Life cycle Dracunculus medinensis or guinea worm

Question 1

What is the classification of Dracunculus medinensis?

Answer 1

Extracellular helminth in the category nematode

Question 2

How is Dracunculus medinensis transmitted?

Answer 2

Through larvae that get into water through blisters in the skin.

Larvae in drinking water
Undercooked fish with infective larvae

Question 3

What are the steps of the Dracunculus medinensis lifecycle inside of the human host?

Answer 3

1. Humans drink unfiltered water containing copepods which are water fleas from species cyclops. These water fleas are infected with 3rd stage larvae from the guinea worm
   alternative transmission route: consumption of undercooked or uncooked fish, frogs or other aquatic animals with infective copepods.
2. Guinea worm larvae are released in the stomach
3. Larvae penetrate and enter the abdominal cavity (stomach) and intestinal wall in 15 days. The parasite sexually matures in 3-4 months after which the male and female worm find each other and mate
4. After copulation male worms become encapsulated and die in 6-7 months while female worms can grow up to 80-120 cm in length and 2 mm in thickness.
5. Fertilized female worm migrates to surface of skin, causes a blister and discharges larvae. Most often in the lower extremities.

Question 4

How long does the migration process of larvae in the human body take?

Answer 4

This migration process takes 10-14 months and full emerging of the larvae’s takes 2-6 weeks. It drops thousands of first stage larvae’s in the fresh water source where it can survive for up to 6 days.

Question 5

What are the lifecycle steps of Dracunculus medinensis lifecycle in the human host?

Answer 5

6. Water fleas actively seek out larvae’s to consume them.
7. After 2 weeks and 2 shedding rounds the larvae’s develop in 3rd stage larvae within the water flea, now infectious to humans

Question 6

What type of life cycle does Dracunculus medinensis have?

Answer 6

Indirect life cycle

Question 7

What is the definitive host and intermediate host of Dracunculus medinesis?

Answer 7

Humans are definitive host

Copepod is intermediate host

Question 8

What are the symptoms of Dracunculus medinensis infection?

Answer 8

swelling and a bister that goes along with painful throbbing, burning sensation and a fever.

To relief the pain the host emerges in water causing the blister to rupture and discharge the larvae. Next an ulcer can be formed for further episodes of embryo expulsion. The wound won’t heal until it’s completely empty.

1% mortality due to secondary infections

Question 9

How long does a Dracunculus medinensis infection take?

Answer 9

Sickness can take up to 12-18 months due to secondary bacterial infections, untreated infection around a joint, calcified worm in joints and allergic reactions due to rapture of worm in tissue.

Question 10

What is the incubation time for Dracunculus medinensis infection?

Answer 10

It can take up to a year.

Question 11

What other species can get Dracunculus medinensis?

Answer 11

Dogs
Cats
Baboons

Question 12

Where is Dracunculus medinensis endemic?

Answer 12

Sub-tropic to tropical regions. Currently only countries in Africa with a total of 27 cases.

Question 13

How is Dracunculus medinensis diagnosed?

Answer 13

Visual examination of emerging worms. X-ray of calcified worms and microscopy of L1 larvae. Intradermal test can be done to test for dracunculus antigen and antibodies can be tested through serology during active infection