Ancylostomiasis
Ancylostomiasis | |
ICD-10 | K29.0-K29.7 |
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ICD-9 | 535.0-535.5 |
DiseasesDB | 34500 |
Ancylostomiasis Microchapters |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Ancylostomiasis from other Diseases
Epidemiology and Demographics
Risk Factors
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms | Physical Examination | Laboratory Findings | Other Imaging Findings | Other Diagnostic Studies
Treatment
Medical Therapy | Surgery | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies
Case Studies
Related Chapters
Causes
The infection is usually contracted by persons walking barefoot over contaminated soil. In penetrating the skin, the larvae may cause an allergic reaction. It is from the itchy patch at the site of entry that the early infection gets its nickname "ground itch". Once larvae have broken through the skin, they enter the bloodstream and are carried to the lungs (unlike ascarids, however, hookworms do not usually cause pneumonia). The larvae migrate from the lungs up the windpipe to be swallowed and carried back down to the intestine. If humans come into contact with larvae of the dog hookworm or the cat hookworm, or of certain other hookworms that do not infect humans, the larvae may penetrate the skin. Sometimes, the larvae are unable to complete their migratory cycle in humans. Instead, the larvae migrate just below the skin producing snake-like markings. This is referred to as a creeping eruption or cutaneous larva migrans. [1]
Diagnosis
They commonly infect the skin, eyes, and viscera in humans.
- Toxocara causes visceral larva migrans.[2]
Prevention
Control of this parasite should be directed against reducing the level of environmental contamination. Treatment of heavily infected individuals is one way to reduce the source of contamination (one study has estimated that 60% of the total worm burden resides in less than 10% of the population). Other obvious methods are to improve access to sanitation, e.g. toilets, but also convincing people to maintaining them in a clean, functional state, thereby making them conducive to use.
Epidemiology
Hookworms still account for high proportion of debilitating disease in the tropics and 50-60,000 deaths per year can be attributed to this disease. [3]
Treatment
The drug of choice for the treatment of hookworm disease is mebendazole which is effective against both species, and in addition, will remove the intestinal worm Ascaris also, if present. The drug is very efficient, requiring only a single dose and is inexpensive, the perfect drug. However, treatment requires more than giving the anthelmintic, the patient should also receive dietary supplements to improve their general level of health, in particular iron supplementation is very important. Iron is an important constituent of a multitude of enzyme systems involved in energy metabolism, DNA synthesis and drug detoxification.
An infection of N. americanus parasites can be treated by using benzimidazoles, albendazole, and mebendazole. A blood transfusion may be necessary in severe cases of anemia. Light infections are usually left untreated in areas where reinfection is common. Iron supplements and a diet high in protein will speed the recovery process.[4] In a case study involving 56-60 men with Trichuris trichiura and/or N. americanus infections, both albendazole and mebendazole were 90% effective in curing T. trichiura. However, albendazole had a 95% cure rate for N. americanus, while mebendazole only had a 21% cure rate. This suggests albendazole is most effective for treating both T. trichiura and N. americanus.[5]
Gallery
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Unstained micrograph of the Ancylostoma duodenale hookworm's mouth parts; Mag. 125X. From Public Health Image Library (PHIL). [6]
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This enlargement shows hookworms, Ancylostoma caninum attached to the intestinal mucosa. From Public Health Image Library (PHIL). [6]
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Micrograph depicting the tail tip of a Strongyloides filariform infective stage larvae on the left, and a hookworm on the right. From Public Health Image Library (PHIL). [6]
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This micrograph depicts a hookworm (Lt), and a Strongyloides (Rt) filariform infective stage larvae. From Public Health Image Library (PHIL). [6]
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This child with hookworm shows visible signs of edema, and was diagnosed with anemia as well. From Public Health Image Library (PHIL). [6]
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The human hookworms include two nematode (roundworm) species, Ancylostoma duodenale and Necator americanus. From Public Health Image Library (PHIL). [6]
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Diagram depicting the various stages in the life cycle of the Strongyloides stercoralis nematode. From Public Health Image Library (PHIL). [6]
References
- ↑ "Hookworm". Retrieved 2008-10-30.
- ↑ "Definition: larva migrans". Retrieved 2008-10-30.
- ↑ "Hookworms: Ancylostoma spp. and Necator spp". Archived from the original on 27 October 2008. Retrieved 2008-10-30.
- ↑ "hookworm disease." Encyclopædia Britannica. 2009. Encyclopædia Britannica Online. 06 Dec. 2009 <http://www.britannica.com/EBchecked/topic/271350/hookworm-disease>.
- ↑ Holzer, B. R.; and Frey, F. J. (February 1987). "Differential efficacy of mebendazole and albendazole against Necator americanus but not for Trichuris trichiura infestations". European Journal of Clinical Pharmacology. 32 (6): 635-637. http://www.springerlink.com/content/k000065915k70257/
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 "Public Health Image Library (PHIL)".