HPA starts its 2005 West Nile virus surveillance scheme, UK

Main Category: Infectious Diseases / Bacteria / Viruses
Article Date: 27 May 2005 - 7:00 PDT

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The Health Protection Agency (HPA) starts its annual enhanced surveillance programme for possible human cases of West Nile virus infection from 1 June 2005. The scheme, in use for the last four years, operates each summer, when there is increased mosquito activity in the UK and other countries.

Dr Dilys Morgan, who coordinates the scheme for the Agency, said, "Although the risk of West Nile Virus (WNV) is low, we need to remain vigilant to the possibility that cases might occur here. Early recognition will be an important factor in the control of the disease. The virus is spread from birds to humans via the bite of an infected mosquito and in a small percentage of people it can cause serious illness. WNV has caused considerable problems in the US, although cases fell dramatically last year. So far, we have seen no cases contracted in the UK, or in people who have travelled to the US or other areas where transmission occurs. Although mosquito species involved in the transmission of WNV are present in the UK, we do not have the same problems as the US with mosquito-borne disease, and indeed transmission of mosquito-borne viral infections is virtually unknown in the UK."

The Health Protection Agency's surveillance scheme is specifically for UK-acquired human WNV infections and involves examining samples from adults with encephalitis or viral meningitis with no known cause, for the presence of West Nile virus. The Agency asks that clinicians and laboratories follow the protocol on the HPA website and refer samples to the Agency's Centre for Emergency Preparedness and Response at Porton, who will carry out laboratory investigations.

The number of cases reported in the US has dropped substantially between 2003 and 2004, down from 9858 case in 2003 to 2470 in 2004. There has also been limited transmission in recent years in South East France and two Irish tourists returning from the Algarve, Portugal in the summer 2004, were diagnosed with WNV infections. The Agency continues to take the potential threat to the UK seriously, and so advice is issued to doctors to consider West Nile virus as a possible diagnosis for unexplained cases of encephalitis and viral meningitis especially in older patients. The Department of Health issued its West Nile Virus Contingency Plan in May 2004. This was developed in collaboration with the HPA and the Department for the Environment, Food and Rural Affairs (Defra), sets out the actions being taken to enhance surveillance of the virus and to advise clinicians on the symptoms of the fever.

The Agency also advises people visiting the US to be aware of the symptoms of West Nile fever; in the majority of patients, there will be no symptoms at all, but symptoms can include a mild flu-like illness, and some patients may experience headaches, sore eyes, disorientation and muscle weakness. The Agency also provides advice on its website to help travellers minimise the risk of contracting West Nile virus and other mosquito-borne infections. This advice includes sensible precautions to prevent insect bites, such as using an effective insect repellent and installing insect-proof screens on windows and doors.

1. For further information please contact the press office on 020 8327 6647/7097

2. Details of the enhanced surveillance scheme, including the surveillance protocol and report forms, and the current recommendations for travel to North America, can be found at: http://www.hpa.org.uk/infections/topics_az/west_nile/menu.htm

Health Protection Agency