectively. All of the high dose had a dissemination of USUV RNA to the heads and none of the filter papers had detectable USUV RNA, but five of the capillary saliva collections were positive, representing 45.5% of the infected mosquitoes. Conclusions: Limited infection of Cx. tarsalis was observed when exposed to bloodmeals with greater than 107 pfu/mL of USUV, indicating this vector is not likely to have a key role in transmission of the virus.

Revisiting the paradigm of anhematophagy in male mosquitoes.

Female mosquitoes are reproductively obligate bloodfeeders which feed on vertebrate blood to obtain nutrients required for egg production (driving transmission of vector-borne pathogens in the process), and which rely on plant sugars for their non-reproductive energy requirements. Male mosquitoes, on the other hand, are thought to rely exclusively on plant sugars for their energetic needs; indeed, this dichotomy is one of the central tenets of medical entomology. Here, we show that male Culex tarsalis and Aedes aegypti mosquitoes will readily take blood from a membrane feeder when reared under dehydration conditions with no toxic effects. Mosquitoes with impaired humidity detection do not increase their bloodfeeding rates when dehydrated compared to wild-type controls. While conventionally reared males ignore a human host, dehydrated males are attracted to and attempt to probe, with some success, although they cannot access host capillaries. However, they will take blood from a vertebrate host wound. When fed a blood meal containing West Nile virus, male mosquitoes can become infected with and orally transmit the pathogen at rates and titers equivalent to females. These data suggest that under some circumstances male mosquitoes may be able to probe and/or ingest blood and transmit pathogens to vertebrate hosts, and that their role in maintaining pathogen transmission cycles should be re-examined.

Microbial community characteristics and pathogens detection in Rhipicephalus sanguineus and Haemaphysalis hystricis from Hainan Island, China.

Microbial communities significantly influence the vector capacity of ticks, which, along with tick-borne diseases, pose an increasing global threat. Due to the substantial individual variability caused by various factors, it is essential to assess tick microbial communities and vectorial capacities under different environmental conditions. However, there is a relative scarcity of research on the microbial communities and pathogen transmission of ticks in different physiological states and environmental conditions, especially in Hainan Island, southern China. From 2021 to 2022, we collected 4,167 tick samples, grouping them by blood meal status, developmental stage, sex, time, geographical location, and tick species. We selected 128 samples for full-length 16S rRNA sequencing to describe microbial community characteristics and identify potential biomarkers. Seven hundred seventy-two samples were tested for seven tick-borne pathogens (Rickettsia, Borrelia burgdorferi, Ehrlichia, Anaplasma, Theileria, Babesia, and Hepatozoon), and sera from 208 residents of Hainan Island were tested for IgG antibodies against Rickettsia and B. burgdorferi. Blood meal status, developmental stage, sex, time, geographical location, and tick species significantly influenced the microbial communities of ticks. We observed distinct microbial community characteristics across different states. We noted the non-random replacement of stable and transient species, with functional differences between parasitic and engorged ticks mainly driven by transient species. Functionally, we observed three distinct response patterns: driven by stable species, transient species, and both together in response to the six factors. We identified 273 potential biomarkers (200 robust core species and 73 robust differential species). Six genera and eight species of pathogens were detected in ticks, with an overall positivity rate of 12.44% (96/772). Among humans, 18.27% (38/208) of serum samples were positive for at least one tick-borne pathogen IgG. Our findings indicate that these six factors significantly influence both tick microbial communities and vectorial capacity, with varying effects on vector competence for different pathogens and inconsistent impacts on microbial communities under different conditions. This study supplemented the understanding of tick microbial communities on Hainan Island, assessed the relatively high risk of tick-borne pathogens in the region, and evaluated the impact of these factors on both microbial communities and vectorial capacity.

Determining the Association Between MSP1/2 Variant and Multiplicity of Infection on Incidence of Severe Malaria in Sudanese Children in Gezira State, Sudan

The Almanagil province located in Gezira scheme, Gezira state, Sudan, represents a suitable environment for the breeding of malaria-carrying mosquitoes. An estimated 5.9% of Sudanese people suffer from malaria, with 87.6% of cases caused by Plasmodium falciparum and 12.4% by Plasmodium vivax. Clinical manifestation of malaria cases range from mild uncomplicated to severe and fatal complications and the genetic variants and multiplicity of falciparum infection can worsen the manifestations of malaria. The objective of this work is to determine the degree of genetic variation in P. falciparum infection in a high-transmission region of central Sudan by analyzing merozoite surface protein-1 (msp1) and merozoite surface protein-2 (msp2) variations. During the rainy season of 2022, Eighty-nine children with confirmed severe falciparum malaria whom admitted to Almanagil Pediatric Hospital were included in this study. Dry blood spots were used to extract the DNA and amplification of three msp1 and two of msp2 allelic subfamilies, namely K1, RO33 and MAD20 and FC27 and IC/3D7, respectively. The data was analyzed by using SPSS computer program (v 23.0). The three genetic subfamilies of msp1 (K1, RO33 and MAD20) and the two alleles of msp2 (FC27 and IC/3D7) were identified. Msp1 variants represent K1 (64/89, 71.9%), RO33 (56/89, 62.9%) and MAD20 (72/89, 80.9%), while msp2 diversity represents ICI/3D7 (52/89, 58.4%), FC27 (62/89, 69.6%) and ICI/3D7/FC27(33/89, 37.1%). The MAD20 and FC27 showed high genetic diversity among both genes respectively. RO33 allele shows a strong association with severity of falciparum malaria (OR 2.572, P 0.045 ), while the K1 was the lowest risk factor for malaria severity. The allele subfamily K1 and MAD20 of msp1 were associated with hypoglycemia (OR 4.21 and 2.91) respectively. Our study revealed high genetic polymorphisms of msp1 and msp2. Among Central Sudanese children with high MOI of P. falciparum isolates, there was a significant frequency of msp1, a strong association between the K1 allele and hypoglycemia, and a substantial association between the RO33 and MAD20 alleles with the severity of the infection. These findings could help develop malaria control strategies.

Host diversity of Aedes albopictus in relation to invasion history: a meta-analysis of blood-feeding studies

BackgroundThe invasive mosquito Aedes albopictus is a major concern for human and animal health given its high potential to spread over large geographical distances, adapt to various habitats and food sources, and act as a vector for pathogens. It is crucial to understand how this species establishes ecological relationships at different locations, as it determines its role in transmission of diseases.MethodsBased on published blood meal surveys, a meta-analysis was performed to investigate how host diversity changes along the process of invasion at a large scale. For 48 independent localities, the Shannon diversity index was calculated and was then assessed against several moderator variables describing invasion status, habitat type, methodology, survey year and the year of introduction for invasive populations.ResultsDiet diversity was higher in the invasive than in the native populations when the strong habitat effects were held constant. Furthermore, the year of introduction also had a significant role, as invasive populations that had been established earlier had wider diet diversity than more recent populations.ConclusionsInvasive Ae. albopictus has considerable ecological flexibility. The species’ ability to adapt to various food sources goes hand in hand with its successful worldwide dispersion, which has strong implications for its role in pathogen transmission.Graphical

Feeding habits and malaria parasite infection of Anopheles mosquitoes in selected agroecological areas of Northwestern Ethiopia

BackgroundSurveillance of the host–anopheline mosquitoes’ interaction is important for assessing malaria transmission risk and guiding vector control. We assume that changes in malaria vector species’ feeding habits, as well as the surrounding environment, have a substantial impact on varied malaria transmission. In this study, we determined the vertebrate host feeding patterns of anopheline mosquitoes to characterize entomologic risk factors for malaria in Jabi Tehnan, Northwestern Ethiopia.MethodsBlood-fed anophelines surveyed during malaria surveillance in Jabi Tehnan district of northwestern Ethiopia were utilized in this study. They were collected using Centers for Disease Control and Prevention (CDC) light traps deployed in selected households per village, placed indoors and outdoors, spanning three agroecological settings (dry mountain, plateau, and semiarid highlands) between June 2020 and May 2021. The engorged mosquitoes were analyzed for host blood meal sources and Plasmodium infection via polymerase chain reaction (PCR) and/or sequencing. Infection rates and bovine and human blood indices were calculated and compared for abundant species; between indoors and outdoors and between agroecology using a chi-squared test for equality of proportion in R package at a significant level of p ≤ 0.05.ResultsA total of 246 mosquitoes were successfully typed (indoor, 121; outdoor, 125), with greater relative abundance indoors in mountain and plateau highlands, and outdoors in semiarid areas. Despite ecological differences in blood-fed capture rates, cattle served as the most utilized blood meal source by 11 anopheline species with an overall bovine blood index (BBI) of 74.4%. This trend was dictated by Anopheles gambiae s.l. (198/246; BBI = 73.7%), which exhibited the most plastic feeding habits that included humans (human blood index = 15.7%) and other livestock and rodents. A total of five anopheline species (An. gambiae s.l., An. funestus s.l., An. coustani s.l., An. pretoriensis, and An. pharoensis) fed on humans, of which the first three were found infected with Plasmodium parasites. Most of the infected specimens were An. arabiensis (5.6%, 11/198) and had recently fed mainly on cattle (72.7%, 8/11); one each of infected An. funestus s.l. and An. coustani s.l. had fed on humans and cattle, respectively.ConclusionsThe results demonstrate communal feeding on cattle by anophelines including primary and secondary malaria vectors. This study also indicates the importance of cattle-targeted interventions for sustainable control of malaria vectors in the study areas.Graphical abstract

Only incandescent light significantly decreases feeding of Anopheles funestus s.s. (Diptera: Culicidae) mosquitoes under laboratory conditions

Recent work has demonstrated that exposure to artificial light at night (ALAN) may alter mosquito feeding behavior and so must be considered a moderator of vector-borne disease transfer. Anopheles funestus mosquitoes are a primary malaria vector in sub-Saharan Africa, but no study to date has tested the impact of ALAN on their feeding behavior. Here we test if the exposure to commonly used household lights (compact fluorescent lights, light-emitting diodes, and incandescent lights) alters Anopheles funestus feeding. Mated, unfed female mosquitoes were exposed to a light treatment, at the onset of darkness, followed by a blood-feeding assay. The light treatments consisted of a 30-min light pulse of one of the three household lights, each in individual experimental containers, versus controls. All three household lights resulted in a reduction in the percentage of females taking a blood meal, but only mosquitoes exposed to incandescent light showed a statistically significant reduction in feeding of 19.6% relative to controls which showed a 42.8% feeding rate. Our results suggest that exposure to some household lights during the night may have an immediate inhibitory effect on Anopheles funestus feeding. By helping identify which light types lead to a suppression of feeding, the findings of this study could provide insight necessary to design household lights that can help minimize mosquito feeding on humans.

Blood, War, and Ritual Meals: Transgressive Consumption in 1 Samuel 14:31–35

Blood, War, and Ritual Meals: Transgressive Consumption in 1 Samuel 14:31–35

Species richness and abundance of wild tsetse flies collected from selected human-wildlife-livestock interface in Tanzania

The successful control of tsetse flies largely depends on understanding of the species available and abundance. This study assessed the species richness, abundance and apparent density of wild collected tsetse flies from selected human-wildlife-livestock interface in Tanzania. Seasonal trapping using baited NZI, Pyramidal and Biconical traps was done across selected wards. Traps were set at 200 m apart, emptied after every 24 h then rotated to the next sites after 72 h. Collected flies were identified morphologically and letter confirmed using the Polymerase Chain Reaction (PCR). Only two Glossina species; Glossina pallidipes (n = 371; 47.32 %) and Glossina morsitans morsitans (n = 413; 52.68 %) were identified. Among them, 96 flies (80 Female, 16 Male) were blood fed; 57(48 Female and 9 Male) G. pallidipes and 39(32 Female and 7 Male) G.m. morsitans. Tsetse fly abundance varied across wards (χ2 = 4.597, df = 1, p = 0.032), villages (χ2 = 9.491, df = 3, p = 0.023), habitats (χ2 = 17.239, df = 2, p < 0.001), months (χ2 = 13.507, df = 3, p = 0.004) and deployed traps (χ2 = 6.348, df = 2, p = 0.04). About 78.82 % of the total catch occurred in Kisaki ward (n = 618; p < 0.001) and 21.17 % (n = 166; p = 0.032) in Bwakila chini. Similarly, 62.37 % of the catch occurred in Mbojoge village. NZI traps (n = 422; 54 %; 4.98 FTD) were most successful traps. Moreover, 78.06 % of the catch occurred in bushed grassland habitat (n = 612; 55.41 FTD) while 5.48 % in farmland (n = 43; 7.17 FTD). This study recommends NZI and Pyramidal traps for tsetse flies control at the interface and proposes wet season as appropriate time for successful trapping of the flies. Finally, it attracts a need for assessing tsetse flies' blood meal sources and the infection status to establish the prevalence to inform existing trypanosome control programs.

Leveraging the Aggregated Protein Dye YAT2150 for Malaria Chemotherapy.

Background/Objectives: YAT2150 is a first-in-class antiplasmodial compound that has been recently proposed as a new interesting drug for malaria therapy. Methods/Results: The fluorescence of YAT2150 rapidly increases upon its entry into Plasmodium, a property that can be of use for the design of highly sensitive diagnostic approaches. YAT2150 blocks the in vitro development of the ookinete stage of Plasmodium and, when added to an infected blood meal, inhibits oocyst formation in the mosquito. Thus, the compound could possibly contribute to future transmission-blocking antimalarial strategies. Cell influx/efflux studies in Caco-2 cells suggest that YAT2150 is internalized by endocytosis and also through the OATP2B1 transporter, whereas its main export route would be via OSTα. YAT2150 has an overall favorable drug metabolism and pharmacokinetics profile, and its moderate cytotoxicity can be significantly reduced upon encapsulation in immunoliposomes, which leads to a dramatic increase in the drug selectivity index to values close to 1000. Although YAT2150 binds amyloid-forming peptides, its in vitro fluorescence emission is stronger upon association with peptides that form amorphous aggregates, suggesting that regions enriched in unstructured proteins are the preferential binding sites of the drug inside Plasmodium cells. The reduction of protein aggregation in the parasite after YAT2150 treatment, which has been suggested to be directly related to the drug's mode of action, is also observed following treatment with quinoline antimalarials like chloroquine and primaquine. Conclusions: Altogether, the data presented here indicate that YAT2150 can represent the spearhead of a new family of compounds for malaria diagnosis and therapy due to its presumed novel mode of action based on the interaction with functional protein aggregates in the pathogen.

Improved nutritional and antioxidant properties of black soldier fly larvae reared on spent coffee grounds and blood meal by-products

Black Soldier Fly larvae (BSFL) are a promising and sustainable alternative to obtain proteins. Due to their high growth rate and ability to use different substrates as feeding stocks, BSFL can be also used to valorize food waste. Thus, the aim of this research was to unravel the potential use of Spent Coffee Grounds (SCG) and blood meal alone or mixed as feedstocks for BSFL and the nutritional changes for BSFL meal, especially after simulated human in vitro digestion and fermentation. Chicken feed was used as a control. Chicken feed showed the highest BSFL growth (P < 0.05) compared with blood meal and the mix made of blood meal and SCG; the latter caused the lowest growth. The meal obtained from BSFL fed with blood meal had the highest protein content, as well as the highest levels of short chain fatty acids (SCFAs) produced after in vitro fermentation by the human gut microbiota. On the other hand, the meal from larvae fed with SCG showed higher antioxidant capacity than the others in the DPPH, FRAP and ABTS assays. The digestibility of macronutrients, release of antioxidant capacity and production of SCFAs of the BSFL meal were improved when using these substrates, compared to chicken feed.

Exploring midgut expression dynamics: longitudinal transcriptomic analysis of adult female Amblyomma americanum midgut and comparative insights with other hard tick species.

Female ticks remain attached to their host for multiple days to complete a blood meal. This prolonged feeding period is accompanied by a significant increase in the tick's size and body weight, paralleled by noteworthy changes to the tick midgut. While the midgut is recognized for its established role in blood storage and processing, its importance extends to playing a crucial role in the acquisition, survival, and proliferation of pathogens. Despite this, our overall understanding of tick midgut biology is limited. We conducted a comprehensive longitudinal transcriptome analysis of the midgut in adult female A. americanum ticks across various feeding stages, including unfed, slow-feeding, and rapid-feeding phases. Our analysis revealed 15,599 putative DNA coding sequences (CDS) classified within 26 functional groups. Dimensional and differential expression analysis highlighted the dynamic transcriptional changes in the tick midgut as feeding progresses, particularly during the initial period of feeding and the transition from the slow-feeding to the rapid-feeding phase. Additionally, we performed an orthology analysis comparing our dataset with midgut transcriptomes from other hard ticks, such as Ixodes scapularis and Rhipicephalus microplus. This comparison allowed us to identify transcripts commonly expressed during different feeding phases across these three species. Our findings provide a detailed temporal resolution of numerous metabolic pathways in A. americanum, emphasizing the dynamic transcriptional changes occurring in the tick midgut throughout the feeding process. Furthermore, we identified conserved transcripts across three different tick species that exhibit similar expression patterns. This knowledge has significant implications for future research aimed at deciphering the physiological pathways relevant within the tick midgut. It also offers potential avenues for developing control methods that target multiple tick species.

Seasonal dynamics, Leishmania diversity, and nanopore-based metabarcoding of blood meal origins in Culicoides spp. in the newly emerging focus of leishmaniasis in Northern Thailand

BackgroundClinical cases of leishmaniasis caused by Leishmania (Mundinia) parasites have been increasingly reported in Southeast Asia, particularly Thailand. Recent evidence has shown that Leishmania (Mundinia) parasites successfully developed into infective metacyclic promastigotes in Culicoides biting midges, strongly supporting their putative role in disease transmission. However, Culicoides diversity, host preference, and Leishmania prevalence in endemic areas remain largely unknown.MethodsWe investigated the seasonal dynamics, infection prevalence, and blood meal identification of Culicoides collected from the emerging focus of visceral leishmaniasis in Lampang Province, Northern Thailand, during 2021–2023. Midge samples were molecularly screened for Leishmania using SSU rRNA-qPCR and ITS1-PCR, followed by Sanger plasmid sequencing, and parasite haplotype diversity was analyzed. Host blood meal origins were comparatively identified using host-specific Cytb-PCRs and a nanopore-based metabarcoding approach.ResultsA total of 501 parous and gravid females and 46 blood-engorged ones belonging to at least 17 species of five subgenera (Remmia, Trithecoides, Avaritia, Hoffmania, and Meijerehelea) and two species groups (Shortti and Calvipalpis) were collected with temporal differences in abundance. Leishmania was detected by SSU rRNA-qPCR in 31 samples of at least 11 midge species, consisting of Culicoides oxystoma, C. guttifer, C. orientalis, C. mahasarakhamense, C (Trithecoides) spp., C. innoxius, C. shortti, C. arakawae, C. sumatrae, C. actoni, and C. fulvus, with the overall infection prevalence of 5.7%. The latter six species represent the new records as putative leishmaniasis vectors in Northern Thailand. The ITS1-PCR and plasmid sequencing revealed that Leishmania martiniquensis was predominantly identified in all qPCR-positive species, whereas L. orientalis was identified only in three C. oxystoma samples. The most dominant haplotype of L. martiniquensis in Thailand was genetically intermixed with those from other geographical regions, confirming its globalization. Neutrality test statistics were also significantly negative on regional and country-wide scales, suggesting rapid population expansion or selective sweeps. Nanopore-based blood meal analysis revealed that most Culicoides species are mammalophilic, with peridomestic and wild mammals (cow, pig, deer, and goat-like species) and humans as hosts, while C. guttifer and C. mahasarakhamense fed preferentially on chickens.ConclusionsThis study revealed seasonal dynamics and sympatric circulation of L. martiniquensis and L. orientalis in different species of Culicoides. Evidence of human blood feeding was also demonstrated, implicating Culicoides as putative vectors of human leishmaniasis in endemic areas. Further research is therefore urgently needed to develop vector control strategies and assess the infection status of their reservoir hosts to effectively minimize disease transmission.Graphical

Mosquito Feeding Habits in Coastal French Guiana: Mammals in the Crosshairs?

Pathogens transmitted by mosquitoes (Diptera, Culicidae) in sylvatic or urban cycles involve wild or domestic animals and humans, driven by various mosquito species with distinct host preferences. Understanding mosquito-host associations is crucial for ecological insights and pathogen surveillance. In this study, we analyzed mosquito blood meals from coastal French Guiana by amplifying and sequencing host DNA from blood-fed females. Using the 12S ribosomal RNA gene and Sanger sequencing, we identified blood meals from 26 mosquito species across six genera, with 59% belonging to the Culex genus. Nanopore sequencing of selected samples showed 12 mosquito species with one to three mixed blood-meal sources. Mammals were the primary hosts (88%), followed by birds (7%), squamates (3%), and amphibians (2%), indicating a strong preference for mammalian hosts. A total of 46 vertebrate host species were identified, demonstrating high host diversity. This research provides insights into mosquito host usage and highlights the complexities of monitoring arboviruses of public health concern.