Recognizing true H5N1 infections in humans during confirmed outbreaks.

INTRODUCTION: The goal of this study was to evaluate whether any characteristics that are evident at presentation for urgent medical attention could be used to differentiate cases of H5N1 in the absence of viral testing. METHODOLOGY: Information about exposure to poultry, clinical signs and symptoms, treatments, and outcomes was abstracted from existing data in the global avian influenza registry (www.avianfluregistry.org) using standardized data collection tools for documented and possible cases of H5N1 infection who presented for medical attention between 2005-2011 during known H5N1 outbreaks in Azerbaijan, Indonesia, Pakistan and Turkey. RESULTS: Demography, exposure to poultry, and presenting symptoms were compared, with only the common symptoms of fever and headache presenting significantly more frequently in confirmed H5N1 cases than in possible cases. Reported exposure to  infected humans was also more common in confirmed cases. In contrast, unexplained respiratory illness, sore throat, excess sputum production, and rhinorrhea were more frequent in possible cases. Overall, oseltamivir treatment showed a survival benefit, with the greatest benefit shown in H5N1 cases who were treated within two days of symptom onset (51% reduction in case fatality). CONCLUSION: Since prompt treatment with antivirals conferred a strong survival benefit for H5N1 cases, presumptive antiviral treatment should be considered for all possible cases presenting during an outbreak of H5N1 as a potentially life-saving measure

Effectiveness of antiviral treatment in human influenza A(H5N1) infections: analysis of a Global Patient Registry.

BACKGROUND: Influenza A(H5N1) continues to cause infections and possesses pandemic potential. METHODS: Data sources were primarily clinical records, published case series, and governmental agency reports. Cox proportional hazards regression was used to estimate the effect of treatment on survival, with adjustment using propensity scores (a composite measure of baseline variables predicting use of treatment). RESULTS: In total, 308 cases were identified from 12 countries: 41 from Azerbaijan, Hong Kong SAR, Nigeria, Pakistan, and Turkey (from clinical records); 175 from Egypt and Indonesia (from various sources); and 92 from Bangladesh, Cambodia, China, Thailand, and Vietnam (from various publications). Overall crude survival was 43.5%; 60% of patients who received ≥1 dose of oseltamivir alone (OS(+)) survived versus 24% of patients who had no evidence of anti-influenza antiviral treatment (OS(-)) (P <.001). Survival rates of OS(+) groups were significantly higher than those of OS(-) groups; benefit persisted with oseltamivir treatment initiation <or=6-8 days after symptom onset. Multivariate modeling showed 49% mortality reduction from oseltamivir treatment. CONCLUSIONS: H5N1 causes high mortality, especially when untreated. Oseltamivir significantly reduces mortality when started up to 6-8 days after symptom onset and appears to benefit all age groups. Prompt diagnosis and early therapeutic intervention should be considered for H5N1 disease