Story Highlights• NEW: Second veterinarian service worker tested for deadly bird flu virus
• Patient may be suffering the annual flu season, UK health agency says
• Both veterinarians worked on avian-flu outbreak on English poultry farm
• 271 human cases of bird flu reported worldwide, most of them fatal
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LONDON, England (CNN) -- Britain's Health Protection Agency Wednesday is testing a second veterinarian service worker who responded to a recent avian flu outbreak on a English poultry farm for the deadly strain of the bird flu virus.
The agency believes the patient may simply be suffering from the annual flu season, but is taking no chances.
"We are not expecting any workers to test positive for avian flu as they have followed all the necessary precautions in terms of protective clothing, hygiene measures and have been offered antiviral drugs," flu expert Dr. Jonathan Van Tam said in a statement released by the agency. (Read how Britain is taking measures to contain bird-flu outbreak)
"We are, however, expecting to see a number of workers with symptoms caused by other non-flu respiratory viruses over the coming week as this is the time of year when we see an increase in these infections."
Lab results from the latest test are expected to be released on Thursday, HPA said.
The patient works for Britain's State Veterinary Service, part of the government's Department for Environment, Food and Rural Affairs.
Earlier in the day, the agency determined that another worker for Britain's state veterinary agency did not have the virus.
The worker had been hospitalized for a "mild respiratory illness" after working on the weekend outbreak at the poultry farm in Holton, Suffolk, about 120 miles northeast of London.
Safety precautions taken by workers leave a low risk for being exposed to the H5N1 virus found on the farm, according to Dr. John Watson, the chief of respiratory illnesses for HPA.
"It should be remembered that chest infections and fevers are common in Europe at this time of year when ordinary seasonal flu circulates," he said Tuesday.
British officials announced Saturday that the H5N1 virus was behind the deaths of 2,500 turkeys on the farm. The remainder of the 160,000 birds were being culled to prevent the further spread of the disease, and veterinary officials were enforcing a "protection zone" around the farm.
Officials from the U.N.'s World Health Organization have confirmed 271 human cases of bird flu worldwide, with 165 of them fatal. Most of the deaths have been in southeast Asia, though the latest fatality was a 22-year-old woman in the Nigerian city of Lagos.
Though WHO officials fear that the H5N1 virus could mutate and be spread from human to human, most people who have contracted avian flu got it by handling diseased or dead birds.
-- CNN's Daniela Berretta contributed to this report
Government vets walk though a Bernard Matthews turkey farm Monday in Halesworth, England.