A Major Factor in the Reduction in the Number of Cases

question 67

Short Answer

A major factor in the reduction in the number of cases of typhoid fever was the introduction of________ and _________ into water purification systems.

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Definitions:

Teratogen

Any agent or substance that can cause malformation of an embryo or fetus.

Birth Defect

A physical or biochemical abnormality that is present at birth and that may affect bodily functions or appearance.

Prenatal Development

The process of growth and development within a woman's uterus before birth.

Embryonic Period

A critical phase of development in early pregnancy, extending from fertilization to the end of the 8th week, during which the basic structures and organs of the organism begin to form.