Ancylostoma duodenale
Encyclopedia
Ancylostoma duodenale is a species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of the worm genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Ancylostoma
Ancylostoma
Ancylostoma is a genus that includes some species of hookworm.Species include:Ancylostoma is a genus that includes some species of hookworm.Species include:Ancylostoma is a genus that includes some species of hookworm....

. It is a parasitic nematode worm and commonly known as Old World hookworm. It lives in the small intestine of host such as humans, cats and dogs.
Ancylostoma duodenale and Necator americanus
Necator americanus
Necator americanus is a species of Necator. It is a class within the phylum Nematodes and commonly known as New World hookworm. It is a parasitic nematode worm that lives in the small intestine of hosts such as humans, dogs and cats. It is responsible for Necatoriasis...

 are the two human hookworms that are normally discussed together as the cause of hookworm infection. 90% asymptomatic can lead to iron deficiency anemia.

They are dioecious
Dioecious
Dioecy is the property of a group of biological organisms that have males and females, but not members that have organs of both sexes at the same time. I.e., those whose individual members can usually produce only one type of gamete; each individual organism is thus distinctly female or male...

.

Ancylostoma duodenale , a member of the Ancylostomidae, is also commonly referred to as a "hookworm". As such, hookworms have the ability to mate and mature in the small intestine of their host.

Ancylostoma duodenale is abundant throughout the world, including the following countries: southern Europe, north Africa, India, China, Southeast Asia, some areas in the United States, Caribbean, and South America.

Morphology

Ancylostoma duodenale is small cylindrical worm,greyish white in color.it has two ventral plates at the anterior margin of the buccal capsule. Each of them has two large teeth that are fused at their bases. A pair of small teeth can be found in the depths of the buccal capsule. Males are 8 mm to 11 mm long with a copulatory bursa at the posterior end. It also has needlelike spicules which are not fused and have simple tips. Females are 10 mm to 13 mm long with the vulva located at the posterior end and can lay 10,000 to 30,000 eggs per day. Their life span is one year.

Life cycle

When a filariform larva (infective stage) penetrates the intact skin, the larva enters the blood circulation. Then it is carried to the lungs, coughed up and swallowed back to the small intestine. The larva later matures into adult in the small intestine and female worms can lay 25,000 eggs per day. The eggs are released into the feces and resided on soil. Embryonated egg on soil will hatch into juvenile 1 stage (rhabditiform or noninfective stage) and mature into filariform larvae. The filariform larvae can then penetrate another exposed skin and begin a new cycle of human infection.

Epidemiology

Ancylostoma duodenale is the first hookworm in which a life cycle was illuminated. It is prevalent in southern Europe, northern Africa, India, China, and Southeast Asia, small areas of United States, Caribbean Islands, and South America. This hookworm is well known in mines because of the consistency in temperature and humidity that provide an ideal habitat for egg and juvenile development. It is estimated 1 billion people are infected with hookworms. Transmission of Ancylostoma duodenale is by contact of skin with soil contaminated with larvae.

Symptoms

Light infection causes abdominal pain, loss of appetite and geophagy
Geophagy
Geophagy is the practice of eating earthy or soil-like substances such as clay, and chalk. It exists in animals in the wild and also in humans, most often in rural or preindustrial societies among children and pregnant women...

. Heavy infection causes severe protein deficiency or iron deficiency anemia. Protein deficiency might have dry skin, edema and potbelly, while iron deficiency anemia might have mental dullness and heart failure.

Laboratory Diagnosis

The eggs of Ancylostoma duodenale and Necator americanus cannot be distinguished. Larvae cannot be found in the stool specimens unless it is left at ambient temperature for a day or more.

Prevention and Control

Education, improved sanitation and controlled disposal of human feces are important. Wearing shoes in endemic areas can reduce the prevalence of infection as well.

Treatment

Ancylostoma duodenale can be treated with albendazole, mebendazole and benzimidazoles. Pyrantel pamoate is an alternative. In severe cases of anemia, blood transfusion might be necessary.

External links

  • http://workforce.cup.edu/buckelew/Ancylostoma%20duodenale%20ova.htm
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