Giuseppe
Emeritus
Viral Shedding and Clinical Illness in Naturally Acquired Influenza Virus Infections. (J Infect Dis., abstract, edited)
[Source: US National Library of Medicine, (LINK). Edited.]
J Infect Dis. 2010 Mar 31. [Epub ahead of print]
Viral Shedding and Clinical Illness in Naturally Acquired Influenza Virus Infections.
Lau LL, Cowling BJ, Fang VJ, Chan KH, Lau EH, Lipsitch M, Cheng CK, Houck PM, Uyeki TM, Peiris JS, Leung GM. - Infectious Disease Epidemiology Group, School of Public Health, and 2Department of Microbiology, University of Hong Kong, Hong Kong, China; 3Harvard School of Public Health, Boston, Massachusetts; 4Seattle Quarantine Station, Division of Global Migration and Quarantine, Centers for Disease Control and Prevention, National Center for Preparedness, Detection and Control of Infectious Diseases, Seattle, Washington; 5Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
Background.
Volunteer challenge studies have provided detailed data on viral shedding from the respiratory tract before and through the course of experimental influenza virus infection. There are no comparable quantitative data to our knowledge on naturally acquired infections.
Methods.
In a community-based study in Hong Kong in 2008, we followed up initially healthy individuals to quantify trends in viral shedding on the basis of cultures and reverse-transcription polymerase chain reaction (RT-PCR) through the course of illness associated with seasonal influenza A and B virus infection.
Results.
Trends in symptom scores more closely matched changes in molecular viral loads measured with RT-PCR for influenza A than for influenza B. For influenza A virus infections, the replicating viral loads determined with cultures decreased to undetectable levels earlier after illness onset than did molecular viral loads. Most viral shedding occurred during the first 2-3 days after illness onset, and we estimated that 1%-8% of infectiousness occurs prior to illness onset. Only 14% of infections with detectable shedding at RT-PCR were asymptomatic, and viral shedding was low in these cases.
Conclusions.
Our results suggest that "silent spreaders" (ie, individuals who are infectious while asymptomatic or presymptomatic) may be less important in the spread of influenza epidemics than previously thought.
PMID: 20377412 [PubMed - as supplied by publisher]
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[Source: US National Library of Medicine, (LINK). Edited.]
J Infect Dis. 2010 Mar 31. [Epub ahead of print]
Viral Shedding and Clinical Illness in Naturally Acquired Influenza Virus Infections.
Lau LL, Cowling BJ, Fang VJ, Chan KH, Lau EH, Lipsitch M, Cheng CK, Houck PM, Uyeki TM, Peiris JS, Leung GM. - Infectious Disease Epidemiology Group, School of Public Health, and 2Department of Microbiology, University of Hong Kong, Hong Kong, China; 3Harvard School of Public Health, Boston, Massachusetts; 4Seattle Quarantine Station, Division of Global Migration and Quarantine, Centers for Disease Control and Prevention, National Center for Preparedness, Detection and Control of Infectious Diseases, Seattle, Washington; 5Influenza Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
Background.
Volunteer challenge studies have provided detailed data on viral shedding from the respiratory tract before and through the course of experimental influenza virus infection. There are no comparable quantitative data to our knowledge on naturally acquired infections.
Methods.
In a community-based study in Hong Kong in 2008, we followed up initially healthy individuals to quantify trends in viral shedding on the basis of cultures and reverse-transcription polymerase chain reaction (RT-PCR) through the course of illness associated with seasonal influenza A and B virus infection.
Results.
Trends in symptom scores more closely matched changes in molecular viral loads measured with RT-PCR for influenza A than for influenza B. For influenza A virus infections, the replicating viral loads determined with cultures decreased to undetectable levels earlier after illness onset than did molecular viral loads. Most viral shedding occurred during the first 2-3 days after illness onset, and we estimated that 1%-8% of infectiousness occurs prior to illness onset. Only 14% of infections with detectable shedding at RT-PCR were asymptomatic, and viral shedding was low in these cases.
Conclusions.
Our results suggest that "silent spreaders" (ie, individuals who are infectious while asymptomatic or presymptomatic) may be less important in the spread of influenza epidemics than previously thought.
PMID: 20377412 [PubMed - as supplied by publisher]
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