Page 41 - Timeliness of Infectious Disease Notification & Response Systems - Corien Swaan
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Timeliness of infectious disease reporting, the Netherlands, 2003-2009 39
of symptoms until notification (Po); the interval between timepoints diagnosis (T2) and notification (T5) was defined as the period from laboratory diagnosis until notification (Pd). We then determined the median of the distributions of Po and Pd for each of the six diseases.
Figure 1. Time-points (T) and intervals (P) in the notification process
Po = period between symptom onset and MHS notification
Pd = period between laboratory diagnosis and MHS notification MHS = Municipal Health Service
RIVM= National Institute for Public Health and the Environment
For comparison with the notification data, we used the midpoint of the range of the incubation period for each disease, as it is defined in the literature and in the national guidelines of the RIVM in the Netherlands [16]. We then calculated the percentage of notifications per disease occurring within one and two incubation periods respectively (in the context of preventing the occurrence of tertiary cases). There is international consensus that for HAV infections and measles, the period of infectiousness starts before onset of symptomatic disease. The incubation period (IP) for these diseases is thus less valid as a proxy for the period in which public health measures are most effective. More adequate for these diseases is the latent period (LP), defined as the period between being infected and be- coming infectious for others [17]. Reporting of the index case should prefera-
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