Professor Beaver's interest in amebiasis dates back to 1947, when he was invited by the Standard Oil Company to assess parasitic infections in Caripito, Venezuela (rain forest), and in Talara, Peru (arid area) (P. C. Beaver, personal communication). He noted with interest that the infection rate of Entamoeba histolytica was high in both regions, about 30%, but amebic disease was present only in people from the rain forest. Dr. Beaver was also impressed by the fact that E. histolytica cysts survived for long periods in soil at high temperatures and therefore, like certain helminths, could be soil transmitted.

While in Latin America, Dr. Beaver showed for the first time that acetic acid in the concentration generally used in vinegar came close to being an ideal disinfectant. Indeed, immersion in 5% acetic acid killed the cysts of E. histolytica without adversely affecting the flavor or appearance of most fresh vegetables. This procedure, however, has not become generally accepted.