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Surveillance Report

02 May 2017

TRAVAX Outbreak Index 2016: Diseases of Public and Travel Health Risk

Introduction

According to Office for National Statistics data,1 there were an estimated 65.7 million journeys from UK airports abroad in 2015 which continued the general rise in travel that has been observed since the 1970s. While most of these journeys were to Europe (79%), North America, Asia and Africa accounted for 6%, 5%, and 4% of journeys, respectively. Latin America and the Caribbean and the Middle East accounted for 3% and 2%, respectively (Figure 1). Similar proportions were observed among the 3.5 million journeys from Scotland in 2015. It is projected that journeys from airports are likely to increase significantly in coming decades.2

TRAVAX (http://www.travax.nhs.uk) is an increasingly important resource across the UK. This is currently reflected by 1.2 million individual log-ins per year by the 4500 subscribing individuals and organisations giving advice to travellers going abroad. Members of the public can also access the freely available fitfortravel (http://www.fitfortravel.nhs.uk/home.aspx) which in 2016 had 4.1 million individual log-ins. The strength of TRAVAX lies in its provision of practical, up-to-date advice and guidance on vaccination, prophylaxis and other travel-health related issues. Additionally, information on current outbreaks abroad is sourced and summarised to ensure travel advisors and travellers themselves have access to the most relevant and useful information worldwide. These are obtained from a variety of sources including WHO, national ministries of health and ProMED.

Relevant outbreaks are published on TRAVAX to highlight increased risk with respect to a range of diseases, and are accompanied by recommendations for travellers so that they can reduce their risk.

While reports on imported infections3 and malaria4 along with publications in the travel literature give an indication of the effectiveness of guidance and advice for Scottish and UK travellers, reports on current outbreaks abroad help inform travellers of new or seasonal risks as they arise.

Maps

The following is a summary of the principal disease outbreaks and their locations which TRAVAX reported in 2016.

The main new risk reported (Map 1) was Zika virus which in 2016 was reported in the majority of Latin American countries and the Caribbean, as well as in the United States. Outbreaks were also reported in many Pacific Islands, countries of South East Asia as well as Guinea Bissau and Cape Verde in Africa.

Other Aedes-borne pathogens were also reported (Map 2). Dengue was reported in the Americas, and the Indian subcontinent in the main. Yellow fever was reported in Africa as well as in China (imported), while cases / outbreaks of Chikungunya were reported from Pakistan through much of South East Asia, as well as Australia and parts of South America.

A range of other arthropod-borne infections were also reported (Maps 3 and 4) including Ross River virus in Australia and West Nile virus across Europe. A significant increase in malaria was reported in Venezuela while Greece also reported autochthonous malaria transmission. In addition to insect-borne infections, increases of tick-borne infections were reported (Map 4). Tick-borne encephalitis (TBE) was reported in the USA, the Czech Republic and the Netherlands – the latter country’s first reported case.

Viral haemorrhagic fever outbreaks were reported in parts of the Indian subcontinent, Central Asia, and West Africa. Crimean Congo haemorrhagic fever (CCHF) cases with no history of travel were also reported in Spain. Imported cases of Lassa were reported by USA and Germany, both cases having resulted from transmission in Togo.

There were outbreaks of a range of vaccine-preventable diseases (Map 6) including measles in the USA, UK, Pakistan and parts of Africa. Polio cases continued to be reported in Pakistan and Afghanistan while meningitis outbreaks were reported from countries in the meningitis belt of sub-Saharan Africa.

A range of respiratory infections were reported with Legionella cases being reported in the USA and Europe, while Legionella in the United Arab Emirates (UAE) resulted in a number of cases in Europe. Saudi Arabia continued to report cases of MERS CoV while human cases of avian influenza continued to be reported from China.

Rabies outbreaks were reported in a variety of countries (Map 8) particularly in South East Asia. Monkey pox resulted in a number of human cases in Central Africa including at least one fatality.

Discussion

The data presented do not represent all the outbreaks reported to WHO, PAHO, ECDC or the various ministries of health. They represent rather those outbreaks that added value to the epidemiological information and clinical advice already present on TRAVAX.

The majority of outbreaks related to arthropod-borne infections which on the whole pose a very low risk to UK public health as the vectors for transmission do not generally occur in the UK.

With the global spread of Zika virus and the international concern over associated congenital abnormalities,5 increased awareness and testing demonstrated that Zika was transmitted in the main by A. aegypti and spread within its natural geographic limits (Map 1). There is much that is unknown as to its epidemiology in Africa and Asia, however, and HPS continues to liaise with Public Health England (PHE) to ensure UK advice is proportionate and evidence-based.

In the context of public health, the outbreaks of vaccine-preventable diseases and respiratory conditions are of interest. A range of vaccine-preventable disease outbreaks were reported, generating associated advice on appropriate vaccinations to consider for travellers. Pertussis and measles outbreaks were reported in North America and Australia. Bearing in mind that North America receives the second largest proportion of travellers from the UK after Europe, it is important that travellers who are not fully immunised are advised of the risk and action to take.

With respect to respiratory infections, outbreaks of Legionella continued to constitute a risk to travellers e.g. transmission in the UAE resulting in cases being identified in Europe. While MERS CoV cases continue to be reported in Saudi Arabia, transmission to travellers remained a low probability even during the Hajj.

After the large Ebola outbreak in West Africa in 2014, countries remain vigilant to both autochthonous transmission in endemic areas as well as to imported cases. Both Germany and USA reported imported cases of Lassa fever while Spain reported two autochthononous cases of CCHF. This, along with virus detection in ticks in Extremadura, suggested a low probability of CCHF transmission in Spain.6

Key issues to note are:

  • The potential role unvaccinated travellers may play in importing measles, mumps, polio etc. into the UK. The pre-travel consultation provides a good opportunity to check a traveller’s history of National Schedule vaccines including influenza and MMR.
  • The importance of taking a good travel history for those seen in GP practice or admitted to hospital. For example cases of Lassa fever, if not identified early may be placed on open wards and so transmit the disease to others. It is also important to indicate recent travel history in any requests made to laboratories for testing so that this data is picked up in national surveillance.

References

  1. Office for National Statistics. Travel Trends: 2015. 2016. Available from: https://www.ons.gov.uk/peoplepopulationandcommunity/leisureandtourism/articles/traveltrends/2015. (accessed 27 April 2017).
  2. Department for Transport. UK Aviation Forecasts. 2011. Available from: https://www.gov.uk/government/publications/uk-aviation-forecasts-2011. (accessed 27 April 2017).
  3. Munro J, Redman C. HPS report on laboratory-confirmed travel-related infections in Scotland during 2015. HPS Weekly Report. 2016;50(3):23-33. Available from: http://www.hps.scot.nhs.uk/ewr/redirect.aspx?id=66664. (accessed 27 April 2017).
  4. Munro J, Denham B, Smith V et al. (2016). Travel health: Malaria reported in Scotland 2015. HPS Weekly Report. 2016;50(28):212-228. Available from: http://www.hps.scot.nhs.uk/ewr/redirect.aspx?id=68721. (accessed 27 April 2017).
  5. World Health Organization. WHO statement on the first meeting of the International Health Regulations (2005) (IHR 2005) Emergency Committee on Zika virus and observed increase in neurological disorders and neonatal malformations. 2016. Available from: http://www.who.int/mediacentre/news/statements/2016/1st-emergency-committee-zika/en/. (accessed 27 April 2017).
  6. European Centre for Disease Prevention and Control. Rapid risk assessment: Crimean–Congo haemorrhagic fever in Spain. 2016. Available from: http://ecdc.europa.eu/en/publications/_layouts/forms/Publication_DispForm.aspx?List=4f55ad51-4aed-4d32-b960-af70113dbb90&ID=1570. (accessed 27 April 2017).
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Author(s): Prepared by: The Travel and International Health Team Vol: 51 No: 17 Year: 2017 Page:

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