Flying insects feeding on feces may occasionally transfer the bacteria through poor hygiene habits and public sanitation conditions.  Public education campaigns encouraging people to wash their hands after defecating and before handling food are an important component in controlling spread of the disease. According to statistics from the United States Center for Disease Control, the chlorination of drinking water has led to dramatic decreases in the transmission of typhoid fever in the U.S. During the colonial period in American history there was no such treatment available so typhoid fever was a frequent killer.