West Nile Virus (WNV)

Starting from 1 May 2024, we will be testing for West Nile Virus (WNV)

We care about your safety and the safety of blood component recipients. That is  why the Welsh Blood Service  have introduced guidelines to manage donors who have recently travelled to WNV risk areas during the mosquito season (1 May to 30 November).

If you have visited a WNV risk area and donate blood within 28 days of returning an additional WNV test will be carried out on your donation. We’ll let you know if the test shows a positive result.

If you become unwell within 28 days of returning from a WNV risk area please let us know. We will defer you from blood donation for six months to reduce the risk of transmitting West Nile Virus to patients receiving blood components.

We understand that this may be disappointing, but we encourage you to donate blood once the deferral period ends, or when we reach out to you inviting you to a local donation clinic.

Remember that every blood donation is vital, and you can help save lives.

If you need any advice, email: donors@wales.nhs.uk or call 0800 252 266 today.

What is West Nile Virus?

WNV is a virus that occurs in many countries and is spread by mosquitos causing an infection in humans called West Nile fever. The virus has an incubation period of 2 – 14 days. Most people who become infected with WNV have no symptoms. Around 20% of those that do become infected may experience a wide spectrum of non-specific symptoms  including:

• Fever / chills
• Headache
• Weakness / fatigue
• Drowsiness
• Skin rash
• Nausea / vomiting / diarrhoea
• Loss of appetite

Symptoms usually resolve within 7-10 days, although fatigue can last for some weeks. There is no vaccine to prevent this disease in humans and there is no specific treatment for WNV infection.

Since 1999, there have been thousands of human cases and many deaths attributable to WNV infection. This is why the Blood Services have rules with regard to donors who have travelled to risk areas during the mosquito season (May to November).