Page 139 - Timeliness of Infectious Disease Notification & Response Systems - Corien Swaan

Timeliness of contact tracing among flight passengers 137
Background
Aircrafts can function as transport vehicle for patients infected with influenza, leading to introduction of a new virus strain to non-endemic areas [1,2]. Alt- hough the risk is small, passengers might be infected by a contagious patient during the flight [3-5,6], as well as during public transport [7]. Transmission du- ring the flight increases the possibility of further transmission in the area of destination. For these reasons, during the initial phase of the influenza A/H1N1 2009 pandemic, many countries initiated contact tracing among flight passen- gers of flights where contagious patients with laboratory confirmed influenza A/ H1N1 2009 were notified.
A risk assessment guideline for infectious diseases transmitted on aircrafts has been developed by the European Centre for Disease Prevention and Control (ECDC) [8], which includes influenza. Literature study revealed on-board trans- mission in flights with a duration of less than 8 h. The majority of infected contacts during these flights were seated on the same row, or one or two rows in front of behind the index [9-12]. Contacts up to 8 and 10 rows distance from the index were infected in one study [10]. As these contacts also had personal contact with the index during the flight, transmission across a distance of so many rows is not proven. The guideline concludes that it is difficult to design a single contact tra- cing algorithm for influenza. Due to the short incubation period of influenza, it is almost impossible to provide contacts with postexposure prophylaxis (PEP) wit- hin the time that it is most effective, which is 48 h after exposure [13]. Therefo- re, the main aim of contact tracing might be to interrupt the chain of transmis- sion by alerting contacts for early diagnosis and treatment. Although the World Health Organization (WHO) developed technical advice for case management of influenza A/H1N1 2009 in air transport during the pandemic [14], no interna- tional standardized protocol for contact tracing for this pathogen was available.
In line with the ECDC guideline [8] and the Dutch guideline for ‘Incidental introduction of a new influenza strain’ [15], in the Netherlands close contacts of a patient with laboratory confirmed pandemic influenza were identified. In case the index had been contagious during a flight with a duration of ≥ 4 h, passen- gers and cabin crew were to be informed on signs and symptoms of the disease and to seek medical care in case they would occur. In addition, close contacts, defined as passengers seated on the same row, two rows in front and two rows behind the index case, as well as the cabin crew working in this compartment, were traced by public health authorities to provide a 10 day prophylactic course of oseltamivir as soon as possible (preferably within 48 h after exposure).
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