Croydon residents have been warned of the dangers of Malaria after the borough had the third largest number of cases in London.
Health chiefs said there was a misconception that people born in West Africa have immunity to the disease, but after moving away from a malaria endemic country immunity rapidly wanes.
Croydon’s high number of cases is suspected to be due to the large proportion of people of black African ethnicity.
Public Health England (PHE) made the warning after 13 Londoners died of the disease last year, most are believed to have contracted the disease visiting relatives in affected countries.
They warned all require malaria medication when visiting an affected country.
There were 1,378 cases of Malaria in the UK last year, half of which occurred in London.
Dr Yvonne Doyle, regional director for PHE in London, said: "Malaria is a preventable disease, so it’s concerning that we continue to see high numbers of cases in London residents who have travelled abroad.
"It’s also worrying that the majority of people (80%) who contracted malaria reported not having taken anti-malarials during travel to areas where the disease is endemic."
88% of cases of malaria in Britain, since 2000, were acquired in sub-Saharan Africa with Nigeria accounting for almost half.
Malaria is transmitted through a bite from the female Anopheles mosquito, symptoms such as a high fever, usually appear within 10-15 days but can develop a year or more after the bite.
Fever, headaches and feeling sick are common symptoms.
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