INTRODUCTION

The hookworm was not discovered until 1838, but attempts have been made to trace the disease back to ancient times. Certain statements in a manuscript of 1550 B.C. are interpreted by many authorities as indicating that both the hookworm and hookworm disease were known to the ancient Egyptians. This interpretation was strongly opposed by F. von Oefele (1901), who studied the original papyrus text. Arthur Looss, the eminent authority on hookworm disease, most of whose work was done in Cairo, believes that von Oefele's views are plausible, and concludes: "It is thus only negatively probable that the ancient Egyptians should have known the Ankylostoma as a distinct animal and as the cause of a definite disease, although both the parasite and the disease were no doubt frequent in ancient times."

Through the records of ancient history run accounts of epidemics of anemia that may reasonably be suspected of having had some connection with the hookworm. Hippocrates, about 440 B.C., draws a suspicious clinical picture of a disease that caused people to eat stones and earth, brought upon them great intestinal disturbances, and, though it was not jaundice, gave people much the same color as did the latter disease. In classical literature the striking pallor of miners is frequently mentioned, appearing, for example, in the works of Lucretius and Lucan (50 B.C. and 50 A.D.). At that time it was the custom to accuse gold of giving off evil exhalations which soon turned the greedy delvers the same color as the metal they sought. No one suspected the existence of the anemiaproducing hookworm.

Certain "round worms" mentioned in an Arabian manuscript by Avicenna have been identified as hookworms, and the symptoms caused by these worms, which Avicenna traced in considerable detail, are apparently those of hookworm disease. Dr. Khalil, who discusses the manuscript and translates sections of it in a recent number of the Journal of Tropical Medicine and Hygiene, thinks this is probably the earliest valid record of Ancylostoma and Ancylostomiasis. During the last three centuries reports have become fairly definite. Piso (1611–1678) in Brazil, Father Labat (1663-1738) in Guadeloupe, and Bryan Edwards (1743-1800) in Jamaica, all describe epidemics of a disease then known under various names, such as anemia, dropsy, intestinal disturbance, and weakness. It was particularly noticed as a cause of death among negro slaves. The symptoms coincide with those of hookworm disease. A great

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deal of misinterpretation has continued down to recent times, especially as regards the relation of malaria to anemia, and as to the correct cause of dirt-eating and other symptoms supposedly caused by warm climates.

Before the hookworm was finally found in man a number of related species were discovered in animals. In 1782 Goeze found some worms in the intestines of a badger (Meles taxus), which, on account of their hair-like shape, he called Ascaris criniformis, though he suspected them of belonging to a genus different from that of the ordinary Ascaris. He noted a membranous expansion of the tail of the male, with two rib-like structures in it which he called hooks. In 1789 similar worms were found in the intestines of foxes by Froelich. He also observed the membranous expansion and the so-called hooks, and therefore gave the name Haakenwurm ("hookworm," or Uncinaria) to the genus. These animal parasites were species of the hookworm, but not the same species that are harbored by

man.

Discovery of the Hookworm

Of the two main species of hookworm which infest man—the Ancylostoma duodenale and Necator americanus-the former was the first to be discovered. Worms of this species were recognized in 1838 by Angelo Dubini, an Italian physician, who found them in the body of a peasant woman who had died of pneumonia in the hospital at Milan. They were encountered a second time at an autopsy in December, 1842. The latter finding led to a systematic examination of one hundred bodies, in twenty of which the parasites were discovered. In 1843 Dubini published a detailed account of the worm, to which he gave the name Agchylostoma duodenale. He noted the true hooks, the four hooklike teeth that stand out from the rounded mouth. Thereafter he continued to come across further specimens, which, as he remarked, were easily found if a proper search were made. The reason these common intestinal parasites had not before been found, he attributed to the imperfect manner in which earlier autopsies had been performed.

Dubini gave a description of the physical aspect of hookworms, but he did not emphasize the harm that they can do to the human system. Although he suspected that the body was not unaffected by their presence, he reported that the mucous membrane to which they attach themselves looked normal, or at worst "arborescent," and that he was unable to name any special symptoms produced by the worms. The individuals harboring the parasites had died from a variety of causes, and it seemed impossible to ascribe any one of the deaths to hookworm infection.

Von Siebold in 1845 classified the hookworm as belonging to the Strongyloidae. Soon afterward, Castiglioni described the occurrence of hookworms in the bodies of dropsical and cachectic individuals, but, like Dubini, did not realize their pathogenic importance.

Scientists elsewhere soon began to connect the parasite with certain diseases, chief among which was Egyptian chlorosis. In 1847 Pruner, while making autopsies, had found the worm in Egypt. Bilharz (1853) and Griesinger (1854) connected the parasites with the extremely prevalent chlorosis which was the cause of more than one fourth of all the deaths in that country. Griesinger was emphatic enough in his statements, but the physicians in Egypt paid little attention to him. Twenty years later most of them remembered only vaguely his work or that of Pruner and Bilharz.

But in other parts of the world the work of Griesinger had a stimulating effect. In Brazil, Wücherer in 1866 found hookworms in the bodies of patients who had died from tropical anemia, and subsequent observations by Brazilian physicians confirmed the suspicion that the parasites were responsible also for this widely prevalent disease. These and other similar studies resulted in the parasite discovered by Dubini being established in the minds of medical men as the cause of a severe anemia found almost everywhere in tropical regions.

Origin of Fecal Diagnosis

Until 1877 the hookworm had been found only at autopsy. A simple method for diagnosing hookworm infection in living beings was wanting. This was supplied as a direct result of extensive research in Italy. In a paper written in 1878 Grassi and two brothers, Ernesto and Corrado Parona, demonstrated that hookworm disease could be recognized from ova passed in the feces. From that date forward it became the custom to search for hookworm eggs in the feces of anemic patients, with the result that constantly increasing numbers of patients of this class were found to be hookworm carriers.

The Saint Gotthard Epidemic

Hookworm disease was still a comparatively unknown malady in 1880, when the Saint Gotthard tunnel was under construction. Though this tunnel was not located in Italy, the men working on it were chiefly Italians; hence, when a violent epidemic of anemia developed among them, the Italian government concerned itself with their welfare and sought and obtained from the Swiss government official information concerning the outbreak.