Cholera infections are most commonly acquired from drinking water in which "V. cholerae" is found naturally or into which it has been introduced from the feces of an infected person. Cholera is most likely to be found and spread in places with inadequate water treatment, poor sanitation, and inadequate hygiene. Other common vehicles include raw or undercooked fish and shellfish. Transmission from person to person is very unlikely, and casual contact with an infected person is not a risk for becoming ill."V. cholerae" thrives in an aquatic environment, particularly in surface water. The primary connection between humans and pathogenic strains is through water, particularly in economically reduced areas that do not have good water purification systems.