Flu Scan for Mar 11, 2015

H7N9 evolution and threat to humans
;
H1N1 flu strains in India
;
WHO confirms H5N1 cases in Egypt

Study shows H7N9 diversity, human threat

An analysis of viruses from the second wave of H7N9 avian flu in China that began in late 2013 shows a rapid expansion both geographically and in genetic diversity, which poses a challenge to disease control and demonstrates the potential of H7N9 to emerge as a pandemic strain in humans, according to a study summarized in a letter to Naturetoday.

An international group of researchers obtained swabs at live-poultry markets in 15 cities of five provinces in eastern China from October 2013 to July 2014. H7N9 was detected in swabs from seven cities, all of which had confirmed human cases. The virus was found in an average of 3% of samples, with a high of 15.4% one month in the city of Nanchang in Jiangxi province.

The investigators also sequenced the complete genomes of 438 isolates and found that as H7N9 spread south, it evolved into three main phylogenetic branches, or clades, each with multiple sub-branches.

They identified many new genetic variants that have become established in chickens and have spread across the country, most likely from poultry movement along trade routes. The researchers propose that control measures such as permanently closing live-poultry markets and inhibiting poultry transport during disease outbreaks will reduce the number of human cases of H7N9.

The authors summarize, "Repeated introductions of viruses from Zhejiang to other provinces and the presence of H7N9 viruses at live poultry markets have fuelled the recurrence of human infections. This rapid expansion of the geographical distribution and genetic diversity of the H7N9 viruses poses a direct challenge to current disease control systems."

They conclude, "Our results also suggest that H7N9 viruses have become enzootic in China and may spread beyond the region, following the pattern previously observed with H5N1 and H9N2 influenza viruses. . . . Therefore, H7N9 viruses should be considered as a major candidate to emerge as a pandemic strain in humans."
Mar 11 Nature letter

 

Researchers: India's current H1N1 flu strain shows mutations

The H1N1 strain of influenza circulating in India this flu season, widely reported in the country to be the same as the 2009 pandemic H1N1 strain (pH1N1) and thus covered by the currently used vaccine, is not identical after all, suggests an analysis today in the journal Cell Host & Microbe.

The researchers, from the Massachusetts Institute of Technology, found that the current H1N1 virus (A/India/6427/2014), which according to a press release from the journal's publisher has caused at least 1,200 deaths, has acquired amino acid mutations T200A and D225N that distinguish it from the pH1N1 (A/California/07/2009) virus and that may render it more virulent and justify reevaluation of the vaccine in use.

Conditions in India provide an environment ripe for influenza reassortment, with billions of farmed birds and animals and a huge human population in crowded conditions in many areas, say the authors. They point out that flu surveillance in India is irregular and reactive, with only two sequences contributed for scientific study this season and the number provided from animals over the past several years "insignificant."

The researchers conclude, "The influenza outbreak in India should be further examined to determine the virulence and potential threat of the virus. Improved surveillance and monitoring of the influenza outbreak will significantly enhance the options of how best we can manage outreach to both treat as well as prevent spread of the virus."
Mar 11 Cell Host Microbe study
Mar 11 Cell Press news release

 

WHO confirms 88 H5N1 cases this year in Egypt

Official World Health Organization (WHO) H5N1 avian flu numbers released late yesterday have added 65 new Egyptian cases to its 2015 total since its previous update on Jan 26, bringing the country's cases so far this year to 88, with 26 deaths.

The WHO totals are similar to numbers that FluTrackers, an infectious disease news message board, has compiled by closely tracking and translating local health agency reports.

Cases confirmed in Egypt from December 2014 through Mar 3—the official date of the case count posted yesterday—bring the country's total to almost 100 more than the second-most affected country. Egypt now has 292 cumulative cases, compared with 197 in Indonesia and 127 in Vietnam. Indonesia still has the most H5N1-attributed deaths, at 165, compared with 99 in Egypt and 64 in Vietnam.

Since November, Egypt has confirmed 115 H5N1 cases and 36 deaths, making it by far the largest H5N1 outbreak ever reported.

Yesterday the WHO also published its iteration of "Influenza at the Human-Animal Interface"—also dated Mar 3—which included similar numbers for Egypt.
Mar 10 WHO case count (dated Mar 3)
Mar 10 WHO human-animal interface report (dated Mar 3)

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