Incubation periods of acute respiratory viral infections: A systematic review

Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA.
The Lancet Infectious Diseases (Impact Factor: 22.43). 06/2009; 9(5):291-300. DOI: 10.1016/S1473-3099(09)70069-6
Source: PubMed


Knowledge of the incubation period is essential in the investigation and control of infectious disease, but statements of incubation period are often poorly referenced, inconsistent, or based on limited data. In a systematic review of the literature on nine respiratory viral infections of public-health importance, we identified 436 articles with statements of incubation period and 38 with data for pooled analysis. We fitted a log-normal distribution to pooled data and found the median incubation period to be 5.6 days (95% CI 4.8-6.3) for adenovirus, 3.2 days (95% CI 2.8-3.7) for human coronavirus, 4.0 days (95% CI 3.6-4.4) for severe acute respiratory syndrome coronavirus, 1.4 days (95% CI 1.3-1.5) for influenza A, 0.6 days (95% CI 0.5-0.6) for influenza B, 12.5 days (95% CI 11.8-13.3) for measles, 2.6 days (95% CI 2.1-3.1) for parainfluenza, 4.4 days (95% CI 3.9-4.9) for respiratory syncytial virus, and 1.9 days (95% CI 1.4-2.4) for rhinovirus. When using the incubation period, it is important to consider its full distribution: the right tail for quarantine policy, the central regions for likely times and sources of infection, and the full distribution for models used in pandemic planning. Our estimates combine published data to give the detail necessary for these and other applications.

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    • "In spite of these epidemiological consequences, precise estimates of the mismatch between the ends of the incubation and latent periods are scarce in the scientific literature. Information on both periods is available for several human diseases (Anderson and May 1992; Bailey 1954; Johansson et al. 2010; Lee et al. 2013; Lessler et al. 2009). However, such data are often approximate (Chan and Johansson 2012), because for obvious ethical reasons most of the related studies are based on observations of naturally infected patients (often resulting in censored data since the infection date is rarely known) and rarely on experimental data. "
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    ABSTRACT: The relative durations of the incubation period (the time between inoculation and symptom expression) and of the latent period (the time between inoculation and infectiousness of the host) are poorly documented for plant diseases. However, the extent of asynchrony between the ends of these two periods (i.e., their mismatch) can be a key determinant of the epidemic dynamics for many diseases and consequently it is of primary interest in the design of disease management strategies. In order to assess this mismatch, an experimental approach was developed and applied using sharka, a severe disease caused by Plum pox virus (PPV, genus Potyvirus, family Potyviridae) affecting trees belonging to the genus Prunus. Leaves of infected young peach trees were used individually as viral sources in aphid-mediated transmission tests carried out at different time points postinoculation in order to bracket symptom onset. By fitting a nonlinear logistic model to the obtained transmission rates, we demonstrated that the first symptoms appear on leaves 1 day before they rapidly become infectious. In addition, among symptomatic leaves, symptom intensity and transmission rate are positively correlated. These results strengthen the conclusion that, under our experimental conditions, incubation and latent periods of PPV infection are almost synchronous.
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    • "In addition, the short follow-up duration of this trial means there is a possible failure to detect some infections. The incubation period of respiratory viruses may range from less than 2 days (e.g., rhinovirus and influenza) to more than 5 days (adenovirus, MERS-CoV) [30] [31]. However, it is believed that post-Hajj Health diaries will reduce this shortcoming to some extent. "
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    • "The present study utilized a case-crossover design which is most suitable for studying relations with the following characteristics: 1) the individual exposure varies within short time intervals; 2) the disease has abrupt onset and short latency for detection; and 3) the induction period is short [17]. For ambient temperature and AH the hazard period was defined as three days preceding the visit to the clinic for a respiratory infection (and when virological samples were collected) on the basis of the estimated incubation period of 1–2 days for influenza [18]. A symmetric bidirectional selection of two reference periods shortly before and after the hazard period was utilized [19]. "
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    ABSTRACT: Both temperature and humidity may independently or jointly contribute to the risk of influenza infections. We examined the relations between the level and decrease of temperature, humidity and the risk of influenza A and B virus infections in a subarctic climate. We conducted a case-crossover study among military conscripts (n = 892) seeking medical attention due to respiratory symptoms during their military training period and identified 66 influenza A and B cases by PCR or serology. Meteorological data such as measures of average and decline in ambient temperature and absolute humidity (AH) during the three preceding days of the onset (hazard period) and two reference periods, prior and after the onset were obtained. The average temperature preceding the influenza onset was -6.8 +/- 5.6[degree sign]C and AH 3.1 +/- 1.3 g/m3. A decrease in both temperature and AH during the hazard period increased the occurrence of influenza so that a 1[degree sign]C decrease in temperature and 0.5 g decrease per m3 in AH increased the estimated risk by 11% [OR 1.11 (1.03 to 1.20)] and 58% [OR 1.58 (1.28 to 1.96)], respectively. The occurrence of influenza infections was positively associated with both the average temperature [OR 1.10 per 1[degree sign]C (95% confidence interval 1.02 to 1.19)] and AH [OR 1.25 per g/m3 (1.05 to 1.49)] during the hazard period prior to onset. Our results demonstrate that a decrease rather than low temperature and humidity per se during the preceding three days increase the risk of influenza episodes in a cold climate.
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