News Scan for May 23, 2016

Avian flu cases
;
Pistachio Salmonella outbreak
;
Flu antigenic mutations

China reports human H7N9 case; Egypt finds H9 infection in toddler

Chinese officials reported another human case of H7N9 avian influenza, the second such infection in Hebei province in nearly 3 years, according to a post yesterday on Avian Flu Diary (AFD). Elsewhere, Egypt documented an H9 case in a toddler, according to a May 19 World Health Organization (WHO) report.

The H7N9 case in China involved a 57-year-old man from Xinji city in Hebei. He experienced onset of headache and fever on May 10 and was hospitalized in Hengshui city on May 16, where he remains in serious condition. The patient is a farmer, and his close contacts are being monitored for signs of illness, AFD said.

The infection is only the second H7N9 case in Hebei province since the virus emerged in China 4 years ago. Hebei's last H7N9 case occurred in July 2013, AFD said.

The new case lifts the global H7N9 total to 789, according to a list maintained by FluTrackers, an infectious disease message board.

Elsewhere, the WHO reported an H9 infection in an 18-month-old boy from Cairo governorate who was exposed to live poultry at a market. The boy developed symptoms on Apr 10 and is in good condition. Though this is not confirmed, his infection is likely due to H9N2, which causes mild illness, the WHO said.

Globally, 28 cases of H9N2 have been reported, and the virus shows no evidence of human-to-human transmission, the WHO said.
May 22 AFD post
FluTrackers H7N9 case list
May 19 WHO report

 

CDC calls Salmonella outbreak tied to pistachios over after 11 cases

A multistate Salmonella outbreak linked to pistachios is considered over, the Centers for Disease Control and Prevention (CDC) said in a May 20 update, noting that two separate Salmonella strains have now been implicated in the 11 infections.

Of the 11 cases initially tied to Salmonella Montevideo, two have been reclassified as Salmonella Senftenberg. Both strains were isolated from pistachios grown by Wonderful Pistachios of Lost Hills, Calif., along with environmental samples from the company's California-based Paramount Farms location. Wonderful Pistachios has now closed the part of the production facility where the two strains were isolated, the CDC said.

The 11 patients from nine states reported illness onset dates between Jan 3 and Mar 25. Patients were between the ages of 27 and 69. Two people required hospitalization, though no deaths occurred, the CDC said.

Affected pistachios were sold in the United States, Canada, Mexico, and Peru under the brand names Wonderful, Paramount Farms, and Trader Joe's. Though the company voluntarily recalled shelled and unshelled nuts on Mar 9, the products have a long shelf life. Consumers should not eat any pistachios affected by the recall, the CDC said.
May 20 CDC update
Mar 10
CIDRAP News story on outbreak

 

Lab studies of flu mutations may help in picking vaccine strains

Flu viruses that underwent random mutations in a laboratory setting became antigenically similar to wild circulating viruses, suggesting that in vitro observation of antigenic behavior may more effectively guide selection of flu vaccine strains than current methods, according to a study today in Nature Microbiology.

Researchers with the Centers of Excellence for Influenza Research and Surveillance (CEIRS) created hemagglutinin libraries from naturally occurring H1N1 and H3N2 viruses isolated during the 2009-10 and 2012-13 flu seasons, respectively, mixed them with convalescent  sera from humans and/or ferrets, and observed which isolates escaped the antibody response.

H1N1 mutants had amino acid changes at key antigenic positions on the hemagglutinin head, resulting in reduced reactivity with antiserum against naturally occurring viruses, the authors said. When immunized mice were challenged with a wild-type and a mutant virus, 12 of 13 mutated strains evaded immune system response and replicated efficiently, while none of the naturally occurring strains replicated. Four mutants replicated in immunized ferrets, suggesting that mutand versions of H1N1 still have pandemic potential, the authors said.

An analysis of 2,555 wild-type H1N1 viruses that circulated between 2009 and 2013 revealed that they differed from vaccine strains by more than 6%, the authors said. Antigenic changes in these naturally occurring viruses were identical to the effects observed in the lab with mutations causing formation of antigenically distinct clusters on the hemagglutinin head.

Amino acid changes at antigenically important sites were also observed in the mutated H3N2 viruses, suggesting that in vitro studies of mutated viruses can help predict patterns in how flu viruses evolve in humans. "Antigenic cartography," the authors said, can simulate and predict flu mutations before they occur and inform the development of effective flu vaccines.
May 23 Nat Microbiol study

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