Serologic Evidence of H1 Swine Influenza Virus Infection in Swine Farm Residents and Employees

We evaluated seropositivity to swine and human H1 influenza viruses in 74 swine farm owners, employees, their family members, and veterinarians in rural south-central Wisconsin, compared with 114 urban Milwaukee, Wisconsin, residents. The number of swine farm participants with positive serum hemagglutination-inhibition (HI) antibody titers >40 to swine influenza viruses (17/74) was significantly higher (p<0.001) than the number of seropositive urban control samples (1/114). The geometric mean serum HI antibody titers to swine influenza viruses were also significantly higher (p<0.001) among the farm participants. Swine virus seropositivity was significantly (p<0.05) associated with being a farm owner or a farm family member, living on a farm, or entering the swine barn >4 days/week. Because pigs can play a role in generating genetically novel influenza viruses, swine farmers may represent an important sentinel population to evaluate the emergence of new pandemic influenza viruses

Chapter 5, Influenza: 5 -1 Chapter 5: Influenza

uring each of 11 of 23 influenza seasons from the 1972-73 season through the 1994-95 season, more than 20,000 influenza-associated deaths occurred, and more than 40,000 deaths occurred during each of six of these seasons. 1,2 More than 90% of influenza-associated deaths now occur among persons age 65 years and older. 3 II. Background Influenza type A and type B viruses can cause epidemics of illness in people. 4 Influenza type A viruses are divided into subtypes based on surface proteins called hemagglutinin (HA) and neuraminidase (NA). The two influenza A subtypes that have co-circulated in human populations since 1977 are influenza A (H1N1) and A (H3N2). Influenza A and B viruses both undergo gradual, continuous change in the HA and NA proteins, known as antigenic drift. As a result of these antigenic changes, antibodies produced to influenza from infection or vaccination with earlier strains may not be protective against viruses circulating in later years. Consequently, yearl

U.S. Pneumonia and Influenza Mortality Surveillance: A New Era

The National Center for Health Statistics (NCHS) and the Influenza Division are collaborating to increase accuracy and decrease resources needed for pneumonia and influenza mortality surveillance in the United States Electronic death registration systems as well as funding to states have made reporting of mortality data to NCHS near real-time. We assessed the timeliness of the NCHS data and compared the data to the 122 Cities Reporting System (CMRS). Because of increased timeliness of the NCHS data and correlation to the 122 CMRS we will continue to monitor data from NCHS as a potential replacement for the 122 CMRS

Influenza-Associated Pediatric Deaths in the United States, 2010–2015

ObjectiveTo characterize and describe influenza-associated pediatric deathsin the United States over five influenza seasons, 2010–11 through2014–15.IntroductionCommunity influenza infection rates are highest among children.In children, influenza can cause severe illness and complicationsincluding, respiratory failure and death. Annual influenza vaccinationis recommended for all persons aged≥6 months. In 2004, influenza-associated deaths in children became a notifiable condition.MethodsDeaths that occurred in children aged &lt;18 years with laboratory-confirmed influenza virus infection were reported from states andterritories to the Centers for Disease Control and Prevention on astandard case report form. We used population estimates from theU.S. Census Bureau, 2011 to 2015, to calculate age group-adjustedincidence. We used Wilcoxon-rank-sum test to compare medians andchi-square and Mantel-Haenszel chi-square to compare differencesbetween proportions of two groups.ResultsFrom October 2010 through September 2015, 590 influenza-associated pediatric deaths were reported. The median age at timeof death was 6 years (interquartile range, 1–12 years). Half of thechildren (285/572) had at least one underlying medical condition.Neurologic conditions (26%) and development delay (21%) weremost commonly reported. The average annual incidence rate was0.16 per 100,000 children (95% confidence interval [CI]: 0.15–0.17)and was highest among children aged &lt;6 months (0.75, 95% CI,0.60–0.94 per 100,000 children), followed by children aged6–23 months (0.34, 95% CI, 0.28–0.41 per 100,000 children). Only21% (87/409) of pediatric deaths in children≥6 months had evidenceof full influenza vaccination. Vaccination coverage was lower inchildren aged 6–23 months (15%) and 5–8 years (17%) than withthose aged 2–4 years and 9–17 years (25%, p&lt;0.01). The majorityof children aged &lt;2 years who died had no underlying medicalconditions (63%, 105/167); this proportion was significantly higherthan that in children aged≥2 years (45%, 182/405, p&lt;0.01).Overall 65% (383) of pediatric deaths had influenza A virusdetected, and 33% had influenza B virus detected. Children infectedwith influenza B virus had a higher frequency of sepsis/shock(41%, 72/174), acute respiratory distress syndrome (ARDS, 33%,58/174), and hemorrhagic pneumonia/pneumonitis (8%, 14/174) thanchildren infected with either influenza A(H1N1) pdm09 or influenzaA(H3N2) virus (p=0.01, 0.03, 0.03, respectively).Overall 81% (421/521) of children had an influenza-associatedcomplication; the most commonly reported were pneumonia (40%),sepsis/shock (31%) and ARDS (29%). Among those with testingreported, invasive bacteria coinfections were identified in 43%(139/322);β-hemolyticStreptococcus(20%) andStaphylococcusaureus(17%) were reported most frequently.Most children (39%, 212/548) died within 3 days of symptomonset, 28% died 4–7 days after onset, and 34% died≥8 days afteronset. The median days from illness onset to death for children withan underlying condition was significantly longer than the time forpreviously healthy children (7 versus 4 days, p&lt;0.01).ConclusionsEach year, a substantial number of influenza-associated deathsoccur among U.S. children, with rates highest among those aged&lt;2 years. While half of the deaths were among children withunderlying conditions, the majority of children &lt;2 years who diedwere previously healthy. Vaccination coverage was very low.Influenza vaccination among pregnant women, young children andchildren with high-risk underlying conditions should be encouragedand could reduce influenza-associated mortality among children

Influenza-Associated Pediatric Deaths in the United States, 2010–2015

ObjectiveTo characterize and describe influenza-associated pediatric deathsin the United States over five influenza seasons, 2010–11 through2014–15.IntroductionCommunity influenza infection rates are highest among children.In children, influenza can cause severe illness and complicationsincluding, respiratory failure and death. Annual influenza vaccinationis recommended for all persons aged≥6 months. In 2004, influenza-associated deaths in children became a notifiable condition.MethodsDeaths that occurred in children aged &lt;18 years with laboratory-confirmed influenza virus infection were reported from states andterritories to the Centers for Disease Control and Prevention on astandard case report form. We used population estimates from theU.S. Census Bureau, 2011 to 2015, to calculate age group-adjustedincidence. We used Wilcoxon-rank-sum test to compare medians andchi-square and Mantel-Haenszel chi-square to compare differencesbetween proportions of two groups.ResultsFrom October 2010 through September 2015, 590 influenza-associated pediatric deaths were reported. The median age at timeof death was 6 years (interquartile range, 1–12 years). Half of thechildren (285/572) had at least one underlying medical condition.Neurologic conditions (26%) and development delay (21%) weremost commonly reported. The average annual incidence rate was0.16 per 100,000 children (95% confidence interval [CI]: 0.15–0.17)and was highest among children aged &lt;6 months (0.75, 95% CI,0.60–0.94 per 100,000 children), followed by children aged6–23 months (0.34, 95% CI, 0.28–0.41 per 100,000 children). Only21% (87/409) of pediatric deaths in children≥6 months had evidenceof full influenza vaccination. Vaccination coverage was lower inchildren aged 6–23 months (15%) and 5–8 years (17%) than withthose aged 2–4 years and 9–17 years (25%, p&lt;0.01). The majorityof children aged &lt;2 years who died had no underlying medicalconditions (63%, 105/167); this proportion was significantly higherthan that in children aged≥2 years (45%, 182/405, p&lt;0.01).Overall 65% (383) of pediatric deaths had influenza A virusdetected, and 33% had influenza B virus detected. Children infectedwith influenza B virus had a higher frequency of sepsis/shock(41%, 72/174), acute respiratory distress syndrome (ARDS, 33%,58/174), and hemorrhagic pneumonia/pneumonitis (8%, 14/174) thanchildren infected with either influenza A(H1N1) pdm09 or influenzaA(H3N2) virus (p=0.01, 0.03, 0.03, respectively).Overall 81% (421/521) of children had an influenza-associatedcomplication; the most commonly reported were pneumonia (40%),sepsis/shock (31%) and ARDS (29%). Among those with testingreported, invasive bacteria coinfections were identified in 43%(139/322);β-hemolyticStreptococcus(20%) andStaphylococcusaureus(17%) were reported most frequently.Most children (39%, 212/548) died within 3 days of symptomonset, 28% died 4–7 days after onset, and 34% died≥8 days afteronset. The median days from illness onset to death for children withan underlying condition was significantly longer than the time forpreviously healthy children (7 versus 4 days, p&lt;0.01).ConclusionsEach year, a substantial number of influenza-associated deathsoccur among U.S. children, with rates highest among those aged&lt;2 years. While half of the deaths were among children withunderlying conditions, the majority of children &lt;2 years who diedwere previously healthy. Vaccination coverage was very low.Influenza vaccination among pregnant women, young children andchildren with high-risk underlying conditions should be encouragedand could reduce influenza-associated mortality among children

Surveillance for influenza--United States, 1997-98, 1998-99, and 1999-00 seasons.

PROBLEM/CONDITION: In the United States, influenza epidemics occur nearly every winter and are responsible for substantial morbidity and mortality, including an average of approximately 114,000 hospitalizations and 20,000 deaths/year. REPORTING PERIOD: This report summarizes both actively and passively collected U.S. influenza surveillance data from October 1997 through September 2000. DESCRIPTION OF SYSTEM: During each October-May in the period covered, CDC received weekly reports from 1) approximately 120 World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories in the United States regarding influenza virus isolations; 2) approximately 230, 375, and 430 sentinel physicians during 1997-98, 1998-99, and 1999-00, respectively, regarding their total number of patient visits and the number of visits for influenza-like illness (ILI); and 3) state and territorial epidemiologists regarding estimates of local influenza activity. WHO collaborating laboratories also submitted influenza isolates to CDC for antigenic analysis. Throughout the year, the vital statistics offices in 122 cities reported weekly on deaths related to pneumonia and influenza (P&I). RESULTS: During the 1997-98 influenza season, influenza A(H3N2) was the most frequently isolated influenza virus type/subtype. Influenza A(H1N1) and B viruses were reported infrequently. The proportion of respiratory specimens testing positive for influenza peaked at 28% in late January. The longest period of sustained excess mortality (when the percentage of deaths attributed to P&I exceeded the epidemic threshold) was 10 consecutive weeks. P&I mortality peaked at 9.8% in January. Visits for ILI to sentinel physicians exceeded baseline levels for 7 weeks and peaked at 5% in mid-January through early February. A total of 45 state epidemiologists reported regional or widespread activity at the peak of the season. During the 1998-99 season, influenza A(H3N2) viruses predominated; however, influenza B viruses were also identified throughout the United States. Influenza A(H1N1) viruses were identified rarely. The proportion of respiratory specimens testing positive for influenza peaked at 28% in early February. P&I mortality exceeded the epidemic threshold for 12 consecutive weeks and peaked at 9.7% in early March. Visits for ILI to sentinel physicians exceeded baseline levels for 7 weeks and peaked at 5% in early through mid-February. Forty-three state epidemiologists reported regional or widespread activity at the peak of the season. During the 1999-00 season, influenza A(H3N2) viruses predominated, but influenza A(H1N1) and B viruses also were identified. The proportion of respiratory specimens testing positive for influenza peaked at 31% in mid- to late December. The proportion of deaths attributed to P&I exceeded the epidemic threshold for 13 consecutive weeks and peaked at 11.2% in mid-January. Visits to sentinel physicians for ILI exceeded baseline levels 4 consecutive weeks and peaked at 6% in late December. Forty-four state epidemiologists reported regional or widespread activity at the peak of the season. INTERPRETATION: Influenza A(H1N1), A(H3N2), and B viruses circulated during 1997-2000, but influenza A(H3N2) was the most frequently reported virus type/subtype during all three seasons. Influenza A(H3N2) is the virus type/subtype most frequently associated with excess P&I mortality. Influenza activity during all three seasons occurred at moderate to severe levels, and excess P&I mortality was reported during > or = 10 weeks each year. PUBLIC HEALTH ACTIONS: CDC conducts active national surveillance during each October-May to detect the emergence and spread of influenza virus variants and to monitor influenza-related morbidity and mortality. Surveillance data are provided weekly throughout the influenza season to public health officials, WHO, and health-care providers and are used to guide vaccine strain selection, prevention and control activities, and patient care. Influenza vaccination is the most effective means for reducing the yearly effect of influenza. Typically, one or two of the influenza vaccine component viruses are updated each year so that vaccine strains will closely match circulating viruses. Surveillance data will continue to be used to select vaccine strains and to monitor the match between vaccine strains and the currently circulating viruses.Link_to_subscribed_fulltex

Influenza-associated hospitalizations in the United States

Context: Respiratory viral infections are responsible for a large number of hospitalizations in the United States each year. Objective: To estimate annual influenza-associated hospitalizations in the United States by hospital discharge category, discharge type, and age group. Design, Setting, and Participants: National Hospital Discharge Survey (NHDS) data and World Health Organization Collaborating Laboratories influenza surveillance data were used to estimate annual average numbers of hospitalizations associated with the circulation of influenza viruses from the 1979-1980 through the 2000-2001 seasons in the United States using age-specific Poisson regression models. Main Outcome Measures: We estimated influenza-associated hospitalizations for primary and any listed pneumonia and influenza and respiratory and circulatory hospitalizations. Results: Annual averages of 94735 (range, 18908-193561) primary and 133900 (range, 30 757-271 529) any listed pneumonia and influenza hospitalizations were associated with influenza virus infections. Annual averages of 226054 (range, 54523-430960) primary and 294128 (range, 86494-544909) any listed respiratory and circulatory hospitalizations were associated with influenza virus infections. Persons 85 years or older had the highest rates of influenza-associated primary respiratory and circulatory hospitalizations (1194.9 per 100 000 persons). Children younger than 5 years (107.9 primary respiratory and circulatory hospitalizations per 100 000 persons) had rates similar to persons aged 50 through 64 years. Estimated rates of influenza-associated hospitalizations were highest during seasons in which A(H3N2) viruses predominated, followed by B and A(H1N1) seasons. After adjusting for the length of each influenza season, influenza-associated primary pneumonia and influenza hospitalizations increased over time among the elderly. There were no significant increases in influenza-associated primary respiratory and circulatory hospitalizations after adjusting for the length of the influenza season. Conclusions: Significant numbers of influenza-associated hospitalizations in the United States occur among the elderly, and the numbers of these hospitalizations have increased substantially over the last 2 decades due in part to the aging of the population. Children younger than 5 years had rates of influenza-associated hospitalizations similar to those among individuals aged 50 through 64 years. These findings highlight the need for improved influenza prevention efforts for both young and older US residents.Link_to_subscribed_fulltex