Publications by authors named "Andrew Letizia"

Tick-borne encephalitis virus (TBEV) causes neurological disease in humans, with varied clinical severity influenced by the viral subtype. TBEV is endemic to Mongolia, where both Siberian and Far-Eastern subtypes are present. is considered the main vector of TBEV in Mongolia; although, the virus has also been detected in species.

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We performed nanopore-based metagenomic screening on 885 ticks collected from 6 locations in Mongolia and divided the results into 68 samples: 23 individual samples and 45 pools of 2-12 tick samples each. We detected bacterial and parasitic pathogens Anaplasma ovis, Babesia microti, Coxiella burnetii, Borrelia miyamotoi, Francisella tularensis subsp. holarctica and novicida, Spiroplasma ixodetis, Theileria equi, and Rickettsia spp.

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Background: Long-term SARS-CoV-2 adverse health outcomes are of significant concern, especially among young adults with the potential for the greatest long-term morbidity. We sought to assess and characterize these outcomes in a cohort of Marines.

Methods: We used a cohort of US Marines from a previous longitudinal, prospective observational study of acute SARS-CoV-2, most of whom were enrolled prior to infection.

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  • Mycoplasma genitalium (MG) is an increasingly recognized sexually transmitted infection (STI) in Ghana, linked to conditions like urethritis and cervicitis, with noted antibiotic resistance to common treatments.
  • This study analyzed over 1,000 patient samples from 2012 to 2020 for MG and found infection rates of 3.1% to 3.4%, with one sample showing macrolide resistance mutations.
  • Despite MG's prevalence, it showed no significant correlation with various demographic factors or other STIs, highlighting the need for further research to understand resistance trends and improve treatment strategies.
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The epigenome influences gene regulation and phenotypes in response to exposures. Epigenome assessment can determine exposure history aiding in diagnosis. Here we developed and implemented a machine learning algorithm, the exposure signature discovery algorithm (ESDA), to identify the most important features present in multiple epigenomic and transcriptomic datasets to produce an integrated exposure signature (ES).

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Background: Surveillance of SARS-CoV-2 circulation is mainly based on real-time reverse transcription-polymerase chain reaction, which requires laboratory facilities and cold chain for sample transportation. This is difficult to achieve in remote rural areas of resource-limited settings. The use of dried blood spots shipped at room temperature has shown good efficiency for the detection of arboviral RNA.

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  • Sepsis is a critical global health issue, and current clinical trials haven't found effective treatments due to the variability in how sepsis manifests in patients.
  • Researchers conducted RNA sequencing on blood samples from 494 sepsis patients across different regions to better understand the disease.
  • They identified four distinct sepsis subtypes linked to different mortality rates, with insights that could help develop targeted therapies and predictive biomarkers for patient outcomes.
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  • Our limited understanding of sepsis mechanisms hinders effective treatment and trial design, especially in low- and middle-income countries with high sepsis rates.
  • This study uses RNA sequencing of blood samples from Ghana to analyze the host's response to sepsis over time.
  • Findings reveal unique gene expression patterns linked to immune responses, which could help in developing targeted interventions to improve sepsis outcomes.
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Background: COVID-19 remains a global public health challenge due to new immune-evasive SARS-CoV-2 variants and heterogeneous immunity.

Methods: In this cross-sectional study, we evaluated the adaptive immune responses in US active duty personnel who completed a COVID-19 primary vaccine series and had heterogenous SARS-CoV-2 vaccination and infection histories to 3 previously dominant variants (ancestral, Delta, BA.5) and 3 circulating variants (XBB.

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Background: Zoonotic and symptomatic and asymptomatic infections occur across endemic areas of Southeast Asia. Most infections are low-parasitemia, with an unknown proportion below routine microscopy detection thresholds. Molecular surveillance tools optimizing the limit of detection (LOD) would allow more accurate estimates of zoonotic malaria prevalence.

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Ticks are important disease vectors affecting animal health and causing substantial economic loss, especially in the tropics and subtropics. To examine the tick burden of cattle and associated risk factors for tick infestation, ticks were collected from 388 cattle within five regions in Ghana. Most of the cattle were males (50.

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Background: Despite its global significance, challenges associated with understanding the epidemiology and accurately detecting, measuring, and characterizing the true burden of seasonal influenza remain in many resource-poor settings.

Methods: A prospective observational study was conducted in Cambodia at 28 health facilities between 2007 and 2020 utilizing passive surveillance data of patients presenting with acute undifferentiated febrile illness (AUFI) to describe the prevalence of influenza A and B and characterize associated risk factors and symptoms using a questionnaire. A comparison of rapid influenza diagnostic tests (RIDTs) and real-time reverse transcription polymerase chain reaction (rRT-PCR) results was also conducted.

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Mosquito-borne diseases pose a significant threat in many Southeast Asian countries, particularly through the sylvatic cycle, which has a wildlife reservoir in forests and rural areas. Studying the composition and diversity of vectors and pathogen transmission is especially challenging in forests and rural areas due to their remoteness, limited accessibility, lack of power, and underdeveloped infrastructure. This study is based on the WHO mosquito sampling protocol, modifies technical details to support mosquito collection in difficult-to-access and resource-limited areas.

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  • The study highlights the risk of infection from tick-borne diseases, particularly for people in Ghana, including military personnel and livestock, which serve as hosts for pathogens.
  • Researchers identified and analyzed a total of 1,493 adult ticks from three genera and discovered a significant presence (56.9%) of Rickettsia species using molecular techniques.
  • The first molecular detection of Rickettsia aeschlimannii and Rickettsia africae in these ticks was reported, indicating a pressing need for control measures to mitigate human infections in Ghana and further research into their clinical impact.
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Background: Unregulated and inappropriate antimicrobial use are major contributors to the evolution of antimicrobial resistance worldwide. It is important to monitor and collect data on the use of antibiotics at health facilities and in the general population in order to support antimicrobial stewardship programs.

Methods: As part of a gonorrhea surveillance study that was conducted from June 2012 to Jan 2018, we administered a questionnaire to elicit information on the types of antimicrobials used by individuals to treat symptoms of a gonorrhea infection prior to presenting at five health facilities in Southern Ghana.

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Vaccination with the primary two-dose series of SARS-CoV-2 mRNA protects against infection with the ancestral strain, and limits the presentation of severe disease after re-infection by multiple variants of concern (VOC), including Omicron, despite the lack of a strong neutralizing response to these variants. We compared antibody responses in serum samples collected from mRNA-1273 (Moderna) vaccinated subjects to identify mechanisms of immune escape and cross-protection. Using pseudovirus constructs containing domain-specific amino acid changes representative of Omicron BA.

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Resolving chromatin-remodeling-linked gene expression changes at cell-type resolution is important for understanding disease states. Here we describe MAGICAL (Multiome Accessibility Gene Integration Calling and Looping), a hierarchical Bayesian approach that leverages paired single-cell RNA sequencing and single-cell transposase-accessible chromatin sequencing from different conditions to map disease-associated transcription factors, chromatin sites, and genes as regulatory circuits. By simultaneously modeling signal variation across cells and conditions in both omics data types, MAGICAL achieved high accuracy on circuit inference.

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Background: Lipids may influence cellular penetrance by viral pathogens and the immune response that they evoke. We deeply phenotyped the lipidomic response to SARs-CoV-2 and compared that with infection with other pathogens in patients admitted with acute respiratory distress syndrome to an intensive care unit (ICU).

Methods: Mass spectrometry was used to characterise lipids and relate them to proteins, peripheral cell immunotypes and disease severity.

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  • Dengue fever is becoming a significant global health issue, with sporadic cases reported in Cameroon over the past few decades, prompting a study on the genetic profile of DENV-1 strains from this region.
  • Researchers conducted genomic analyses using phylogenetic methods to trace the outbreak's origin, revealing the Cameroonian strains are closely related to a 2012 strain from Gabon and estimate their most recent common ancestor dates back to around 2008.
  • Comparing the new strains to existing vaccines showed notable amino acid differences, indicating potential challenges for immunotherapy and vaccine effectiveness, necessitating continued monitoring and further research into therapeutic options for DENV in Africa.
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Malaria remains the leading cause of acute febrile illness (AFI) in Africa despite successful control measures and programs. Acute febrile illnesses can be misdiagnosed as malaria as a result of the overlapping spectrum of nonspecific symptoms or may not be pursued because of limited diagnostic capabilities. This study investigated potential etiologies of AFIs in Ghana and determined the relationship between coinfection between malaria and Q fever, leptospirosis, and culturable bacteria in febrile patients.

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This study tested the hypothesis that high frequencies of natural killer (NK) cells are protective against symptomatic SARS-CoV-2 infection. Samples were utilized from the COVID-19 Health Action Response for Marines study, a prospective, observational study of SARS-CoV-2 infection in which participants were enrolled prior to infection and then serially monitored for development of symptomatic or asymptomatic infection. Frequencies and phenotypes of NK cells (CD3CD14CD19CD56) were assessed by flow cytometry.

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  • Gonorrhoea is increasingly resistant to antibiotics, which poses a serious public health threat. A study in Ghana examines the genetic profiles of gonorrhoea strains to understand their resistance patterns.
  • Researchers utilized whole genome sequencing on 56 isolates, identifying 22 sequence types (STs) with high resistance levels to tetracycline, penicillin, and ciprofloxacin. Six novel STs were discovered, highlighting unique resistance profiles in Ghanaian strains.
  • The study found that most isolates carried genes for beta-lactam and tetracycline resistance, with a notable cefixime-resistant strain linked to widespread cephalosporin resistance, underscoring the urgent need to monitor and manage gonorrhoea treatment
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Lipids may influence cellular penetrance by pathogens and the immune response that they evoke. Here we find a broad based lipidomic storm driven predominantly by secretory (s) phospholipase A (sPLA ) dependent eicosanoid production occurs in patients with sepsis of viral and bacterial origin and relates to disease severity in COVID-19. Elevations in the cyclooxygenase (COX) products of arachidonic acid (AA), PGD and PGI , and the AA lipoxygenase (LOX) product, 12-HETE, and a reduction in the high abundance lipids, ChoE 18:3, LPC-O-16:0 and PC-O-30:0 exhibit relative specificity for COVID-19 amongst such patients, correlate with the inflammatory response and link to disease severity.

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Ticks and tick-borne diseases represent major threats to the public health of the Mongolian population, of which an estimated 26% live a traditional nomadic pastoralist lifestyle that puts them at increased risk for exposure. Ticks were collected by dragging and removal from livestock in Khentii, Selenge, Tuv, and Umnugovi aimags (provinces) during March-May 2020. Using next-generation sequencing (NGS) with confirmatory PCR and DNA sequencing, we sought to characterize the microbial species present in Dermacentor nuttalli (n = 98), Hyalomma asiaticum (n = 38), and Ixodes persulcatus (n = 72) tick pools.

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