Warming temperatures are causing organisms to migrate, Professor Paul Hunter told a conference in the UK.
In Europe, ocean swimmers have been infected with illnesses normally associated with warmer waters.
And Professor Hunter warned not enough was being done to monitor the spread, due to the warming of the Earth, of big killers such as malaria in Africa.
Professor Hunter, head of health protection at the UK’s University of East Anglia, presented research tracking the movement of disease-causing organisms in Europe and North America to the Festival of Science in the UK city of Norwich.
“There are already significant indications of disease burden occurring in Europe as a result of climate change,” he told the conference.