Limited novel influenza A (H1N1) 09 infection in travelling high-school tour group

Abstract

Please cite this paper as: Mardani et al. (2011) Limited novel influenza A (H1N1) 09 infection in travelling high‐school tour group. Influenza and Other Respiratory Viruses 5(1), 47–51. Background A single case of novel influenza A (H1N1) 09 infection was identified by PCR among a New Zealand high‐school group that toured California in April 2009. Close monitoring of the tour group and their New Zealand contacts identified 11 other tour members with respiratory symptoms who were investigated. In all nine instances where nasopharyngeal swabs were indicated, tests were negative for novel influenza A (H1N1) 09 by PCR. Objective To determine whether serology could identify any cases of novel influenza A (H1N1) 09 that had not been detected by PCR. Methods Acute and convalescent serological testing for antibodies against pandemic (H1N1) 2009 and seasonal A (H1N1) influenza viruses using haemagglutination inhibition assays and microneutralisation assays. Results Serological analysis of symptomatic tour members identified a further possible case of novel influenza A (H1N1) 09 infection. The possible case had not been tested by PCR because he or she had already received prophylaxis with oseltamivir. Conclusions These findings suggest infection among tour group members was limited despite prolonged periods of close contact during travel. Furthermore, multiple public health interventions are likely to have effectively prevented an outbreak following the tour group’s return.

Attack Rates Assessment of the 2009 Pandemic H1N1 Influenza A in Children and Their Contacts: A Systematic Review and Meta-Analysis

“…One group member became symptomatic due to the 2009 pandemic H1N1 influenza A, one hour after arrival in New Zealand. None of the other 11 group members who developed respiratory symptoms were positive for the virus by RT PCR, and only one of them was moderately positive by serology [38]. This low rate of transmission occurred despite a 6 hour bus ride that [38] the group took after the index case became symptomatic [38].…”

“…Figure 1 presents a flow chart of the selection process. The selected reports included outbreak analyses from the following countries: Australia [10], [12]–[14], Canada [15]–[18], Chile [19], China [20]–[22], Finland [23], France [24]–[27], Germany [28], [29],Hong Kong [30], [31], India [32], Japan [33]–[35], Kenya [36], Republic of Korea [37], Netherlands [7], New Zealand [38], Taiwan [39], United Kingdom (UK) [6], [40]–[45], and the United States (USA) [8], [9], [11], [38], [46]–[55]. Four reports provided analysis related to one outbreak in the USA [8], [9], [11], [51].…”

“…A different outcome of a prolonged journey was seen among members of a high school musical group from New Zealand that toured California USA for one week during the time that human transmission of the pandemic 2009 H1N1 influenza A was detected in the USA [38]. The tour included travel within California, a 12 hour flight to New Zealand (sitting in the same airplane section) and a six hour bus ride in New Zealand.…”

Risk factors and effectiveness of preventive measures against influenza in the community

“… 7 found no difference in the probability of a diagnosis of influenza in regular users of public transport, but an increased risk in adults with their own cars, and Mardani et al. 13 described limited transmission in prolonged periods of close contact during travel.…”

“…The influenza virus is transmitted in the community by infected people with or without symptoms, mostly by aerosol, but also by hand contact 1–3 . Propagation is favoured by large numbers of people in enclosed places, home, educational and occupational environments and public transport 4–13 . Various measures have proven efficacy in preventing influenza.…”