Ancylostoma duodenale

Dubini, 1843; Griesinger, 1854

Ancylostoma duodenale (from ankylos = crooked) is a hookworm in the family Ancylostomatidae and the genus Ancylostoma. Ancylostoma duodenale is the causative agent of ancylostomiasis (ancylostomatidosis) or hookworm disease of a chronic intestinal infection.

Ancylostomatidae are a family of nematodes. The parasites are 0.7-1.8cm long and filamentous. Their anterior end is hooked . Characteristic of these worms is a mouth papule with tooth-like structures

About 50 million patients are symptomatically ill worldwide; 400-900 million people are asymptomatic hosts. Ancylostoma used to be a disease of miners and workers in tunnel construction and the like. This is no longer the case. Today, its distribution is restricted to tropical and subtropical regions. In endemic areas (Africa, Southern Europe, Central and South America, Southern USA) a considerable part of the population is infected. Worm infection mainly occurs during work in rice fields and when walking barefoot on contaminated soil.

Infection is predominantly percutaneous. Invasion of hookworm larvae occurs on uncovered skin (mostly soles/back of feet). Subsequent larval migration by the blood or lymphatic route into the pulmonary vessels (heart-lung passage). In the lungs they cause a volatile inflammation which clinically appears as eosinophilic Löffler's infiltrate. The lungs are exited via alveoli, bronchi, trachea. Larvae enter the pharynx, are swallowed, and ultimately settle in the jejunum and ileum. There development to sexual maturity.

Adult hookworms attach to the mucosa and suck blood. The presence of the worms causes abdominal pain, flatulence, loss of appetite with weight loss, and permanent iron deficiency anemia. The female worms release about 20,000 eggs daily, which enter the environment with the feces.

Inflammation of the skin with itching at the site of penetration of the 0.6mm larvae. Often eczematization and superinfection of the lesions by scratching, urticaria.

Later, depending on the migration routes of the larvae, there may be pulmonary symptoms (eosinophilia, radiographic cloud-like pulmonary infiltrates - Löffler infiltrate), anemia, heart failure, digestive disorders, malnutrition. If the larvae are not swallowed, they settle in the throat and cause hoarseness, nausea, salivation and cough.

Detection of worm eggs in fresh stool!

Albendazole (Eskazole®): 400 mg p.o. as ED.

Alternative: Pyrantel (e.g. Helmex®) single ED of 10 mg/kg bw/day (max. 1 g).

Alternative: Mebendazole (e.g. Vermox®) 2 times/day 100 mg for 3 days or

Ivermectin (Mectizan®): 150-200 μg/kg bw p.o. as ED.

Ancylostoma duodenale, old world hookworm (the name "duodenal" is absolutely misleading as the live adult worms do not live in the duodenum but in the jejunum and ileum). Necator americanus and Ancylostoma ceylanicum are the new world hookworm species.

1. Albonico M et al. (2003) Efficacy of mebendazole and levamisole alone or in combination against intestinal nematode infections after repeated targeted mebendazole treatment in Zanzibar. Bull World Health Organ 81: 343-352
2. Brenner MA et al (2003) Cutaneous larva migrans: the creeping eruption. Cutis 72: 111-115
3. Caumes E et al (1992) Efficacy of ivermectin in the therapy of cutaneous larva migrans. Arch Dermatol 128: 83-87
4. Chu S et al (2013) Hookworm dermatitis due to Uncinaria stenocephala in a dog from Saskatchewan. Can Vet J 54:743-747.
5. Cooper PJ et al (2003) Reduced risk of atopy among school-age children infected with geohelminth parasites in a rural area of the tropics. J Allergy Clin Immunol 111: 995-1000
6. Dubini A (1843) Nuovo verme intestinal umano (Ancylostoma duodenale) constituente un sesto genere die nematoidea propri dell' uomo. Ann Universali Med 106: 5-13
7. Griesinger W (1854) Clinical and anatomical observations on the diseases of Egypt. Arch Physiol Heilkd 13: 528-575.
8. Kim SC et al (2003) Pruritic skin eruption on the left foot of a 36-year-old woman. Clin Infect Dis 37: 406, 448-449
9. Ponnighaus JM et al (2000) Pruritus of dark skin in hookworm infection. Dermatologist 51: 953-955