Claims that a unique killer strain of malaria once haunted England's marshlands have been challenged by a new study.
For some years, experts believed that the mosquito-borne disease was responsible for raising mortality rates along the banks of the river Thames, around the Essex and Kent coasts and on the Somerset Levels, to several times those of elsewhere in the country.
The disease can be caused by a number of different protozoa, and the English bug, Plasmodium vivax , was not usually associated with death. Experts suggested that England must have been hit by a now-extinct super virulent variety. Some people even suggested that it could reappear as an indirect result of climate change.
But research by Rob Hutchinson, a PhD student at the University of Durham, and his supervisor, Steve Lindsay, professor in disease ecology, has found no evidence that anyone died in the years before the last cases were reported at the end of the first world war. Their study instead suggests that the high levels of mortality in marshy areas was caused by food poisoning.
Mr Hutchinson analysed parish records for the marshy Isle of Sheppey, the less marshy Isle of Thanet and the relatively healthy North Downs from 1700 until 1925.
He also looked at admissions records for the Kent General Hospital from 1882.
From this data, he found that mortality levels in Sheppey and Thanet rose in spring and autumn each year, with peaks in February, March and September. When he compared this data with epidemiological patterns, the autumn peak did not match up to malaria but rather to known cycles of gastro-intestinal infections such as salmonella.
Mr Hutchinson went back to historical records and was struck by the fact that no deaths were mentioned in relation to the disease. It seems English malaria, called ague, was not a killer.
The results are due to be revealed at the annual meeting of the Royal Entomological Society in Cardiff today.