But it is as an epidemic disease that it has caused most alarm and loss. The United States, Spain, and the West Indies have suffered most severely in this respect. It has been epidemic as far north as Quebec in North America. In 1805, some fifty-five cases occurred among the English troops stationed there. In Europe, it has been epidemic as far north as Swansea, Wales. In the year 1865, the sailing ship _Hecla_ from Cuba, introduced yellow fever into Swansea, and twenty-two cases developed in the town in persons who had no communication with the vessel. France has never had a yellow-fever epidemic of any consequence, though it has been demonstrated that under favorable conditions, the disease might become epidemic. At St. Nazaire, in the year 1861, yellow fever was introduced by the sailing ship _Anne-Marie_, and forty cases resulted, with twenty-three deaths. Yellow fever has appeared in epidemic form several times in Italy, but has never extended further east. Leghorn is the most eastern point to which yellow fever has ever reached. There in 1804 a severe epidemic occurred in which some two thousand persons died. On the west coast of Africa epidemics have occurred as far south as St. Paul de Loanda. The island of Ascension, about the same latitude as St. Paul but in the mid-Atlantic, has suffered very severely. In 1823, the British sloop _Bann_ brought yellow fever from Sierra Leon to Ascension. Ninety-nine cases occurred on the _Bann_, with thirty-four deaths, and on the island itself twenty-eight cases occurred with fifteen deaths. Yellow fever has been epidemic on the east coast of South America as far south as Montevideo, and on the west coast as far south as Valparaiso, and on this same coast as far north as Guaymas, Mexico. The epidemic area of yellow fever has been very much more extensive than the endemic area. This epidemic area would then be bounded by a line commencing on the north at Quebec, Canada, extending east to Swansea, Wales; from Swansea south to St. Nazaire, France; from St. Nazaire southeast to Leghorn, Italy; from Leghorn south to Loanda, on the west coast of Africa; from Loanda west across the Atlantic to the island of Ascension; from Ascension still west across the Atlantic to Montevideo; from Montevideo still west across South America to Valparaiso, Chili; from Valparaiso northwest to Guaymas, and from Guaymas northeast back to Quebec. By lines of latitude and longitude the epidemic area would be bounded on the north by the forty-fifth degree, north latitude; on the south by the thirty-fifth degree, south latitude; on the east by the tenth degree, east from Greenwich, and on the west by the one hundred and tenth degree, west from Greenwich.