Did Salmonella Kill Off the Aztecs?

After Spanish conquistadors arrived in Mexico in 1519, one of the worst epidemics in human history tore through the once-mighty Aztec civilization. Within a century of the Spaniards’ arrival, the Aztec population had been reduced from some 25 million to just 1 million. Though speculation has long swirled over what caused the devastating outbreaks of disease, no one knows for sure. Now, a team of scientists has presented the first DNA evidence of bacteria found in the bodies of victims killed in one of the worst outbreaks. They suggest the culprit may have been a species of Salmonella bacteria, specifically a now-rare strain known as Paratyphi C.

Today, those of us who are unlucky enough to get salmonella (or technically salmonellosis) will probably get it from eating undercooked meat, poultry or eggs. It’ll make us sick for about a week, including stomach cramps, nausea, vomiting, diarrhea, chills and fever. A nasty bug, yes—but not life-threatening.

But some strains of salmonella bacteria can cause serious illnesses, such as typhoid fever, and can even be deadly. One strain in particular, known as Paratyphi C, causes enteric fever, or fever in the intestines. When left untreated, the bug can kill up to 10 to 15 percent of those it infects. Paratyphi C is now extremely rare, and mostly strikes people in developing countries, where sanitary conditions may be poor. According to new DNA research, however, an outbreak of this deadly form of salmonella may have contributed to the 16th-century downfall of the Aztecs.