Study: H5N1 seroprevalence 2% in poultry-exposed Egyptians
A 2-year serology study using stringent criteria found antibodies to H5N1 avian flu in 2.1% of Egyptians exposed to poultry, a finding that National Institutes of Health (NIH) officials said demonstrates that the virus poses a low pandemic risk.
Scientists from St. Jude Children's Research Hospital in Memphis, Tenn., and the National Research Center in Giza, Egypt, analyzed blood samples from 750 people with poultry exposure, 731 of whom were exposed to backyard poultry, according to their paper in the Journal of Infectious Diseases. Of those, 455 (61.3%) reported daily exposure to poultry. They also collected serum samples from 250 people who had no poultry exposure.
To avoid the cross-reactivity that can result from antibodies to H1N1 and H3N2 viruses, the researchers considered an antibody titer of 80 or higher to indicate seropositivity, which matches the World Health Organization diagnostic criterion. Measurements were taken at baseline (from November 2010 to July 2011), 1 year later, and 2 years later.
They found that 15 of 708 poultry-exposed volunteers (2.1%) had antibodies to H5N1 at baseline, with the prevalence dropping to 0.4% after 1 year and 0.6% after 2 years. The control group had no seropositive results at all three test times.
The team also found that seropositive rates for H9N2 antibodies were 1.1% at baseline, 7.5% after 1 year, and 5.9% after 2 years, compared with 0%, 0.7%, and 1.0% in controls, respectively.
Regarding their H5N1 findings, the authors conclude, "This prevalence demonstrates that the number of cases is greatly underreported and that the case-fatality rate [CFR] is consequently greatly overestimated." They note, however, that, given Egypt's low CFR, the results might not apply to other regions.
In an accompanying commentary, David Morens, MD, and Jeffery Taubenberger, MD, PhD, of the NIH's National Institute of Allergy and Infectious Diseases, wrote, "While it is important to be vigilant about the potential risks posed by all influenza viruses, including A(H5N1), and while we cannot conclude that the A(H5N1) risk is nonexistent, we see no compelling virologic or epidemiologic evidence to suggest that A(H5N1) or any other avian influenza virus is currently evolving toward human transmissibility, let alone pandemicity, or that such viruses are even capable of doing so."
They said that greater pandemic threats include reassortment of circulating H1N1 and H3N2 strains with zoonotic strains, lab release of the 1957 H2N2 pandemic strain, or evolving influenza strains in swine.
Morens and Taubenberger also wrote that the low H5N1 CFR indicated by the study undercuts the arguments of opponents of some influenza gain-of-function studies who decry them as too dangerous.
Oct 29 J Infect Dis abstract
Oct 29 J Infect Dis commentary
Flublok influenza vaccine approved for adults and seniors
The US Food and Drug Administration (FDA) approved Flublok, an egg- and preservative-free flu vaccine, for adults 18 years and older, which expands approval to those 50 and older, according to an Oct 30 press release from its manufacturer, Protein Sciences Corporation.
Flublok's approval for adults 50 years of age and older came under the FDA's accelerated approval of biological products regulations.
Flublok is currently the only vaccine produced using modern recombinant (cell culture) technology and is free of eggs, thimerosal, latex, formaldehyde, and gelatin, the release said.
The vaccine contains three times more antigen than traditional egg-based flu vaccines and has been shown to stimulate high antibody levels in seniors, according to Protein Sciences.
Oct 30 Protein Sciences Corporation press release
FDA links Listeria infections to Miami-based cheese producer
Listeria found in soft cheese produced by Oasis Brands, Inc., was found to match a strain that sickened three people in 2013 and 2014, according to an Oct 29 Centers for Disease Control and Prevention (CDC) report.
An FDA investigation identified Listeria monocytogenes in environmental samples at Oasis Brands' Miami-based processing location. The strain was linked to three cases of listeriosis in patients who had eaten soft Mexican cheeses sold under Oasis' Lacteos Santa Martha brand, the report said.
The cases occurred in New York, Tennessee, and Texas. All patients required hospitalization, and one of them died. The CDC said that one case was in a newborn related to Listeria infection during pregnancy.
The FDA's investigation is ongoing. Oasis Brands, Inc., began recalls of affected cheese products in August, the report said.
Oct 30 CDC report