Seventh cholera pandemic

The seventh cholera pandemic (also called by some the 1961–1975 cholera pandemic) is the seventh major outbreak of cholera and occurred principally from the years 1961 to 1975, but the strain involved persists to the present. WHO and some other authorities believe this should be considered as an ongoing pandemic. As stated in its cholera factsheet dated 30 March 2022, the World Health Organization (WHO) continues to define this outbreak as a current pandemic, and with cholera having become endemic in many countries. In 2017, WHO announced a global strategy aiming to end this pandemic by 2030.

This pandemic is based on the strain called El Tor; it started in Indonesia in 1961 and spread to East Pakistan (now Bangladesh), by 1963. It went to India in 1964, and into the Soviet Union by 1966. In July 1970, there was an outbreak in Odessa (now Ukraine) and in 1972 there were reports of outbreaks in Baku, but the Soviet Union suppressed this information. Cholera reached Italy in 1973 from North Africa. Japan and the South Pacific saw a few outbreaks by the late 1970s. In 1971, the number of cases reported worldwide was 155,000. But in 1991, it reached 570,000. The spread of the disease was helped by modern transportation and mass migrations. Mortality rates, however, dropped markedly as governments began modern curative and preventive measures. The usual mortality rate of 50% dropped to 10% by the 1980s and less than 3% by the 1990s.

In 1991, the strain made a comeback in Latin America. It began in Peru, where it killed roughly 10,000 people. Research has traced the origin of the strain to the seventh cholera pandemic. Researchers initially suspected the strain came to Latin America through Asia from contaminated water, but samples from Latin America and samples from Africa were found to be identical.

This rapid transmission of the pathogen around the globe in the 20th century can be attributed chiefly to the major hub, the Bay of Bengal, from where the disease spread.

This pandemic can be categorized into two main periods. During Period 1 (1961–1969), 24 Asian countries reported 419,968 cholera cases. In Period 2 (1970–1975), 73 countries from Asia, Africa, Europe and the Americas reported 706,261 cases. Cholera is caused by eating food or drinking water that is contaminated with the bacteria V. cholerae. It affects both children and adults, causing severe watery diarrhea with dehydration. But, as noted, the El Tor strain has persisted for decades to the present, causing repeated epidemics in varied locations, with 570,000 cases in 1991 alone. WHO and other authorities believe that the seventh pandemic continues.