Tourists either were unaware that they needed booster jabs, or were prepared to travel without any immunisations at all.

The dangers posed by going to tropical countries without the necessary treatment were highlighted this week after a German tourist died from yellow fever in a Berlin Hospital, following his return from Africa.

Modern tourists are far more likely to travel to unusual destinations, such as Goa in India, and Asia, and are placing themselves at increased risk.

Even travel to countries such as the Dominican Republic, a source of low-price Caribbean-style holidays, involve the risk of hepatitis A infection, but many tourists do not go to their GPs for advice before leaving.

Another commonly-visited country where infection is possible is Malaysia.

Travel agents asked for advice

In fact, the survey, conducted on behalf of a drug company, found that tourists were more likely to ask their travel agent for advice than their family doctor.

Although many people told the researchers that they knew they were up-to-date with vaccinations, many of these did not know how long their jabs could protect them.

Over a third of travellers had received the typhoid vaccine with the past year, but four out of five did not know for how long they were protected.

Over the last year more than 100 cases of typhoid have been reported in England and Wales from returning travellers.

And almost a third had no idea of which jabs they had received.

One in eight fall ill

About 12% of tourists fell ill while on holiday - but this figure rises to a quarter of all those travelling to the Caribbean and Africa.

Most of the illnesses were simple stomach upsets, and those in the 18 to 30 age group were more likely to get ill.