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In this article we will discuss about Ancylostoma Duodenale:- 1. Discovery of Ancylostoma Duodenale 2. Life Cycle of Ancylostoma Duodenale 3. Pathogenesis 4. Treatment and Control of Disease.
Discovery of Ancylostoma Duodenale:
Ancylostoma Duodenale was discovered by an Italian physician, Angelo Ducini Looss in 1898. It is found in the small intestine of millions of people chiefly in Europe, Africa, India, China, Japan, Srilanka and Pacific Islands.
The male worm is 8 to 11 mm x 0.4 mm in size. The posterior end of the body forms a bursa made of three lobes, out of which one is dorsal and two are lateral. A pair of long spicules passes from the genital canal to the outside through cloaca. A gubernaculum is also used during copulation to help guide the spicules.
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The female averages 10 to 13 mm x 0.6 mm in size. The posterior end of the body tapers to a rather blunt point. The vulva is located at a point about two-thirds the length of the body from the anterior end. Eggs are ovoidal, thin-shelled and measure 56 to 60 um x 34 – 40 um.
Life Cycle of Ancylostoma Duodenale:
There is no intermediate host, so Ancylostoma duodenale is monogenetic. The life cycle starts with a fertilized egg. By the time it reaches the soil through human faeces, it is on the way to becoming a juvenile. The daily output of eggs from a single female worm is about 10000 to 20000.
Within 24 hours in moist warm soil, rhabditiform larvae hatch from the eggs. Free oxygen is essential for hatching and for further development. Larvae grow rapidly, molt twice and in about a week become non-feeding, slender, filariform larvae. This third larval stage is infective to man.
If a filariform larva comes in contact with skin of a new host, it burrows into the skin. It gets deeps, enters blood or lymph vessel and is eventually carried to the lungs. Here it leaves the blood stream, penetrates the lung tissue and arrives in the air spaces. From the lungs the worm passes up the trachea to the mouth cavity and is swallowed. Thus it arrives in the small intestine.
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A final molt occurs and the young worm attacks the host by clinging to the intestinal wall. It begins to suck blood and matures to adult stage. The interval which takes place between penetration of skin and first appearance of eggs in the faeces is about five weeks.
Pathogenesis of Ancylostoma Duodenale:
Ancylostoma duodenale is the causative agent for the disease “Ancylostomiasis” or “Hookworm disease”. Symptom of ancylostomiasis start with the “ground itch” occurring during the penetration of skin by filariform larvae. Cutaneous migration of the larva result in itching, burning, erythema, edema and vesicle formation. Pulmonary inflammation and minute haemorrhages are associated with lung penetration.
Anemia of iron deficiency is the principal host reaction to the intestinal infection by adult worms. Other symptoms are fever, abdominal pain, diarrhoea, food fermentation, constipation, myocarditis, eosinophilia, loss of health and collapse. Children are more susceptible than adults. Mental and physical growth is retarded in children and growing youth.
To check the epigastric pain, the patient may start eating even dirt, so called “dirt eaters”. If the infection is not controlled, it may lead to fatty degeneration of heart, liver and kidneys, ending in the death of the patient.
Treatment and Control of Disease Caused by Ancylostoma Duodenale:
Many drugs are available to treat ancylostomiasis. The most commonly used drug is tetrachloroethylene or blephenium hydroxynaphthoate, because of its high efficiency and low toxicity. Other antihelmintic drugs used are Hexylresorcinol, thymol, oil of chenopodium, dithiazanine iodide, piperazine salt, pyrvinium pamoate. Thioabendazole can be given, but only under strict supervision of a physician. Food is usually supplemented by iron to compensate haemoglobin deficiency.
Control:
1. Proper sewage disposal in affected areas.
2. Keep soil free from contamination of larvae.
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3. Educate the people in endemic area concerning the source of infection.
4. Wear shoes regularly.
