Lassa fever- Annual Epidemiological Report, 2016 [2014 data]
In 2014, no cases of Lassa fever or other arenaviruses responsible for viral haemorrhagic fevers were reported in the EU/EEA.
- In 2014, no cases of Lassa fever or other arenaviruses responsible for viral haemorrhagic fevers were reported in the EU/EEA.
- Data were obtained from 23 EU/EEA countries.
- The EU case definition was used by 15 countries, three countries used an alternative case definition, and five countries did not specify the case definition they used.
- Surveillance is compulsory in 20 EU/EEA countries, comprehensive in 21 countries, and mostly passive (active surveillance only in the Czech Republic, Slovakia and the United Kingdom) (Annex). Data reporting is case based and done at the national level.
No cases of Lassa fever were reported in EU and EEA countries in 2014.
Lassa fever is an acute viral illness that occurs in West Africa, mainly in Nigeria, Sierra Leone, Liberia and Guinea. A few cases were also reported in Cote d’Ivoire, Ghana and Benin. The viral aetiology of the disease was identified in 1969. The name refers to the town of Lassa, Nigeria, where the disease was first described. The reservoir of Lassa virus is a rodent known as the multimammate rat (Mastomys natalensis). Several other rodent-borne arenaviruses infecting humans (e.g. Junin, Machupo, Guanarito) circulate in South America .
Humans become infected through contact with the excreta of infected rodents. While about 80% of the infected people are asymptomatic, the remaining patients develop severe multi-system disease, and up to 15% of the hospitalised cases may die. Lassa fever is also associated with occasional epidemics, including nosocomial outbreaks, during which the case–fatality rate can reach 50%. Early treatment with the antiviral drug ribavirin is effective, and infection can be prevented by practising good hygiene.
Several studies estimate that between 100 000 and 300 000 Lassa fever cases with about 5 000 deaths occur each year . In Nigeria, 989 cases with 36 deaths were reported in 2014; in 2013, 1 195 cases with 39 deaths were reported. In Liberia, the Ministry of Health has notified WHO of an outbreak of Lassa fever in February/March 2014 (14 laboratory-confirmed cases). In Benin, 16 cases (two confirmed, seven probable and seven suspected cases), nine of them fatal, were reported in 2014 [3,4].
The last travel-related case of Lassa fever in Europe was reported in the United Kingdom in 2009 . In 2015, the US notified a fatal Lassa fever case in a traveller from Liberia to the United States. This case was the sixth known occurrence of Lassa fever in a traveller returning to the United States since 1969 . In 2016, one case of Lassa fever was medically evacuated from Togo to Germany. The patient later died in a German hospital. When the corpse was prepared for flight repatriation, a staff member of the funeral home caught the disease .
Public health conclusions
Primary transmission of the Lassa virus from its host to humans can be prevented by avoiding contact with Mastomys rodents, especially in regions where outbreaks occur .
- European Centre for Disease Prevention and Control. ECDC fact sheet: Arenavirus infection [Internet]. 2008 [Oct 2014]. Available from: http://ecdc.europa.eu/en/healthtopics/arenavirus/Pages/factsheet-health-professionals.aspx
- Centers for Disease Control and Prevention. Lassa fever [internet]. 2015 [cited 2015 June 2]. Available from: http://www.cdc.gov/vhf/lassa/index.html
- World Health Organization. Lassa fever, Nigeria 2014 [cited 2014 Mar 24]. Available from: http://www.afro.who.int/index.php?option=com_docman&task=doc_download&gid=9298&Itemid=2593
- World Health Organization. Lassa fever in Benin [Internet]. 2014 [cited 2014 Dec 19]. Available from: https://www.humanitarianresponse.info/system/files/documents/files/WHO_Outbreak_bulletin_%235_%20Dec2014.pdf
- Kitching A, Addiman S, Cathcart S, Bischop L, Krahe D, Nicholas M, et al. A fatal case of Lassa fever in London, January 2009. Euro Surveill. 2009 Feb 12;14(6).
- Centers for Disease Control and Prevention. Lassa fever confirmed in death of US traveler returning from Liberia 2015 [cited 2015 May 25]. Available from: http://www.cdc.gov/vhf/lassa/announcements/death-of-us-traveler-returning-from-liberia.html
- European Centre for Disease Prevention and Control. Lassa fever in Nigeria, Benin, Togo, Germany and USA – 23 March 2016, Stockholm, 2016. Available from: http://ecdc.europa.eu/en/publications/Publications/RRA-Lassa-fever-Germany-march-2016.pdf
Table. Lassa fever, surveillance systems overview, 2014