Structure and life history of Ancylostoma duodenale.

Structure ofAncylostoma duodenal

The structure of Ancylostoma duodenal includes external feature related to shape size colour,buccal capsule, copulatory bursa body wall digestive system excretory system reproduction.Description of each is discussed below.

1. Shape size and colour:These are small and cylindrical in shape. Sexes are separated: the male is about 8mm in length and 0.4 mm in diameter,while a female is generally longer 12.5 mm in length and 0.6mm in diameter. When freshly passed, it has brown colour due to ingested blood in its intestinal tract.

2. Buccal capsule:Anterior end of the male and female is similar, somewhat narrow, curved dorsally. These are also known as hookworm.The mouth of the worm is usually lead into a large cup- shaped cavity or buccal region or capsule,lined internally by the cuticle.Entrance to mouth is armed with a pair of chitinous centre- literally cutting plates bearing teeth.Two sharp teeth are also present at the base of the buccal capsule which serves for attachment with the intestinal wall of the host.Dorsal curing of the anterior end of body permits a better grip of cheerios and lancets on the hosts intestinal epithelium.

3. Copulatory bursa: Posterior end of female tapers, while the of the male is in the form of broad, umbrella-like structure , the copulatory bursa,surrounding the cloaca.Bursa is supported by fleshly bursal rays and teeth I buccal capsule are of taxonomic value.

4.Body wall:in cross section, body wall includes from the outside of cuticle, an epidermis, and a longitudinally directed musculature. The body cavity is a pseudocoel surrounded the following organ systems.

5.Digestive system:It is a tubular and very simple. It consists of the mouth,buccal capsule, muscular pharynx heaving a triradiate lumen lined by cuticle,oesophageal bulb, intestine,rectum, and cloaca in male but an anus in the female. There are five glands connected with the digestive systems: one of them called the oesophageal gland,secretes a ferment which prevents the clotting of blood so that the worm can suck blood from the host.In fact, the food consists of intestinal mucous membrane and blood. In the process, the tiny teeth and cutting plates of buccal capsule make small wounds in the intestinal mucosa through which the food fluid is sucked by the sectorial action of the pharynx. After feeding it leave the bleeding wound and move to another location.An adult worm is said to suck nearly 0.8ml of blood in a day from the host causing severe anaemia.Digestive is, however, completed in the intestine. The mode of respiration, excretory system, nerve system,and receptors are those of Ascaris lumber cioids.

6. Reproductive system:Male has a single tubular thread like tests twisted around the intestine in the middle of the body.It leads posteriorly into a vas deferens, followed by a seminal vesicle.The posterior end of seminal vesical tapers into an ejaculatory duct which enters the cloaca.

Female has two much convoluted ovarian tubules, one anterior and the other posterior,to the level of gonopore. Each ovary leads into a short oviduct that opens into a direct dilated seminal receptacle.From the latter arises , a muscular uterus that terminates into a vagina. Two vaginal become confluent and open through the common gonopore or valve.

7. Excretory system:

An excretory system is similar to the Ascaris. It includes two longitudinal canals in the lateral chords and short anterior excretory canal which open to the exterior through the excretory pore.

Life history of Ancylostoma duodenal;

Life history of Ancylostoma is monogenetic as no intermediate host is required man is the only main host for Ancylostoma. Life history of Ancylostoma include population nd fertilization,Eggs, Larva, Infection of a new host larva migration.which is discussed as below.

1. Copulation and fertilization:Copulation occur in the small intestine of the host.During copulation, bursa of the male is applied on the vulva of female and sperms transferred.Fertilization occurs in the seminal receptacles.In fact, during the copulation ( a male and female ) assume a Y- shaped figure owing to the position of the genital opening.The sperm thus transferred come to lie in the seminal receptacles here fertilization take place The fertilized eggs are then pushed into the uteri for lying through vagina and gonopore.

Eggs:Fertilized eggs pass out with the host's faeces. Each female produces about 9,000 fertile eggs per day. Eggs are oval in shape and protected by hyaline chitinous shells. Zygote within has already cleaved into a four or eight- celled embryo.

Larvae: Under favourable environment condition of moisture, oxygen supply, and temperature (68-85degF ), the first embryo develops in first stage juvenile or radiciform larva which hatches out within 24-48 hours. Newly hatches larva has a mouth, buccal capsule,an elongated pharynx, with an oesophageal bulb, and an intestine which mainly feed on bacteria of faeces or other organic debris of soil for 4 to 5 days and moult twice to form a third stage juvenile or filariform larva. This juvenile is about 0.5mm long and infective for man.But, it remains alive and infective for several weeks under favourable condition.

4.Infection of the new host:The filiform larva is infective to man. The larva cast off their skin of a human host. The anterior end of the larva is provided with oral spears by which it penetrates the soft skin of the feet and hands, generally through hair follicle.

5. Migration and later development:On reaching the subcutaneous tissues, the larvae enter into the lymphatics and small venules. They pass through the lymphatic vascular system into the venous circulation and are carried through the right heart into the pulmonary capillaries, where they break through the capillary walls to enter into the alveolar spaces.

Then they migrate on the bronchi to trachea to the larynx, and crawl over the epiglottis to the back of the pharynx and are finally saw called.During its migration, when its third moulting occurs and a terminal buccal capsule is formed.The time taken in this migration is about 10 days.

Thus, finally, the growing larvae settle down in the small intestine and undergo fourth and final moult to become the adult. in about 3 to 4 weeks time Male and female copulate and female starts laying eggs which pass out in the faecal material of human host.

Diagnosis: Hookworm infection diagnosed by the observation of hyaline "eggs" in a faecal smear from infection.

.Pathogenicity/symptom/Therapy/control of Ancylostoma

Pathogenicity:The infective larva causes some kind of eruption of the skin which may be pustular, known as ground itch. Pathogenicity is fairly extensive involving skin lungs and small intestine.This host infected with adult worms become anaemic as a result of the loss of blood from the intestinal wound. Besides the anaemic conditions, the hosts become susceptible to the hosts become susceptible to all diseases particularly tuberculosis because of the damage was done by the larva during their transit from the heart to the final abode.

Intestinal wound leads to the various forms detrimental infection.Deleterious toxins secreted by glands in the head region of worms cause stomach pain,food fermentation diarrhoea, constipation,dyspnea, palpitation of the heart, eosinophilia, loss of health and collapse. Mental and physical growth grow this retarded in children and growing youth.Unchecked infection may lead to fatty degeneration of heart,liver kidney and ending in death.

Treatment: Treatment usually involves administration of drugs such as carbon chloroethyl, hexylresorcinol,carbon tetrachloride thymol,oil of chenopodium, and delphinium.Iron is usually prescribed to overcome the haemoglobin deficiency due to anaemia.

Control:The hookworm disease is responsible for considering the economic loss as well as poor health. Important prophylactic or preventive measures include wearing shoes and sanitary disposal of human faeces in affected areas so that soil may not be polluted.

Reference:

Bhamrah, H.S., and Kavita, Juneja. A Text Book of Invertebrates, New Delhi: Anmol Publications Pvt Ltd, 2011.

Jordan E.L. and P. S., Verma. Invertebrate Zoology, New Delhi,: S. Chand and Company Pvt. Ltd., 2011.

Kotpal, R. L., Modern Text Book of Zoology: Invertebrates, New Delhi, India: Rastogi Publications,2011.

http://www.biologydiscussion.com/

http://www.parasitesinhumans.org/

https://web.stanford.edu/class/

https://en.m.wikipedia.org/wiki/Main/Ancylostoma_duodenale