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.