When adult worms attach to the villi of the small intestine, they suck on the host's blood, which may cause abdominal pain, diarrhea, cramps, and weight loss that can lead to anorexia.

Once larvae break through the alveoli and are swallowed, they enter the gastrointestinal tract and attach to the intestinal mucosa where they mature into adult worms.

The major issue results from this intestinal blood loss which can lead to iron-deficiency anemia in moderate to heavy infections.

[citation needed] The standard method for diagnosing necatoriasis is through identification of N. americanus eggs in a fecal sample using a microscope.

Eggs can be difficult to visualize in a lightly infected sample so a concentration method is generally used such as flotation or sedimentation.

[citation needed] Education, improved sanitation, and controlled disposal of human feces are critical for prevention.

[8] Cryotherapy by application of liquid nitrogen to the skin has been used to kill cutaneous larvae migrans, but the procedure has a low cure rate and a high incidence of pain and severe skin damage, so it now is passed over in favor of suitable pharmaceuticals.

Later, it was found to be indigenous in Africa, China, southwest Pacific islands, India, and Southeast Asia.

[citation needed] Transmission of N. americanus infection requires the deposition of egg-containing feces on shady, well-drained soil and is favored by warm, humid (tropical) conditions.