Parasite infestations of the gastrointestinal tract can cause anemia. Hookworms will feed on the blood, while tapeworms will rob nutrients. Anemia can result from the blood loss or to nutritional deficiencies, particularly that of of folate, iron, and/or Vitamin B12.
The effects of this type of anemia include fatigue, irritability, fever, abdominal discomfort, nausea, vomiting, and other gastrointestinal complaints. Treatment is with an antiparasite medication along with nutritional therapy.
The most common culprit is the hookworm, an intestinal parasite of humans that usually causes mild diarrhea or cramps. Heavy infestations can create serious health problems, including anemia. Hookworm infections occur mostly in tropical and subtropical climates and are estimated to infect over a billion people or, about one-sixth of the world’s population. Infection occurs by direct contact with contaminated soil, that is, generally walking barefoot or accidentally swallowing contaminated soil, that is, eating food that has not been washed properly.
One of the most common species of hookworm is the Ancylostoma duodenale, found in southern Europe, northern Africa, northern Asia, and parts of South America.
A second species, Necator americanus, was widespread in the southeastern United States; but the Rockefeller Sanitary Commission (founded in response to the situation early in the 20th century), has stated that the hookworm infection has been largely controlled. Keyword being – largely – therefore, it is still wise not to go barefoot outside very often.