A 9-year-old girl infected with swine flu has died in Britain, the third swine flu fatality in the U.K., a hospital reported Monday.

Birmingham Children's Hospital said the girl who died Friday had other serious underlying health problems. But it did not elaborate on those health issues, or say what exactly she died from, or respond to questions about whether the virus she had was drug-resistant.

Britain's health ministry also reported another 1,604 new cases of swine flu since Friday, bringing the total in the U.K. to 5,937. Britain has been the hardest-hit nation in Europe amid the global swine flu epidemic.

Two other people, a 38-year-old pregnant woman and a 73-year-old man, have also died in the U.K. after catching swine flu.

Swine flu is airborne and is easily transmitted when people cough or sneeze. Because it is a new virus, most people have no natural immunity. Most cases of swine flu are mild and don't need treatment to get better. Globally, the World Health Organization has reported almost 60,000 cases.

When WHO declared swine flu to be a pandemic — a global epidemic — earlier this month, it called the virus "unstoppable." But Britain is still trying to contain the flu in most parts of the country by liberally giving out the drug Tamiflu to confirmed cases and their contacts.

Some health officials worry that such widespread use of the antiviral could lead to drug resistance. Roche Holding AG, Tamiflu's producer said it had found one patient in Denmark who showed resistance to the drug.

Of the people who have died from swine flu, about half were previously healthy. The other half have been patients with other health conditions like obesity, diabetes or pregnancy.

Fears of swine flu hitting Wimbledon surfaced Monday as the All-England Club told a handful of ball boys and girls suffering from flu-like illnesses to stay home as "a precautionary measure."

However, All England Club spokesman Henry O'Grady said there was no reason to suspect that swine flu had reached the tennis tournament.

"They haven't been tested for swine flu, and they're not going to be tested," he said.

Over the weekend, officials at Glastonbury, one of Britain's biggest music festivals, sent three people home after they were diagnosed with swine flu. Nearly 180,000 people attended Glastonbury, where revelers mix in close quarters at concerts and campsites.

When WHO declared swine flu a pandemic, it said the virus was of "moderate" severity. As swine flu continues to spread worldwide, experts say many more cases and deaths are inevitable.