NEWS SCAN: Irradiating hamburger, nuts; antibodies to 2 avian flu strains; flu vaccine receipt vs risk; malaria hearing

Dec 6, 2011

Studies test irradiation methods to fight microbes in hamburger, nuts
A recent study supports the use of irradiation in combination with certain packaging technologies to control Escherichia coli O175:H7 in ground beef patties, while a separate study suggests irradiation could be used to reduce Salmonella in almonds. In the ground beef study, a team of industry and academic researchers used irradiation in combination with vacuum packaging or modified-atmosphere packaging (MAP) to treat ground beef patties inoculated with E coli O157, according to a report in the Journal of Food Protection. The modified atmosphere used consisted of 99.6% carbon dioxide and 0.4% carbon monoxide. Irradiation at 1.5 kiloGray (kGy) reduced E coli O157 by 3.0 to 3.3 log. (Recommended irradiation doses for fresh ground beef range up to 4.5 kGy.) After irradiation, the E coli burden in the refrigerated patties did not change significantly for 6 weeks. With "temperature abuse"—storage at 25ºC (77ºF)—the pathogen grew in the vacuum-packed patties but not in the MAP patties. The authors concluded that the two combinations controlled E coli O157 in chilled patties about equally well but that MAP was more effective after temperature abuse.
December J Food Prot abstract
In the other study, researchers at Michigan State University inoculated almonds and walnuts with two strains of Salmonella and then conditioned the nuts to have four different levels of water activity (which is related to water content and is defined as the degree to which water associates with non-aqueous substances in a material). The researchers then used a low-energy x-ray irradiator to achieve up to a 5-log reduction in Salmonella in the nuts, according to their report in the International Journal of Food Microbiology. The x-ray dose needed to remove 90% of surface Salmonella was lower for almonds than for walnuts at all water activities. The researchers found that irradiating the nuts enough to achieve a 5-log reduction in Salmonella did not change the flavor of almonds but imparted an off flavor or "fishy taste" to walnuts. After the treatment, bacterial counts on the nuts did not change during 120 days of storage. The authors concluded that low-dose x-ray irradiation looks promising for certain types of nuts.
Dec 1 Int J Food Microbiol abstract

Chinese scientists find evidence of avian flu infection with 2 strains
Chinese researchers identified several villagers who didn't handle poultry to be seropositive for avian flu, including a man who tested seropositive for two strains, according to their letter in Clinical Infectious Diseases yesterday. They conducted a serologic analysis of 605 Beijing-area residents, randomly selected from 24 villages ,who did not have a history of handling poultry. The investigators found antibodies against H9 avian flu by hemagglutination inhibition assay in five of the villagers, and one of these, a 55-year-old man, also tested positive for H5 antibodies. The group also tested for H7 antibodies, with no positive results. The 55-year-old man's son also tested positive for H9 antibodies, but neither his wife nor his daughter-in-law tested seropositive for avian flu. The authors conclude, "Standard surveillance systems for preparedness and response to pandemic influenza, focusing mainly on poultry workers, seem insufficient. Our findings warrant enhanced surveillance of general populations in the future, especially of populations dwelling in rural areas."
Dec 5 Clin Infect Dis letter extract

Those at higher risk for flu may not be getting vaccinated
Reception of flu vaccine may not match with having an increased risk of contracting flu, a study by US researchers found. Using data from the 2007 National Health Interview Survey, which collected information on self-reported receipt of flu vaccine and flu infection, they sought to assess whether vaccinated people were at greater risk of infection had they not been vaccinated. For their multivariate regression analysis, they divided the respondents into high-priority and non-priority groups using the federal definition of high priority: the elderly, pregnant women, healthcare workers, and those with medical conditions. They assessed infection risk from self-reported incidence of flu in the no-vaccine group, then addressed this selection bias by using a Heckman Probit model that jointly estimates the probability of not being vaccinated and the probability of flu infection and allows for both decisions to be correlated based on certain factors. The scientists found that people in high-priority groups were more likely to be vaccinated than the general public but that the risk of flu infection in both groups was negatively correlated with vaccination rates. They found this correlation to be higher, however, in the high-priority groups. They conclude, "The analysis suggests that, within each priority group, many people with a higher propensity to vaccinate actually had a lower probability of contracting the flu if unvaccinated. Specifically, people with more social resources (higher education, health insurance coverage) and people who took good care of their health (physically active people, non-smokers, non-drinkers and those who use preventive care) were more motivated to protect themselves from flu through vaccination . . . In contrast, people with more kids in their family and people who work for pay were at greater risk of infection but were less likely to vaccinate."
Dec 2 PLoS One study

US House committee airs malaria progress, challenges
Though the world has made progress toward eliminating malaria, important challenges remain, such as maintaining the support of international donors and combating a rise in fake and poor-quality malaria drugs, according to an expert panel that briefed a US House committee yesterday. The experts appeared at a hearing on malaria progress held by the US House Subcommittee on Africa, Global Health, and Human Rights. Dr Roger Bate, a fellow at the American Enterprise Institute and director of the Africa Fighting Malaria research organization, told members of Congress that about half of malaria drugs fail quality-control tests, a problem that is contributing to drug resistance and is not illegal in some of the affected countries, Agence France-Presse (AFP) reported yesterday. Another expert, Dr Dennis Schmatz, president of the Medicines for Malaria Venture, told the group said a new goal is to develop drugs that can be sold only as fixed-dose combinations, a strategy that could thwart the sale of monotherapies that contribute to resistance.

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