U.K. hospitals missing true scope of swine flu infection

The extent of swine flu infection in the United Kingdom is being underestimated because hospitals are failing to test patients with respiratory illnesses for the virus, according to one of the world’s leading experts on the disease. Professor Neil Ferguson, an epidemiologist at Imperial College London, who advises the government and the World Health Organization, said that serious cases of swine flu were almost certainly being missed because hospital surveillance was “almost non-existent.”

Speaking at the Times Cheltenham Science Festival, he said that there was anecdotal evidence of “significant numbers” of cases of severe respiratory illness in London, which should be checked in case they were caused by swine flu. Surveillance strategies needed to be rethought with the H1N1 virus apparently spreading widely. “One thing I am concerned about is that surveillance of severe disease is almost non-existent,” Ferguson said. “If you go into hospital and have severe respiratory disease, you will not be tested for H1N1. Anecdotally, I am hearing reports of a quite significant number of severe cases of respiratory illness in London. We need to be testing them. We need hospital-based surveillance, but while it’s being thought about it’s not been brought in yet. “We’re not assessing respiratory patients for H1N1, and that is going to be important over the coming weeks.”

The United Kingdom needed to learn from the approach taken in the United States, where the epidemic was much more advanced, Ferguson said. “In the U.S., they’ve stopped trying to do individual case surveillance and they’re focusing on testing healthy young adults hospitalized with respiratory disease. That’s the direction we need to follow.” While 557 cases had been officially confirmed, the true figure was several times higher and there was a danger that serious cases were not being picked up. Another fifteen were confirmed in England yesterday, as well as one in Northern Ireland. At least a dozen people have been reported to have needed hospital treatment for H1N1, though the Health Protection Agency could not provide confirmed statistics.

Ferguson said that the agency’s tally at best covered only half the total number of infections. GPs identified six cases last month not linked to known infections. Extrapolations suggest that between 500 and 1,000 people with swine flu consulted a doctor last month but were not tested. As only a minority of patients with mild flu-like illnesses see a GP, even that is an underestimate, and two to three times as many people have probably had swine flu.

The HPA said that it had already asked hospitals to test for swine flu. “As part of the agency’s enhanced surveillance all hospital labs in England have been asked by the HPA to refer specimens from all patients with flu-like illness to their HPA regional laboratory for testing,” a spokeswoman said. A pilot program was being established at several hospitals to test patients with other acute respiratory illnesses consistent with flu.

At present, swine flu surveillance has concentrated on tracing the contacts of people known to have the virus. Ferguson said that while case tracing had been valuable in the early phases of the outbreak, the spread of the disease meant that that was unsustainable. The virus, he said, was spreading much faster in the southern hemisphere, where it is winter, than in Europe and North America. In Chile, each patient was infecting about 1.7 people, compared with about 1.2 in the UK, and similar transmission rates could be expected here in the autumn. “We’re getting some sense of what will happen from the southern hemisphere,” he said.