NEWS SCAN: Flu death in kids, births after 1918 pandemic, ground turkey Salmonella cases, flu activity, virulent H1N1-H5N1 combo, flu from pigs, cytokine storm discovery

Sep 15, 2011

CDC: Report on flu deaths in kids suggests vaccines, antivirals underused
An overview of 115 pediatric influenza deaths that occurred during the United States' 2010-11 flu season suggests that many of them could have been prevented with vaccines and antiviral drugs, the US Centers for Disease Control and Prevention (CDC) reported today. The findings, which appeared today in Morbidity and Mortality Weekly Report (MMWR), cover from September 2010 through August 2011. Despite a recommendation that all children age 6 months and older be vaccinated, only 23% (17) of the 74 children with a known immunization history had been fully vaccinated against influenza last season, the CDC reported. Of 94 kids who died in emergency departments or hospitals, only half had received antiviral treatment. Lyn Finelli, MD, chief of the CDC's surveillance and outbreak response team, said in a press release that although the flu vaccine isn't 100% effective, especially in youngsters with underlying conditions, it's important that the two tools are fully utilized. "Vaccinate first; then use influenza antiviral drugs as a second line of defense against the flu," she added. The CDC's analysis also found that 49% of children who died from flu had no underlying medical conditions that put them at risk for complications. Previously healthy kids also had a shorter interval between illness onset and death, were more likely to die at home or in the emergency department, and were more likely to have a positive bacterial culture from a sterile site.
Sep 16 MMWR report
Sep 15 CDC press release

Study: 1918 pandemic lowered birth rates in spring of 1919
Birth rates in the United States and Scandinavia declined about 6 months after the peak of the 1918 influenza pandemic, suggesting that the pandemic caused an increase in first-trimester miscarriages, according to a study published by an international team in the Journal of Infectious Diseases. The team examined birth rates in the United States, Denmark, Sweden, and Norway from 1911 to 1930 to identify periods of unusually low or high birth rates and looked at the timing of the pandemic peaks in the four countries. They also identified pregnancy stages at which women are at highest risk for flu-related miscarriage. They found that birth rates declined by an average of 2.2 births per 1,000 population, signaling a 5% to 15% drop from baseline levels. The declines were greatest between 6.1 and 6.8 months after the pandemic peak in the fall of 1918. This suggests that the pandemic caused first-trimester miscarriages in about 1 in 10 women, they concluded, adding, "Pandemic-related mortality was insufficient to explain observed patterns." In an accompanying editorial, W. Paul Glezen of Baylor College of Medicine in Houston writes that the study adds to a growing body of evidence about the risk that maternal influenza poses for the fetus and underscores the importance of flu vaccination for pregnant women.
J Infect Dis report abstract
J Infect Dis editorial introduction

CDC reports 8 more Salmonella cases in ground turkey outbreak
The number of cases linked to a nationwide Salmonella Heidelberg outbreak linked to Cargill ground turkey has risen to 119 people from 32 states, the CDC said yesterday. The total reflects an increase of 8 more cases and 1 more state since the CDC's last report on Aug 18. The number of deaths remained at 1. The outbreak has been linked to ground turkey from a Cargill Meat Solutions plant in Springdale, Ark., which recalled nearly 36 million pounds of the product on Aug 3, and then expanded the recall on Sep 11 by 185,000 pounds after tests on a product sample suggested further contamination with the same strain. Outbreak illnesses were caused by two closely related pulsed-field gel electrophoresis patterns of Salmonella Heidelberg, which were found in ground turkey collected from the home of an Ohio patient and in a retail sample during surveillance. Though samples from ground turkey and patients show that the outbreak strain is resistant to several antibiotics, the human isolates are sensitive to several common ones.
Sep 14 CDC outbreak update

CDC reports normal summertime flu activity locally, globally
Influenza activity both in the United States and worldwide remained at normal levels over the summer, according to a report published today in Morbidity and Mortality Weekly Report (MMWR) by the Centers for Disease Control and Prevention (CDC). From May 22 through Sep 3, US labs tested 20,868 specimens for influenza, and 122 (0.6%) tested positive—71% influenza A and 29% influenza B. Of the 87 influenza A viruses tested, 39 (45%) were subtyped: 24 (62%) were H3N2 and 15 (38%) were 2009 H1N1. The southeastern United States had the highest percentage of positive findings. Throughout the period outpatient visits for flu-like illness remained below baseline. The report also said the Southern Hemisphere saw typical seasonal flu activity and elsewhere in the Northern Hemisphere flu activity mirrored the US experience. The CDC also reported identifying 154 oseltamivir (Tamiflu)-resistant isolates: 61 2009 H1N1, 53 H3N2, and 30 influenza B. All but 10 resistant viruses were from outside the country.
Sep 16 MMWR report

Study: H1N1-H5N1 recombinant as virulent as H5N1 virus
A pandemic 2009 H1N1 flu (pH1N1) virus combined with an H5N1 avian flu strain produced a hybrid as virulent as the H5N1 parent, according to researchers at St. Jude Children's Research Hospital in Memphis, Tenn. In their study, published in the Journal of Virology, they used reverse genetics to create several pH1N1 (A/California/04/2009) viruses expressing individual genes from an H5N1 strain (A/Hong Kong/483/1997) and observed increased replication in one recombinant that expressed the hemagglutinin gene of HK/483. Greater replication also corresponded to increased virulence in mice, similar to that of the parent H5N1 strain. The team also observed that serial passage of the hybrid virus through human lung epithelial cells "resulted in increased pathogenicity, suggesting that these viruses may easily adapt to humans and become more virulent." When the parent H5N1 strain was passed sequentially through these cells, in contrast, it grew weaker.
Sep 14 J Virol abstract

Students contracted triple-reassortant swine flu virus at livestock event
After identifying a triple-reassortant swine flu virus infection in a college student months before the 2009 H1N1 pandemic began, investigators found serologic evidence of infection in 40% of other students who were exposed to pigs at the same event as the index case, but there was no evidence of human-to-human transmission. Researchers from South Dakota, Iowa, and the CDC identified the reassortant strain as an H1N1 swine flu virus that was similar to others that have circulated in US pigs in recent years and was distinct from the 2009 pandemic virus. They then contacted 99 students who had been exposed to pigs at the livestock event. Of the 42 who provided serum samples, 17 (40%) were seropositive and 5 (12%) met case criteria. Of 9 students exposed to other pigs, 2 (22%) were seropositive. This compares with no seropositive cases among 8 students who were exposed to the index case and among 10 who had no exposures. The researchers conclude that rapid detection of animal flu outbreaks among humans "remains critical to the timely recognition of novel influenza viruses with pandemic potential."
Oct 15 J Infect Dis abstract

Scientists say they have found mechanism of flu-triggered cytokine storm
Scientists at the Scripps Research Institute say they have identified the mechanism that governs the immune system overreaction to influenza known as the cytokine storm, possibly opening the way for drugs to prevent it. Cytokine storm causes severe illness by filling the lungs with fluid and immune cells. The study is published in the Sep 16 issue of Cell. The research team sought to determine the role of a receptor molecule called Sphingosine-1-phosphate, or S1P1, using chemical and genetic approaches the permit the tracking and modulation of receptor function in real time, according to a Scripps press release. The previous assumption was that cytokines were released from virus-infected cells or other cells lining the lungs, but the researchers were surprised to find that manipulating the S1P1 receptors in the endothelial cells of lung blood vessels affected cytokine release. The team then used this finding to try to limit cytokine storm in mice infected with the pandemic 2009 H1N1 virus. Using a molecule that bound to the S1P1 receptor, they managed to reduce the immune overreaction, thereby improving the mice's survival, according to the release. Hugh Rosen, MD, PhD, co-leader of the study, predicted that the findings could lead to an oral drug that would prevent cytokine storm if given early in the illness. James M. Andreason, MD, PhD, of the National Institutes of Health, which funded the study, said the results have "greatly increased our understanding of the biological basis of cytokine storm, opening the door to development of new treatments for this potentially fatal immune reaction."
Sep 15 Scripps news release
Cell abtract

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