Eurosurveillance - Volume 13, Issue 23, 05 June 2008

Air travel has increased over the last few decades resulting in greater risk of the spread of infectious diseases carried by infectious travellers. The risk of transmission of pathogens is particularly important for airborne organisms raising concern among public health agencies and the public. Despite limited research on the risk of tuberculosis associated with air travel, several reports have published evidence of the transmission of tuberculosis infection, including multidrug-resistant tuberculosis (MDR-TB) [1, 2].

An analysis of sentinel surveillance data of TropNetEurop shows 453 imported cases of falciparum malaria for 2007 - 442 with falciparum (97.6%) only and 11 with mixed plasmodial infections [1]. Previous comparisons with national notification data have shown that the sentinel system of TropNetEurop, with 53 member countries, covers approximately 12% of all imported malaria cases in Europe. Thus, although the analysis does not give a complete picture, we feel it gives a good indication of the quantity and quality of this infection in northern Europe. Although this trend is not mirrored in all countries in a similar way, overall numbers have been decreasing since a peak of 928 cases of falciparum malaria in 2003. The reasons for this are unclear, but decreased infection risks for travellers due to decreased vector exposure may play a significant role. .

The potential spread of tuberculosis (TB) from infectious passengers during air travel has recently received increasing attention in the media and from public health authorities. We reviewed all air travel-related tuberculosis incidents reported to the Health Protection Agency Centre for Infections between January 2007 and February 2008 in England and Wales and investigated the effectiveness of contact investigation. Incidents involving air travel were defined according to the World Health Organization's guidelines on TB and Air Travel. We collected data on the index case, the incident and the outcome of contact investigation where available. We identified 24 incidents involving 39 flights. The median flight duration was 8.9 hours (inter-quartile range (IQR) 8 to 11.7). Most flights (36) were from or to a high burden country and 19 of the 24 incidents reported had a smear-positive index case. Two index cases had multidrug-resistant tuberculosis. In 17 incidents, no further investigation could be undertaken due to the lack of passenger information. In the remaining seven incidents, the quality of contact information obtained was variable. No further cases of TB infection or disease were identified. This study suggests that the process of investigating passenger contacts of a TB infected individual travelling by air is complicated and usually unsuccessful without dedicated resources and availability of high-quality contact information from airlines. Further research into the effectiveness of contact investigation in this setting is needed. .

Since 1994, the incidence of gonorrhoea in Østfold county, Norway, has remained within the range of 1-8 cases per year, with 40% of cases being imported from abroad. On 20 January 2008, a general practitioner in the county diagnosed two seemingly unrelated domestic cases of gonorrhoea in three days and started contact tracing. A case was defined as a person with clinical symptoms of gonorrhoea who was a part of the sexual network. Available isolates from the samples taken were tested for resistance. Among 13 contacts identified in the sexual network, eight were classified as cases on the basis of symptoms, four of whom had laboratory-confirmed gonorrhoea. The index case acquired the infection abroad. The three isolated strains were resistant to ciprofloxacin, but sensitive to ceftriaxone which was used for treatment. In the outbreak described, most cases were diagnosed only after contact tracing although they had had symptoms. A quinolone-resistant strain was imported from abroad and introduced into the population. The Norwegian national treatment guidelines, which still recommend quinolones for empirical treatment, should be updated. .

While the authors raise valid points with regards to a more concerted approach to personal hygiene, there are two issues in the report which we wish to respond to.

We agree that promulgating the hygiene hypothesis and related environmental issues to the public can serve to confuse, rather than to inform. The reality is however that these issues have already received widespread coverage by the media, which tends to leave the public concerned and confused about the role of hygiene and cleanliness, particularly in relation to the functioning of the immune system.