Yellow fever in South Wales, 1865.

The only known occasion on which yellow fever was transmitted within the British Isles was during an epidemic in Swansea in September/October 1865. The only other similar epidemic in Northern Europe was in St Nazaire in 1861.1 These appear to have been rare instances of mosquito-borne epidemics in which all the mosquitoes carrying the virus, and involved in transmission, were released from a single source over a short period (perhaps of hours). Although the Swansea outbreak is mentioned in a number of reviews, 2,3,4 its details are to be found only in the Eighth Report of the Medical Officer to the Privy Council, 1866, with an excellent appendix by George Buchanan.5