Horses: West Nile virus test (WNV02)
Source: gov.uk (2025-08-15)

Test horses for West Nile virus for import, export, confirm vaccination status, seroprevalence studies, and to test to exclude from differential diagnoses.

Vets can use this form to submit samples from horses to test for West Nile virus (WNV) for the purposes of:
- import
- export
- confirming seroconversion after vaccination or seroprevalence studies
- Testing To Exclude (TTE) WNV from differential diagnoses
Testing is carried out by the Animal and Plant Health Agency (APHA).

Contact the APHA helpline if you suspect WNV

If you suspect West Nile fever (https://www.gov.uk/guidance/west-nile-fever), you must report it immediately by calling the APHA helpline on:
- xx-xxxx-xxxx if you’re in England
- xx-xxxx-xxxx if you’re in Wales
- your local Field Services Office (https://www.gov.uk/guidance/contact-apha#scotland-apha-field-services) if you’re in Scotland
West Nile fever is a notifiable disease (https://www.gov.uk/government/collections/notifiable-diseases-in-animals). If you do not report it, you’re breaking the law.

Download and print our poster for vets about how to spot and report West Nile fever (https://www.gov.uk/government/publications/west-nile-fever-poster).

Available tests

These Enzyme-Linked Immunosorbent Assay (ELISA) tests cannot differentiate between vaccinated and infected animals.

APHA offers 2 tests for WNV serology:
- TC0868: IgM Ab detection ELISA which will give an indication of an early infection
- TC0869: total Ab detection cELISA which will provide evidence of current or past infections and confirm vaccination status
Fees, test codes and turnaround times

Maximum turnaround time for both tests is 5 working days from when the laboratory receives the sample.

You can find the fee for these tests on the APHA price lists.

APHA Surveillance price list
- TC0869 (https://science.vla.gov.uk/Tests/SearchResults.aspx?SiteName=DST&Search=TC0869&PriceListCategoryId=0): competition ELISA to provide evidence of current or past infections and confirm vaccination status
APHA Scientific price list
- TC0868 (https://science.vla.gov.uk/Tests/SearchResults.aspx?SiteName=CDT&Search=TC0868&PriceListCategoryId=0): IgM capture ELISA to indicate early infection
- TC0869 (https://science.vla.gov.uk/Tests/SearchResults.aspx?SiteName=CDT&Search=TC0869+&PriceListCategoryId=0): competition ELISA to provide evidence of current or past infections and confirm vaccination status
Submitting samples

In a plain leak-proof tube submit either:
- a minimum of 1ml serum (preferable)
- 2ml clotted blood
Write the following on the label:
- owner’s name
- animal’s name
- animal’s microchip or ID number
Complete the form in full. You must indicate which test is needed on the form. If the test is for export purposes, check the import requirements of the destination country. You are responsible for choosing the correct test. Your results may be delayed if you do not provide all the required information.

Send this form and the samples to:

West Nile virus SerologyAPHA Weybridge Woodham LaneNew Haw Addlestone Surrey KT15 3NB

You must follow the rules for packaging and sending pathological material (https://www.gov.uk/guidance/how-to-pack-and-label-samples-for-submission-to-apha).

Submitting samples from outside the EU

You can get more advice about packaging and import requirements by emailing xxx@xxx.xx (mailto:xxx@xxx.xx).

How to pay

You enter into a contract with APHA when the Veterinary Investigation Centre (VIC) receives your sample and submission form.

You will be sent an invoice with instructions on how to set up an account to make payment. You must pay within 28 days of the date of invoice. APHA reserves the right to withhold services for accounts in arrears.

See our general terms and conditions (https://www.gov.uk/government/publications/apha-standard-terms-and-conditions) that apply to testing where no specific contract is signed.

Receiving your test results

Test reports are sent to the submitting practice unless otherwise indicated on the submission form. Duplicate reports may subsequently be provided but only with the written consent of the submitting veterinary surgeon. TTE test reports will also be sent to the APHA Customer Advice Duty team.

Test results are returned as soon as possible. If you need the findings urgently, you should include this on the form.

Reports are sent by email. You can ask for the report to be sent by post. Reports sent by special delivery will result in extra charges and you will need to ask the centre for this service. You can also ask that results are sent to recipients other than yourself.

Contact APHA

For queries about the tests and import requirements

Email: xxx@xxx.xx (mailto:xxx@xxx.xx)

For all other queries

Telephone: xx-xxxx-xxxx Email: xxx@xxx.xx (mailto:xxx@xxx.xx)