dracunculus.pptx

Dracunculas Medinensis

1. Dracunculus medinensis Presentation by : Prazuna B ajgain B.Sc.MLT 3 rd yea r

2. CONTENTS Introduction Geographical distribution Habitat Morphology Life cycle Pathogenesis Host immunity Clinical features Laboratory diagnosis Treatment Prophylaxis

3. INTRODUCTION DRACUNCULIASIS : Also known as guinea worm , medina worm, dragon worm disease . Vector borne parasitic disease. Involves subcutaneous tissues(leg and foot). Caused by nematode parasite, Dracunculus medinensis . Its not lethal but disable its victim temporarily. Transmitted exclusively when people drink stagnant water contaminated with parasite infected water fleas. It affects people in rural, deprived and isolated communities who depend mainly on open surface water sources such as ponds and wells.

4. The Guinea worm is found in predominantly in Africa from Senegal (west) to Ethiopia (east). Also found in India, Pakistan, Saudi Arabia, and Yemen. The majority of human infections occur in parts of West Africa, East Africa, and India.

5. H abitat subcutaneous tissue specially part that contact with water(foot ,leg, shoulder,and back )

6. Morphology One of the largest nematode known. They are milky white in colour. They are cylindrical and unsegmented . Adult females have been recorded to 1.20 m long. Males are shorter and some are known to grow to 40 mm

7. Adult female worm It is slender,long,60cm -1m in length and 0.9-1.7mm diameter The cuticle is smooth . The posterior end is blunt and bent to form a hook . The body of gravid female is virtually filled with the branches of an enormous uterus that contain about 3 million embryos . It is viviparous .Life span is 1yr.

8. Length : 0.01 – 0.04 m Diameter : 0.4 mm Mostly dies after fertilization. Posterior end of male is coiled. Adult male worm

9. Larva Large ,measuring 500 -700 um in length. 5- 25 um in diameter. Anterior end is rounded Tail is pointed and long. Tail looks coiled bodies in wet preparation. Cuticle shows prominent striations. Larva swims about with a coiling and Uncoiling motion.

10. Host factor Man is the definitive host. Also infects dogs. Multiple and repeated infection may occur to same individual. No immunity is developed after prior infections Habit of bathing and drinking surface water makes them prone to infections. Infection can occur to people of all age but young adults (15-45)are mostly infected.

11. Host factor Copepods specially water flea act as the intermediate host.

12. Environmental factors Season : I nfection mostly occur during the months from March to May from the step wells. It is dry during this time. Contact between guinea worm and the source of drinking water is very high. During June to September the source of infection is ponds

13. Environmental factors Temperature : Larva develop well between the temperature 25 to 30 deg. C. It will not develop below temperature 19 deg. C. Thus it is limited to tropical and sub tropical regions.

14. MODE OF TRANSMISSION : Disease is transmitted entirely through the consumption of water containing cyclops harboring the infective stage of the parasite. Guinea worm disease is a totally water-based disease .

15. Lifecycle Passes life cycle in two hosts :man and cyclops Definitive Host -.Man . Harbours the adult parasite in the subcutaneous tissues Intermediate host-Cyclops, in which larvae undergo certain development changes before they become infective to man.

16. Lifecycle First stage larvae are released by female into the water by the female worm . Female releases millions of first stage larva into water. They remain in water for up to 1 weeks until they are ingested by suitable copepods. Inside the copepods they moult twice to form third stage larvae which is its infective form.

17. Lifecycle Infection to man takes place when the ingest the contaminated water consisting of infected copepods. The copepod is dissolved by the digestive juices in stomach releasing the third stage larvae . It penetrates the tissue through the duodenum and migrate to the lower limb growing and developing there.

18. Lifecycle After three months the male mates and dies . Female continues to grow and travel down the muscle planes . The female emerges after 10 to 14 months to release millions of larvae in water to complete its lifecycle.

19. Pathogenesis SIGN/SYMPTOMS : Intense burning pain localized to path of travel of worm(the fiery serpent Fever Nausea Vomiting Allergic reaction Arthritis and paralysis (due to death of adult worm in joint). Skin blisters , which when rupture form ulcers Adult worms protrude from these ulcers.

20. Blister formation This occurs usually 1 year after infection Reddish spot or papule appears in the skin . In majority of the cases lower limbs are involved but it may also involve umblicus , grion , palm ,wrist and upper arm . The head of the gravid worms tries to come to the surface resulting in an itching sensation at the area.

21. The worm produces a toxin that converts the small red papule into a small belb or blister of 2-7 cm The fluid in the blister contains bacteriologically sterile fluid lymphocyte neutrophil eosinophil and larvae . Finally the blister ruptures revealings a small superficial erosion . The worm protudes its head through a small hole at the centre of the erosion whenever the part of the body comes in contact with water. The central hole leads to a tunnel in the subcutaneous tissue where the gravid female worm lies. Contd …

22. Lab diagnosis Detection of adult worm : Gravid female appears at the surface of skin After death gets calcified and can be detected radiologically.

23. Detection of larvae : Exposure to water releases large amount of larva. It is microscopically examined

24. Serology Antibody seen in serum by ELISA. It can also be demonstrated by fluorecents antibody test

25. Skin tests Antigen is injected intra dermally to see the allergic reactions.

26. Treatment Removal of worm by: Twisting it around the stick inch by inch for weeks to months. Surgical removal Metronidazole, niridazole are found effective in deworming programmes . Antibiotics are given to prevent secondary infection in ulcers. Analgesics are given to reduce the pain.

27. Prevention Use of boileed water and filtered water. Patients should not be allowed to dip their legs in source of drinking water. Use of insecticides to clean the stagnant water sources. Early detection and treatment of patients.

28. ` Parasitology (K. D. Chatterjee 13 th edition) Textbook of Medical Parasitology ( Subhash Chandra Parija 2 nd edition) REFERENCE