They exist primarily in sandy or loamy soil and cannot live in clay or muck. Rainfall averages must be more than 1,000 mm (39 in) a year for them to survive. Only if these conditions exist can the eggs hatch. Infective larvae of N. americanus can survive at higher temperatures, whereas those of A. duodenale are better adapted to cooler climates. Generally, they live for only a few weeks at most under natural conditions, and die almost immediately on exposure to direct sunlight or desiccation.Infection of the host is by the larvae, not the eggs. While A. duodenale can be ingested, the usual method of infection is through the skin; this is commonly caused by walking barefoot through areas contaminated with fecal matter. The larvae are able to penetrate the skin of the foot, and once inside the body, they migrate through the vascular system to the lungs, and from there up the trachea, and are swallowed. They then pass down the esophagus and enter the digestive system, finishing their journey in the intestine, where the larvae mature into adult worms.Once in the host gut, Necator tends to cause a prolonged infection, generally 1 to 5 years (many worms die within a year or two of infecting), though some adult worms have been recorded to live for 15 years or more. Ancylostoma adults are short-lived, surviving on average for only about 6 months.
Most research regarding diagnostic tools is now focused on the creation of a rapid and cost-effective assay for the specific diagnosis of hookworm infection. Many are hopeful that its development can be achieved within the next five years. History
Discovery
The symptoms now attributed to hookworm appear in papyrus papers of ancient Egypt (c. 1500 BC), described as a derangement characterized by anemia. Avicenna, a Persian physician of the eleventh century, discovered the worm in several of his patients and related it to their disease. In later times, the condition was noticeably prevalent in the mining industry in England, France, Germany, Belgium, North Queensland, and elsewhere.Italian physician Angelo Dubini was the modern-day discoverer of the worm in 1838 after an autopsy of a peasant woman. Dubini published details in 1843 and identified the species as A. duodenale. Working in the Egyptian medical system in 1852 German physician Theodor Bilharz, drawing upon the work of colleague Wilhelm Griesinger, found these worms during autopsies and went a step further in linking them to local endemic occurrences of chlorosis, which would probably be called iron-deficiency anemia today. A breakthrough came 25 years later following a diarrhea and anemia epidemic that took place among Italian workmen employed on the Gotthard Rail Tunnel. In an 1880 paper, physicians Camillo Bozzolo, Edoardo Perroncito, and Luigi Pagliani correctly hypothesized that hookworm was linked to the fact that workers had to defecate inside the 15 km tunnel, and that many wore worn-out shoes.