Studies of cholera El Tor in the Philippines. 4. Transmission of infection among neighbourhood and community contacts of cholera patients.

As part of a broad study on the epidemiology of cholera El Tor in the Philippines, the authors conducted bacteriological surveys among the community contacts of suspect cholera patients hospitalized in the Negros Occidental Provincial Hospital from August through October 1962. Fourteen (2%) of 698 community contacts of persons with confirmed cholera patients were found on initial culture to be infected.Intensive studies in two communities suggested that infection was spread primarily by close personal contact; in a third community, contamined well-water presumably served as a vehicle for the transmission of infection. Diagnosed and undiagnosed cases, undiagnosed cholera deaths and asymptomatic infections all played a role in cholera transmission.The studies tend to confirm that the second or recurrent epidemic in Negros Occidental was primarily caused by person-to-person spread. Although the seemingly isolated or sporadic cases were sometimes associated with a more general distribution of the cholera vibrio, the cholera infections invariably were highly localized among close contacts even within densely populated areas with poor sanitation.