Chadwick Y. Yasuda

United States Naval Research Laboratory

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Matthew R. Kasper

Defense Health Agency

Thomas F. Wierzba

Wake Forest University

Patrick J. Blair

Naval Health Research Center

Tomasz A. Łęski

United States Naval Research Laboratory

Shannon D. Putnam

Naval Health Research Center

Chris R. Taitt

United States Naval Research Laboratory

Joseph Lahai

United States Naval Research Laboratory

Umaru Bangura

Njala University

Rashid Ansumana

Njala University

Joseph M. Lamin

Njala University

Cooperative Institutions

Institut Pasteur du Cambodge

Cambodia-Oxford Medical Research Unit

Ministry of Health

Naval Medical Research Unit Six

Naval Medical Research Command

United States Naval Research Laboratory

National Institute of Public Health

Institut Pasteur

CHI Health Mercy Council Bluffs

Cooper Green Mercy Hospital

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Seroprevalence of hepatitis B surface antigen (HBsAg) in Bo, Sierra Leone, 2012–2013

BMC Research Notes (2018)

Rashid Ansumana Donald F. Dariano Kathryn H. Jacobsen Tomasz A. Łęski Joseph M. Lamin

The aim of this study was to determine the prevalence of hepatitis B surface antigen (HBsAg) among febrile individuals tested at Mercy Hospital Research Laboratory (MHRL) in Bo, Sierra Leone.A total of 860 febrile individuals ages 5 years and older were tested by MHRL between July 2012 and June 2013 with a Standard Diagnostics Bioline HBsAg rapid diagnostic test. The overall HBsAg prevalence rate was 13.7%, including a rate of 15.5% among males and 12.6% among females. The HBsAg rate did not differ by child or adult age group (p > 0.5). The prevalence rate in Bo was similar to the 11-15% HBsAg prevalence rates reported in the past decade from other studies across West Africa. Scaling up the infant hepatitis B vaccination program in Sierra Leone will be important for reducing the future burden of disease and premature death attributable to chronic viral hepatitis B disease.

Seroprevalence

Hepatitis B

10.1186/s13104-018-3218-8

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Citations (16)

Epidemiological characteristics, clinical presentation and diagnosis at point-of-care during the first wave of the H1N1 influenza pandemic in Cambodia.

PubMed (2012)

Chadwick Y. Yasuda Sovann Ly Matthew R. Kasper Maya Williams Thomas F. Wierzba

We conducted clinic-based surveillance for influenza virus among cases with acute febrile illness at 9 medical clinics in south-central Cambodia during 2006-2009. Patients greater than or equal to 24 months old presenting with acute fever (> 38 degrees C) were enrolled. In late July 2009, the study identified its first case of pandemic H1N1 (pH1N1) influenza virus infection. The prevalence of pH1N1 infections increased rapidly during August and September and by October, pH1N1 infections had peaked replacing H3N2 as the dominant subtype. The incidence of pH1N1 subsequently decreased, with only one case identified in late December. From late July through December 2009, 42.4% of all influenza cases were caused by pH1N1. Except for headache, less frequently reported among pH1N1-infected patients, patients infected with the pH1N1 reported symptoms (eg, cough, diarrhea, vomiting and nausea) similar to seasonal H3N2 and B virus infections. Among children 6 to 12 years old, there was a higher number of hospitalizations campared to other age groups. Identification of influenza virus types A and B using the QuickVue rapid diagnostic test was found to be equally sensitive for pH1N1 (50.4%), H3N2 (51.7%) and influenza B (53.9%) viruses, although the sensitivity was low among all subtypes. The pH1N1 virus rapidly became the dominant virus subtype in 2009 in Cambodia, but no symptoms consistently distinguished the pandemic strain from other influenza virus subtypes. The QuickVue test was as sensitive for detecting pH1N1 viral as well as other circulating seasonal influenza viruses.

Pandemic

Influenza-like illness

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Citations (2)

Evidence for avian H9N2 influenza virus infections among rural villagers in Cambodia

Journal of Infection and Public Health (2013)

Patrick J. Blair Shannon D. Putnam Whitney S. Krueger Channimol Chum Thomas F. Wierzba

10.1016/j.jiph.2012.11.005

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Citations (54)

Complete Genome Sequences of Five Zika Virus Isolates

Genome Announcements (2016)

Jason T. Ladner Michael R. Wiley Karla Prieto Chadwick Y. Yasuda Elyse R. Nagle

Zika virus is an emerging human pathogen of great concern due to putative links to microcephaly and Guillain-Barre syndrome. Here, we report the complete genomes, including the 5' and 3' untranslated regions, of five Zika virus isolates, one from the Asian lineage and four from the African lineage.

Zika Virus

Microcephaly

Lineage (genetic)

10.1128/genomea.00377-16

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Citations (43)

Multicountry Prospective Clinical Evaluation of Two Enzyme-Linked Immunosorbent Assays and Two Rapid Diagnostic Tests for Diagnosing Dengue Fever

Journal of Clinical Microbiology (2015)

Curtis G. Hayes Allison L. Dauner Andrea Valks Brett M. Forshey Kanya C. Long

ABSTRACT We evaluated four dengue diagnostic devices from Alere, including the SD Bioline Dengue Duo (nonstructural [NS] 1 Ag and IgG/IgM), the Panbio Dengue Duo Cassette (IgM/IgG) rapid diagnostic tests (RDTs), and the Panbio dengue IgM and IgG capture enzyme-linked immunosorbent assays (ELISAs) in a prospective, controlled, multicenter study in Peru, Venezuela, Cambodia, and the United States, using samples from 1,021 febrile individuals. Archived, well-characterized samples from an additional 135 febrile individuals from Thailand were also used. Reference testing was performed on all samples using an algorithm involving virus isolation, in-house IgM and IgG capture ELISAs, and plaque reduction neutralization tests (PRNT) to determine the infection status of the individual. The primary endpoints were the clinical sensitivities and specificities of these devices. The SD Bioline Dengue Duo had an overall sensitivity of 87.3% (95% confidence interval [CI], 84.1 to 90.2%) and specificity of 86.8% (95% CI, 83.9 to 89.3%) during the first 14 days post-symptom onset (p.s.o.). The Panbio Dengue Duo Cassette demonstrated a sensitivity of 92.1% (87.8 to 95.2%) and specificity of 62.2% (54.5 to 69.5%) during days 4 to 14 p.s.o. The Panbio IgM capture ELISA had a sensitivity of 87.6% (82.7 to 91.4%) and specificity of 88.1% (82.2 to 92.6%) during days 4 to 14 p.s.o. Finally, the Panbio IgG capture ELISA had a sensitivity of 69.6% (62.1 to 76.4%) and a specificity of 88.4% (82.6 to 92.8%) during days 4 to 14 p.s.o. for identification of secondary dengue infections. This multicountry prospective study resulted in reliable real-world performance data that will facilitate data-driven laboratory test choices for managing patient care during dengue outbreaks.

Immunoglobulin M

10.1128/jcm.03042-14

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Citations (53)

Little Evidence of Subclinical Avian Influenza Virus Infections among Rural Villagers in Cambodia

PLoS ONE (2014)

Gregory C. Gray Whitney S. Krueger Channimol Chum Shannon D. Putnam Thomas F. Wierzba

In 2008, 800 adults living within rural Kampong Cham Province, Cambodia were enrolled in a prospective cohort study of zoonotic influenza transmission. After enrollment, participants were contacted weekly for 24 months to identify acute influenza-like illnesses (ILI). Follow-up sera were collected at 12 and 24 months. A transmission substudy was also conducted among the family contacts of cohort members reporting ILI who were influenza A positive. Samples were assessed using serological or molecular techniques looking for evidence of infection with human and avian influenza viruses. Over 24 months, 438 ILI investigations among 284 cohort members were conducted. One cohort member was hospitalized with a H5N1 highly pathogenic avian influenza (HPAI) virus infection and withdrew from the study. Ninety-seven ILI cases (22.1%) were identified as influenza A virus infections by real-time RT-PCR; none yielded evidence for AIV. During the 2 years of follow-up, 21 participants (3.0%) had detectable antibody titers (≥1∶10) against the studied AIVs: 1 against an avian-like A/Migratory duck/Hong Kong/MPS180/2003(H4N6), 3 against an avian-like A/Teal/Hong Kong/w312/97(H6N1), 9 (3 of which had detectible antibody titers at both 12- and 24-month follow-up) against an avian-like A/Hong Kong/1073/1999(H9N2), 6 (1 detected at both 12- and 24-month follow-up) against an avian-like A/Duck/Memphis/546/74(H11N9), and 2 against an avian-like A/Duck/Alberta/60/76(H12N5). With the exception of the one hospitalized cohort member with H5N1 infection, no other symptomatic avian influenza infections were detected among the cohort. Serological evidence for subclinical infections was sparse with only one subject showing a 4-fold rise in microneutralization titer over time against AvH12N5. In summary, despite conducting this closely monitored cohort study in a region enzootic for H5N1 HPAI, we were unable to detect subclinical avian influenza infections, suggesting either that these infections are rare or that our assays are insensitive at detecting them.

Subclinical infection

Seroconversion

10.1371/journal.pone.0097097

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Citations (9)

Rapid-Test Based Identification of Influenza as an Etiology of Acute Febrile Illness in Cambodia

American Journal of Tropical Medicine and Hygiene (2011)

Matthew R. Kasper Shannon D. Putnam Sovann Ly Chadwick Y. Yasuda Patrick J. Blair

Influenza can be manifested as an acute febrile illness, with symptoms similar to many pathogens endemic to Cambodia. The objective of this study was to evaluate the Quickvue influenza A+B rapid test to identify the etiology of acute febrile illness in Cambodia. During December 2006–May 2008, patients enrolled in a study to identify the etiology of acute febrile illnesses were tested for influenza by real-time reverse transcriptase PCR (RT-PCR) and Quickvue influenza A+B rapid test. The prevalence of influenza was 19.7% by RT-PCR. Compared with RT-PCR, the sensitivity and specificity of the rapid test were 52.1% and 92.5%, respectively. The influenza rapid test identified the etiology in 10.2% of enrollees and ≥ 35% during peak times of influenza activity. This study suggests that rapid influenza tests may be useful during peak times of influenza activity in an area where several different etiologies can present as an acute febrile illness.

Etiology

Influenza-like illness

10.4269/ajtmh.2011.11-0390

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Citations (1)

Dynamic of H5N1 virus in Cambodia and emergence of a novel endemic sub-clade

Infection Genetics and Evolution (2012)

San Sorn Sok Touch Sovann Ly Sareth Rith Nguyen Tung

Lineage (genetic)

10.1016/j.meegid.2012.05.013

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Citations (26)

Prevalence of malaria resistance-associated mutations in Plasmodium falciparum circulating in 2017–2018, Bo, Sierra Leone

Frontiers in Microbiology (2022)

Tomasz A. Łęski Chris R. Taitt Sophie M. Colston Umaru Bangura Andrew Holtz

In spite of promising medical, sociological, and engineering strategies and interventions to reduce the burden of disease, malaria remains a source of significant morbidity and mortality, especially among children in sub-Saharan Africa. In particular, progress in the development and administration of chemotherapeutic agents is threatened by evolved resistance to most of the antimalarials currently in use, including artemisinins.This study analyzed the prevalence of mutations associated with antimalarial resistance in Plasmodium falciparum from 95 clinical samples collected from individuals with clinically confirmed malaria at a hospital in Bo, Sierra Leone between May 2017 and December 2018. The combination of polymerase chain reaction amplification and subsequent high throughput DNA sequencing was used to determine the presence of resistance-associated mutations in five P. falciparum genes - pfcrt, pfmdr1, pfdhfr, pfdhps and pfkelch13. The geographic origin of parasites was assigned using mitochondrial sequences.Relevant mutations were detected in the pfcrt (22%), pfmdr1 (>58%), pfdhfr (100%) and pfdhps (>80%) genes while no resistance-associated mutations were found in the pfkelch13 gene. The mitochondrial barcodes were consistent with a West African parasite origin with one exception indicating an isolate imported from East Africa.Detection of the pfmdr1 NFSND haplotype in 50% of the samples indicated the increasing prevalence of strains with elevated tolerance to artemeter + lumefantrine (AL) threatening the combination currently used to treat uncomplicated malaria in Sierra Leone. The frequency of mutations linked to resistance to antifolates suggests widespread resistance to the drug combination used for intermittent preventive treatment during pregnancy.

Dihydropteroate synthase

10.3389/fmicb.2022.1059695

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Citations (5)

Infectious Etiologies of Acute Febrile Illness among Patients Seeking Health Care in South-Central Cambodia

American Journal of Tropical Medicine and Hygiene (2012)

Matthew R. Kasper Patrick J. Blair Sok Touch Buth Sokhal Chadwick Y. Yasuda

The agents of human febrile illness can vary by region and country suggesting that diagnosis, treatment, and control programs need to be based on a methodical evaluation of area-specific etiologies. From December 2006 to December 2009, 9,997 individuals presenting with acute febrile illness at nine health care clinics in south-central Cambodia were enrolled in a study to elucidate the etiologies. Upon enrollment, respiratory specimens, whole blood, and serum were collected. Testing was performed for viral, bacterial, and parasitic pathogens. Etiologies were identified in 38.0% of patients. Influenza was the most frequent pathogen, followed by dengue, malaria, and bacterial pathogens isolated from blood culture. In addition, 3.5% of enrolled patients were infected with more than one pathogen. Our data provide the first systematic assessment of the etiologies of acute febrile illness in south-central Cambodia. Data from syndromic-based surveillance studies can help guide public health responses in developing nations.

Etiology

Influenza-like illness

10.4269/ajtmh.2012.11-0409

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Citations (113)