Original article from Kent Live
Most people know malaria as a tropical disease carried by mosquitos, mainly in places like Africa.
Probably fewer are aware it was once prevalent here in the Garden of England.
Some say residents were dying of it in their thousands as recently as the 19th century.
Romney Marsh, still classed as a coastal wetland, had even more severe water-related issues before the Royal Military Canal was built in 1806.
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The new canal greatly increased drainage, but until then malaria – known more commonly at the time as ague or marsh fever – was rife.
Mortality rates on the Marsh were said to be twice as high as they were in villages just a few miles away.
The Romney Marsh Research Trust has produced an entire paper on the phenomenon.
Its author Mary Dobson noted that Romney Marsh "in the 17th and 18th centuries was known for its high prevalence of disease and death…
"The results show that mortality in the marshes was exceptionally high, with rates of infant mortality some two to three times higher than in neighbouring Downland parishes.
"This paper suggests that the peculiar demographic and epidemiological characteristics of the marshes can be accounted for by endemic malaria."
It points to a large scale study of parish death registers that suggest Romney Marsh was one of the deadliest places in Britain.
Edward Hasted, at the close of the 18th century, said that the 'airs and waters' of Romney Marsh were both "foul and fatal".
A mosquito-borne infectious disease, malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches.
In severe cases it can cause yellow skin, seizures, coma or death.
Experts say the strain prevalent on the Romney Marsh was most probably Plasmodium vivax, as records and texts from the time describe agues or fevers at three or four-day intervals.
Some studies suggest the same strain could even be at risk of returning thanks to climate change.
One from 2018, published in the International Journal of Environmental Research and Public Health, notes that: "a model developed for P. vivax predicted two months of climatic suitability in Great Britain and four months of climatic suitability in southeast England by 2030.
"So far, we are not seeing regular endemic malaria transmission across the Mediterranean Basin, although the recent outbreaks of vivax malaria in Greece suggest that we need to remain vigilant."
The report also notes the West Nile Virus, carried by a particular type of mosquito prevalent in north Kent called Culex modestus.
It said that surveys conducted by Public Health England and colleagues at University of Greenwich found "the distribution of this species is now known to extend along ditches across grazing marshes in north Kent between Swanscombe (near Dartford) and Stodmarsh (near Canterbury).
It added: "Recent field studies on Culex modestus in north Kent confirm both its ornithophagic habit and that it is a prolific human biter".
Another report published in the British Medical Journal also suggests there is chance malaria could establish itself in Kent again.
Dr Philip Welsby, working out of Western General Hospital in Edinburgh, pointed to the combination of greater international travel and warmer temperatures expected through climate change.
He said: "For centuries ague was endemic in the Fens, the marshes of the Thames estuary and south-east Kent".
He goes on to note "a strong relationship between high summer temperatures (above 16°C) and mid-19th century ague in Kent" and: "There was an unusually hot summer in 1661 in which, according to Pepys 'the heat lasted on unbroken into the winter, which as to warmth and every other thing (is) just as it were the middle of May or June' and during this time the whole year 'hath been very sickly'."
Dr Welsby concludes that "outbreaks of indigenous malaria will probably be small and confined to a limited geographical area, most likely in marshy or coastal areas of south and east England".
He said: "Return of indigenous malaria in the UK has not yet occurred.
"The greater availability of cheap tropical and subtropical travel will result in more primary infections of humans with blood that could infect home grown mosquitoes.
"Within the next few decades tertiary spread of infection may occur in the UK, with spread to at least one other person.
"Indigenous malaria will then be with us."