Young Britons should stop doing charity work in developing countries in case they take swine flu with them, a Department of Health adviser on the virus has urged.

Idealistic young people may want to do good by building schools and teaching children in places like sub-Saharan Africa but it is their moral duty to stay at home, says Professor Robert Dingwall. "What's the point of going to a village and helping to build a school if the child population of the village is decimated by swine flu because you have brought it with you?"

Poorer health among locals, especially those with immune systems weakened by HIV and Aids, meant that many people might die if the pandemic was brought into their community, says Dingwall, a member of the Department of Health's committee on ethical aspects of pandemic influenza.

He writes in today's Observer: "Even if travel bans are not justifiable, UK travellers cannot avoid thinking about their personal ethical responsibilities to the people of the countries that they are visiting. Staying at home this year will often be the morally right thing to do."

Britain has one of the world's highest number of recorded cases of H1N1 infection, many of them young people. Cancellation is the "responsible and ethical thing to do", said Dingwall. Anyone who had recently left a school that had cases of swine flu in recent months would be wrong to press ahead with their plans.

An estimated 240,000 18- to 24-year-olds a year go on independent holidays abroad such as a backpacking trip, working break, voluntary project or internship. Some 35,000 school-leavers are thought to have deferred going to university this autumn in order to have a year off, often abroad. And the government has announced plans to sponsor 500 graduates to join volunteer projects overseas.

Last night operators that arrange overseas breaks for young people rejected Dingwall's plea. The Year Out Group placed 53,000 young people in more than 90 countries through 37 member companies last year. Richard Oliver, its chief executive, said: "This is impractical. I understand the ethical argument and it's a point worth considering for those who have not yet invested any money in their gap year. But people who have already paid to go on these trips wouldn't get their money back from the insurance company."

Steve Holt of Worldwide Experience, which specialises in animal and marine conservation breaks in South Africa, said: "If South Africa had any thoughts about that [potential H1N1 carriers from Britain causing problems] we would have had advice from that end not to send people at the moment."

Catherine Raynor of VSO said it had weighed up the risk of volunteers spreading infection against the benefits they bring. "We believe that the countries we work with are in the best position to balance these two factors and we will continue our development programmes until the countries we work with request us to stop or international decisions are made to close borders."

Last month Kenya had its first cases of swine flu after several Nottingham University students fell ill there while on a charity trip after contracting the virus at home. A World Health Organisation spokeswoman said it did not support travel restrictions, but that governments might want to issue advice.