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Ascaris lumbricoides Is a parasite that can cause ascariasis in humans. It belongs to the phylum Aschelminthes and is a roundworm with the genus Ascaris.
- They are approximately 40 cm in length, apart from this they have three lips.
- The worms are mainly found in pigs.
- There are approximately 1 billion people who get infected by A.lumbricoides worldwide and is more predominant in Sub Saharan Africa, China, and East Asia.
- The eggs of A.lumbricoides are highly resistant to chemicals and desiccation.
- The eggs thus can be viable for several years.
| Table of Content |
Key terms: Ascaris lumbricoides, phylum Aschelminthes, desiccation, pigs, sexual dimorphism, roundworms
Morphology of Ascaris
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Ascaris have both separate males and females and they are morphologically different. They exhibit sexual dimorphism.
- One of the distinct features of males and females is the presence of curved and bluntly pointed tails of males.
- The size of the male is around 2 to 4 mm in diameter and about 15 to 31 cm in length.
- The females, on the other hand, are 3 to 6 mm wide and 20 to 49 cm long.
- One-third of the body is occupied by the vulva which is located in the anterior end.
- At a time the uteri will contain 27 million eggs and each day approximately 200,000 are laid.
| Male ascaris | Female Ascaris |
|---|---|
| They are thin, short, and hooked. | They are wide, long, and straight worms |
| The pineal spicules and papillae are near the posterior opening | They do not have pineal spicules |
| They do not have such opening | The reproductive opening is present in the posterior third of the body |
| For the reproductive system, a single straight tube is present | There are two tubes present in a Y-shaped structure |
| The length is 15 to 30 cm | The length is 20 to 49 cm |
Life Cycle of Ascaris
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The life cycle of a roundworm is given below:
- The roundworm infects humans via the faecal-oral route. The eggs of the female are released in the faeces.
- The unfertilized eggs die, but the fertilised eggs become infective within 18 days to several weeks in the soil.
- When a human ingests contaminated food with embryonated eggs, infection occurs.
- Rhabditiform larvae will hatch from the embryonated eggs. It will then penetrate the mucosa and submucosa, thus entering into the lymphatic vessels.
- The larvae will then enter into the pulmonary circulation and enter into the alveoli.
- The juvenile worms move from the alveoli to the bronchi and then into the trachea. An inflammatory reaction can take place at this stage.
- Once they have reached the trachea, they are coughed to the pharynx and swallowed again. They will move through the stomach to the intestine. Here they will mature as adults.
Life Cycle of Ascaris
Read more: Infectious diseases
Symptoms of Ascariasis
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Ascariasis is a disease that is caused by the parasite Ascaris.
- The disease is asymptomatic, but depending on the number of Ascaris infected there can be symptoms.
- Some of the symptoms are fever, diarrhoea, swelling, etc.
- Ascariasis is the most common cause of Loffler’s syndrome. The standard diagnostic symptom is the opacity of stools.
Prevention of Ascariasis
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Some of the measures that can be taken to prevent the disease are as follows:
- Maintaining hygiene and effective faecal treatment systems.
- The eggs of A.lumbricoides can be reduced by the hot composting method, but killing them requires alcohol, iodine, etc.
- Drinking purified water
- Washing hands regularly and cleaning the bathroom regularly.
- Contact with the infected person should be avoided.
Read More:
| Related Topics | ||
|---|---|---|
| Human Health and Diseases | Vaccines | Infectious Diseases |
| Dengue Fever Symptoms | Immunity | Plague |
Things to Remember
- Ascaris belongs to the phylum Aschelminthes and is a parasite that can cause ascariasis.
- They have males and females exhibiting sexual dimorphism.
- Males are shorter than females.
- The roundworm infects humans via the faecal-oral route
- The eggs have a protective coating, making them viable for several years.
- The disease is generally asymptomatic
- It can be prevented by maintaining proper hygiene.
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Sample Questions
Ques: What is the morphology of A.lumbricoides? (3 marks)
Ans: A lumbricoide has both males and females. They exhibit sexual dimorphism means that males and females can be distinguished by their morphology. The males are shorter than the females. The males have hooked(curved) tails whereas the female has pointed straight tails. The males have pineal spicules that are not present in females. In females the reproductive opening is present in the posterior third of the body, this cannot be observed in males. Females have two tubes of the reproductive system that are Y shaped.
Ques: What are the symptoms and prevention of Ascariasis? (5 marks)
Ans: Ascariasis is generally asymptomatic but the symptoms may arise depending on the number of roundworms that are affecting the person. Some of the symptoms that may aris are as follows:
- Fever
- Loss of appetite
- Diarrhoea
- Nausea
- Muscular pain
- Bloody mucus
- Swelling
Prevention of the diseases can be done by the following methods:
- Maintaining proper hygiene
- Proper sanitation
- Drinking purified water
- Bathrooms and toilets should be cleaned
Ques: What are the characteristics of the phylum Aschelminthes? (3 marks)
Ans: Phylum Aschelminthes are commonly referred to as roundworms. Their bodies appear circular when seen in a traverse cross-sectional view. Some of the characteristics of this phylum are as follows:
- They are not segmented.
- They have a three-layer of body wall, a cuticle layer, a syncytial epidermis, and a muscle layer.
- They have a pseudocoelom body cavity.
- The alimentary canal of this phylum includes the pharynx.
- The gas exchange takes place via diffusion while aerobic respiration.
- They have renette cells for excretion.
Ques: What are the causes of Ascariasis? (3 marks)
Ans: The human gets infected with the diseases via the faecal-oral route. Some of the causes of the disease are as follows:
- Consuming contaminated food with rhabditiform larvae.
- Getting in contact with the infected person.
- Maintaining an unhygienic environment.
- Uses things of the infected person that are contaminated by the pathogen.
- Using accessories of the infected person.
Ques: What are parasites? (2 marks)
Ans: Parasites are organisms that live inside the body of another organism that is called a host. It derives nutrients from the host. The parasite takes advantage of the host by harming the host as they are deprived of nutrients. Example: Ascaris
Ques: How can the disease be diagnosed? (1 mark)
Ans: Ascariasis can be diagnosed by sonography, the level of contamination can also be observed through the stool. Other methods are MRI, CT scan, etc.
Ques: Write the difference between male and female ascaris. (3 marks)
Ans:
| Male ascaris | Female Ascaris |
|---|---|
| Males are thin, short, and hooked. | Females on the other hand are wide, long, and straight worms |
| The pineal spicules and papillae are near the posterior opening | Females do not have pineal spicules |
| No such opening is present | The reproductive opening is present in the posterior third of the body |
| For the reproductive system, a single straight tube is present | There are two tubes present in a Y-shaped structure |
| The length of a male ascaris is 15 to 30 cm | The length of the female ascaris is 20 to 49 cm |
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