A second yellow fever epidemic in less than a year was declared in Malaga on 29 July 1804, as the viral disease saw a dramatic increase in both cases and deaths, with some 11,464 people dying during the following three months.
Juan Manuel de Aréjula, a renowned surgeon and chemist, arrived in Málaga on 25 August 1804 and he came across the disease "in full force". The upward trend in cases lasted until 7 September; deaths began to slow down by 12th and there were hardly any infected by the 28th of the month.
In Brief Description of Yellow Fever, a book published in 1806, Aréjula documented the causes, effects and evolution of the yellow fever disease in Andalucía at the start of the 19th century. He was then entrusted with what measures should be taken in the affected locations.
The fever had resurfaced in Malaga city at the end of June 1804, but it was contained to the Santos Mártires church in Calle Pozos Dulces. Aréjula confirmed that street as the epicentre of the outbreak because of the rapid spread of cases in the area. "The Santos Mártires parish has 2,500 populated homes, [...] between 1 and 23 July there were no more than 32 deaths, of which 16 were infected and residents of Calle Pozos Dulces," he wrote.
But once the disease left that area, it spread like wildfire and preventative measures were taken. Two lazarettos (a quarantine station intended to be used by maritime travellers) were set up outside the city, buildings were fumigated and furniture was sanitised.
The yellow fever still managed to escape the city and make its way inland. Aréjula was sent to Antequera to investigate, among other things, how it reached the town. "I figured out that the first sick person in Antequera was an official named José Delgado, a 22-year-old lad, who fled Malaga and the street where there were the most infected on 23 July," Aréjula wrote. "He fell ill on 27 July and died on 2 August."
The disease would quickly spread to other Andalusian towns thanks to its presence in Malaga and Antequera. In La Rambla, a mule driver who was transporting wheat from Malaga carried the yellow fever because he touched a cart full of disease-ridden corpses; it spread to Montilla through an infected priest and also made its way to Ronda.
The yellow fever outbreak that Malaga suffered the year before, during the summer months of 1803 and until December, claimed the lives of 6,884 people.