The deadly hookworm. Why did the Puerto Ricans die?
D000747:Anemia, Hypochromic / Q000209:etiology*; D049672:History, 19th Century; D049673:History, 20th Century; D006725:Hookworm Infections / Q000150:complications* / Q000266:history; D006801:Humans; D009332:Necatoriasis / Q000453:epidemiology; D011647:Puerto Rico; D013182:Sprue, Tropical / Q000150:complications / Q000453:epidemiology; D014481:United States