Cholera outbreaks in the classical biotype era

Area of Science:

• Epidemiology
• Microbiology
• History of Medicine

Background:

• Cholera's historical presence in the Indian subcontinent dates back to ancient texts (~400-500 BC).
• The modern history of cholera pandemics began in 1817, with seven major global outbreaks causing significant mortality.
• Vibrio cholerae O1, the causative agent, was identified during the fifth pandemic and exists in Classical and El Tor biotypes.

Observation:

• The fifth and sixth cholera pandemics were caused by the Classical biotype of Vibrio cholerae O1.
• The seventh pandemic, starting in the early 1960s, was driven by the El Tor biotype originating in Indonesia.
• The El Tor biotype rapidly spread worldwide, displacing the Classical biotype in most regions within 50 years.

Findings:

• The reasons for the emergence and cessation of earlier cholera pandemics remain unclear.
• The displacement of the Classical biotype by the El Tor biotype is a significant, yet unexplained, epidemiological event.
• Bangladesh experienced a unique co-existence of Classical and El Tor biotypes of Vibrio cholerae O1 from 1963 to 1991.

Implications:

• Understanding the dynamics of biotype displacement offers insights into pathogen evolution and pandemic spread.
• The prolonged co-existence in Bangladesh presents a valuable opportunity to study cholera's epidemiology and pathogenesis.
• Further research is needed to elucidate the factors driving pandemic emergence, resolution, and biotype dominance in Vibrio cholerae O1.