Volume 13, Number 9—September 2007
Frequent Travelers and Rate of Spread of Epidemics
|Basic reproductive number||R0||2.5 (13)||1.8 (14)|
|Latent period, d||TL||4 (13)||1.5 (14)|
|Infectious period, d||TI||10 (13)||1.1 (14)|
|Generation time, d||Tg = TL + TI||14||2.6|
|Epidemic doubling time, d||td = Tg / (R0 – 1) ln2||6.5||2.3|
|Proportion of population who are high-frequency fliers||r||0–0.5|
|Mixing between groups: φ = 1, random mixing; φ = 0, assortative mixing||φ||0–1|
|Relative probability of flying of high-frequency fliers||f||20|
|Mean probability of flying per day||ε||0.005 (9)|
|Probability of flying per day of high-frequency fliers||εH = f / 1 + (f – 1)r ε||0.084|
|Probability of flying per day of low-frequency fliers||εL = 1 / 1 + (f – 1)r ε||0.042|
|Probability of a case being exported|
|Homogeneous flying patterns||L = TLε||0.02||0.008|
|High-frequency fliers||lH = TLεH||0.34||0.13|
|Low-frequency fliers||lL = TLεL||0.017||0.006|
*SARS, severe acute respiratory syndrome.
- Denstadli JM. Analysing air travel: a comparison of different survey methods and data collection procedures. J Travel Res. 2000;39:4–10.
- Office for National Statistics. Travel trends 2004: a report on the international passenger survey. Basingstoke (UK): Palgrave Macmillan; 2005.
- Severe Acute Respiratory Syndrome (SARS) Expert Committee. SARS in Hong Kong: from experience to action: severe acute respiratory syndrome (SARS). Expert Committee of Hong Kong. 2003. [cited 2007 Jun 21]. Available from http://www.sars-expertcom.gov.hk/english/reports/reports.html
- Hufnagel L, Brockmann D, Geisel T. Forecast and control of epidemics in a globalized world. Proc Natl Acad Sci U S A. 2004;101:15124–9.
- Guimera R, Mossa S, Turtschi A, Amaral LA. The worldwide air transportation network: anomalous centrality, community structure, and cities’ global roles. Proc Natl Acad Sci U S A. 2005;102:7794–9.
- Colizza V, Barrat A, Barthelemy M, Vespignani A. The role of the airline transportation network in the prediction and predictability of global epidemics. Proc Natl Acad Sci U S A. 2006;103:2015–20.
- Pitman RJ, Cooper BS, Trotter CL, Gay NJ, Edmunds WJ. Entry screening for severe acute respiratory syndrome (SARS) or influenza: policy evaluation. BMJ. 2005;331:1242–3.
- Cooper BS, Pitman RJ, Edmunds WJ, Gay NJ. Delaying the international spread of pandemic influenza. PLoS Med. 2006;3:e212.
- Hollingsworth TD, Ferguson NM, Anderson RM. Will travel restrictions control the international spread of pandemic influenza? Nat Med. 2006;12:497–9.
- Ferguson NM, Cummings DA, Fraser C, Cajka JC, Cooley PC, Burke DS. Strategies for mitigating an influenza pandemic. Nature. 2006;442:448–52.
- Brownstein JS, Wolfe CJ, Mandl KD. Empirical evidence for the effect of airline travel on inter-regional influenza spread in the United States. PLoS Med. 2006;3:e401.
- Colizza V, Barrat A, Barthelemy M, Valleron AJ, Vespignani A. Modeling the worldwide spread of pandemic influenza: baseline case and containment interventions. PLoS Med. 2007;4:e13.
- Donnelly CA, Fisher MC, Fraser C, Ghani AC, Riley S, Ferguson NM, Epidemiological and genetic analysis of severe acute respiratory syndrome. Lancet Infect Dis. 2004;4:672–83.
- Ferguson NM, Cummings DA, Cauchemez S, Fraser C, Riley S, Meeyai A, Strategies for containing an emerging influenza pandemic in Southeast Asia. Nature. 2005;437:209–14.
- Anderson RM, Fraser C, Ghani AC, Donnelly CA, Riley S, Ferguson NM, Epidemiology, transmission dynamics and control of SARS: the 2002–2003 epidemic. Philos Trans R Soc Lond B Biol Sci. 2004;359:1091–105.
- Yu F, Le MQ, Inoue S, Thai HT, Hasebe F, Del Carmen Parquet M, Evaluation of inapparent nosocomial severe acute respiratory syndrome coronavirus infection in Vietnam by use of highly specific recombinant truncated nucleocapsid protein-based enzyme-linked immunosorbent assay. Clin Diagn Lab Immunol. 2005;12:848–54.
- Wilder-Smith A, Teleman MD, Heng BH, Earnest A, Ling AE, Leo YS. Asymptomatic SARS coronavirus infection among healthcare workers, Singapore. Emerg Infect Dis. 2005;11:1142–5.
- Leung GM, Lim WW, Ho LM, Lam TH, Ghani AC, Donnelly CA, Seroprevalence of IgG antibodies to SARS-coronavirus in asymptomatic or subclinical population groups. Epidemiol Infect. 2006;134:211–21.
- Leung GM, Chung PH, Tsang T, Lim W, Chan SK, Chau P, SARS-CoV antibody prevalence in all Hong Kong patient contacts. Emerg Infect Dis. 2004;10:1653–6.
- Lee PP, Wong WH, Leung GM, Chiu SS, Chan KH, Peiris JS, Risk-stratified seroprevalence of severe acute respiratory syndrome coronavirus among children in Hong Kong. Pediatrics. 2006;117:e1156–62.
- Centers for Disease Control and Prevention. Prevalence of IgG antibody to SARS-associated coronavirus in animal traders—Guangdong Province, China, 2003. MMWR Morb Mortal Wkly Rep. 2003;52:986–7.
- Longini IM Jr, Nizam A, Xu S, Ungchusak K, Hanshaoworakul W, Cummings DA, Containing pandemic influenza at the source. Science. 2005;309:1083–7.
- Germann TC, Kadau K, Longini IM Jr, Macken CA. Mitigation strategies for pandemic influenza in the United States. Proc Natl Acad Sci U S A. 2006;103:5935–40.
- Bell DM; World Health Organization Writing Group. Nonpharmaceutical interventions for pandemic influenza, international measures. Emerg Infect Dis. 2006;12:81–7.
Page created: July 01, 2010
Page updated: July 01, 2010
Page reviewed: July 01, 2010
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.