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News Archives

  

Volume 2 No 24; 13 June 2008

 

The prevention and control of air travel associated tuberculosis

The World Health Organization (WHO) has published the 3rd edition of its guidelines Tuberculosis and air travel: guidelines for prevention and control [1]. The guidelines aim to provide greater clarity for public health authorities, passengers and airlines.

Air travel has become increasingly common over the last few decades resulting in greater risk of the spread of infectious diseases. The risk of transmission in an enclosed environment is particularly important with regard to diseases involving airborne transmission such as tuberculosis (TB). Although no case of clinical or culture-confirmed TB attributable to exposure during air travel has been established, several studies have published evidence supporting the transmission of TB during air travel [2,3]. Such risk of transmission raises concern among passengers, public health authorities and airlines. The WHO first published guidelines regarding the prevention and control of air travel related TB in 1998, which were revised in 2006.

The emergence of extensively drug-resistant TB (XDR-TB), the revision of the International Health Regulations [4] and the experiences of public health authorities involved in investigating increasing numbers of incidents highlighted the need for updated international guidelines. The 3 rd edition of Tuberculosis and air travel was prepared by the WHO in collaboration with national public health authorities, including the Health Protection Agency (HPA), and international experts in travel medicine and the prevention and control of TB. The latest edition provides greater clarity in the definition of index cases considered to be infectious and more detail regarding the roles and responsibilities of the agencies involved in the follow-up of contacts. The guidelines also allow greater flexibility for following national recommendations and recognise that further research is needed to improve our understanding of the transmission of TB during air travel and the effectiveness of contact investigation.

The release of the new guidelines by the WHO coincides with the publication of an HPA study which highlights the difficulties for public health authorities investigating contacts of air travel-associated cases of TB [5].

The study, published in Eurosurveillance , identified 24 air travel-related TB incidents, reported between January 2007 and February 2008, which required follow-up of passenger contacts in accordance with the WHO guidelines. In 17 incidents, no further investigation of contacts was possible other than obtaining passenger lists due to a lack of information available from airlines. In the remaining incidents, variable quality of contact information was obtained; no further cases of TB infection or disease were identified. The findings of the study suggest that the process of investigating contacts of air travel-associated TB cases is complicated and usually unsuccessful without dedicated resources and the availability of good quality contact information from airlines. In view of this, the approach to contact investigation recommended in UK guidelines published by the National Institute for Health and Clinical Excellence [6] provides a pragmatic way to respond to these incidents.

References

1. World Health Organization. Tuberculosis and air travel: guidelines for prevention and control. 3rd Edition. WHO/HTM/TB/2008.399. Geneva, World Health Organization, 2008

2. Driver CR, Valway SE, Morgan WM, Onorato IM, Castro KG. Transmission of Mycobacterium tuberculosis associated with air travel. JAMA. 1994;272(13):1031-5.

3. Kenyon TA, Valway SE, Ihle WW, Onorato IM, Castro, KG. Transmission of multidrug-resistant Mycobacterium tuberculosis during a long airplane flight. N Engl J Med. 1996;334(15):933-938.

4. World Health Organization. International Health Regulations (2005). Available online: http://www.who.int/gb/ebwha/pdf_files/WHA58/WHA58_3-en.pdf.

5. Abubakar I, Welfare R, Moore J, Watson, JM. Surveillance of air-travel-related tuberculosis incidents, England and Wales: 2007-2008. Euro Surveill. [serial online] 2008 [accessed 12 June 2008];13(23): pii18896. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=18896.

6. National Collaborating Centre for Chronic Conditions. Tuberculosis: clinical diagnosis and management of tuberculosis, and measures for its prevention and control. 2006. London, Royal College of Physicians.

 

Epidemiological investigation of hepatitis E on a cruise ship (update 3)

The on-going cross Agency investigation [1,2,3] into hepatitis E among passengers on a cruise ship has now identified a total of 36 positive individuals of whom 11 are classed as cases (symptomatic), 16 are recent acute infections and nine are possible recent infections.

To date 707 completed questionnaires and 757 blood samples have been received. So far 621 of the participants have provided both sample and questionnaire. Of the 757 blood samples tested, 36 (5%) were positive (as described above). A further 149 (20%) were positive for IgG antibodies only, indicating past infection which is unlikely to have occurred during the cruise, and 572 (75%) were negative with no indication of hepatitis E infection.

Participants have been notified of their results and those who were reactive for IgG with other markers compatible with possible infection have also been followed up. The analysis of the questionnaires will commence once data entry is completed and a summary of the findings will be sent to all participants.

References

1. Hepatitis E in passengers on a cruise ship, http://www.hpa.org.uk/hpr/archives/2008/news1408.htm#hepE

2. Update on the investigation of Hepatitis E on a cruise ship, http://www.hpa.org.uk/hpr/archives/2008/news1908.htm#hepE

3. Epidemiological investigation of Hepatitis E on a cruise ship (update 2), http://www.hpa.org.uk/hpr/archives/2008/news2008.htm