Tamiflu-resistant swine flu to become more common

Tamiflu-resistant swine flu which has broken out in Wales will become much more common as the virus mutates, a flu expert said today.

Tamiflu-resistant swine flu which has broken out in Wales will become much more common as the virus mutates, a flu expert said today.

Three out of five patients diagnosed with the Tamiflu-resistant strain remain in hospital today, after it was revealed they could be the world’s first cases of person-to-person transmission of the resistant virus, the National Public Health Service for Wales (NPHS) said.

Professor Nigel Dimmock, a virologist at the University of Warwick said: “This is just the beginning. You have got a lot of viruses and if you use Tamiflu at the level they are using it you get resistance.

“However, they probably aren’t resistant to Relenza, the other antiviral. You need other mutations to make it resistant to Relenza.

“Also, the vaccine is coming on so people regard Tamiflu as a stopgap and there’s no need to panic.”

He added it was unsurprising person-to-person transmissions had started. He said: “This is the trouble with going into hospitals, where you can get MRSA, C.diff, Norovirus and so on. You go in with something and you come out with a virus, it’s a well-known problem.”

Three of the five people on a unit for severe underlying health conditions at the University Hospital of Wales, in Cardiff, appear to have acquired the infection on the ward, the NPHS said yesterday.

Two of the five have recovered and have been discharged from hospital. One is in critical care and two are being treated on the ward.

Professor Dimmock said the likelihood of the cases in Cardiff causing an outbreak of the resistant strain depend on how well the virus has been contained.

He said: “It depends how well the people in Cardiff have been able to restrict the spread of the virus. US figures show that one in 80 are diagnosed, meaning for every person that knows they are sick, there are 79 that do not know they have it.

“If it has affected more people and they don’t know, it could spread.”

Cardiff and Vale University Health Board has put appropriate infection control measures in place on the unit, the NPHS said.

Professor Dimmock added: “The fact people have recovered is a good sign, there doesn’t seem to be anything sinister about developing a resistance and it is what everybody expected.

“This is probably the first time an antiviral has been deployed on a global scale. Everybody knows if you put an antiviral in front of a virus it will mutate because viruses don’t have DNA, they have RNA.

“DNA can correct itself but RNA can‘t so mutations stick. Resistance will become more and more common so we will use Relenza and then it will become resistant to Relenza. These drugs are useful but they are short term.”

The British government last night played down fears that the resistant strain could now become widespread after the Health Protection Agency (HPA) confirmed there had previously been “no documented episodes of person-to-person transmission”.

A Department of Health spokeswoman said: “Examples of Tamiflu resistance are very rare, but when this does occur it has often been among these especially vulnerable patients. In other words, because their immune systems are compromised, it is more likely for resistant viruses to develop.”

On Thursday the World Health Organisation (WHO), which has reported 57 incidents of Tamiflu resistance worldwide, received four reports of possible person-to-person transmission in a US hospital.

An HPA spokesman said the possibility that the American viruses have been transmitted within the hospital was also being investigated.

The Welsh cases occurred in patients with haematological problems who had compromised immune systems because of their disorder or because of chemotherapy, the agency added.

The HPA said in a statement: “To date, a total of nine (swine flu) confirmed cases have been reported amongst patients on a hospital ward in Wales.

“Five of these cases are known to be resistant to oseltamivir (Tamiflu), one is sensitive and for three resistance status is presently unknown.”

The statement said the risk to the general healthy population was “low”.

It added: “There is no evidence that the oseltamivir-resistant virus is any more virulent than any other type of flu. The situation is being kept under review.

“Further follow-up of cases and their close contacts both on the ward and in the community is under way to ascertain if there is evidence of onward transmission.

“The virus remains sensitive to the other frontline drug, Relenza, which is being used as an alternative anti-viral and patients are responding well.

“Although further epidemiological investigation is under way, it would seem likely that transmission of oseltamivir-resistant H1N1 virus has taken place.”

Dr Roland Salmon, director of the NPHS Communicable Disease Surveillance Centre, said the emergence of a resistant strain was “not unexpected” in patients with serious underlying conditions.

He added: “In this case, the resistant strain of swine flu does not appear to be any more severe than the swine flu virus that has been circulating since April.

“For the vast majority of people, Tamiflu has proved effective in reducing the severity of illness.”

Wales’s Chief Medical Officer Dr Tony Jewell said people with suppressed immune systems were designated as a priority group for vaccination because they were known to be more susceptible to the virus.

“Treatment with Tamiflu is still appropriate for swine flu and people should continue to take Tamiflu when they are prescribed it,” he said.

The Centres for Disease Control and Prevention (CDC) in the US has previously investigated a case of two girls at a summer camp in North Carolina.

Both girls had the same strain of Tamiflu-resistant swine flu, with one possibly passing the strain to the other.

However, the CDC said it could not be ruled out that each might have developed Tamiflu resistance independently.

News of the strain came a day after it was announced that more than three million healthy children under five across the UK are to be offered the swine flu jab.

Parents will be invited by their GPs to bring their children into surgeries, with vaccinations expected to start in December.

Figures released on Thursday showed an estimated 53,000 new cases of swine flu in England in the last week, down from 64,000 the week before.

In Scotland, the figure was 21,200, down from about 21,500 in the previous seven days.

The rate of flu-like illnesses diagnosed by GPs in Wales dropped to 36 cases for every 100,000 people from 65.8 the previous week.

Seven swine flu-related deaths were recorded in Wales in the previous week, taking the total to 21.

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