Characteristics Of Influenza-like Illness Research Articles

A Population-Based Susceptible, Infected, Recovered Simulation Model of the Spread of Influenza-Like-Illness in the Homeless versus Non-Homeless Population

PurposeTo examine the prevalence and characteristics of influenza-like illness (ILI) related presentations among people experiencing homelessness compared to the general population as well as to use the Susceptible, Infected, Recovered (SIR) simulation model parameters β and γ to model infectious interactivity, recovery rate, and population-level basic reproduction number (R0). MethodsUsing administrative health data from emergency department (ED) visits in the province of Ontario, Canada from 2010 to 2017, an SIR model was used to calculate the R0 for ILI in both the general population and the population of homeless individuals. ResultsFrom 2010 to 2017, a total of 17,056 homeless and 85,553 non-homeless individuals presented with an ILI to an ED in Ontario. The estimated infectious interactivity (β) was lower while the recovery rate (γ) was longer for infected people experiencing homelessness. ConclusionsOur results suggest that infections of ILI will result in more secondary cases in the homeless population compared to the homed population. This evaluation of the dynamics of ILI spread in the homeless population provides insight into how illnesses such as COVID-19 may be much more infectious in this population compared to the homed population.

Co-circulation of influenza A(H1N1), A(H3N2), B(Yamagata) and B(Victoria) during the 2017−2018 influenza season in Zhejiang Province, China

Influenza is a major human respiratory pathogen. Due to the high levels of influenza-like illness (ILI) in Zhejiang, China, the control and prevention of influenza was challenging during the 2017-2018 season. To identify the clinical spectrum of illness related to influenza and characterise the circulating influenza virus strains during this period, the characteristics of ILI were studied. Viral sequencing and phylogenetic analyses were conducted to investigate the virus types, substitutions at the amino acid level and phylogenetic relationships between sequences. This study has shown that the 2017/18 influenza season was characterised by the co-circulation of influenza A (H1N1) pdm09, A (H3N2) and B viruses (both Yamagata and Victoria lineage). From week 36 of 2017 to week 12 of 2018, ILI cases accounted for 5.58% of the total number of outpatient and emergency patient visits at the surveillance sites. Several amino acid substitutions were detected. Vaccination mismatch may be a potential reason for the high percentage of ILI. Furthermore, it is likely that multiple viral introductions played a role in the endemic co-circulation of influenza in Zhejiang, China. More detailed information regarding the molecular epidemiology of influenza should be included in long-term influenza surveillance.

2641. The Characteristics of Influenza-Like Illness (ILI) Management in Japan

BackgroundInfluenza-like illness (ILI) is a common disease that imposes a severe disease burden at the population level. ILI management is important in view of population health, and Japan’s management is distinct from that in other countries, especially regarding diagnosis and treatment of seasonal influenza. This study’s main objective was to quantitatively assess ILI management in Japanese healthcare settings.MethodsIn February 2019, we conducted an online survey of 600 participants in 200 households concerning ILI and its management in Japan. Respondents reported ILI episodes they and/or their family members experienced during January 2019. The 12-Item Short-Form Health Survey, Version 2 (SF-12v2) was included in the questionnaire to estimate quality of life (QOL) lost through ILI, and quality-adjusted life years (QALYs) lost in that way. We analyzed participants’ healthcare-seeking behavior to clarify the characteristics of Japanese ambulatory care for ILI.ResultsOf the participants, 261 of 600 (43.5%) reported at least one episode of ILI during January 2019. Of these, 194 (75.5%) visited healthcare facilities and 167 (86.1%) visited facilities within 2 days of symptom onset. A rapid influenza diagnostic test (RIDT) was given to 169 of 191 (88.5%) and 101 patients received a diagnosis of influenza, rather than ILI. Antivirals were used to treat 92.2% of the influenza cases. The median values of QOL and QALYs lost during a symptomatic period of ILI were 0.67 (interquartile range: 0.60–0.79) and 0.0055 (interquartile range: 0.0040–0.0072), respectively.ConclusionIn Japan, most ILI patients visit healthcare facilities in the early phase of symptoms, and most physicians examine them using the RIDT. Most laboratory-diagnosed influenza cases are treated using antivirals. Future work should examine the relation between this early diagnosis and treatment practice, and the duration and severity of ILI symptoms. Disclosures All authors: No reported disclosures.

Clinical Characteristics of Parainfluenza Virus Infection among Healthy Subjects with Influenza-like Illness

Abstract Background Parainfluenza virus (PIV) is a chief cause of croup. Less is known about the role of PIV in causing influenza-like illness (ILI) among healthy adults and children. We evaluated clinical characteristics of PIV compared with influenza (flu) infection in healthy subjects diagnosed with ILI. Methods The Acute Respiratory Infection Consortium (ARIC) conducted an observational, longitudinal study of ILI at five US military treatment facilities from 2009 to 2016. Participants were otherwise healthy military members, retirees, and their dependents. Symptom data were captured prospectively on days 0, 3, and 7 by interview and patient diary. Nasopharyngeal specimens were collected for etiologic determination by multiplex assay (Diatherix Laboratories, LLC.) Severity scores were calculated for upper respiratory, lower respiratory, GI, composite and systemic symptoms Results PIV did not account for a large proportion of ILI in our population with 43/961(4.7%) PIV+ vs. 153/961(15.9%) that were flu+. Age < 5 years was associated with increased detection of PIV (10% in <5 years vs. 3.2% in 5–65 years, P < 0.01). Additionally, on multivariable analysis, the presence of a child aged <5 years in the household was associated with an increased risk of PIV detection (OR = 2.58; 95% CI:1.39, 4.80). Sex, geographic location, year of detection, race/ethnicity, smoking status and obesity were all unrelated to PIV detection. Codetections occurred in 8/43 (18.6%) subjects, but codetected viruses did not show any specific pattern, with 5 different viruses found. When comparing demographic characteristics of ILI caused by flu vs. PIV, the only difference was that flu+ subjects were more often ≥5 years (P < 0.01). Comparing symptom profile and severity of adults with PIV + ILI vs. flu+, we found no differences in the presence or severity of 20 symptoms, nor in severity scores for each of the 5 categories. Rates of hospitalization, antibiotic use, or duration of illness were also indistinguishable. Conclusion This is one of a few studies to detail the clinical characteristics of PIV presenting as ILI in healthy subjects. PIV is more often detected in young children with ILI. Although PIV was detected 25% as often as flu, it had an indistinguishable clinical course from influenza associated ILI in adults. Disclosures L. Malone, diatherix: Employee, Salary. E. Grigorenko, Diatherix Laboratories: Employee, Salary. D. Stalons, Diatherix Laboratories: Employee, Salary.

Etiology and clinical characteristics of influenza-like illness in healthy adults by hospitalization status

BackgroundViral respiratory infections are a common cause of hospitalization for younger, otherwise-healthy populations. In this study, we describe the epidemiology of influenza-like illness in non-elderly adults within the U.S. Military Health System (MHS) by pathogen and hospitalization status.MethodsThe Acute Respiratory Infection Consortium (ARIC) is a prospective cohort of patients with influenza-like illness within the MHS. Participants between 18 and 65 years of age were identified in outpatient settings between 2012 and 2017, and were excluded if pregnant, if reporting chronic cardiac, respiratory, renal, or neurologic disease, or if on long-term aspirin therapy. Demographics, nasopharyngeal swabs and symptom data were collected; swabs were tested for viral pathogens using a target-enriched multiplex PCR panel (TEM-PCRTM, Diatherix LLC). Data were analyzed to compare clinical features and risks for hospitalization.Results397 participants met inclusion criteria. 34 participants required hospitalization; 363 were outpatients. Median length of hospitalization was 2 days. A virus was identified in 58.4% of outpatients (OP) and 55.9% of inpatients (IP); coronaviruses (63/363), enteroviruses (50/363), and influenza A (73/363) predominated in OP, whereas influenza A predominated among IP (35.3%, 12/34). There were no significant differences between OP and IP in terms of age, gender, ethnicity, or tobacco use. IP were more likely to be obese (BMI ≥30, 43.3% vs. 20.5%, P = 0.004) and less likely to have received influenza vaccination (45.5% vs. 16.9%, P > 0.001). IP with influenza did not report more severe symptoms (chills, cough, sore throat, diarrhea, myalgia, or headache) on enrollment but were more likely to have fever (temperature ≥38.0⁰ C) than OP (92.9 vs. 57.1%, P = 0.014).ConclusionInfluenza A is the most frequently identified cause of hospitalization among healthy, non-elderly adults with viral respiratory infection. Although age and tobacco use may be risks for viral acquisition, they do not appear to increase the risk of hospitalization in infected patients. Non-obese BMI and influenza vaccination appear protective against hospitalization, even in a relatively healthy cohort.Disclosures L. Malone, Diatherix Laboratories: Employee, Salary; E. Grigorenko, Diatherix Laboratories: Employee, Salary; D. Stalons, Diatherix Laboratories: Employee, Salary

Predictors of influenza in the adult population during seasonal and A(H1N1)pdm09 pandemic influenza periods

We aimed to assess whether the characteristics of influenza-like illness (ILI) cases in the general population were similar during the seasonal and pandemic A(H1N1)pdm09 influenza periods. We conducted a study using a general population database, which included demographic (sex, age) and clinical (underlying medical conditions, influenza vaccination status) information on more than 80 000 subjects. We assessed the most important predictors of ILI during each season by using multiple logistic regression. We descriptively compared whether they were similar during different seasons. The model, including all demographic and clinical characteristics, showed that age ⩾60 years decreased the odds for ILI by 52% and 81% during the seasonal and A(H1N1)pdm09 pandemic periods, respectively. Being vaccinated decreased the odds of ILI for seasonal influenza by 32%, while suffering from the comorbidities other than lung or cardiovascular diseases doubled the odds of ILI during the A(H1N1)pdm09 pandemic.