It was not until the latter part of the 1800s that ships were required to have a physician on board. Sickness on the larger, more crowded boats could quickly become an epidemic - and did.
Yellow fever outbreaks in New Orleans and on ships arriving in port have been documented since 1769. Some years were truly devastating. The death rate for 1817 has been estimated as high as 1,142 for New Orleans, alone.
More severe outbreaks appeared later in the century. On October 31, 1848 the Swanton left Le Havre, France for New Orleans. Before it arrived, there was at least one case of cholera on board.
The ship Cromwell arrived in New Orleans from Le Havre on October 15, 1849, with only part of its passengers still alive. Twelve had died on board. The ship was refused entry at New Orleans and forced up river to St. Louis, regardless of the passenger's travel intentions.
The next month, the Gypsy from Liverpool arrived in New Orleans after 19 of her 322 passengers died. A day after, the Fingal arrived with 37 dead out of her 322 passengers.
August of 1853 saw 5,189 deaths. During investigations into the cause, a Dr. Dowler testified that the death rate was about one death every six or seven minutes for an entire month.
Even if an emigrant was not on one of these ships, they were still unsafe. Cholera was often spread in ports where the ship stopped to pick up or deliver freight or passengers enroute to New Orleans.
As a result of testimony by the Public Health Commission, there exists a unique description of life on board the ships. Search Google Books for "yellow fever" and you'll find a tremendous amount of information including passenger names and their individual experiences on the seas.
Reading through the reports from the Report of the Sanitary Commission of New Orleans on the Epidemic Yellow you'll find some victims' names given, including those who survived. Some testimony even identifies where yellow fever victims had been living, as the commission was trying to pinpoint the origin of the infection.
It has been said that yellow fever was one of the defenses against outsiders. Those who grew up in the tropical climates were less susceptible to yellow fever, having development immunity as children.
The Charity Hospital of New Orleans was created through one seaman's legacy in 1736. It remains the second oldest hospital in the country, with New York's Bellevue Hospital being the only one older.
The Touro Infirmary opened in 1854 and was involved with the yellow fever epidemics. It continues to thrive.
Only the hardiest survived the trip across the ocean. Once they were back on land, life was still hard. But survivors had a new and perhaps healthier life to look forward to, leaving behind the famine and poverty they were escaping.
At least 2,500 immigrants arrived between 1699 and 1712. At the end of that time, only 400 Caucasians and 20 African Americans survived. The passenger lists might be one of the last recorded vital records bearing your ancestor's name while they were still alive.