The complete blood count test is done to see if there is an infection in the body based on the number of white blood cells present in the sample. (wagwalking.com)
The most common cause of vomiting in babies is an infection of the intestinal tract by any virus that happens to be going around. (parents.com)
For instance, pelvic inflammatory disease is an infection in the upper reproductive system that can prevent ovulation and pregnancy. (thefashionablehousewife.com)