Ancylostoma duodenale (hookwormi)2015

MICEO BIOLOHY

1. Ancylostoma duodenale (Dubini) GYANESHWAR CHAUDHARY

2. INTRODUCTION Common name : The old world hookworm The parasite was first discovered in 1838 by an Italian physician Angelo Dubini. Geographical distribution: It is widely distributed in all tropical and sub tropical countries. It is found in Europe, North Africa, India (Punjab and U.P)

3. Contd….. Habitat: The adult worm lives in the small intestine of man, particularly in the jejunum. Morphology: It is small, greyish white, cylindrical worm. It appears reddish brown when freshly passed in faeces due to ingested blood in its intestinal tract. The anterior end of the worm is bent slightly dorsally, hence the name hookworm.

4. Contd… The buccal cavity is armed with two pairs of teeth and two knob like plates. It has both digestive and excretory system. There are 5 glands connected with the digestive system, one of them called an oesophageal gland, secretes a ferment which prevents the clotting of blood from the site of bite.

5. Contd… Male Size: Smaller, 8mm in length. Shape of tail: Expanded in an umbrella like fashion(copulatory bursa). Genital opening: Posteriorly opens with cloaca. Female Size: Longer than male 12.5mmin length. Shape of tail: Tapering, no expanded bursa. Genital opening: middle third of the body

6. Contd… The worm assumes a Y-shaped figure during copulation. Copulatory bursa: This consist of 3 lobes : 1 dorsal and 2 lateral. Each lobe is supported by chitinous rays; Total number of rays are 13. Life span of the adult worms is about 3-4 years.

7. Contd…

8. Contd…

9. Contd…

10. Eggs - Oval or elliptical in shape measuring 65x40um. - Colourless. - Surrounded by a transparent hyaline shell membrane. - Contains a segmented ovum usually with 4 blastomeres ; has a clear space between the egg shell and segmented ovum. - Floats in saturated solution of common salt. - The eggs when passed out in faeces, are not infective to man.

11. Contd..

12. Contd…

13. Larvae - There are 2 types of larva Rhabditiform larva and Filariform larva. - The Rhabditiform larva (250um in length ) hatches out in soil in 48hrs. - The Rhabditiform larva moults twice, on 3 rd day and 5 th day, it then develops into filariform larvae (500-600um) in length. This is the infective stage of parasite. - The time taken for the development from eggs to filariform larvae is on an average 8-10 days .

14. Life Cycle No intermediate host is required. Man is only the definitive host for A. duodenale. The various stages of life cycle are as follows: Stage I: Passage of eggs from infected host: The eggs containing segmented ova with 4 blastomeres, are passed out in the faeces of the human host.

15. Contd…… Stage II: Development in soil: - From each egg a Rhabditiform larva (250um in length) hatches out in the soil in about 48 hours. - The Rhabditiform larva moults twice ( 3 rd and 5 th day) - Later it then develops into a filariform larva ( 500-600um ) in length, the infective stage of the parasite. - The time taken for development from egg to filariform larvae is 8-10 days.

16. Contd… Stage III: Entrance into a new host: The filariform larva are infective to man. The larvae gain entrance to the body by penetrating the skin. Stage IV: Migration: The larvae penetrate the skin and enter into the lymphatics or small venules. It is then carried to the heart and lungs. In the lungs, it breaks the capillaries and enters the alveoli. They then migrate on to the bronchi, trachea and

17. Contd… larynx, crawl over the epiglottis to the back of the pharynx and are ultimately swallowed. On entering the oesophagus, a 3 rd moulting takes place and a terminal buccal capsule is formed. Stage V: Localisation and Laying of eggs: - The larvae settle down in the small intestine . - The larvae with the help of buccal capsule, attach to the intestinal mucosa and grows into an adult worm. - In about a months they are sexually mature and eggs are laid by the female. The eggs are passed in stool and then the cycle is repeated.

18. Contd…

19. Pathogenicity and Clinical features The worm causes hookworm disease or ancylostomiasis in man. Mode of infection: This occurs when man walks bare foot on the faecally contaminated soil. The filariform larvae penetrate directly through the skin with which they come in contact. The most common sites of their entry are:

20. Contd… the thin skin between the toes. the dorsum of the feet. the inner side of the soles. The larvae can penetrate any part of the skin which is sufficiently thin. - Infection may also occur by the accidental drinking of water contaminated with filariform larvae.

21. Contd… Infecting agent: Filariform larvae Migration: through lungs. Portal of entry: skin Site of localisation : small intestine. Pathogenic effects: These may be considered under two heads. 1. Pathogenic effect caused by Ancylostoma larvae. 2. Pathogenic effect caused by Adult worms.

22. Contd… 1. Pathogenic effect caused by Ancylostoma larvae. a) Lesions in the skin: i ) Ancylostome dermatitis(ground itch) ii) Creeping eruption. Ground itch: occurs at the site of entry disappears in 1-2 weeks.

23. Contd..

24. Contd…. Creeping eruption : is a condition in which filariform larvae wander about through the skin for several weeks and months (upto 2 yrs) producing a reddish itchy papule. Lesions in the lungs: Bronchitis and bronchopneumonia may occur when the larvae break through the pulmonary capillaries and enter alveolar space. A marked eosinophilia occurs at this stage.

25. Contd… 2. Pathogenic effect caused by adult worms: The adult worm inhabit the small intestine (jejunum of man , attaching themselves to the mucous membrane by means of their powerful buccal. Anemia of microcytic hypochromic type develops.

26. Contd… Causes of anemia: i ) chronic blood loss: A duodenalae sucks about 260ul ( 0.2ml ) blood per day, but a greater amount of blood is lost by bleeding from the site of bite. It is facilitiated by an anticoagulant like substance secreted by the oesophageal gland. ii ) Nutritional defects: deficiency of the available iron and haemopoietic substances in the diet.

27. Contd… - with iron deficiency a microcytic hypochromic anemia. - with deficiency of folic acid and vitB12 a macrocytic type of anemia. Clinical features: This may be considered under two heads;

28. Contd… Gestrointestinal manifestation: - duodenal ulcer - abnormal appetite - hypoacidity - Achlorhydria Effects of Anaemia: - The skin assumes a swallow appearance (light yellow color). - The mucous membrane of the eye, lips and tongue show extreme pallor(lack of color).

29. Diagnosis - Examination of stool in the faeces. - Detection of larvae in the sputum. - Occult blood test positive. - Blood examination shows eosinophilia. Treatment: - Albendazole 400mg once - Ferrous sulphate 400mg thrice daily. - Folic acid and vitB12

30. Contd…. Prophylaxis : - Prevention of soil pollution by proper control of sewage disposal. - Personal protection – wearing of boots and gloves.