Ancylostomiasis
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Ancylostomiasis is a hookworm disease caused by infection with '' Ancylostoma''
hookworm Hookworms are Gastrointestinal tract, intestinal, Hematophagy, blood-feeding, parasitic Nematode, roundworms that cause types of infection known as helminthiases. Hookworm infection is found in many parts of the world, and is common in areas with ...
s. The name is derived from Greek ancylos αγκύλος "crooked, bent" and stoma στόμα "mouth". Ancylostomiasis is also known as miner's anaemia, tunnel disease, brickmaker's anaemia and Egyptian chlorosis.
Helminthiasis Helminthiasis, also known as worm infection, is any macroparasite, macroparasitic disease of humans and other animals in which a part of the body is infected with parasitism, parasitic worms, known as helminths. There are numerous species of the ...
may also refer to ancylostomiasis, but this term also refers to all other
parasitic worm Parasitic worms, also known as helminths, are a polyphyletic group of large macroparasites; adults can generally be seen with the naked eye. Many are intestinal worms that are soil-transmitted and infect the gastrointestinal tract. Other par ...
diseases as well. In the United Kingdom, if acquired in the context of working in a mine, the condition is eligible for Industrial Injuries Disability Benefit. It is a prescribed disease (B4) under the relevant legislation.§ Ancylostomiasis is caused when hookworms, present in large numbers, produce an
iron deficiency anemia Iron-deficiency anemia is anemia caused by a lack of iron. Anemia is defined as a decrease in the number of red blood cells or the amount of hemoglobin in the blood. When onset is slow, symptoms are often vague such as feeling tired, weak, sh ...
by sucking blood from the host's intestinal walls.


Signs and symptoms

Depending on the organism, the signs and symptoms vary. '' Ancylostoma duodenale'' and ''
Necator americanus ''Necator americanus'' is a species of hookworm (a type of helminth) commonly known as the New World hookworm. Like other hookworms, it is a member of the phylum Nematoda. It is an obligatory parasitic nematode that lives in the small intestin ...
'' can enter the blood stream while '' Ancylostoma braziliensis'' cannot. Signs and symptoms of ''Ancylostoma duodenale'' and ''Necator americanus'' are given in corresponding page. In ''Ancylostoma braziliensis'' as the larvae are in an abnormal host, they do not mature to adults but instead migrate through the skin until killed by the host's inflammatory response. This migration causes local intense itching and a red serpiginous lesion. Treatment with a single dose of oral
ivermectin Ivermectin is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, it is used to treat infestations including head lice ...
results in cure rates of 94–100%.


Causes

The infection is usually contracted by people walking barefoot over contaminated soil. In penetrating the skin, the larvae may cause an allergic reaction. It is due to 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 (however, unlike ascarids, 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 dog hookworms or cat hookworms, 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. However, '' Ancylostoma ceylanicum'', a canid and felid hookworm, is able to establish patent intestinal infection in humans and is thus a
zoonotic A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a virus, bacterium, parasite, fungi, or prion) that can jump from a non-human vertebrate to a human. When h ...
cause of ancylostomiasis.


Diagnosis

They commonly infect the skin, eyes, and viscera in humans. * '' Ancylostoma brasiliensis'' causes
cutaneous larva migrans Cutaneous larva migrans (abbreviated CLM) is a skin disease in humans, caused by the larvae of various nematode parasites of the hookworm family ( Ancylostomatidae). The parasites live in the intestines of dogs, cats, and wild animals; they should ...
. * ''
Toxocara The Toxocaridae are a zoonotic family of parasitic nematodes that infect canids and felids and which cause toxocariasis in humans ( visceral larva migrans and ocular larva migrans). The worms are unable to reproduce in humans. Notable species ...
'' causes visceral larva migrans.


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 Sanitation refers to public health conditions related to clean drinking water and treatment and disposal of human excreta and sewage. Preventing human contact with feces is part of sanitation, as is hand washing with soap. Sanitation systems ...
, e.g.
toilets A toilet is a piece of sanitary hardware that collects human waste (urine and Human feces, feces) and sometimes toilet paper, usually for disposal. Flush toilets use water, while dry toilet, dry or non-flush toilets do not. They can be desi ...
, but also convincing people to maintaining them in a clean, functional state, thereby making them conducive to use.


Treatment

The drug of choice for the treatment of hookworm disease is
mebendazole Mebendazole (MBZ), sold under the brand name Vermox among others, is a medication used to treat a number of parasitic worm infestations. This includes ascariasis, pinworm infection, hookworm infections, guinea worm infections and hydatid di ...
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. 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 Benzimidazole is a heterocyclic aromatic organic compound. This bicyclic compound may be viewed as fused rings of the aromatic compounds benzene and imidazole. It is a white solid that appears in form of tabular crystals. Preparation Be ...
,
albendazole Albendazole is a broad-spectrum antihelmintic and antiprotozoal agent of the benzimidazole type. It is used for the treatment of a variety of intestinal parasite infections, including ascariasis, pinworm infection, hookworm infection, trichuri ...
, and
mebendazole Mebendazole (MBZ), sold under the brand name Vermox among others, is a medication used to treat a number of parasitic worm infestations. This includes ascariasis, pinworm infection, hookworm infections, guinea worm infections and hydatid di ...
. 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. In a case study involving 56–60 men with ''
Trichuris trichiura ''Trichuris trichiura, Trichocephalus trichiuris'' or whipworm, is a parasitic roundworm (a type of helminth) that causes trichuriasis (a type of helminthiasis which is one of the neglected tropical diseases) when it infects a human large inte ...
'' 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''. During the 1910s, common treatments for hookworm included
thymol Thymol (also known as 2-isopropyl-5-methylphenol, IPMP), , is a toxic monoterpenoid phenol derivative of ''p''-Cymene, isomeric with carvacrol. It occurs naturally in the oil of thyme, and it is extracted from ''Thymus vulgaris'' (common thy ...
, 2-naphthol,
chloroform Chloroform, or trichloromethane (often abbreviated as TCM), is an organochloride with the formula and a common solvent. It is a volatile, colorless, sweet-smelling, dense liquid produced on a large scale as a precursor to refrigerants and po ...
,
gasoline Gasoline ( North American English) or petrol ( Commonwealth English) is a petrochemical product characterized as a transparent, yellowish, and flammable liquid normally used as a fuel for spark-ignited internal combustion engines. When for ...
, and
eucalyptus oil Eucalyptus oil is the generic name for distilled oil from the leaves of ''Eucalyptus'', a genus of the plant family Myrtaceae, mostly native to Australia but cultivated worldwide. Eucalyptus oil has a history of wide application, as a pharmace ...
. By the 1940s, the treatment of choice was
tetrachloroethylene Tetrachloroethylene, also known as perchloroethylene or under the systematic name tetrachloroethene, and abbreviations such as perc (or PERC), and PCE, is a chlorocarbon with the formula . It is a non-flammable, stable, colorless and heavy liqu ...
, given as 3 to 4 cc in the fasting state, followed by 30 to 45 g of
sodium sulfate Sodium sulfate (also known as sodium sulphate or sulfate of soda) is the inorganic compound with formula Na2SO4 as well as several related hydrates. All forms are white solids that are highly soluble in water. With an annual production of 6 mill ...
. Tetrachloroethylene was reported to have a cure rate of 80 percent for Necator infections, but 25 percent in Ancylostoma infections, requiring re-treatment.


Epidemiology

Hookworm anaemia was first described by Wilhelm Griesenger in Egypt, Cairo in 1852. He found thousands of adult ancylostomes in the small bowel of a 20-year old soldier who was suffering from severe diarrhoea and anaemia (labelled at the time as Egyptian chlorosis). The subject was revisited in Europe when there was an outbreak of "miner's anaemia" in Italy. During the construction of the Gotthard Tunnel in
Switzerland Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...
(1871–81), a large number of
miner A miner is a person who extracts ore, coal, chalk, clay, or other minerals from the earth through mining. There are two senses in which the term is used. In its narrowest sense, a miner is someone who works at the rock face (mining), face; cutt ...
s suffered from severe
anaemia Anemia (also spelt anaemia in British English) is a blood disorder in which the blood has a reduced ability to carry oxygen. This can be due to a lower than normal number of red blood cells, a reduction in the amount of hemoglobin availab ...
of unknown cause. Medical investigations let to the understanding that it was caused by '' Ancylostoma duodenale'' (favoured by high temperatures and humidity) and to "major advances in
parasitology Parasitology is the study of parasites, their host (biology), hosts, and the relationship between them. As a List of biology disciplines, biological discipline, the scope of parasitology is not determined by the organism or environment in questio ...
, by way of research into the aetiology, epidemiology and treatment of ancylostomiasis". 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.


See also

* Necatoriasis


References


External links

{{Portal bar, Medicine Parasitic infestations, stings, and bites of the skin Helminthiases