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result(s) for
"Ramirez, Ana L"
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Not all mosquitoes are created equal: A synthesis of vector competence experiments reinforces virus associations of Australian mosquitoes
2022
The globalization of mosquito-borne arboviral diseases has placed more than half of the human population at risk. Understanding arbovirus ecology, including the role individual mosquito species play in virus transmission cycles, is critical for limiting disease. Canonical virus-vector groupings, such as
Aedes
- or
Culex
-associated flaviviruses, have historically been defined using virus detection in field-collected mosquitoes, mosquito feeding patterns, and vector competence, which quantifies the intrinsic ability of a mosquito to become infected with and transmit a virus during a subsequent blood feed. Herein, we quantitatively synthesize data from 68 laboratory-based vector competence studies of 111 mosquito-virus pairings of Australian mosquito species and viruses of public health concern to further substantiate existing canonical vector-virus groupings and quantify variation within these groupings. Our synthesis reinforces current canonical vector-virus groupings but reveals substantial variation within them. While
Aedes
species were generally the most competent vectors of canonical “
Aedes
-associated flaviviruses” (such as dengue, Zika, and yellow fever viruses), there are some notable exceptions; for example,
Aedes notoscriptus
is an incompetent vector of dengue viruses.
Culex
spp. were the most competent vectors of many traditionally
Culex
-associated flaviviruses including West Nile, Japanese encephalitis and Murray Valley encephalitis viruses, although some
Aedes
spp. are also moderately competent vectors of these viruses. Conversely, many different mosquito genera were associated with the transmission of the arthritogenic alphaviruses, Ross River, Barmah Forest, and chikungunya viruses. We also confirm that vector competence is impacted by multiple barriers to infection and transmission within the mesenteron and salivary glands of the mosquito. Although these barriers represent important bottlenecks, species that were susceptible to infection with a virus were often likely to transmit it. Importantly, this synthesis provides essential information on what species need to be targeted in mosquito control programs.
Journal Article
Behavioral signatures of Y-like neuronal responses in human vision
by
Ramirez, Ana L.
,
Thompson, Lowell W.
,
Rosenberg, Ari
in
631/378/3917
,
631/443/376
,
631/477/2811
2022
Retinal ganglion cells initiating the magnocellular/Y-cell visual pathways respond nonlinearly to high spatial frequencies (SFs) and temporal frequencies (TFs). This nonlinearity is implicated in the processing of contrast modulation (CM) stimuli in cats and monkeys, but its contribution to human visual perception is not well understood. Here, we evaluate human psychophysical performance for CM stimuli, consisting of a high SF grating carrier whose contrast is modulated by a low SF sinewave envelope. Subjects reported the direction of motion of CM envelopes or luminance modulation (LM) gratings at different eccentricities. The performance on SF (for LMs) or carrier SF (for CMs) was measured for different TFs (LMs) or carrier TFs (CMs). The best performance for LMs was at lower TFs and SFs, decreasing systematically with eccentricity. However, performance with CMs was bandpass with carrier SF, largely independent of carrier TF, and at the highest carrier TF (20 Hz) decreased minimally with eccentricity. Since the nonlinear subunits of Y-cells respond better at higher TFs compared to the linear response components and respond best at higher SFs that are relatively independent of eccentricity, these results suggest that behavioral tasks employing CM stimuli might reveal nonlinear contributions of retinal Y-like cells to human perception.
Journal Article
Stability of West Nile Virus (Flaviviridae: Flavivirus) RNA in Mosquito Excreta
by
Hewitson, Glen R.
,
McMahon, Jamie L.
,
Hurk, Andrew F. van den
in
Animals
,
Aquatic insects
,
arbovirus
2019
Arbovirus surveillance is crucial for the implementation of vector-borne disease control measures. Recently, it has been demonstrated that mosquitoes with a disseminated arbovirus infection excrete viral RNA, which can be detected by molecular methods. Thereby, mosquito excreta has been proposed as a sample type that could be utilized for arbovirus surveillance. In this study, we evaluated if West Nile virus (Kunjin strain, WNVKUN) RNA in Culex annulirostris Skuse (Diptera: Culicidae) excreta deposited on different substrates could be detected after storage for up to 2 wk at tropical conditions of high heat and humidity. No significant drop in relative quantity of WNVKUN RNA (determined by comparison of Ct values) in excreta deposited on Flinders Associate Technologies (FTA) cards was observed over 14 d, suggesting that RNA was stable for that time. There was no significant difference in relative quantity of WNVKUN RNA in excreta deposited on FTA cards or polycarbonate substrates after 24 h. However, after 7 and 14 d, there was a significant decline in the relative quantity of viral RNA in the excreta stored on polycarbonate substrates. For incorporation in arbovirus surveillance programs, we recommend the use of polycarbonate substrates for excreta collection in mosquito traps deployed overnight, and the integration of FTA cards in traps serviced weekly or fortnightly. Polycarbonate substrates facilitate the collection of the majority of excreta from a trap, and while FTA cards offer limited area coverage, they enable preservation of viral RNA in tropical conditions for extended periods of time.
Journal Article
Expanding considerations for treating avoidant/restrictive food intake disorder at a higher level of care
by
Ramirez, Ana L.
,
Richson, Brianne N.
,
Deville, Danielle C.
in
Analysis
,
ARFID
,
Attention deficit hyperactivity disorder
2024
Existing descriptions of the treatment of avoidant/restrictive food intake disorder (ARFID) at higher levels of care (HLOC) for eating disorders are limited, despite HLOC settings frequently serving patients with ARFID. The purpose of this commentary is to expand on the preliminary literature that describes pediatric ARFID treatment at HLOC by describing two specific components of our approach to treating pediatric ARFID that may not yet have traction in the current literature. Specifically, we highlight the utility of (1) treatment accommodations that appropriately account for patients’ neurodevelopmental needs (e.g., executive functioning, sensory processing) and (2) the adjunctive use of Dialectical Behavior Therapy (DBT) elements within family-based pediatric ARFID treatment. We also describe necessary future directions for research in these domains to clarify if incorporating these considerations and approaches into pediatric ARFID treatment at HLOC does indeed improve treatment outcomes.
Journal Article
Searching for the proverbial needle in a haystack: advances in mosquito-borne arbovirus surveillance
by
Ritchie, Scott A.
,
Ramírez, Ana L.
,
van den Hurk, Andrew F.
in
Aedes aegypti
,
Animals
,
Antibodies
2018
Surveillance is critical for the prevention and control of mosquito-borne arboviruses. Detection of elevated or emergent virus activity serves as a warning system to implement appropriate actions to reduce outbreaks. Traditionally, surveillance of arboviruses has relied on the detection of specific antibodies in sentinel animals and/or detection of viruses in pools of mosquitoes collected using a variety of sampling methods. These methods, although immensely useful, have limitations, including the need for a cold chain for sample transport, cross-reactivity between related viruses in serological assays, the requirement for specialized equipment or infrastructure, and overall expense. Advances have recently been made on developing new strategies for arbovirus surveillance. These strategies include sugar-based surveillance, whereby mosquitoes are collected in purpose-built traps and allowed to expectorate on nucleic acid preservation cards which are submitted for virus detection. New diagnostic approaches, such as next-generation sequencing, have the potential to expand the genetic information obtained from samples and aid in virus discovery. Here, we review the advancement of arbovirus surveillance systems over the past decade. Some of the novel approaches presented here have already been validated and are currently being integrated into surveillance programs. Other strategies are still at the experimental stage, and their feasibility in the field is yet to be evaluated.
Journal Article
Understanding Kerion Celsi in Children: Diagnosis and Therapeutic Guidelines Through an Algorithm
by
Shuchleib Cukiert, Mario
,
Figueroa Basurto, Carla I
,
Ramírez Terán, Ana L
in
Alopecia
,
Antifungal agents
,
Baldness
2024
Kerion celsi (KC), known as scalp ringworm, is the most common dermatophytosis in children. In Mexico, it ranks fourth among dermatophytoses, with a frequency of 4%-10%. KC is the inflammatory variety of tinea capitis (TC), with the most common causative agents being
and
We present the clinical case of a six-year-old male diagnosed with KC. Direct examination stained with chlorazol black and cultures were performed, yielding negative results. Histopathological study revealed spores and short hyphae within and surrounding the hair shaft. Treatment with itraconazole was initiated based on suspicion of
spp. from the trichoscopy findings. We propose a diagnostic and therapeutic algorithm for kerion celsi.
Journal Article
Human influenza A virus H1N1 in marine mammals in California, 2019
2023
From 2011–2018, we conducted surveillance in marine mammals along the California coast for influenza A virus (IAV), frequently detecting anti-influenza antibodies and intermittently detecting IAV. In spring 2019, this pattern changed. Despite no change in surveillance intensity, we detected IAV RNA in 10 samples in March and April, mostly in nasal and rectal swabs from northern elephant seals (
Mirounga angustirostris
). Although virus isolation was unsuccessful, IAV sequenced from one northern elephant seal nasal swab showed close genetic identity with pandemic H1N1 IAV subclade 6B.1A.1 that was concurrently circulating in humans in the 2018/19 influenza season. This represents the first report of human A(H1N1)pdm09 IAV in northern elephant seals since 2010, suggesting IAV continues to spill over from humans to pinnipeds.
Journal Article
Development and Field Evaluation of a System to Collect Mosquito Excreta for the Detection of Arboviruses
2019
Mosquito-borne diseases are a major public health concern globally and early detection of pathogens is critical to implement vector management and control strategies. Existing methods for pathogen detection include screening sentinel animals for antibodies and analyzing mosquitoes for pathogen presence. While these methods are effective, they are also expensive, labor-intense, and logistically challenging. To address these limitations, a new method was developed whereby mosquito saliva is collected on honey-coated nucleic acid preservation cards which are analyzed by molecular assays for detection of pathogens. However, mosquitoes only expel small amounts of saliva when feeding on these cards, potentially leading to false negatives. Another bodily fluid that is expelled by mosquitoes in larger volumes than saliva is excreta, and recent laboratory experiments have demonstrated that a range of mosquito-borne pathogens can be detected in mosquito excreta. In the current study, we have modified light and passive mosquito traps to collect their excreta and assessed their efficacy in field evaluations. From these field-collections, we detected West Nile, Ross River, and Murray Valley encephalitis viruses. Our findings suggest that mosquito traps are easily modified to collect excreta and, that this system has the potential to enhance detection of pathogens.
Journal Article
Mosquito excreta: A sample type with many potential applications for the investigation of Ross River virus and West Nile virus ecology
by
Hewitson, Glen R.
,
McMahon, Jamie L.
,
Ritchie, Scott A.
in
Animals
,
Biology and Life Sciences
,
Culicidae - virology
2018
Emerging and re-emerging arthropod-borne viruses (arboviruses) cause human and animal disease globally. Field and laboratory investigation of mosquito-borne arboviruses requires analysis of mosquito samples, either individually, in pools, or a body component, or secretion such as saliva. We assessed the applicability of mosquito excreta as a sample type that could be utilized during studies of Ross River and West Nile viruses, which could be applied to the study of other arboviruses.
Mosquitoes were fed separate blood meals spiked with Ross River virus and West Nile virus. Excreta was collected daily by swabbing the bottom of containers containing batches and individual mosquitoes at different time points. The samples were analyzed by real-time RT-PCR or cell culture enzyme immunoassay. Viral RNA in excreta from batches of mosquitoes was detected continuously from day 2 to day 15 post feeding. Viral RNA was detected in excreta from at least one individual mosquito at all timepoints, with 64% and 27% of samples positive for RRV and WNV, respectively. Excretion of viral RNA was correlated with viral dissemination in the mosquito. The proportion of positive excreta samples was higher than the proportion of positive saliva samples, suggesting that excreta offers an attractive sample for analysis and could be used as an indicator of potential transmission. Importantly, only low levels of infectious virus were detected by cell culture, suggesting a relatively low risk to personnel handling mosquito excreta.
Mosquito excreta is easily collected and provides a simple and efficient method for assessing viral dissemination, with applications ranging from vector competence experiments to complementing sugar-based arbovirus surveillance in the field, or potentially as a sample system for virus discovery.
Journal Article
Infection, Dissemination, and Replication of Urban and Sylvatic Strains of Dengue Virus Type 2 (Flaviviridae: Flavivirus) in Australian Aedes aegypti (Diptera: Culicidae)
by
Barcelon, Jean
,
Ramirez, Ana L.
,
McMahon, Jamie
in
Aedes aegypti
,
Aquatic insects
,
Australian Aedes aegypti
2021
The dengue viruses (DENVs) occur throughout tropical and subtropical regions of the world where they infect 100s of millions of people annually. In Australia, the dengue receptive zone is confined to the northern state of Queensland where the principal vector Aedes aegypti (L.) is present. In the current study, two populations of Ae. aegypti from north Queensland were exposed to two urban outbreak strains and one sylvatic strain of dengue virus type 2 (DENV-2). The titer of virus required to infect 50% of mosquitoes was between 105 and 106 50% tissue culture infectious dose (TCID)50/ml and was influenced by the combination of the origin of Ae. aegypti population and virus strain. When exposed to infectious bloodmeal titers > 106TCID50/ml, infection and dissemination rates were all > 50% and were significantly affected by the origin of the mosquito population but not by the strain of DENV-2. Replication of DENV-2 was also significantly affected by the mosquito population and the titer of the infectious bloodmeal that mosquitoes were exposed to. The results of this study are discussed in the context of DENV transmission dynamics in northern Australia and the relative fitness of the sylvatic virus strain in urban Ae. aegypti populations.
Journal Article