Abstract Anopheles gambiae are a major vector of malaria in sub-Saharan Africa. Viruses that naturally infect these mosquitoes may impact their physiology and ability to transmit pathogens. We ...therefore used metagenomics sequencing to search for viruses in adult Anopheles mosquitoes collected from Liberia, Senegal, and Burkina Faso. We identified a number of virus and virus-like sequences from mosquito midgut contents, including 14 coding-complete genome segments and 26 partial sequences. The coding-complete sequences define new viruses in the order Mononegavirales, and the families Flaviviridae, and Totiviridae. The identification of a flavivirus infecting Anopheles mosquitoes broadens our understanding of the evolution and host range of this virus family. This study increases our understanding of virus diversity in general, begins to define the virome of a medically important vector in its natural setting, and lays groundwork for future studies examining the potential impact of these viruses on anopheles biology and disease transmission.
The 2013–present Western African Ebola virus disease (EVD) outbreak is the largest ever recorded with >28,000 reported cases. Ebola virus (EBOV) genome sequencing has played an important role ...throughout this outbreak; however, relatively few sequences have been determined from patients in Liberia, the second worst-affected country. Here, we report 140 EBOV genome sequences from the second wave of the Liberian outbreak and analyze them in combination with 782 previously published sequences from throughout the Western African outbreak. While multiple early introductions of EBOV to Liberia are evident, the majority of Liberian EVD cases are consistent with a single introduction, followed by spread and diversification within the country. Movement of the virus within Liberia was widespread, and reintroductions from Liberia served as an important source for the continuation of the already ongoing EVD outbreak in Guinea. Overall, little evidence was found for incremental adaptation of EBOV to the human host.
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•140 EBOV genomes from Liberian patients sequenced and analyzed with 782 other sequences•Multiple EBOV introductions into Liberia, but one led to most cases and spread•Re-introductions from Liberia helped sustain the Guinea and Mali outbreaks•Limited evidence of incremental Ebola virus adaptation to the human host
Ladner et al. sequenced 140 Ebola virus genomes sampled throughout 11 months across 13 Liberian counties. Analysis of these and 782 other sequences reveals that, despite multiple introductions, the Liberian outbreak was driven by within-country spread and diversification. Multiple re-introductions of Ebola virus from Liberia contributed to transmission within Guinea.
Tick-borne pathogens harm livestock production and pose a significant risk to public health. To combat these effects, it is necessary to identify the circulating pathogens to create effective control ...measures. This study identified
Anaplasma
and
Ehrlichia
species in ticks collected from livestock in the Kassena-Nankana Districts between February 2020 and December 2020. A total of 1550 ticks were collected from cattle, sheep and goats. The ticks were morphologically identified, pooled and screened for pathogens using primers that amplify a 345 bp fragment of the 16SrRNA gene and Sanger sequencing. The predominant tick species collected was
Amblyomma variegatum
(62.98%). From the 491 tick pools screened, 34 (6.92%) were positive for
Ehrlichia
and
Anaplasma
. The pathogens identified were
Ehrlichia canis
(4.28%),
Ehrlichia minasensis
(1.63%),
Anaplasma capra
(0.81%) and
Anaplasma marginale
(0.20%). This study reports the first molecular identification of the above-mentioned
Ehrlichia
and
Anaplasma
species in ticks from Ghana. With the association of human infections with the zoonotic pathogen
A. capra
, livestock owners are at risk of infections, calling for the development of effective control measures.
Sampled ticks were screened for Crimean-Congo haemorrhagic fever virus (CCHFV) using an assay that targets the nucleoprotein gene region of the S segment, a conserved region of the CCHFV genome. ...Minimum infection rates of 0.34% and 0.10% were obtained when testing pools of
Hyalomma rufipes
and
Amblyomma variegatum
, respectively. Next-generation sequencing and phylogenetic analysis showed that the S and L segments of the CCHFV isolate clustered with those of similar isolates of genotype III. However, analysis of the M segment showed that reassortment had occurred, causing this segment to cluster with those of isolates of genotype I, providing the first evidence of such an occurrence in Ghana.
Ticks are important vectors of various pathogenic protozoa, bacteria and viruses that cause serious and life-threatening illnesses in humans and animals worldwide. Estimating tick-borne pathogen ...prevalence in tick populations is necessary to delineate how geographical differences, environmental variability and host factors influence pathogen prevalence and transmission. This study identified ticks and tick-borne pathogens in samples collected from June 2016 to December 2017 at seven sites within the Coastal, Sudan and Guinea savanna ecological zones of Ghana.
A total of 2016 ticks were collected from domestic animals including cattle, goats and dogs. Ticks were morphologically identified and analysed for pathogens such as Crimean-Congo haemorrhagic fever virus (CCHFV), Alkhurma haemorrhagic fever virus (AHFV), Rickettsia spp. and Coxiella burnetii using polymerase chain reaction assays (PCR) and sequence analysis.
Seven species were identified, with Amblyomma variegatum (60%) most frequently found, followed by Rhipicephalus sanguineus sensu lato (21%), Rhipicephalus spp. (9%), Hyalomma truncatum (6%), Hyalomma rufipes (3%), Rhipicephalus evertsi (1%) and Rhipicephalus (Boophilus) sp. (0.1%). Out of 912 pools of ticks tested, Rickettsia spp. and Coxiella burnetii DNA was found in 45.6% and 16.7% of pools, respectively, whereas no CCHFV or AHFV RNA were detected. Co-infection of bacterial DNA was identified in 9.6% of tick pools, with no statistical difference among the ecozones studied.
Based on these data, humans and animals in these ecological zones are likely at the highest risk of exposure to rickettsiosis, since ticks infected with Rickettsia spp. displayed the highest rates of infection and co-infection with C. burnetii, compared to other tick-borne pathogens in Ghana.
Mass drug administration (MDA) of ivermectin to humans for control and elimination of filarial parasites can kill biting malaria vectors and lead to Plasmodium transmission reduction. This study ...examines the degree and duration of mosquitocidal effects resulting from single MDAs conducted in three different West African countries, and the subsequent reductions in parity and Plasmodium sporozoite rates.
Indoor-resting, blood-fed and outdoor host-seeking Anopheles spp. were captured on days surrounding MDAs from 2008-2013 in Senegalese, Liberian and Burkinabé villages. Mortality was assessed on a portion of the indoor collection, and parity status was determined on host-seeking mosquitoes. The effect of MDA was then analysed against the time relative to the MDA, the distributed drugs and environmental variables.
Anopheles gambiae survivorship was reduced by 33.9% for one week following MDA and parity rates were significantly reduced for more than two weeks after the MDAs. Sporozoite rates were significantly reduced by >77% for two weeks following the MDAs in treatment villages despite occurring in the middle of intense transmission seasons. These observed effects were consistent across three different West African transmission dynamics.
These data provide a comprehensive and crucial evidence base for the significant reduction in malaria transmission following single ivermectin MDAs across diverse field sites. Despite the limited duration of transmission reduction, these results support the hypothesis that repeated MDAs with optimal timing could help sustainably control malaria as well as filarial transmission.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Novel surveillance strategies are needed to detect the rapid and continuous emergence of infectious disease agents. Ideally, new sampling strategies should be simple to implement, technologically ...uncomplicated, and applicable to areas where emergence events are known to occur. To this end, xenosurveillance is a technique that makes use of blood collected by hematophagous arthropods to monitor and identify vertebrate pathogens. Mosquitoes are largely ubiquitous animals that often exist in sizable populations. As well, many domestic or peridomestic species of mosquitoes will preferentially take blood-meals from humans, making them a unique and largely untapped reservoir to collect human blood.
We sought to take advantage of this phenomenon by systematically collecting blood-fed mosquitoes during a field trail in Northern Liberia to determine whether pathogen sequences from blood engorged mosquitoes accurately mirror those obtained directly from humans. Specifically, blood was collected from humans via finger-stick and by aspirating bloodfed mosquitoes from the inside of houses. Shotgun metagenomic sequencing of RNA and DNA derived from these specimens was performed to detect pathogen sequences. Samples obtained from xenosurveillance and from finger-stick blood collection produced a similar number and quality of reads aligning to two human viruses, GB virus C and hepatitis B virus.
This study represents the first systematic comparison between xenosurveillance and more traditional sampling methodologies, while also demonstrating the viability of xenosurveillance as a tool to sample human blood for circulating pathogens.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The ability of ticks to adapt to different ecological zones, coupled with the spread of infectious pathogens negatively affects livestock production and thus, there is a need for better control ...strategies. However, control measures within a geographical region can only be effective if there is available information on tick population dynamics and ecology. This study focused on ticks infesting livestock in the Kassena-Nankana Districts of the Upper East Region of Ghana. The ticks were morphologically identified, variables such as season, animal host, and predilection sites were recorded, and the data were analyzed using STATA version 13. Out of 448 livestock examined, tick infestation in cattle was (78.60%), followed by sheep (25%) and goats (5.88%). A total of 1,550 ticks including nymphs (303) and adults (1,247) were collected. Adult ticks were found to be significantly associated with season (p<0.001), with a high burden in the wet season. The nymph burden and body parts of livestock hosts were significantly associated with more nymphs collected from male animals than females (p<0.001). Three genera of ticks, Amblyomma (62.97%), Hyalomma (18.71%), and Rhipicephalus (18.32%) were morphologically identified with the most predominant tick species recorded as Amblyomma variegatum (62.97%). Matured A. variegatum was sampled primarily in the wet season with their predilection site as the udder/scrotum (p<0.001). However, adult Hyalomma truncatum was observed to have a significant association with the anal region (p<0.001). Findings from this study are essential for formulating tick control measures to prevent the spread of infectious pathogens.
Mosquitoes of various species mate in swarms comprised of tens of thousands of flying males. In this study, we examined Aedes aegypti swarming behavior and identified associated chemical cues. Novel ...evidence is provided that Ae. aegypti females aggregate by means of olfactory cues, such as aggregation pheromones. Isolation of Ae. aegypti aggregation pheromones was achieved by aeration of confined mosquitoes and collection of associated volatiles by glass filters. The collected volatiles were identified through gas chromatography mass spectrometry (GCMS). Three aggregation pheromones were collected and identified as 2,6,6-trimethylcyclohex-2-ene-1,4-dione (ketoisophorone) (CAS# 1125-21-9, tR = 18.75), 2,2,6-trimethylcyclohexane-1,4-dione (the saturated analog of ketoisophorone) (CAS# 20547-99-3, tR = 20.05), and 1-(4-ethylphenyl) ethanone (CAS# 937-30-4, tR = 24.22). Our biological studies revealed that the identified compounds stimulated mosquito behavior under laboratory conditions. The mechanism of mosquito swarm formation is discussed in light of our behavioral study findings. A preliminary field trial demonstrated the potential application of the isolated aggregation pheromones in controlling Ae. Aegypti.
Over the past decades, the extensive use of pyrethroids insecticides for vector control has resulted in the development of insecticide resistance. Cytochrome P450 has been recognized to play a ...critical role in the metabolic detoxification of insecticides. In the current study, Culex pipiens mosquitoes were collected from Giza Governorate in Egypt and tested for insecticide susceptibility against deltamethrin. First detection of Knockdown resistance gene (Kdr) mutations in field collected mosquitoes was performed. Activities of cytochrome oxidase P450 detoxification enzyme that synchronized with the resistance development, was assessed. Expression profiles of cytochrome P450s and their putative corresponding regulating miRNAs, which was previously reported in Cx. pipiens pallens were evaluated in pyrethroid resistant field-collected Cx. pipiens using RT-qPCR and stem-loop RT-qPCR, respectively. Specific stem-loop reverse transcription primers and forward primers were designed for miRNAs profiling. Our results elucidated the pyrethroid resistance development and revealed its relation to the metabolic and target site modification mechanisms with a first report of L1014F-kdr mutation detection. RT-qPCR results have showed an up-regulation in the expression of the studied P450 transcripts. Negative correlations were found between the expression of P450s and their regulatory miRNAs except for CYP9J35, where positive correlation was found with its corresponding miR-13. Interestingly, our data was the first to detect negative correlation between miR-285 and its putative CYP6Cp1 target gene. These findings highlighted the significance of identifying P450 gene along with regulatory miRNAs as a key mechanism implicated in pyrethroid resistance in field Culex vector population. The elucidation of this mechanism would shed light on the development of insecticide resistance and would help in shaping strategies to combat such vectors.
•Significant pyrethroid resistance in Cx. pipiens from Egypt.•First report of L1014F-kdr mutation in Cx. pipiens.•First report of expression profiling of P450s and its putative regulating miRNAs.•Positive expression pattern between miR-13 and its CYP9J35 target.•Negative expression pattern between miR-285 and its potential CYP6Cp1 target.
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