Clinical Updates
3 September 2010
West Nile virus (humans): Greece, Hungary, Romania and the Russian Federation
The outbreak of West Nile virus (WNV) on the Greek mainland, first reported in early July, 2010, is continuing [1]. As of 3 September 2010, 173 cases including 15 deaths have been confirmed in the region of Central Macedonia and its capital, Thessaloniki [2]. Although WNV has been previously identified in animals in Greece, the current outbreak is the first to involve humans [3]. Mosquito control measures have been implemented and surveillance systems enhanced [4]. The situation is being closely monitored by public health authorities in Greece and by the European Centre for Disease Prevention and Control [4, 5].
WNV is an emerging disease in southern Europe [6, 7] and is endemic in other parts of Europe and the Mediterranean basin [8]. In Portugal, one probable human case was reported in July 2010 [4]. The Russian Federation has reported 231 cases since the beginning of July until 31 August 2010, with the majority from Volograd region [9]. On 30 August 2010, the Health Ministry, Bucharest, Romania issued guidance on protective measures against mosquitoes following seven confirmed cases of WNV with two deaths [10]. Confirmed and probable cases have been reported from Alba, Bucharest, Cluj, Constanta, Dolj, Galati, Mures, Sibiu and Teleorman. On 1 September 2010, three cases of WNV were reported in Hungary, one case from Budapest and one case in each of the counties of Bekes and Pest [11].
West Nile virus
WNV infection is caused by a flavivirus. The primary hosts are birds and horses and the virus is transmitted by Culex spp. mosquitoes.
The majority of WNV infections (around 80%) are asymptomatic. Less than 20% of infected persons will experience a mild, self-limited illness with fever, headache, myalgias, and rash; less than 1% will develop a more severe neurological syndrome of meningitis and/or encephalitis.
Advice for travellers
There is a very low risk of contracting WNV during travel to Greece or the rest of Europe. Individuals over 50 years of age are at highest risk of developing severe neurological disease following WNV infection [12].
During travel to risk areas, individuals should take mosquito bite avoidance measures. There are no vaccines that prevent WNV in humans.
Advice for health care professionals
The Health Protection Agency (HPA) undertakes enhanced surveillance for human WNV in the UK.
Physicians who see travellers with a characteristic febrile illness, who have returned from WNV endemic areas, should be alert to the possibility of WNV infection. Relevant samples for testing together with a full clinical and travel history should be submitted to the Health Protection Agency Special Pathogens Reference Unit.
References
1. Papa A, Danis K Baka A et al. Ongoing outbreak of West Nile virus infections in humans in Greece, July – August 2010. Euro Surveill. 26 August 2010;15(34):pii=19644. [Accessed 3 September 2010]. Available at: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19644
2. Centre of Control and Prevention of Disease. Athens, Greece. Daily Report of Epidemiological Surveillance of West Nile Virus Infection in Greece. 3 September 2010. [Accessed 3 September 2010]. Available at: http://www.keelpno.gr/keelpno/2010/id990/daily_report_
3. Kantzanou MN, Moschiddis ZM, Kremastinou G, et al. Searching for West Nile virus (WNV) in Greece. Transfusion Med. 20:113–7, 2010.
4. Zeller H, Lenglet A, Van Bortel W. West Nile virus: the need to strengthen preparedness in Europe. Euro Surveill. 2010;15(34):pii=19647. [Accessed 3 September 2010]. Available at: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=19647
5. European Centre for Disease Prevention and Control. West Nile virus outbreak in Greece. 26 August 2010. [Accessed 3 September 2010]. Available at: http://www.ecdc.europa.eu/en/activities/sciadvice/Lists/ECDC%
20Reviews/ECDC_DispForm.aspx?List=512ff74f%2D77d4%2
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6. Hubalek Z, Halouzka J. West Nile Fever – a re-emerging mosquito-borne viral disease in Europe. Emerg Inf Dis. 5:643-50, 1999.
7. Health Protection Agency. West Nile virus activity in Southern Europe. 12 March 2010. [Accessed 3 September 2010]. Available at: http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPA
8. Calistri P, Giovannini A, Hubalek Z, et al. Epidemiology of West Nile in Europe and in the Mediterranean Basin. Open Virol J. 4:29-37, 2010. [Accessed 3 September 2010]. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2878979/pdf/TOVJ-4-29.pdf
9. Rospotrebna. Press release: The epidemiology of West Nile Fever [In Russian]. 1 September 2010. [Accessed 3 September 2010]. Available at: http://www.rospotrebnadzor.ru/press_center/
10. The Health Ministry. Romania. Ministry of Health recommends protective measures against mosquitoes [In Romanian]. Press Release 30 August 2010. [Accessed 3 September 2010]. Available at: http://www.ms.ro/?pag=62&id=8551&pg=1
11. National National Epidemiology Centre, Hungary [Personal Communication, 1 September 2010].
12. European Centre for Disease Prevention and Control. West Nile Fever fact sheet. [Accessed 3 September 2010]. Available at: http://www.ecdc.europa.eu/en/healthtopics/west_nile_fever/
basic_facts/Pages/factsheet_health_professionals.aspx
Links
European Centre for Disease Prevention and Control. West Nile Fever factsheet
Health Protection Agency: West Nile virus - Advice for Health Professionals
Health Protection Agency: Special Pathogens Reference Unit
Health Protection Agency: West Nile Virus
NaTHNaC Clinical Update: 11 August 2010, West Nile Virus Central Macedonia, Greece
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