Cholera

Cholera is a disease caused by the bacteria Vibrio cholera. The disease first emerged in the 1800s from Calcutta, India where it had caused disease for centuries. Since then, 7 cholera pandemics have swept through the world. 16 strains of Vibrio cholera have been discovered with the deadliest being the 01 and 0139 strains of the bacteria. The bacterium secretes chloride to block the small intestine's ability to absorb sodium, which produces thin, grayish brown, mucoid diarrhea in the victims. Victims lose 10-12 liters of fluids a day.

The First Asiatic Cholera Pandemic, suspected to have begun at the Kumbh festival on the upper Ganges River, lasted from 1817 to 1823. 10,000 British troops and countless Indians died during this pandemic. By 1820, the pandemic had spread to Thailand and Indonesia, and then spread throughout Asia to Russia and Turkey leaving destruction in its path. The severe winter of 1823-4 stopped the pandemic at the doorsteps of Europe in the Caspian Sea area.

The Second Pandemic lasted from 1826 to 1837. It spread from the Indian subcontinent to Afghanistan and Russia by 1827, and Poland, Hungary, Germany, and the British Isles by 1831. Immigrants brought the deadly pandemic to Canada and the United States in 1832, and cholera spread down to Mexico and Cuba. The pandemic reached Portugal and Spain by 1833 and then spread across to France and Italy between 1834 and 1836. Through other branches of the pandemic, cholera was spread to Syria, Palestine, Mecca, and Cairo. The disease spread along the trade routes, from port to port, aided by the urbanization of the industrial revolution.

The Third Pandemic began in India and spanned from 1846 to 1863. It was the most deadly of the cholera pandemics. The pandemic began in the lower Bengal region and spread to Afghanistan in 1839. The bacteria was transported by British troops to China in 1840 and spread through the Philippines and Burma by 1844. In 1845, the pandemic reappeared in India and devastated the Middle East. After a brief pause, it spread up the Caspian coast to penetrate Russia, and by 1848, it had unleashed its fury on Europe. In 1854, 23,000 victims died in Britain alone. Cholera entered the United States through New York and New Orleans. The pandemic also spread throughout the Americas and Africa, repeatedly being renewed from its Indian source.

John Snow and the Broad Street Pump

Besides being dubbed the "Father of Epidemiology" for solving the mystery of cholera, John Snow was also a renowned anesthesiologist and credited as the first to use chloroform. Unlike most during the 19th century, Snow believed that the cholera contagion entered the victim through the mouth rather than being brought by "miasma" or a cloud of bad vapor in the air that descended on victim after victim. In 1849, Snow published an essay titled "On the Mode of Communication of Cholera" arguing that "cholera poison" spread through contaminated food or water.

During the 1853-4 outbreak of cholera in London (Third Cholera Pandemic), John Snow was able to test his theory. In late August 1854, a heavy outbreak occurred in the area of Golden Square and Soho Square south of London's Oxford Street. Snow carefully reviewed records of all fatal cases of cholera in the area at the General Register's office and conducted interviews of family members of the victims. Though his detective work, Snow constructed a spatial tally of all deaths in the area. There were thirteen water pumps in the area. Snow discovered that the heaviest casualties were clustered around the Broad Street water pump.

According to Snow's records, most public houses and coffee shops in the area mixed pump water with spirits. At a local coffee shop, a popular place frequented by mechanics, water was had with dinner. The shop reported 9 dead among its customers. A local brewery that had its own water supply and allocated to its employees a free allowance of beer suffered no cholera deaths among its 70 workmen. A lady who moved away from the Soho area to Hampstead, where there was no epidemic, but still drank from the Broad Street pump because she enjoyed the taste of its water, also contracted cholera and died. A gentleman who came to see his dying brother arrived too late. He stayed only 20 minutes, but drank water from the Broad Street pump, and was attacked with cholera the next day and died. In his famous spatial analysis, Snow charted 616 deaths around the Broad Street pump.

Snow recommended to the local authorities that the handle be removed from the Broad Street pump, which was done in 8 September 1854. The removal of the pump handle correlated with a decline in cholera cases, but this decline may have been due to the natural shape of the epidemic and the fact that possible human hosts had deserted the area rather than the removal of the pump handle. It was disclosed that the Broad Street pump reached 28 feet into the ground within yards of a sewer at 22 feet. Authorities remained skeptical; Snow had not produced direct evidence of the "cholera poison" he claimed had caused the disease. Snow further attempted to dispel their skepticism through what he called "The Grand Experiment."

Two water companies serviced the London area: the Lambeth Water Company and the Southwark and Vauxhall Water Company. While the former took its water from the Thames about 20 miles upstream from the London city sewers, the later took its water downstream. Snow examined records of the households serviced by the two water companies. Those serviced by Lambeth Water Company saw 37 deaths every 10,000 households and those serviced by Southwark and Vauxhall Water Company saw 315 deaths every 10,000 households. Snow's results showed a strong correlation between the consumption of polluted London waters and cholera deaths.

Fighting Cholera

The Fourth Pandemic began in 1865 in the Lower Bengal region of India. It was suspected that Indian Muslim pilgrims visiting Mecca spread the disease to the Middle East. Mecca was dubbed the relay point of cholera from east to west. It was reported that at least 30,000 of the 90,000 pilgrims were victims of the disease. The pandemic spread into Europe by 1865, and killed 90,000 in Russia in 1866. The disease returned to Russia from 1868 to 1869 and ravaged the Black Sea ports in 1871. Africa and the United States were heavily affected.

Robert Koch in 1876 isolated and cultivated the curved bacillus of cholera Vibrio cholera, a bacterium that continued to appear in a victim's feces long after symptoms subsided. Scientific evidence finally supported what John Snow hypothesized: cholera was spread from person to person through contaminated food and water. The deadly pandemics were helped along by open sewers, overflowing cesspools and latrines, and the absence of urban sanitation measures. In 1879, Louis Pasteur developed a cholera vaccine for fowl. Waldemar Haffkine, a student of Pasteur, developed a human vaccine for cholera and in 1892 tested the vaccine on himself, his first human subject. In a report to the Biological Society of Paris on 30 July 1892, Haffkine shared the success of his experiment: the side effects of the human vaccine were no more than slight fever, pain, and swelling. In 1893, Haffkine took the vaccine to India where he eventually inoculated over 20,000 subjects. Cholera fatality rate among the test subjects was 2% while they raged at 22-45% among the remaining population. Later, Haffkine also developed a vaccine for bubonic plague. In 1902, a public scandal transpired when a laboratory contamination of tetanus killed 19 cholera vaccine patients, but Haffkine was eventually exonerated of guilt. An inexperienced laboratory assistant had accidentally contaminated the vaccine. In 1925, the Plague Research Laboratory in Bombay was renamed the Haffkine Laboratory.

The Fifth Pandemic began in 1881 in the Bengal region and spread throughout India to Korea, Thailand, China and Japan. Robert Koch's discovery of Vibrio cholera allowed authorities to impose quarantine measures to fight the pandemic. Although cholera breached the strict quarantine measures and outbreaks occurred in France, Italy and Spain in 1884, this cholera pandemic was kept out of Britain and the United States thanks to quarantine measures. Despite these quarantine successes, the pandemic swept through Asia, South America, Africa, and parts of France and Germany.

The Sixth Pandemic from 1899 to 1923 also originated in northern India and caused more than 800,000 deaths in India in 1900, the highest recorded in India for a single year. India continued to suffer from cholera outbreaks during the first decades of the century. The pandemic moved up the Black Sea region into Mesopotamia, Persia, and then Russia by 1910. The Americas escaped from the pandemic except for the islands of Madeira in the Atlantic. Russian immigrants in 1910 brought the disease to Madeira. Incidents of cholera in Western Europe were rare, but central and southeastern Europe was affected. In 1910, gypsies brought the disease from Russia to Italy. During World War I, Austria and Hungary suffered from outbreaks, but German troops were vaccinated against cholera.

The Seventh Pandemic was named the El Tor pandemic caused by a strain of cholera, Vibrio comma, isolated by F. Gottslich in 1905 when he examined six dead Muslim pilgrims in El Tor quarantine station outside of Mecca. The Seventh Pandemic began in Sulawesi, Indonesia, and in 1961-62, spread among the Pacific islands of southwest Asia. In 1963, the pandemic arrived on the Asian mainland and traveled to India, Pakistan, the Middle East and the Soviet Union. In 1970, the pandemic arrived in Ethiopia and spread through the African continent. Cholera was still active in Africa in 1994 when the refugee camps set up after the Rwandan Genocide created ideal conditions for an outbreak. In 1991, a El Tor cholera outbreak occurred in Peru where cholera was last seen a century before. Epidemiologists hypothesized the disease was brought to Peru on ships from Asia, or that the marine environment acted as a holding space for cholera.

In the early 1990s, a new strain, cholera 0139, was discovered in Bangladesh and India. The 0139 strain is a more virulent, infectious, and robust strain on which traditional cholera vaccines has limited effect. Many scientists believed this to be the beginning of a new, eighth, global pandemic.

As of turn of the 21st century, epidemiologists are still uncertain about the origins of cholera pandemics, but all global pandemics originated on the Indian subcontinent. Scientists hypothesized that the disease flourishes on a seasonal, ecological cycle when the water is at the correct temperatures and salinity. Scientists also linked cholera bloom to phytoplankton blooms. Research by Dr. Colwell of the National Science Foundation connected cholera bacteria to copepods, crustaceans in the zooplankton family. Cholera bacteria ride on the backs of copepods and colonize in their intestines. Dr. Colwell also noted that cholera can enter a dormant, spore-like state that allows it to survive in adverse aqueous environments while remaining infectious.

Few cases of cholera occur in the developed world due to improvements in sanitation standards and urban building codes, but the developing world still suffer from the Seventh and the new 0139 Cholera Pandemic.

Cholera as a Biological Weapon

During World War II, the Japanese biological weapons program known as Unit 731 located in Pingfan Manchuria (24 kilometers south of Harbin) experimented with Vibrio cholera as a weapons agent. It was reported that the Japanese dropped cholera and typhus cultures into more than 1,000 Chinese wells and reportedly caused 10,000 cases in 1941. However, an estimated 1,700 of the deaths were Japanese soldiers, a testimony to the difficulty of protecting one's own troops from biological agents and controlling infections.

South Africa's biological weapons program, Project Coast (1981-1994), under the direction of Colonel Wouter Basson, developed cholera as a possible biological agent. It was reported that during South Africa's civil war, cholera, anthrax and other bacteria were released into water in rebel-held areas.

Iraq's biological weapons program reportedly began with the start of the Al-Hazen Institute in 1974 where cholera was one of the biological agents under study. North Korea reportedly also studied cholera as a possible biological weapons agent.