Incidence Of Influenza Infection Research Articles

Bleomycin-Induced Lung Injury Increases Resistance to Influenza Virus Infection in a Type I Interferon-Dependent Manner.

Acute lung injury (ALI) results in acute respiratory disease that causes fatal respiratory diseases; however, little is known about the incidence of influenza infection in ALI. Using a ALI-mouse model, we investigated the pro-inflammatory cytokine response to ALI and influenza infection. Mice treated with bleomycin (BLM), which induces ALI, were more resistant to influenza virus infection and exhibited higher levels of type I interferon (IFN-I) transcription during the early infection period than that in PBS-treated control mice. BLM-treated mice also exhibited a lower viral burden, reduced pro-inflammatory cytokine production, and neutrophil levels. In contrast, BLM-treated IFN-I receptor 1 (IFNAR1)-knockout mice failed to show this attenuated phenotype, indicating that IFN-I is key to the antiviral response in ALI-induced mice. The STING/TBK1/IRF3 pathway was found to be involved in IFN-I production and the establishment of an antiviral environment in the lung. The depletion of plasmacytoid dendritic cells (pDCs) reduced the effect of BLM treatment against influenza virus infection, suggesting that pDCs are the major source of IFN-I and are crucial for defense against viral infection in BLM-induced lung injury. Overall, this study showed that BLM-mediated ALI in mice induced the release of double-stranded DNA, which in turn potentiated IFN-I-dependent pulmonary viral resistance by activating the STING/TBK1/IRF3 pathway in association with pDCs.

Asymptomatic transmission and high community burden of seasonal influenza in an urban and a rural community in South Africa, 2017–18 (PHIRST): a population cohort study

SummaryBackgroundData on influenza community burden and transmission are important to plan interventions especially in resource-limited settings. However, data are limited, particularly from low-income and middle-income countries. We aimed to evaluate the community burden and transmission of influenza in a rural and an urban setting in South Africa.MethodsIn this prospective cohort study approximately 50 households were selected sequentially from both a rural setting (Agincourt, Mpumalanga Province, South Africa; with a health and sociodemographic surveillance system) and an urban setting (Klerksdorp, Northwest Province, South Africa; using global positioning system data), enrolled, and followed up for 10 months in 2017 and 2018. Different households were enrolled in each year. Households of more than two individuals in which 80% or more of the occupants agreed to participate were included in the study. Nasopharyngeal swabs were collected twice per week from participating household members irrespective of symptoms and tested for influenza using real-time RT-PCR. The primary outcome was the incidence of influenza infection, defined as the number of real-time RT-PCR-positive episodes divided by the person-time under observation. Household cumulative infection risk (HCIR) was defined as the number of subsequent infections within a household following influenza introduction.Findings81 430 nasopharyngeal samples were collected from 1116 participants in 225 households (follow-up rate 88%). 917 (1%) tested positive for influenza; 178 (79%) of 225 households had one or more influenza-positive individual. The incidence of influenza infection was 43·6 (95% CI 39·8–47·7) per 100 person-seasons. 69 (17%) of 408 individuals who had one influenza infection had a repeat influenza infection during the same season. The incidence (67·4 per 100 person-seasons) and proportion with repeat infections (22 [23%] of 97 children) were highest in children younger than 5 years and decreased with increasing age (p<0·0001). Overall, 268 (56%) of 478 infections were symptomatic and 66 (14%) of 478 infections were medically attended. The overall HCIR was 10% (109 of 1088 exposed household members infected [95% CI 9–13%). Transmission (HCIR) from index cases was highest in participants aged 1–4 years (16%; 40 of 252 exposed household members) and individuals with two or more symptoms (17%; 68 of 396 exposed household members). Individuals with asymptomatic influenza transmitted infection to 29 (6%) of 509 household contacts. HIV infection, affecting 167 (16%) of 1075 individuals, was not associated with increased incidence or HCIR.InterpretationApproximately half of influenza infections were symptomatic, with asymptomatic individuals transmitting influenza to 6% of household contacts. This suggests that strategies, such as quarantine and isolation, might be ineffective to control influenza. Vaccination of children, with the aim of reducing influenza transmission might be effective in African settings given the young population and high influenza burden.

Surveillance of the current situation regarding influenza vaccination according to medical oncologists in Japan.

This study aimed to clarify the attitude of oncologists toward influenza vaccination and the current situation and issues regarding influenza vaccination for patients on chemotherapy in Japan. A web‐based survey of medical oncologists certified by the Japanese Society of Medical Oncology was conducted between November 1 and December 31, 2019. Of the 1369 medical oncologists who were invited to participate, 415 (30.3%) responded to our survey. The questionnaire comprised 4 sections: “oncologist characteristics,” “oncologist attitude toward influenza vaccines and the current status of influenza vaccination for cancer patients undergoing chemotherapy,” “incidence of influenza infection and associated treatment complications,” and “treatment policy for influenza infection.” In total, 153 (36.9%) physicians replied that they did not actively encourage influenza vaccination for patients undergoing chemotherapy. The primary reasons given were lack of evidence (48/153, 31.4%) and uncertainty of appropriate timing (46/153, 30.1%). There was diverse variation in the timing of vaccination and in the levels of encouragement based on the cancer location and medication type. Two hundred eighty‐three (68.2%) oncologists reported that their cancer patients had experienced influenza infection while undergoing chemotherapy, and 169 (40.7%) responded that their patients had experienced an administration delay or discontinuation of medication because of influenza infection. Our surveillance revealed some oncologists considered evidence regarding the administration of influenza vaccine to cancer patients undergoing chemotherapy (particularly the optimal timing and level of recommendation by cancer location and medication) to be lacking. It also exposed the adverse impact of influenza infection in cancer patients.

Discovery of an Association Between Influenza Infection Rates and the Incidences of Craniosynostosis in the United States: A Potentially Modifiable Risk Factor

Objective: Maternal immune activation secondary to influenza infection during critical periods of fetal development is a significant risk factor for neuropsychiatric and neurodevelopmental disorders. The association between influenza and craniosynostosis is not well documented. We investigate the association between the incidence of influenza infection and incidence of craniosynostosis in the United States. Materials and Methods: Retrospective population-based observational study spanning using the National Inpatient Sample Database, the United States Center for Disease Control and Prevention FluView databases, including infants born with craniosynostosis in the United States from 2004 to 2013 and monthly influenza incidence in the United States from 2003 to 2013. Mixed-effects logistic regression tested the association between 2 variables: national influenza incidences and rate of craniosynostosis. Odds ratios were calculated for the occurrence of craniosynostosis in relation to previous months’ flu incidence. E-values were calculated to evaluate unmeasured confounders. Results: Retrospective analysis performed on 45 356 newborns with craniosynostosis. Mixed-effects logistic regression revealed for each additional influenza case per 1000 people, the odds of craniosynostosis event occurring 6 months later increased by 3.4 (adjusted P = .009, OR = 3.444, CI = 1.756-6.754). For each additional influenza case per 1000 people, the odds of craniosynostosis event occurring 7 and 2 months later decreased by 3.8 and 6.1, respectively (OR = 0.262 and 0.165; adjusted P value = .007 and &lt;.001). E-value for the association between influenza and craniosynostosis incidence 6 months later was 6.35. The E-values for the association between influenza and craniosynostosis incidences 7 months and 2 months later were 7.1 and 11.6. Conclusion: There is an increased risk for craniosynostosis with influenza occurring in third month of pregnancy. There are protective effects against craniosynostosis with influenza occurring in second and seventh months of pregnancy. To our knowledge, this is the first study demonstrating an association between the rate of influenza and craniosynostosis, suggesting a potentially important connection, though not necessarily causality, between maternal immune activation and craniosynostosis.

Incidence of Influenza Infections and Determination of Vaccination Coverage Rate Among Healthcare Workers

Incidence of Influenza Infections and Determination of Vaccination Coverage Rate Among Healthcare Workers

Temporal distribution and genetic variants in influenza A(H1N1)pdm09 virus circulating in Mexico, seasons 2012 and 2013.

The 2012 and 2013 annual influenza epidemics in Mexico were characterized by presenting different seasonal patterns. In 2012 the A(H1N1)pdm09 virus caused a high incidence of influenza infections after a two-year period of low circulation; whereas the 2013 epidemic presented circulation of the A(H1N1)pdm09 virus throughout the year. We have characterized the molecular composition of the Hemagglutinin (HA) and Neuraminidase (NA) genes of the A(H1N1)pdm09 virus from both epidemic seasons, emphasizing the genetic characteristics of viruses isolated from Yucatan in Southern Mexico. The molecular analysis of viruses from the 2012 revealed that all viruses from Mexico were predominantly grouped in clade 7. Strikingly, the molecular characterization of viruses from 2013 revealed that viruses circulating in Yucatan were genetically different to viruses from other regions of Mexico. In fact, we identified the occurrence of two genetic variants containing relevant mutations at both the HA and NA surface antigens. There was a difference on the temporal circulation of each genetic variant, viruses containing the mutations HA-A141T / NA-N341S were detected in May, June and July; whereas viruses containing the mutations HA-S162I / NA-L206S circulated in August and September. We discuss the significance of these novel genetic changes.

Development of intracranial sinusogenic complcations in the period of increased incidence of influenza infections - analysis of 6 patients hospitalized in the Department of Otolaryngology, Head and Neck Surgery of Poznan University of Medical Sciences in the year 2013

Development of intracranial sinusogenic complcations in the period of increased incidence of influenza infections - analysis of 6 patients hospitalized in the Department of Otolaryngology, Head and Neck Surgery of Poznan University of Medical Sciences in the year 2013

CD8+ cytotoxic T lymphocytes in human influenza virus infection.

CD8+ cytotoxic T lymphocytes in human influenza virus infection.

Impact of influenza season and environmental factors on the clinical presentation and outcome of invasive pneumococcal disease.

Influenza and meteorological factors have been associated with increases in the incidence of invasive pneumococcal disease (IPD). However, scant data regarding the impact of influenza and the environment on the clinical presentation of IPD are available. An observational study of all adults hospitalized with IPD was performed between 1996 and 2012 in our hospital. The incidence of IPD correlated with the incidence rates of influenza and with environmental data. A negative binominal regression was used to assess the relationship between these factors. Clinical presentation of IPD during the influenza and non-influenza periods was compared. During the study, 1,150 episodes of IPD were diagnosed. After adjusting for confounding variables, factors correlating with the rates of IPD were the incidence of influenza infection (IRR 1.229, 95% CI 1.025-1.472) and the average ambient temperature (IRR 0.921, 95% CI 0.88-0.964). Patients with IPD during the influenza period had a worse respiratory status. A greater proportion of patients had respiratory failure (45.6% vs 52%, p = 0.032) and higher requirements for ICU admission (19.3% vs 24.7%, p = 0.018) and mechanical ventilation (11% vs 15.1%, p = 0.038). When we stratified by invasiveness of pneumococcal serotypes and the presence of comorbid conditions, the increase in the severity of clinical presentation was focused on healthy adults with IPD caused by nonhighly invasive serotypes. Beyond the increase in the burden of IPD associated with influenza, a more severe clinical pattern of pneumococcal disease was observed in the influenza period. This effect varied according to pneumococcal serotype, host comorbidities, and age.

Understanding the burden of influenza infection among adults in Canadian hospitals: A comparison of the 2009-2010 pandemic season with the prepandemic and postpandemic seasons

The degree to which the 2009-2010 influenza pandemic season differed from previous and subsequent influenza seasons in Canadian hospitals has not yet been assessed. Surveillance for laboratory-confirmed influenza among adults in 51 Canadian Nosocomial Infection Surveillance Program hospitals was conducted between November 1, 2006, and May 31, 2011. Inpatient characteristics, treatment, and outcomes of influenza cases in the pandemic season (2009-2010) were compared with those in the prepandemic (2006-2007 to 2008-2009) and postpandemic (2010-2011) seasons. The incidence of influenza infection was lower in the postpandemic season (1.59/1,000 admissions) compared with the prepandemic seasons (2.00/1,000 admissions; P < .001) and the pandemic season (1.80/1,000 admissions; P < .001). The proportion of cases classified as health care-associated was much smaller during the pandemic season (6.6%) than in either the prepandemic season (23.2%; P < .001) or the postpandemic season (23.6%; P < .001). Inpatients in the pandemic season were significantly younger compared with those in the prepandemic and postpandemic seasons (P < .001). Inpatients in the pandemic season were less likely to have been vaccinated (P < .001), but more likely to be treated with antiviral agents (P < .001), than inpatients in both the prepandemic and postpandemic seasons. Intensive care unit admission was greater during the pandemic season, but there were no significant differences in 30-day mortality among the seasons. Among adult inpatients, the pH1N1 pandemic season differed from seasonal influenza in terms of age, vaccination status, antiviral use, and intensive care unit admission, but not in terms of 30-day mortality.

Green Tea Consumption Is Inversely Associated with the Incidence of Influenza Infection among Schoolchildren in a Tea Plantation Area of Japan

Green tea is known to contain antiviral components that prevent influenza infection. A limited number of adult clinical studies have been undertaken, but there is a paucity of clinical evidence concerning children. We conducted an observational study to determine the association between green tea consumption and the incidence of influenza infection among schoolchildren. Anonymous questionnaire surveys were undertaken twice during the influenza season from November 2008 to February 2009 (endemic seasonal type A influenza infection); each survey was conducted for 2663 pupils across all elementary schools in Kikugawa City (a tea plantation area), Japan. Each questionnaire was completed and submitted by 2050 pupils (response rate, 77.0%; age range, 6–13 y). The adjusted OR associated with the consumption of green tea for ≥6 d/wk compared with <3 d/wk was 0.60 [(95% CI = 0.39–0.92); P = 0.02] in cases of influenza confirmed by the antigen test. Meanwhile, the adjusted OR inversely associated with the consumption of 1 cup/d to <3 cups/d (1 cup = 200 mL) and 3–5 cups/d compared with <1 cup/d were 0.62 [(95% CI = 0.41–0.95); P = 0.03] and 0.54 >5 cups/d. Our findings thus suggest that the consumption of 1–5 cups/d of green tea may prevent influenza infection in children.

Clinical importance and impact on the households of oseltamivir-resistant seasonal A/H1N1 influenza virus in healthy children in Italy

A resistance of A/H1N1 influenza viruses to oseltamivir has recently emerged in a number of countries. However, the clinical and socioeconomic importance of this resistance has not been precisely defined. As children have the highest incidence of influenza infection and are at high risk of severe disease, the aim of this study was to evaluate the clinical importance and the impact on the households of oseltamivir-resistant seasonal A/H1N1 influenza virus in an otherwise healthy pediatric population. A total of 4,726 healthy children younger than 15 years with influenza-like illness were tested for influenza viruses by real-time polymerase chain reaction in the winters of 2007-2008 and 2008-2009 in Italy. The influenza A virus-positive samples underwent neuraminidase gene analysis using pyrosequencing to identify mutations H275Y and N294 S in A/H1N1, and E119V, R292K, and N294 S in A/H3N2. Among the A/H1N1 subtypes, the H275Y mutation was found in 2/126 samples taken in 2007-2008 (1.6%) and in all 17 samples (100%; p < 0.0001) taken in 2008-2009. No other mutation was identified in any of the A/H1N1 or A/H3N2 influenza viruses. No significant differences were found in terms of clinical importance or impact on the households between the children with oseltamivir-resistant seasonal A/H1N1 influenza virus and those with the wild-type. The spread of H275Y-mutated A/H1N1 seasonal influenza virus is a common phenomenon and the clinical importance and impact on the households of the mutated virus is similar to that of the wild-type in an otherwise healthy pediatric population.

Gargling with Tea Catechin Extracts for the Prevention of Influenza Infection in Elderly Nursing Home Residents: A Prospective Clinical Study

To evaluate the effects of gargling tea catechin extracts on the prevention of influenza infection in elderly nursing home residents. A prospective study conducted for 3 months from January to March 2005. A nursing home in Japan. A total of 124 elderly residents of at least 65 years of age were enrolled in the study. Seventy-six residents (83 +/-8.2 years, mean +/-standard deviation; 24 men, 52 women) gargled with tea catechin extract (catechin group) and were compared with 48 age- and sex-matched residents who gargled without tea catechin extracts (control group). All the residents were vaccinated with an influenza vaccine until early December 2004. catechin group: gargling with the tea catechin extract solution (200 microg/mL catechins, 60% of catechins comprise epigallocatechin gallate); control group: gargling without the catechin extract solution. In both groups, gargling was performed three times daily for 3 months. The incidence of influenza infection during the study was compared between the two groups. A safety evaluation was conducted to observe adverse events during the study. The incidence of influenza infection was significantly lower in the catechin group (1.3%, one resident) than in the control group (10%, five residents) calculated by multivariate logistic regression analysis (p = 0.028; odds ratio, 15.711; 95% confidence interval, 1.883-399.658). No adverse events, such as respiratory tract irritation, an obstruction, or allergic bronchial spasm, were observed during the study. This prospective study demonstrating the effect of catechin gargling on the prevention of influenza infection in the elderly is the first to be reported in the literature. Further randomized, controlled studies are needed to confirm the effects of catechin gargling on the prevention of influenza infection.

Adjuvanted Influenza Vaccine

Currently available influenza vaccines consist of inactivated whole virus vaccines or subunit (or split) vaccines. These inactivated vaccines have been shown to reduce the incidence of influenza infections and to reduce the severity of the illness in vaccinees who become infected. The protective efficacy of these vaccines is greatest in healthy youngadultsandleastintheelderlywhoareathigh risk of the morbidity and mortality associated with influenza-related illnesses. Influenza outbreaks have been reported among vaccinated individuals from long-term care facilities, even when the vaccine being administered was well matched to the circulating virus strains. [1] A meta-analysis of the efficacyoftheinfluenzavaccineintheelderlyconcluded that, overall, the efficacy of conventional inactivated vaccines was 56%for the prevention of respiratory illness and 68% for the prevention of death as a result of influenza. [2] These efficacy rates with the inactivated vaccine are probably due to lowimmuneresponsesandtheshortdurationfor which antibodies are produced at greater than protective levels in the elderly or immunocompromised individuals. Many alternative vaccination strategies have been proposed to induce a better immune response in at-risk populations and, ultimately,toimproveprotectiveefficacy.Afewof these strategies have been clinically tested.

Influenza Viral Infections

Each year, 20,000 to 40,000 people in the United States die of influenza and associated complications. Influenza infections account for several billion dollars in health care expenditures each year. Two important measures to minimize the incidence of influenza infection are vaccination and chemoprophylaxis with antiviral agents. Vaccinations must be given annually for two reasons: the antigenic changes that influenza strains, particularly influenza A, undergo and the diminished antibody response that occurs over time. Specific efforts should be targeted to high-risk groups. The adverse effects of the vaccine are generally mild, with a sore arm being the most common complaint. Chemoprophylaxis is the recommended substitute for vaccination in people with egg allergy. The vaccine is effective 70% to 90% of the time in preventing illness in healthy individuals. Unfortunately, less than 30% of the targeted population receives the vaccination each year. More research must be conducted on ways to improve the organization and administration of influenza vaccinations.

Influenza in children with cancer

We prospectively followed a group of unimmunized, immunosuppressed children with cancer to determine their relative risk of influenza and the severity of infection compared with those of siblings or matched community controls. The incidence of influenza infection was higher in children with cancer (23/73, 32%) than in control subjects (10/70, 14%, p = 0.02). A preseason hemagglutination inhibition titer greater than or equal to 1:32, generally used as a marker of successful immunization in vaccine trials, was protective for all children in the control groups, but did not prevent influenza infection in 24% of the patients with cancer. Infection rates of patients and community controls with titers greater than or equal to 1:32 differed significantly (p = 0.006). No significant differences were noted in duration of reported symptoms between groups, and clinical complications occurred too infrequently to analyze. However, 2 (11%) of 18 of the cancer patients with positive culture results were hospitalized during the illness and one patient developed a nosocomial infection. None of the control children was hospitalized. These findings suggest the need for further study of the immunologic response of immunosuppressed children to influenza infection and a clinical efficacy trial of the influenza vaccine in these patients.

Effect of passive maternal antibody on influenza illness in children: a prospective study of influenza A in mother-infant pairs.

To determine the effect of passive antibody on the incidence of influenza in infants, infants born to mothers with serum antibody to influenza A (immune) and those born to mothers without evidence for this serum antibody (non-immune) were followed during the influenza H1N1 epidemic of 1979. Immune mothers had higher H1-specific antibody titers before the epidemic (P less than 0.001), were less frequently culture positive, showed fewer titer rises (P less than 0.001) and were less symptomatic than were nonimmune mothers. Infants of immune mothers had higher H1-specific passive antibody titers that correlated with their mother's antibody titers. Although infants of both groups showed no difference in incidence of influenza infection, infants of immune mothers had influenza symptoms that were delayed in onset (P = 0.02) and were of shorter mean duration compared with infants of nonimmune mothers. These findings suggest that passive maternal antibody delays the onset and decreases the severity of influenza disease in young infants.

Comparaison de l'immunite serique anti influenza a de diverses populations humaines et des porcs

Using the radial haemolysis for detection of antibody, it was shown in pigs, that a mixture of A/Port Chalmers/73 and A/Victoria/75 related strains still spread in 1979. A/Texas/77-related strains gave detectable RH (radial haemolysis) antibodies in pigs as soon as April 1978. There is no A/Swine-like virus infection detectable neither in man nor in pig. H1N1 and New Jersey/76 RH antibodies were shown mainly in animals carrying also anti A/Port Chalmers/73, A/Victoria/75 and/or A/Texas/77 antibodies. There is a correlation between the frequency of influenza antibody in breeders and the incidence of influenza infection in pigs. Anti A/Port Chalmers/73 and A/Victoria/75 antibodies are significantly higher in humans in close contact with pigs than in urban and rural populations. Because of the high turnover of the pigs in breeding there is a persistence of human influenza strains in this reservoir and exchanges between animal reservoir and human seem to go both ways.