Even though very few people die from cholera nowadays, it remains one of the most dangerous infections. According to data from the World Health Organization, 3 - 5 million new cases of cholera are registered yearly, from which between 100 000 and 120 000 people die.
For years, it has sown terror in ancient peoples. Cholera epidemics have taken thousands of human lives. It appeared for the first time in Europe during the 19th century, killing millions.
A team of Australian and Canadian scientists have managed to identify a strain of the cholera bacteria, responsible for the pandemic. They have discovered the genome sequence of this pathogenic microorganism.
For their research, the scientists acquired genetic material from the intestines of a victim of the epidemic. They have been kept in the Museum of Medical History in Philadelphia since 1858, a few years after the cholera outbreak there.
The so-called Vibrio Cholerae is the bacterium responsible for cholera. It propagates in water and has been confirmed to be one of the two causes responsible for 5 out of the 7 major epidemics in the 19th century in Europe - the classic cholera bacteria.
All epidemics of cholera originate from the Bay of Bengal area. The origin of the causative bacteria had not been found for a long time, since scientists had not had a specimen to examine.
Its discovery was made even more difficult by the fact that it hides in the intestines of the diseased and cannot be found in the bones or teeth. This way, there are practically no DNA remains of the bacteria.
From the tissues preserved in the museum, scientists used a sample of the intestinal tissue of a man who died from cholera in 1849. They determined that this strain of bacteria, labeled as classical, and the second (El Tor) have coexisted with humans for centuries before the epidemic outbreaks in the 19th century.
The reason for the sudden change is still being searched for. Epidemiologists today are still puzzled by the origin of the vibrio. There are numerous cases where the source of infection has even been a small forest spring, whose water people have used for years on end. Apparently, a similar case occurred in the 19th century.