Ascaris lumbricoides

Large Intestinal Roundworm

Physiology and Structure: 
  • A. lumbricoides are large (20cm to 35cm long), pink worms.
  • The egg releases a larval worm which penetrates the duodenal wall and enters the bloodstream which is then carried to the liver and heart and finally into the pulmonary circulation.
  • In the lungs, they break free and start to molt. 
  • The larvae would be coughed up, swallowed and returned to the small intestine. This process takes around 3 weeks.
  • The worms mature in the small intestine.
  • Up to 200,000 eggs can be produced in a day.
  • Fertilized eggs become infectious after 2 weeks of exposure to soil.

 


Ascaris lumbricoides

https://www.flickr.com/photos/15930189@N02/1955295826/

 

 

 

 

 


 

 

 

Lifecycle of Ascaris lumbricoides

 

 https://www.stanford.edu/class/humbio103/ParaSites2005/Ascaris/JLora_ParaSite_files/image006.gif

 

Clinical Syndromes
  • Infections caused by the ingestion of a few eggs may produce no symptoms.
  • The ingestion of a single adult worm may be dangerous as it is able to travel into the bile duct and liver and destroy tissue.
  • Infections with many larvae would produce pneumonitis,similar to an asthma attack, when larvae migrate to the lungs.
  • Prolonged exposure would cause eosinophilia and oxygen desaturation.
  • Worms tangled in the intestines would cause obstruction, perforation and occulsion of the appendix.
  • Victims would also experience symptoms like abdominal tenderness, fever, distention and vomiting.

 

Treatment, Prevention and Control
  • Treatment of symptomatic infection with mebendazole is effective.
  • Patients who have mixed infection in the stool have to be treated for ascariasis to prevent the migration of worms and intestinal perforation.
  • Sanitary facilities should be maintained to prevent contamination of the soil with human feces.
  • Practice of using human feces as fertilizer should be avoided. 

 

We do not take credit for any of the information found in this website. All the information is obtained from various forms of literature.

Parasite is defined as an organism that derives its nutrients from another living organism, the host. Parasitic diseases are usually referred to those caused by protozoa, helminths and arthropods which love at the expense of their host. Successful parasites are the ones who are able to maintain their own life processes without killing their host.

Several ways to distinguish parasites infection and bacteria/viruses infection:

  1. Parasites have a complex life cycle that involves the formation of resistant cyst in the organism. (it can usually survive for long periods outside the host.)
  2. Life cycle might involve an insect vector (carrier) that is important for the transmission of disease. In most cases, it is impossible to eliminate the vector effectively.
  3. Some parasites are capable of infecting both humans and animals, thus both can act as reservoirs for the infection. This is true for most protozal infections carried by insects.
  4. Many parasites has life cycle that requires enough time to allow for the various stages to mature, either in soil or in an insect or host.