Outbreak Settings Research Articles

Characterization and analytical validation of a new antigenic rapid diagnostic test for Ebola virus disease detection.

Hemorrhagic fever outbreaks are difficult to diagnose and control in part because of a lack of low-cost and easily accessible diagnostic structures in countries where etiologic agents are present. Furthermore, initial clinical symptoms are common and shared with other endemic diseases such as malaria or typhoid fever. Current molecular diagnostic methods such as polymerase chain reaction require trained personnel and laboratory infrastructure, hindering diagnostics at the point of need, particularly in outbreak settings. Therefore, rapid diagnostic tests such as lateral flow can be broadly deployed and are typically well-suited to rapidly diagnose hemorrhagic fever viruses, such as Ebola virus. Early detection and control of Ebola outbreaks require simple, easy-to-use assays that can detect very low amount of virus in blood. Here, we developed and characterized an immunoassay test based on immunochromatography coupled to silver amplification technology to detect the secreted glycoprotein of EBOV. The glycoprotein is among the first viral proteins to be detected in blood. This strategy aims at identifying infected patients early following onset of symptoms by detecting low amount of sGP protein in blood samples. The limit of detection achieved by this sGP-targeted kit is 2.2 x 104 genome copies/ml in plasma as assayed in a monkey analytical cohort. Clinical performance evaluation showed a specificity of 100% and a sensitivity of 85.7% when evaluated with plasma samples from healthy controls and patients infected with Zaire Ebola virus from Macenta, Guinea. This rapid and accurate diagnostic test could therefore be used in endemic countries for early detection of infected individuals in point of care settings. Moreover, it could also support efficient clinical triage in hospitals or clinical centers and thus reducing transmission rates to prevent and better manage future severe outbreaks.

Recurrent tuberculosis in patients infected with the predominant Mycobacterium tuberculosis outbreak strain in Denmark. New insights gained through whole genome sequencing

ObjectivesRecurrent tuberculosis (TB) is defined by more than one TB episode per patient and is caused by reinfection with a new M. tuberculosis (Mtb) strain or relapse with the previous strain. In Denmark, a major TB outbreak caused by one specific Mtb genotype “DKC2” is ongoing. Of the 892 patients infected with DKC2 between 1992 and 2014, 32 had recurrent TB with 67 TB episodes in total. MethodsThe 32 cases were evaluated in terms of number of single-nucleotide polymorphism (SNP) differences and time between episodes derived from whole-genome sequencing data. ResultsFor four TB cases, the subsequent episodes could be confirmed as relapse and for one case as reinfection. Eight cases with SNP differences <6, theoretically indicating relapse, could be classified as likely reinfections based on phylogenetic analysis in combination with geographical data. Subsequent TB episodes for the remaining 19 cases could not be classified as relapse or reinfection even though they all had a SNP difference of <6 SNPs. ConclusionsIn newer studies, investigating recurrent TB with the use of WGS, the number of SNPs has been used to distinguish between relapse and reinfection. The algorithm proposed for this is not valid in the Danish TB outbreak setting as our findings challenge the interpretation of few SNP differences as representing relapse. However, when including phylogenetic analysis and geographical data in the analysis, classification of 13 of the 32 cases were possible.

An evaluation of the clinical features of measles virus infection for diagnosis in children within a limited resources setting

BackgroundMeasles is a recurrent health problem in both advanced and developed countries. The World Health Organization (WHO) recommends anti-measles immunoglobulin M (Ig M) as the standard method of detecting the virus; however, many areas still present the inability to perform a serology test of anti-measles IgM. Therefore, a typical clinical feature is necessary to establish the diagnosis of measles. The objective of this study was to evaluate hyperpigmented rash and other clinical features as the diagnostic tools with respect to measles, especially in an outbreak setting.MethodsIn this observational diagnostic study, the inclusion criteria were as follows: between 6 and 144 months of age, fever, maculopapular rash for 3 days or more, accompanied by a cough, or coryza, or conjunctivitis. Those with a prior history of measles vaccination (1–6 weeks) were excluded, in addition to those with histories of corticosteroid for 2 weeks or more and immunocompromised conditions. The samples were taken from Dr. Soetomo General Academic Hospital in Surabaya, Indonesia. We evaluated the sensitivity, specificity, the positive predictive value, and the negative predictive value of such clinical features. Hyperpigmented rash was validated using Kappa and Mc Nemar tests. Anti-measles Ig M was considered as the gold standard.ResultsThis study gathered 82 participants. The clinical manifestations of all subjects included fever, cough, coryza, conjunctivitis, Koplik spots, and maculopapular rash (which turns into hyperpigmented rash along the course of the illness). Most maculopapular rashes turn out to be hyperpigmented (89%). Sensitivity, specificity, positive predictive value, and negative predictive values ​​of the combination of fever, maculopapular rash, and hyperpigmented rash were found to be at 90.7, 28.6, 93.2, and 22.2%, respectively. The Mc Nemar and Kappa tests showed p values of 0.774 and 0.119, respectively.ConclusionThe combination of fever, maculopapular rash, and hyperpigmented rash can be used as a screening tool regarding measles infection in an outbreak setting, which can then be confirmed by anti-measles Ig M. Cough, coryza, and Koplik’s spot can be added to this combination, albeit with a slight reduction of sensitivity value.

High Prevalence of SARS-CoV-2 Antibodies in Care Homes Affected by COVID-19; Prospective Cohort Study, England

Background: We investigated six London care homes experiencing a COVID-19 outbreak and found very high rates of SARS-CoV-2 infection among residents and staff. Here we report follow-up investigations including antibody testing in the same care homes five weeks later.Methods: Residents and staff involved in the initial investigation had a repeat nasal swab for SARS-CoV-2 RT-PCR and a blood test for SARS CoV-2 antibodies using ELISA based on SARS-CoV-2 native viral antigens derived from infected cells and virus neutralisation.Findings: Of the 518 residents and staff in the initial investigation, 208/241 (86.3%) surviving residents and 186/254 (73.2%) staff underwent repeat testing. Almost all SARS-CoV-2 RT-PCR positive residents and staff were also antibody positive five weeks later, whether symptomatic (residents 35/35, 100%; staff, 22/22, 100%) or asymptomatic (residents 32/33, 97.0%; staff 21/22, 95.1%). Symptomatic but SARS-CoV-2 RT-PCR negative residents and staff also had high seropositivity rates (residents 23/27, 85.2%; staff 18/21, 85.7%) as did asymptomatic RT-PCR negative individuals (residents 62/92, 67.3%; staff 95/143, 66.4%). Neutralising antibody was present in 118/132 (89.4%) seropositive individuals and was not associated with age or symptoms. Ten residents (10/108, 9.3%) remained RT-PCR positive but with lower RT-PCR cycle threshold values; all 7 tested were seropositive. New infections were detected in three residents and one staff.Interpretation: RT PCR provides a point prevalence of SARS-CoV-2 infection but significantly underestimates total exposure in outbreak settings. In care homes experiencing large COVID-19 outbreaks, most residents and staff had neutralising SARS-CoV-2 antibodies, which was not associated with age or symptoms.Funding: NoneDeclaration of Interests: None.Ethics Approval Statement: The research protocol was approved by the PHE Research Ethics and Governance Group (REGG Ref: NR0204, 07 May 2020).

How Should the WHO Guide Access and Benefit Sharing During Infectious Disease Outbreaks?

In response to the 2013-2016 Ebola virus disease (EVD) outbreak primarily affecting Guinea, Sierra Leone, and Liberia, the World Health Organization (WHO) set out Guidance for Managing Ethical Issues in Infectious Disease Outbreaks, which covered social distancing, research in outbreak settings, and clinical care. This article assesses the Guidance's recommendations on research and long-term storage of biological specimens during infectious disease outbreaks and argues that the Guidance does not provide adequate direction for responders', researchers', and organizations' actions. It considers local persons' access to benefits of research in the aftermath of outbreaks and preparedness for outbreaks, drawing on lessons from both the 2013-2016 EVD outbreak and ongoing research in the Democratic Republic of the Congo.

Post-infectious neurological disorders.

A multitude of environmental factors can result in breakdown of immune tolerance in susceptible hosts. Infectious pathogens are among the most important environmental triggers in the pathogenesis of autoimmunity. Certain autoimmune disorders have a strong association with specific infections. Several neurological autoimmune disorders are thought to occur through post-infectious mechanisms. In this review, we discuss the proposed mechanisms underlying pathogen-induced autoimmunity, and highlight the clinical presentation and treatment of several post-infectious autoimmune neurological disorders. We also highlight post-infectious neurological disorders in the setting of recent outbreaks.

The Importance of Prioritizing Pre and Posttransplant Immunizations in an Era of Vaccine Refusal and Epidemic Outbreaks.

Vaccine-preventable infections are occurring at epidemic rates both nationally and internationally. At the same time, rates of vaccine hesitancy and refusal are increasing across the country leading to decreased herd immunity. For immunosuppressed transplant recipients, this situation poses great risk. Currently, 1 in 6 pediatric solid organ transplant recipients is hospitalized with a vaccine-preventable infection in the first 5 years posttransplant. For many recipients, these infections result in significant morbidity, mortality, and increased hospitalization costs. Surprisingly, despite this risk many transplant recipients are not up-to-date on age appropriate immunizations at the time of transplant and thereafter. As a transplant community, we must prioritize immunizations in both pre and posttransplant care. Research is needed to understand how to monitor immune response to vaccines in immunosuppressed patients and when to optimally immunize patients posttransplant. Finally, recommendations about administration of live vaccines posttransplant may need to be reevaluated in the setting of measles outbreaks and decreased herd immunity.

The Joint Mobile Emerging Disease Clinical Capability (JMEDICC) laboratory approach: Capabilities for high-consequence pathogen clinical research.

Following the 2013–2016 Ebola virus outbreak in West Africa, numerous groups advocated for the importance of executing clinical trials in outbreak settings. The difficulties associated with obtaining reliable data to support regulatory approval of investigational vaccines and therapeutics during that outbreak were a disappointment on a research and product development level, as well as on a humanitarian level. In response to lessons learned from the outbreak, the United States Department of Defense established a multi-institute project called the Joint Mobile Emerging Disease Intervention Clinical Capability (JMEDICC). JMEDICC’s primary objective is to establish the technical capability in western Uganda to execute clinical trials during outbreaks of high-consequence pathogens such as the Ebola virus. A critical component of clinical trial execution is the establishment of laboratory operations. Technical, logistical, and political challenges complicate laboratory operations, and these challenges have been mitigated by JMEDICC to enable readiness for laboratory outbreak response operations.

Event-based surveillance at health facility and community level in low-income and middle-income countries: a systematic review

BackgroundThe International Health Regulations require member states to establish “capacity to detect, assess, notify and report events”. Event-based surveillance (EBS) can contribute to rapid detection of acute public health events....

2788. Case Report: Severe Community-Acquired Human Adenovirus 7 Infection in a Mother and Son

BackgroundWe present the case of a 42-year-old male (Patient 1) with a history of morbid obesity and cirrhosis of unclear etiology who died of acute hypoxic respiratory failure and devastating encephalitis after community-acquired infection with human adenovirus 7 (HAdV7) in spite of antiviral treatment with Cidofovir. Patient 1’s course is outlined in Figure 1. During his stay, the patient’s mother (Patient 2) was also hospitalized in the same unit following a similar presentation with 10 days of flu-like symptoms that progressed to ARDS requiring intubation. Patient 2 recovered from her infection with no specific antiviral treatment.MethodsN/A.ResultsThese cases illustrate particularly fulminant presentations of HAdV7 infection and highlight the high pathogenicity of HAdV7 compared with other adenovirus subtypes. Severe lower respiratory tract HAdV7 infections have been reported most commonly as outbreaks of respiratory illness among military recruits and infants. A notable recent outbreak of HAdV-7d in New Jersey in 2016–2017 resulted in 12 confirmed cases with 4 deaths; however, all deaths occurred in patients with significant medical comorbidities.1 In a case particularly striking for its similarity to the one presented here, a healthy 44-year-old male along with his 68-year-old father were hospitalized with human adenovirus 7 days infection in Chicago in December 2014, with the son requiring ECMO for ARDS and the father briefly requiring ICU-level care.2ConclusionWhile our patient’s case is by no means unprecedented, it does represent an uncommon and potentially serious infection that points to need for continuing nosocomial testing efforts and deserves special attention in outbreak settings. In the future, perhaps use of the extant vaccine for human adenovirus serotypes 4 and 7 (currently licensed for military personnel3) could be expanded for use in civilian populations could be explored and potentially expanded for use in outbreak settings. Disclosures All authors: No reported disclosures.

Toward Control? The Prospects and Challenges of Typhoid Conjugate Vaccine Introduction.

With a newly World Health Organization (WHO)–prequalified typhoid conjugate vaccine (TCV), Gavi funding for eligible countries, and a WHO policy recommendation for TCV use, now is the time for countries to introduce TCVs as part of an integrated typhoid control program, particularly in light of the increasing burden of antimicrobial resistance. Continued vaccine development efforts will lead to secure supply of low-cost vaccines, and ongoing vaccine studies will provide critical vaccine performance data and inform optimal deployment strategies, in both routine use and in outbreak settings. TCV programs should include thoughtful communication planning and community engagement to counter vaccine hesitancy.

Spotting sporotrichosis skin infection: The first Australian paediatric case series.

Sporotrichosis is a dermatomycosis caused by the dimorphic fungus, Sporothrix schenckii, with various outbreaks across Australia attributed to mouldy hay. Our objective was to investigate the clinical presentation and management of cutaneous sporotrichosis in a paediatric population of Western Australia. A retrospective case review was performed for S. schenckii infections in children below 18 years, between January 2000 and November 2017. Cases were identified from the state-wide laboratory database and additional clinical data obtained from medical records. Thirty-two cases of microbiologically proven S. schenckii infection were identified, mostly from rural areas (n = 20, 63%). Complete clinical data were available for 11 cases (34%). The most common risk factors were exposure to farm animals and hay, arthropod bites and outdoor activities. The median duration from symptom onset to correct diagnosis was 6 weeks (interquartile range: 4-7 weeks). Most cases were initially treated with multiple, broad-spectrum antibacterial agents (n = 7, 64%). Targeted therapy (itraconazole) was used in all cases once the diagnosis was made, with a median treatment duration of 5 months (interquartile range: 4-6 months). Morbidity included scarring (n = 4, 31%), itraconazole associated diarrhoea (n = 1, 8%) and mild hepatotoxicity (n = 1, 8%). Summarising the clinical experience of these cases is a useful guide for clinical recognition and may serve to shorten the interval between onset and diagnosis, and avoid the need for antibacterial therapy. These data highlight the importance of recognising Sporotrichosis in children outside an outbreak setting, leading to timely diagnosis and appropriate treatment with antifungal agents.

Measles-associated pneumonia and hepatitis during the measles outbreak of 2018.

Background Between 2017 and 2018, Greece experienced a measles outbreak, affecting >3000 patients, most of which were unvaccinated. Measles-associated pneumonia (MAP) is the most common serious compilation of the disease, but very few recent reports regarding its presentation are available. Materials and Methods Between January and May 2018, 11 adult patients presented to our department with acute measles virus infection, hypoxia and findings on chest X-ray. Clinical, laboratory and radiological data were collected and assessed. Nine out of eleven patients had hypoxic respiratory failure. Other complications included hepatitis, cholestasis and myositis, which were observed in the majority of patients. All patients received supplementary oxygen administration, whereas five patients required continuous positive airway pressure ventilation. Scoring of the radiological examinations performed was most notable for the presence of reticular opacities and consolidations. Statistical analysis demonstrated a significant association between PaO2/FiO2 values and the presence of reticular opacities, with PaO2/FiO2 decreasing as the mean value of the reticular opacities score increased (P=.02). Conclusion To our knowledge, this is the first report demonstrating an association between PaO2/FiO2 values and the presence of reticular opacities in patients with MAP. MAP should be suspected in any patient presenting with acute onset hypoxaemia and a reticular pattern on radiological examination, especially in outbreak settings. What is known Measles infections are on the rise in Europe, with epidemics affecting several European countries, resulting from suboptimal immunisation. The most common serious complication of measles is pneumonia, which is more common in adult patients and can cause significant morbidity. It is the most common cause of death due to measles. What is new In this report, we present 11 adults with measles-associated pneumonia, who presented with the combination of acute measles virus infection, hypoxia and findings on chest X-ray. To our knowledge, this is the first report demonstrating an association between the severity of hypoxaemia and the presence of reticular opacities on chest imaging studies.

2479 Autoimmune Hepatitis Triggered by Hepatitis A: An Interesting Case and Review of Pathophysiology

INTRODUCTION: Autoimmune hepatitis (AIH) is an immune-mediated disorder of the liver, whose pathophysiology involves triggering of T-cell mediated events by environmental agents in the liver in a host genetically predisposed to this disease. One trigger described in literature has been the hepatitis A virus (HAV). Hence, occasionally cases which clinically appear to be that of relapsing HAV are in fact concealing underlying autoimmune hepatitis that has been provoked from the initial episode of HAV. We describe one such case. CASE DESCRIPTION/METHODS: A 45 year old Caucasian male with past medical history of chronic hepatitis C and acute hepatitis two months prior to admission was admitted for multifocal pneumonia. During his initial evaluation, the patient was found to have generalized jaundice, and laboratory evaluation revealed elevated transaminases with a hepatocellular pattern. He was initially thought to have reactivation of the hepatitis A, however non-improvement with conservative measures led to further serological testing, which revealed positive anti-smooth muscle antibody. Autoimmune hepatitis was confirmed by biopsy, and patient was started or oral steroids. The patient's clinical status and liver function improved significantly, and he was discharged with outpatient follow-up. DISCUSSION: It is hypothesized that environmental agents trigger T-cell–mediated events directed at liver antigens in a host genetically predisposed to AIH, leading to a progressive necro-inflammatory and fibrotic process in the liver. Studies have shown hepatotropic viruses including HAV to be associated with AIH. Defects in suppressor-inducer T lymphocytes specifically controlling immune responses to the asialoglycoprotein receptor may be the cause of susceptibility. It has also been shown that humoral immune responses to liver cell surface antigens are frequently provoked by hepatitis A and B viruses. Newer research is also exploring molecular mimicry between the infectious particle and the liver constituent as the mechanism, although specific data has not been discovered on HAV. In the setting of the recent outbreaks of HAV, such pathology may become more commonplace. It is important for a clinician to distinguish between relapses of HAV (documented to be between 3-20% of patients in the first 6 months) and onset of AIH, as treatment modalities and prognosis are vastly different. A high level of awareness of this pathology allows for its prompt recognition and the potential for successful treatment.

High performance of rapid influenza diagnostic test and variable effectiveness of influenza vaccines in Mexico

ObjectivesTo evaluate the performance of rapid influenza diagnostic tests (RIDT) and influenza vaccines’ effectiveness (VE) during an outbreak setting. MethodsWe compared the performance of a RIDT with RT-PCR for influenza virus detection in influenza-like illness (ILI) patients enrolled during the 2016/17 season in Mexico City. Using the test-negative design, we estimated influenza VE in all participants and stratified by age, virus subtype, and vaccine type (trivalent vs quadrivalent inactivated vaccines). The protective value of some clinical variables was evaluated by regression analyses. ResultsWe enrolled 592 patients. RT-PCR detected 93 cases of influenza A(H1N1)pdm09, 55 of AH3N2, 141 of B, and 13 A/B virus infections. RIDT showed 90.7% sensitivity and 95.7% specificity for influenza A virus detection, and 91.5% sensitivity and 95.3% specificity for influenza B virus detection. Overall VE was 33.2% (95% CI: 3.0–54.0; p = 0.02) against any laboratory-confirmed influenza infection. VE estimates against influenza B were higher for the quadrivalent vaccine. Immunization and occupational exposure were protective factors against influenza. ConclusionsThe RIDT was useful to detect influenza cases during an outbreak setting. Effectiveness of 2016/17 influenza vaccines administered in Mexico was low but significant. Our data should be considered for future local epidemiological policies.

Multicenter Clinical Validation of the Molecular BD Max Enteric Viral Panel for Detection of Enteric Pathogens.

The conventional methodology for gastrointestinal pathogen detection remains time-consuming, expensive, and of limited sensitivity. The objective of this study was to evaluate the performance of the BD Max enteric viral panel (Max EVP) assay for identification of viral pathogens in stool specimens from individuals with symptoms of acute gastroenteritis, enteritis, or colitis. Prospective and archival stool specimens from adult and pediatric patients with diarrhea were collected in Cary-Blair medium or unpreserved containers. The results for specimens tested by the Max EVP (on the BD Max platform) were compared to those obtained by the reference method (alternate PCR assays, followed by bidirectional sequencing). Positive percent agreement (PPA) and negative percent agreement (NPA) were calculated. A total of 2,239 specimens were collected, with 2,148 being included for analysis. In this population, 39.6% of specimens were from outpatients, 42.1% were from patients <21 years old, and 49.7% were from females. Prevalence rates for prospective specimens were 7.3%, 4.5%, 3.5%, 2.4%, and 1.2% for norovirus, sapovirus, astrovirus, rotavirus, and adenovirus, respectively. PPA was 92.8%, 84.9%, 93.0%, 100%, and 95.6%, for norovirus, sapovirus, astrovirus, rotavirus, and adenovirus, respectively. NPA was ≥99.4% for all targets. In conjunction with the clinical presentation, laboratory findings, and epidemiological information, the Max EVP assay is effective for the differential diagnosis of enteric disease caused by norovirus, sapovirus, astrovirus, rotavirus, and adenovirus. This assay can be used individually for patients at high risk for a viral enteropathogen (e.g., in outbreak settings) or as an adjunct to other enteric bacterial panels.

Clinical and Epidemiological Aspects of Diphtheria: A Systematic Review and Pooled Analysis.

Diphtheria, once a major cause of childhood morbidity and mortality, all but disappeared following introduction of diphtheria vaccine. Recent outbreaks highlight the risk diphtheria poses when civil unrest interrupts vaccination and healthcare access. Lack of interest over the last century resulted in knowledge gaps about diphtheria's epidemiology, transmission, and control. We conducted 9 distinct systematic reviews on PubMed and Scopus (March-May 2018). We pooled and analyzed extracted data to fill in these key knowledge gaps. We identified 6934 articles, reviewed 781 full texts, and included 266. From this, we estimate that the median incubation period is 1.4 days. On average, untreated cases are colonized for 18.5 days (95% credible interval [CrI], 17.7-19.4 days), and 95% clear Corynebacterium diphtheriae within 48 days (95% CrI, 46-51 days). Asymptomatic carriers cause 76% (95% confidence interval, 59%-87%) fewer cases over the course of infection than symptomatic cases. The basic reproductive number is 1.7-4.3. Receipt of 3 doses of diphtheria toxoid vaccine is 87% (95% CrI, 68%-97%) effective against symptomatic disease and reduces transmission by 60% (95% CrI, 51%-68%). Vaccinated individuals can become colonized and transmit; consequently, vaccination alone can only interrupt transmission in 28% of outbreak settings, making isolation and antibiotics essential. While antibiotics reduce the duration of infection, they must be paired with diphtheria antitoxin to limit morbidity. Appropriate tools to confront diphtheria exist; however, accurate understanding of the unique characteristics is crucial and lifesaving treatments must be made widely available. This comprehensive update provides clinical and public health guidance for diphtheria-specific preparedness and response.

Genetic Diversity of Sapoviruses among Inpatients in Germany, 2008-2018.

Sapovirus enteric disease affects people of all ages across the globe, in both sporadic cases and outbreak settings. Sapovirus is seldom assessed in Germany and its epidemiology in the country is essentially unknown. Thus, sapovirus occurrence and genetic diversity were studied by real-time reverse transcription polymerase chain reaction (RT-PCR) and partial sequencing of major viral structural protein (VP1) gene in two different sets of stool samples: (1) a selection of 342 diarrheal stools collected from inpatient children during 2008−2009, and (2) 5555 stool samples collected during 2010–2018 from inpatients of all age groups with gastrointestinal complaints. Results showed year-round circulation of sapoviruses, with peaks during cooler months. In total, 30 samples (8.8%) of the first and 112 samples of the second set of samples (2.0%) were sapovirus positive. Capsid gene sequencing was successful in 134/142 samples (94.4%) and showed circulation of all known human pathogenic genogroups. Genotype GI.1 predominated (31.8%), followed by GII.1 (16.7%), GII.3 (14.5%), GI.2 (13.8%) and GV.1 (12.3%). Additionally, minor circulation of GI.3, GI.6, GII.2, GII.4, GII.6 and GIV.1 was shown. Consequently, sapovirus diagnostics need broadly reactive RT-PCR protocols and should particularly be considered in infants and young children. Further studies from other sampling sites are essential to extend our knowledge on sapovirus epidemiology in Germany.

Use of ethylene-oxide gas sterilisation to terminate multidrug-resistant bacterial outbreaks linked to duodenoscopes

BackgroundCleaning and high-level disinfection have been the standard in the USA and other countries for reprocessing flexible endoscopes, including duodenoscopes and other types of gastrointestinal endoscopes. For decades, this practice...

A33 Using serological and surveillance data to infer the introduction date and unobserved transmission dynamics of Zika virus in Fiji 2013–7

Zika virus (ZIKV) has been circulating in the South Pacific since 2007, and transmission in Fiji was first confirmed in 2015. To better understand the history and transmission dynamics of ZIKV in Fiji, we combined a transmission dynamic model with serological and surveillance data from Central Division, Fiji. A longitudinal population representative of seroepidemiological data were available from participants sampled in 2013, 2015, and 2017. In addition, ZIKV case reports were available from 2015 and 2016. Using a Bayesian approach, we fitted a transmission dynamic model with a seasonally varying transmission to these data. We also estimated the virus introduction date, given the effect this has on transmission dynamics as it interacts with the observed seasonal pattern of transmission. We found evidence that the virus was introduced in October 2013 (95% credible interval: April 2013–April 2014) and that the strong seasonal transmission pattern meant the virus persisted for several years with multiple waves of infection in consecutive years. It is important to corroborate this evidence against other work done in the same area. A phylogenetic analysis was performed on 5 ZIKV strains obtained from Fiji in 2015 and 2016, which were aligned with 33 E gene sequences from the Pacific, Americas, and Africa. This analysis showed evidence of virus persistence over multiple years in Central Division, Fiji. The estimated most recent common ancestor of the group isolated from Central Division was November 2013 (95% credible interval: March 2013–July 2015). Our modeling estimate is consistent with these results despite the very different methods being used. The availability of detailed case and serology data in an island outbreak setting, combined with mathematical models, presented a unique opportunity to gain crucial insights into these infections. Our analysis provides evidence that seasonal variation in transmission, combined with other co-circulating flaviviruses, means the timing of ZIKV introduction can have a major impact on outbreak transmission dynamics.