Apr 6, 2012
Study: No increased virulence in novel H3N2 viruses, related swine strains
US researchers say they found no evidence of increased virulence in a novel reassortant H3N2 influenza virus (H3N2v) from one of the 12 human cases identified in the United States last year or in several related H3N2 viruses from pigs. The 12 H3N2v infections detected last summer and fall involved swine-origin H3N2 strains that included the M (matrix) gene from the pandemic 2009 H1N1 (pH1N1) virus. The report in the Journal of Virology says that swine H3N2 viruses with triple-reassortant internal genes (H3N2-TRIG) have been widespread in the United States since 1998. Transmission of the pH1N1 virus from humans to pigs resulted in reassortant H3N2 viruses that included genetic elements from pH1N1, which the authors call rH3N2p. They say their genome analysis of H3N2 viruses collected from swine from 2009 to 2011 revealed six different rH3N2p genotypes in the US swine population, all of which include the M gene from pH1N1. The team compared the pathogenic, transmission, genetic, and antigenic properties of a human H3N2v isolate and two swine H3N2 isolates—an H3N2-TRIG and an rH3N2p. They found that in pigs, the H3N2v and rH3N2p viruses were no more virulent than the background H3N2-TRIG strain, with most infected pigs showing mild illness. The authors also found that some recent rH3N2p isolates seem to be forming a separate genetic cluster with the human H3N2v strain. The findings, they say, add to the evidence that influenza A viruses readily pass between humans and animals and that pigs play a role in generating reassortant viruses. "Continued monitoring of these H3N2 viruses is necessary to evaluate evolution and potential loss of population immunity in swine and humans," the report concludes.
Apr 4 J Virol abstract
Dec 28, 2011, CIDRAP News story on novel H3N2 cases
Medical students not swayed by antivaccine YouTube clips
Medical students aren't swayed by YouTube antivaccine messages, though they do use social media sites as sources of medical information, a study in Vaccine found. The study of 41 first-year medical students was conducted in Sep 2010 by researchers from Ontario. The students took surveys before and after they watched one of two of the top-rated YouTube videos that are critical of the flu vaccine. One video had a more "evidence-based" academic style, and the other was a collage of mainstream media clips, highlighting anecdotal reports of vaccine injury and conspiracy. The pre-intervention survey found that the students were generally supportive of vaccination, though only 31.7% said they always got the annual flu vaccine. The students were frequent users of YouTube for all purposes, with 42% using it for health-related purposes and 12% using it for health-related information. They also reported frequently using Google and Wikipedia for health information, alongside medical databases. However, their trust in the sources varied, and was low for YouTube. Based on the pre- and post-surveys, researchers found that viewing the antivaccine videos did not sway the students' attitudes.
Apr 5 Vaccine abstract
Younger Shanghai kids more likely to be affected by flu, study finds
Among Shanghai children affected by pandemic 2009 H1N1 (pH1N1) and seasonal flu, the disease hits the youngest most often, according to a study of outpatients published in The Pediatric Infectious Disease Journal. Chinese researchers conducted prospective surveillance of flu among 2,356 children visiting outpatient clinics for influenza-like illness (ILI) from June 2009 through May 2011. Respiratory samples were collected from all patients. Of the ILI cases, 608 (26%) were virologically confirmed as flu, with 468 (77%) of those influenza A. Among influenza A cases, 236 (50%) were H3N2, 219 (47%) pH1N1, 4 (1%) seasonal H1N1, 3 (1%) H3N2/pH1N1 co-infection, and 6 (1%) untyped. Of 603 children with a single virus infection, 289 (48%) were less than 3 years old and 283 (47%) had close contact with someone, typically a family member, who had a fever or respiratory infection. The researchers found that, when outbreaks happened while school was in session, children living in institutions were disproportionately affected.
Apr 4 Ped Infect Dis J abstract
WHO confirms H5N1 case in Cambodia
A fatal human case of avian influenza (H5N1) in Cambodia was added yesterday to the World Health Organization's (WHO's) official count of H5N1 cases. The patient was a 6-year-old girl from Kampong Chhnang province. Her symptoms began Mar 22, she was hospitalized Mar 28 in Phnom Penh, and she died Mar 30. The girl had had contact with sick or dead poultry before symptom onset, says a WHO alert. Her case was reported by news outlets earlier this week. The case brings the total number of human H5N1 cases in Cambodia since 2005 to 20, with 18 deaths.
Apr 5 WHO alert
Apr 5 WHO global H5N1 case count
Salmonella outbreak expands to 100 cases
An outbreak of Salmonella Bareilly with suspected links to sushi has sickened 7 more people, raising the total to 100 so far, the US Centers for Disease Control and Prevention (CDC) said today. The number of affected states remained the same at 19, plus the District of Columbia. At least 10 people have been hospitalized, but no deaths have been reported.
Apr 6 CDC update