Cholera historical perspective


 * Associate Editors-In-Chief: Priyamvada Singh, MBBS [mailto:psingh@perfuse.org]

Overview
The cholera bacterium had been originally isolated in 1855 by Italian anatomist Filippo Pacini, but its exact nature and his results were not widely known. One of the major contributions to fighting cholera was made by the physician and pioneer medical scientist John Snow (1813–1858), who in 1854 found a link between cholera and contaminated drinking water. Dr. Snow proposed a microbial origin for epidemic cholera in 1849.

Historical perspective

 * The bacterium had been originally isolated 45 years earlier (1855) by Italian anatomist Filippo Pacini, but its exact nature and his results were not widely known.
 * The Russian-born bacteriologist Waldemar Haffkine developed the first cholera vaccine around 1900.
 * One of the major contributions to fighting cholera was made by the physician and pioneer medical scientist John Snow (1813–1858), who in 1854 found a link between cholera and contaminated drinking water. Dr. Snow proposed a microbial origin for epidemic cholera in 1849.
 * In his major "state of the art" review of 1855, he proposed a substantially complete and correct model for the etiology of the disease.
 * In two pioneering epidemiological field studies, he was able to demonstrate human sewage contamination was the most probable disease vector in two major epidemics in London in 1854. His model was not immediately accepted, but it was seen to be the more plausible, as medical microbiology developed over the next 30 years or so.
 * Cities in developed nations made massive investment in clean water supply and well-separated sewage treatment infrastructures between the mid-1850s and the 1900s. This eliminated the threat of cholera epidemics from the major developed cities in the world. In 1883, Robert Koch identified V. cholerae with a microscope as the bacillus causing the disease.
 * Cholera has been a laboratory for the study of evolution of virulence. The province of Bengal in British India was partitioned into West Bengal and East Pakistan in 1947. Prior to partition, both regions had cholera pathogens with similar characteristics. After 1947, India made more progress on public health than East Pakistan (now Bangladesh). As a consequence, the strains of the pathogen that succeeded in India had a greater incentive in the longevity of the host. They have become less virulent than the strains prevailing in Bangladesh.  These draw upon the resources of the host population and rapidly kill many victims.
 * More recently, in 2002, Alam, et al., studied stool samples from patients at the International Centre for Diarrhoeal Disease in Dhaka, Bangladesh. From the various experiments they conducted, the researchers found a correlation between the passage of V. cholerae through the human digestive system and an increased infectivity state. Furthermore, the researchers found the bacterium creates a hyperinfected state where genes that control biosynthesis of amino acids, iron uptake systems, and formation of periplasmic nitrate reductase complexes were induced just before defecation. These induced characteristics allow the cholera vibrios to survive in the "rice water" stools, an environment of limited oxygen and iron, of patients with a cholera infection.
 * The term cholera morbus was used in the 19th and early 20th century to describe both non-epidemic cholera and gastrointestinal diseases that mimicked cholera. The term is not in current use, but is found in many older references.