Find the best tutors and institutes for Class 12 Tuition
Q3(c):
How does the transmission of each of the following diseases take place?
(c) Ascariasis
Solution :
1. Biological Etiology and Vector Dynamics
Ascariasis is an intestinal helminthic infection caused by the nematode Ascaris lumbricoides (the common roundworm). The transmission cycle is strictly fecal-oral, as the parasite does not require an intermediate host to complete its lifecycle [Per the classification of monoxenous parasites].
2. Step-by-Step Transmission Mechanism
- Step 1: Contamination of Environment: Infected individuals pass embryonated eggs of Ascaris through their feces. These eggs are highly resistant to environmental stressors and can persist in soil for several years [Ref: Environmental Biology of Nematodes].
- Step 2: Vector Mediators: Soil particles, contaminated water, or raw vegetables become vectors for the infective stage (the embryonated egg containing the second-stage larva, $L_2$).
- Step 3: Ingestion: The transmission occurs when humans consume food or water contaminated with these embryonated eggs.
- Step 4: Mechanical Transfer: Houseflies often act as mechanical carriers, transferring eggs from human excreta to food products.
3. Post-Ingestion Pathogenesis
Upon reaching the small intestine of the human host, the following biochemical transition occurs:
- The gastric acid and intestinal enzymes trigger the hatching of the eggs.
- The liberated larvae penetrate the intestinal mucosa.
- The larvae enter the systemic circulation to undergo a mandatory pulmonary migration (heart-lung-trachea-pharynx route) before being swallowed back into the intestine to reach maturity [Ref: Life Cycle of Ascaris lumbricoides].
4. Visual Representation of Transmission Cycle
5. Summary of Transmission Factors
| Transmission Route | Primary Medium | Infective Stage |
|---|---|---|
| Fecal-Oral | Contaminated Water/Vegetables | Embryonated Egg ($L_2$ larva) |
Final Solution: The transmission of Ascariasis takes place via the ingestion of embryonated eggs of Ascaris lumbricoides through contaminated food, water, and soil, or by mechanical carriage of eggs by houseflies from fecal matter to food surfaces.
More Questions from Class 12 Biology Human Health and Disease EXERCISES
- Q1: What are the various public health measures, which you would suggest as safeguard against infectious diseases?
- Q1: What are the various public health measures, which you would suggest as safeguard against infectious diseases?
- Q2: In which way has the study of biology helped us to control infectious diseases?
- Q2: In which way has the study of biology helped us to control infectious diseases?
- Q3(a): How does the transmission of each of the following diseases take place? (a) Amoebiasis
- Q3(a): How does the transmission of each of the following diseases take place? (a) Amoebiasis
- Q3(b): How does the transmission of each of the following diseases take place? (b) Malaria
- Q3(b): How does the transmission of each of the following diseases take place? (b) Malaria
- Q3(c): How does the transmission of each of the following diseases take place? (c) Ascariasis
- Q3(d): How does the transmission of each of the following diseases take place? (d) Pneumonia
- Q3(d): How does the transmission of each of the following diseases take place? (d) Pneumonia
- Q4: What measure would you take to prevent water-borne diseases?
- Q4: What measure would you take to prevent water-borne diseases?
- Q5: Discuss with your teacher what does ‘a suitable gene’ means, in the context of DNA vaccines.
- Q5: Discuss with your teacher what does ‘a suitable gene’ means, in the context of DNA vaccines.
- Q6: Name the primary and secondary lymphoid organs.
- Q6: Name the primary and secondary lymphoid organs.
- Q7(a): The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (a) MALT
- Q7(a): The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (a) MALT
- Q7(b): The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (b) CMI
- Q7(b): The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (b) CMI
- Q7(c): The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (c) AIDS
- Q7(c): The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (c) AIDS
- Q7(d): The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (d) NACO
- Q7(d): The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (d) NACO
- Q7(e): The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (e) HIV
- Q7(e): The following are some well-known abbreviations, which have been used in this chapter. Expand each one to its full form: (e) HIV
- Q8(a): Differentiate the following and give examples of each: (a) Innate and acquired immunity
- Q8(a): Differentiate the following and give examples of each: (a) Innate and acquired immunity
- Q8(b): Differentiate the following and give examples of each: (b) Active and passive immunity
- Q8(b): Differentiate the following and give examples of each: (b) Active and passive immunity
- Q9: Draw a well-labelled diagram of an antibody molecule.
- Q9: Draw a well-labelled diagram of an antibody molecule.
- Q10: What are the various routes by which transmission of human immuno-deficiency virus takes place?
- Q10: What are the various routes by which transmission of human immuno-deficiency virus takes place?
- Q11: What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?
- Q11: What is the mechanism by which the AIDS virus causes deficiency of immune system of the infected person?
- Q12: How is a cancerous cell different from a normal cell?
- Q12: How is a cancerous cell different from a normal cell?
- Q13: Explain what is meant by metastasis.
- Q13: Explain what is meant by metastasis.
- Q14: List the harmful effects caused by alcohol/drug abuse.
- Q14: List the harmful effects caused by alcohol/drug abuse.
- Q15: Do you think that friends can influence one to take alcohol/drugs? If yes, how may one protect himself/herself from such an influence?
- Q15: Do you think that friends can influence one to take alcohol/drugs? If yes, how may one protect himself/herself from such an influence?
- Q16: Why is that once a person starts taking alcohol or drugs, it is difficult to get rid of this habit? Discuss it with your teacher.
- Q16: Why is that once a person starts taking alcohol or drugs, it is difficult to get rid of this habit? Discuss it with your teacher.
- Q17: In your view what motivates youngsters to take to alcohol or drugs and how can this be avoided?
- Q17: In your view what motivates youngsters to take to alcohol or drugs and how can this be avoided?
CBSE Solutions for Class 12 Biology Human Health and Disease
Chapters in CBSE - Class 12 Biology
- Reproduction in Organisms
- Human Reproduction
- Reproductive Health
- Principles of Inheritance and Variation
- Molecular Basis of Inheritance
- Evolution
- Strategies for Enhancement in Food Production
- Microbes in Human Welfare
- Biotechnology: Principles and Processes
- Biotechnology and Its Applications
- Organisms and Populations
- Ecosystem
- Biodiversity and Conservation
- Environmental Issues
Top Tutors who teach Human Health and Disease
Top Tutor
Bhopal, Bhopal
4 yrs of
Exp
1 student
75 hrs of classes completed
300
per hour
Online Classes
I am a mechanical engineer currently I am in pre final year in NIT BHOPAL. I have cracked jee on my own in first attempt and I also scored 90% in 12 with cbse board. I have been teaching my friends from class 11th itself. I can make subject really easy for you.
Super Tutor
Besant Nagar, Chennai
20 yrs of
Exp
23 students
886 hrs of classes completed
750
per hour
Online Classes
am geetha, from Chennai, a very dedicated and sincere professional from my end and I ensure that it is inculcated and reciprocated by the students as well. I have been in the teaching field since 2005 after my master's. I have tutored more 350 students in various batches and have boosted their confidence in Math, making the subject enjoyable for them. All of my past students have passed in flying colors and are flourishing in their professional careers now My class will be focused on strengthening the basic concepts and foundation that is essential to break down complex problems by using simple methods. I focus on clearing all the doubts step by step and conducting test papers after the completion of every lesson which will make it easier for the students to crack their school quarterly, half-yearly, and final exams with ease. Thank you, best regards from geetha Kumar.
Geetha Ma'am explains well and is ready to clear doubts. So far the experience has been very good and helpful to us.
Top Tutor
Malleshpalya, Bangalore
12 yrs of
Exp
2 students
17 hrs of classes completed
200
per hour
Online Classes
Have been taking classes since 2005 in bangalore for physics and maths for xi,neet,jee mains,thanks.
Top Tutor
Vaishali Nagar, Jaipur
9 yrs of
Exp
31 students
787 hrs of classes completed
500
per hour
Online Classes
I am a certified and top-ranked tutor on this platform, with over 9 years of teaching experience and 7 years of industry experience in Accounting, Auditing, and Taxation. I specialize in teaching Class 12 Accountancy for CBSE and ISC board students, with a strong focus on conceptual clarity, exam-oriented preparation, and real-world application.
Top Tutor
Anna Nagar, Chennai
15 yrs of
Exp
2 students
63 hrs of classes completed
300
per hour
Online Classes
I have 15 years of teaching experience in Mathematics, teaching students from Class 9 to 12 in both online and offline modes. I have experience teaching students from India and abroad, covering CBSE, ICSE, State Boards, IGCSE, IB, and US curricula. My teaching focuses on strong conceptual understanding, problem-solving skills, exam preparation, and helping students achieve excellent academic results.
