ASCARIS LUMBRICOIDES:


Phylum:- Nemathelminthes 
Class:- Nematoda
Common name:- Roundworm

HABITAT:-

The adult worms live in a lumen of the small intestine of humans.

MORPHOLOGY:-

It is found in two forms:-

  1. Adult form.
  2. Larval form. 

1. Adult form:- 

Adult male:-

  • It measures about 15-30 centimeters in length and 2-4mm in diameter.
  • The anterior end show mouth surrounded by 3 toothed lip.
  • The posterior end is coiled and posses two spicules.

Adult Female:-

  • Female is longer and stouter then the male parasites.
  • It measures about 20-40 cm in length and 5-6 mm in diameter.
  • The posterior end is straight and conical. 
  • The vulva is situated on the ventral surface at the function of the anterior and middle third of the body known as the vulvar waist.

EGGS :-

There are two types of egg librated by the female is described- 

Fertilized egg:

  • These are round and oval and measures about 60×40 um in diameter.
  • They are yellowish-brown enclosed in the eggshell as an unsegmented ovum. 
  • There is clear space between ovum and eggshells at both the poles of the egg. The eggshell is covered by albuminous coat.
  • In suitable environmental temperature fertilized egg developed in soil over 30-40 days to become infective to human beings. 
Unfertilized Egg:                
  • They are more elliptical and longer measures about 90×45um in diameter.
  • They enclosed in the eggshell as an atrophic ovum with a mass of disorganized and highly refractile lobules of various sizes.
  • There is no space between content and eggshell.

LIFE CYCLE:- 

Ascaris lumbricoides has a simple life cycle. It requires only one host to complete type its life cycle. The infective form is the human being is a fully developed egg-containing Larva.

Fertilized eggs are passes with feces.
⇩
Rhabditiform larva developed from the unsegmented within the eggshell in the soil in 10-14 days. 
⇩
Ingestion of infected eggs through contaminated food, drink or raw material.
⇩
Egg reaches the small intestine where it hatches to reduce larva.
⇩
This motile larva penetrate to mucosa to enter the portal circulation and reach the liver.
⇩
After stay 3-4 days in the liver larva enter the systemic circulation to reach the lungs.
⇩
After 10-15 days of development in the lungs the larva penetrates through the capillaries.
⇩
Larva now enters the Alveoli.
⇩
From here ascend to the branchial tree, trachea, larynx, pharynx.
⇩
Larva than crawl over the epiglottis and swallow with the saliva again.
⇩
Finally reach to the S.I and grow in adult work in 6-10 weeks.
⇩
After meeting with the female produce fertilized egg.
⇩
The eggs embryonated in the soil to repeat the life cycle. 


MOULTING:

The larva undergoes Moulting 4 times-

  • One outside within the egg shell.
  • Two times in the lungs .
  • One time again in the intestine.

PATHOGENICITY & CLINICAL FEATURES:


1. Due to larva 


Ascariasis:- It includes:

  • The patient developed non-productive cough.
  • Substernal discomfort.
  • Dyspnea.
  • Blood tinched sputum.
  • Urticaria.
  • Fever.
  • Eosinophilia.
  • Penetrating the larva produces microhemorrhages induces an eosinophilic response in host resulting in pneumonia called LOEFFLER'S SYNDROME.

2. Due to adult Worm:

Adult Worm causes asymptomatic infection but when present in a large number especially in children Causes protein-energy malnutrition & vitamin efficiency. 
The symptoms produce are - 

  • Intestinal obstruction.
  • Appendicitis.
  • Biliary colic.
  • Pancreatitis.
  • Cholecystitis.
  • Peritonitis. 
  • An adult worm may migrate through the esophagus reach to the larynx cause asphyxia.

LAB DIAGNOSIS:-


  • Shoot examination - For adult worms and eggs.
  • Sputum examination- For larva.
  • USG. 
  • Blood examination.
  • Skin test.
  • Serological test.

TREATMENT:-


  • Albendazole.
  • Pyrantel pamoate. 
  • Piperzine citrate.

PREVENTION:-


  • Maintenance of proper hygiene and sensitization.
  • Proper treatment and disposal of sewege reduces infection range.
  • Drinking water should be filtered.
  • Vegetables should be washed.