Page 198 - Timeliness of Infectious Disease Notification & Response Systems - Corien Swaan

196 Chapter 9
the maximum reporting delay for which it is still possible to control disease transmission, i.e. for which the expected number of onward trans-missions by a first generation case at the moment of notification of the index case is below 1 (R x PIR2<1). A stricter outbreak control condition, which requires that the expected number of onward transmissions by the index case is below 1 at the moment of notification, is hard to achieve in practice, and we therefore did not consider it in this thesis.
We used Osiris data of notifications to the MHS between July 2003 and Jan- uary 2012 to determine the median total local reporting delay (D1) per disease, and concluded that only hepatitis A and hepatitis B were within this outbreak control limit of 17 and 52 days respectively, during that period. Total local re- porting delays of measles and mumps was within reach of outbreak control, and needed to be reduced by only a few days (measles 4 days and mumps 1 day). For shigellosis and pertussis the outbreak control limit was considered beyond reach, as for shigellosis the median total local reporting delay needed to be reduced by more than 11 days (from 14.6 to 3 days) and for pertussis by more than 5 weeks (from 40.8 to 4.5 days).
Notifications between 2013 and November 2017 show that, besides hepa- titis A and hepatitis B, also measles is notified below the outbreak control limit as median D1 decreased from 9 to 4 days. This probably is a consequence of the measles outbreak in 2013-2014 during which doctor’s delay was reduced by increased awareness through MHS and RIVM alerts, and laboratory delay was prevented as epidemiologically linked cases did not need laboratory confirma- tion. Applying the 80% threshold, only 72.2% of notifications in 2016-2017 were within the timeframe of 5 days. As import of cases is likely to continue with the measles outbreaks in Europe, further reduction of patient, doctor and laborato- ry delay is important.
The delays for mumps, shigellosis and pertussis did not improve substan- tially and did not reach the outbreak control timeframe. Delays in pertussis no- tifications have been observed by other countries as well and are related to the nonspecific symptoms in the initial phase of the disease. Crabbe et al. describe that in the UK, only 11% of notifications, either after laboratory confirmation or upon clinical suspicion, were made within 21 days of disease onset, the time- frame for prophylactic treatment for contacts (17). Heil et al. calculated an iden- tical median delay of 34 days in the south of the Netherlands as on national level (18). Both Heil and Crabbe urge to decrease notification delay through better awareness of physicians and laboratories. In our opinion, the outbreak control limit of 4.5 days is beyond reach, and besides reducing laboratory and