FLU NEWS SCAN: Low US flu levels, call for peramivir, flu mutations and severity

Nov 1, 2010

CDC reports low levels of US flu activity
The US Centers for Disease Control and Prevention (CDC) reported in its Oct 29 update that influenza activity remains at low levels in the country, with physician visits for influenza-like illness (ILI) down slightly from the week before. For the week ending Oct 23, only 3% of respiratory specimens tested were positive for influenza, with the proportion of deaths for pneumonia and flu and the proportion of outpatient visits for ILI below baseline levels. Two states reported local flu activity, 22 states reported sporadic activity, and 26 states reported no activity, while Guam and the US Virgin Islands reported local flu activity.
Oct 27 CDC FluView report

Committee recommends peramivir for use in Indian state
An advisory committee in the Indian state of Maharashtra has recommended that the state import the intravenous antiviral drug peramivir to better combat pandemic 2009 H1N1 influenza, according the Mumbai Mirror today. The state has confirmed 4,677 novel H1N1 cases, including 518 deaths, since Apr 1. An audit by the committee suggested that oseltamivir (Tamiflu) has failed to prevent death in high-risk patients and when treatment is delayed. It said that most deaths in the populous state, which includes Mumbai, have resulted from comorbidities and treatment delay. "Such patients have not responded to Tamiflu and have eventually succumbed," said committee member Dr Om Shrivastav. Shrivastav said peramivir may help reduce deaths in the state, which remain higher than in other parts of the country. The drug is not currently approved for use in India. It was approved for use in certain high-rish US patients during the H1N1 pandemic through an emergency use authorization.

Analysis suggests treading cautiously when making mutation-severity links
Apparent links between influenza-virus mutations and disease severity may instead be at least in part attributable to "founder effects," according to an analysis published today that examined whole-genome phylogenetic trees, 3D structural modeling, and complete clinical epidemiologic data. The researchers, from Brazil and Singapore, compared the mutations hemagglutinin (HA)-Q310H, PB2-K340N, HA-D239N, and HA-D239G. They note that phylogenetic analysis points to the role of founder effects, which refers to limited genetic variation in a new virus such as novel H1N1 flu. They refer to one of the mutations as an example: "Considering the prevailing viral genomic background, shared origin of samples (all from the city of Sao Paulo) and narrow temporal window (all death case samples within 1 month), it becomes clear that HA-Q310H was actually a generally common mutation in the region at that time which could readily explain its increased occurrence among the few analyzed fatal cases without requiring necessarily an association with severity. In further support of this, we highlight 3 mild cases with the HA-Q310H mutation." The authors conclude, "We argue that claims of severity of any current and future flu mutation need to be critically considered in the light of phylogenetic, structural, and detailed epidemiological data to distinguish increased occurrence due to possible founder effects rather than real phenotypic changes."
Nov 1 Virol J abstract

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