Community Medicine
8 questionsWhich study design is most effective for investigating rare adverse effects of a drug?
Bladder cancer can occur in those who are working in dye industry for 25 years. Which study design is most appropriate for establishing a causal relationship between dye industry work and bladder cancer?
Which of the following is an example of a case-control study?
Immunity starts after how many days of yellow fever vaccination ?
Which Diphtheria vaccine is recommended for a 14-year-old girl?
Droplet nuclei is a type of ?
Which of the following is an example of indirect transmission by a living vector?
Which vaccine is the most widely used globally in childhood vaccination programs, aside from the Oral Polio Vaccine (OPV)?
NEET-PG 2015 - Community Medicine NEET-PG Practice Questions and MCQs
Question 941: Which study design is most effective for investigating rare adverse effects of a drug?
- A. Cohort study
- B. Cross-sectional study
- C. Case-control study (Correct Answer)
- D. Clinical trial/experimental study
Explanation: ***Case-control study*** - This design starts by identifying individuals with the **rare adverse effect (cases)** and a control group without the effect to look back for exposure to the drug. - It is efficient for studying rare outcomes because it doesn't require following a large population for a long time to observe few events. *Cohort study* - A **cohort study** follows a group of individuals exposed and unexposed to a drug forward in time to observe outcomes. - While good for common outcomes, it would require an **extremely large sample size** and a long follow-up period to observe rare adverse drug effects. *Cross-sectional study* - A **cross-sectional study** assesses exposure and outcome simultaneously at a single point in time. - This design is suitable for determining **prevalence** but cannot establish temporal relationships between drug exposure and rare adverse effects, nor is it efficient for rare outcomes. *Clinical trial/experimental study* - **Clinical trials** are primarily designed to test the efficacy and safety of new interventions, usually focusing on common adverse effects. - They are generally **not powered** or long enough to detect rare adverse events, as such events would occur in very few participants, if any.
Question 942: Bladder cancer can occur in those who are working in dye industry for 25 years. Which study design is most appropriate for establishing a causal relationship between dye industry work and bladder cancer?
- A. Cross-sectional study
- B. Case-control study
- C. Cohort study (Correct Answer)
- D. Randomized control trial
Explanation: ***Cohort study*** - A **cohort study** tracks a group of individuals exposed to a risk factor (dye industry work) and a group not exposed over time to see who develops the outcome (bladder cancer). - This design allows for the calculation of **incidence rates** and relative risk, which are crucial for establishing a causal link, especially when the exposure is rare or specific. - Cohort studies establish **temporal relationship** (exposure precedes disease) and can demonstrate a **dose-response relationship**, both essential for proving causality. *Cross-sectional study* - A **cross-sectional study** assesses exposure and outcome simultaneously at a single point in time, making it difficult to determine the temporal sequence of events. - While it can identify associations, it cannot definitively establish a **cause-and-effect relationship** because it doesn't observe outcomes developing over time. *Case-control study* - A **case-control study** compares individuals with the outcome (cases) to individuals without the outcome (controls) and retrospectively looks for differences in past exposures. - While useful for studying **rare diseases** and can suggest associations, it is prone to **recall bias** regarding exposure history and cannot establish causality as definitively as cohort studies. *Randomized control trial* - A **randomized controlled trial (RCT)** involves randomly assigning participants to an intervention group or a control group and following them prospectively. - While RCTs provide the strongest evidence for causality, it would be **unethical** to intentionally expose people to a known carcinogen like dye industry chemicals for research purposes.
Question 943: Which of the following is an example of a case-control study?
- A. Framingham heart study
- B. PVC exposure and angiosarcoma of the liver (Correct Answer)
- C. Doll & Hill Study
- D. Thalidomide exposure and its association with teratogenicity
Explanation: ***PVC exposure and angiosarcoma of the liver*** - This is a classic example of a **case-control study** where individuals with a rare disease (angiosarcoma of the liver) are identified (cases) and compared to a control group without the disease to determine past exposures (PVC). - The study looked back in time to identify differences in exposure between cases and controls. *Framingham heart study (cohort study)* - The Framingham Heart Study is a well-known **prospective cohort study** that has followed participants over time to observe the development of cardiovascular disease. - In a cohort study, researchers identify a group of individuals and follow them forward in time to see who develops the outcome of interest, making it different from a case-control design. *Doll & Hill Study (cohort study)* - The Doll & Hill study is a landmark **cohort study** that investigated the association between smoking and lung cancer by following a group of British doctors over several years. - This study started with healthy individuals and observed them over time to see who developed lung cancer, which is characteristic of a cohort design. *Thalidomide exposure and its association with teratogenicity* - While the thalidomide tragedy led to crucial epidemiological investigations, the initial identification of the association was often through **case series** or **descriptive epidemiology**, noting an unusual clustering of rare birth defects among infants whose mothers took thalidomide. - Subsequent studies might have incorporated case-control elements, but the prompt asks for an example of a case-control study, and this event itself is generally cited for its role in pharmacovigilance and observational studies rather than a single, classic case-control study example in the way "PVC and angiosarcoma" is.
Question 944: Immunity starts after how many days of yellow fever vaccination ?
- A. 7-10 days (Correct Answer)
- B. 2-3 weeks
- C. 4-5 weeks
- D. 2-3 months
Explanation: ***Correct: 7-10 days*** - The **onset of immunity** after yellow fever vaccination typically occurs within **7-10 days** for most individuals. - This period is crucial for the body to develop a protective immune response, which is why travelers are advised to get vaccinated at least **10 days before potential exposure** as per WHO guidelines. - Approximately **95% of vaccinees** develop protective immunity by day 10. *Incorrect: 2-3 weeks* - While immunity continues to strengthen over this period, **initial protective immunity** is established earlier, typically by 7-10 days. - This option represents a slightly delayed timetable for the initial establishment of immunity. *Incorrect: 4-5 weeks* - This duration is significantly longer than the time required for the initial protective immunity to develop after yellow fever vaccination. - At this point, robust and **long-lasting immunity** would generally be established, but it's not when immunity "starts." *Incorrect: 2-3 months* - This timeframe is far too long for the *start* of immunity following yellow fever vaccination. - By this point, immunity is not only well-established but also **lifelong** (the vaccine provides protection for life after a single dose).
Question 945: Which Diphtheria vaccine is recommended for a 14-year-old girl?
- A. DT vaccine (Diphtheria, Tetanus)
- B. No suitable vaccine
- C. DPT vaccine (Diphtheria, Pertussis, Tetanus)
- D. Tdap vaccine (Tetanus, Diphtheria, Pertussis) (Correct Answer)
Explanation: ***Tdap vaccine (Tetanus, Diphtheria, Pertussis)*** - For a **14-year-old adolescent**, the **Tdap vaccine** is an appropriate choice as it provides protection against tetanus, diphtheria, and pertussis with reduced antigen content suitable for this age group. - In **Indian practice**, the **Td vaccine** (tetanus-diphtheria, adult formulation) is more commonly recommended as per **IAP guidelines** for the 10-16 years age group, but **Tdap is equally acceptable** and provides additional pertussis protection. - The **adolescent booster dose** at 10-16 years is crucial as immunity from childhood vaccination wanes over time. - Among the given options, **Tdap is the most appropriate vaccine** for this 14-year-old girl. *DPT vaccine (Diphtheria, Pertussis, Tetanus)* - **DPT** refers to the **whole-cell pertussis vaccine** used in the **primary childhood series** (typically at 6, 10, and 14 weeks). - It is **not recommended for adolescents or adults** due to higher reactogenicity and increased side effects (local reactions, fever) from the whole-cell pertussis component. - The childhood formulation has higher antigen concentrations unsuitable for older age groups. *DT vaccine (Diphtheria, Tetanus)* - **DT vaccine** is the **pediatric formulation** (higher diphtheria antigen) used for children **under 7 years of age** who have contraindications to the pertussis component. - It is **not the standard choice for adolescents**, who require the adult formulation (Td/Tdap) with reduced diphtheria toxoid content to minimize adverse reactions. - It does not provide pertussis protection, which is important for adolescents to prevent transmission to vulnerable infants. *No suitable vaccine* - This is **incorrect** as specific vaccine formulations (Tdap/Td) are available and recommended for adolescents. - **Adolescent booster vaccination** is an essential component of the immunization schedule to maintain immunity against diphtheria, tetanus, and pertussis.
Question 946: Droplet nuclei is a type of ?
- A. Direct transmission of infectious agents
- B. Vertical transmission of pathogens
- C. Biological transmission of pathogens
- D. Indirect transmission of pathogens (Correct Answer)
Explanation: ***Indirect transmission of pathogens*** - **Droplet nuclei** are tiny airborne particles remaining after the evaporation of respiratory droplets, suspended in the air for prolonged periods, allowing pathogens to travel over longer distances. - This mode of transmission is considered **indirect** because it involves an environmental medium (air) rather than direct contact between individuals. *Vertical transmission of pathogens* - This refers to the transmission of a pathogen from a **mother to her offspring**, either during pregnancy, childbirth, or breastfeeding. - Examples include HIV and rubella, which are transmitted directly from parent to child, unlike airborne droplet nuclei. *Direct transmission of infectious agents* - This involves immediate physical contact or exposure between an infected individual and a susceptible host (e.g., touching, kissing, sexual contact). - It does not involve an intermediate environmental vehicle such as airborne particles that travel through the air from their source. *Biological transmission of pathogens* - This type of transmission involves an **arthropod vector** that not only transmits the pathogen but also allows it to multiply or develop within its body before transmission. - Examples include malaria transmitted by mosquitoes or Lyme disease by ticks, which is distinct from airborne droplet nuclei transmission.
Question 947: Which of the following is an example of indirect transmission by a living vector?
- A. Transmission by mosquito (Correct Answer)
- B. Vertical transmission
- C. Soil contact
- D. Droplet infection
Explanation: ***Transmission by mosquito*** - This is the classic example of **vector-borne transmission**, where a living biological vector (the mosquito) acts as an intermediary to transmit the infectious agent from an infected host to a susceptible one. - The disease-causing microorganism does not pass directly from person to person but is carried and transmitted by the living vector. - Examples include malaria, dengue, and filariasis. *Vertical transmission* - This refers to transmission of disease from a **mother to her child** during pregnancy, childbirth, or breastfeeding. - This is a form of **direct transmission** where the pathogen passes directly between biologically related individuals without an intermediate living vector. *Soil contact* - This represents **vehicle-borne transmission** where soil acts as a non-living vehicle (fomite) carrying pathogens. - While this is technically indirect transmission, it does not involve a **living biological vector** as specified in the question. - Examples include tetanus, hookworm, and ascariasis transmitted through contaminated soil. *Droplet infection* - This is a form of **direct transmission** where infectious droplets are expelled from the respiratory tract of an infected person and directly contact the mucous membranes of a susceptible person. - The droplets travel a short distance in close proximity, representing direct person-to-person transfer without any intermediate vector.
Question 948: Which vaccine is the most widely used globally in childhood vaccination programs, aside from the Oral Polio Vaccine (OPV)?
- A. BCG vaccine
- B. DPT vaccine (Correct Answer)
- C. Influenza vaccine
- D. Pneumococcal vaccine
Explanation: ***DPT vaccine*** - The **DPT (diphtheria, pertussis, and tetanus) vaccine** is the most widely used childhood vaccine globally after OPV, forming the backbone of the **WHO's Expanded Programme on Immunization (EPI)**. - It has **near-universal adoption** across countries worldwide with approximately **86% global coverage** and is administered as a **3-dose primary series** to all children, making it the standard benchmark for measuring immunization program performance. - Its widespread use reflects the global burden of these three bacterial diseases and the vaccine's proven efficacy in preventing severe outcomes and transmission. *BCG vaccine* - The **BCG (Bacillus Calmette-Guérin) vaccine** protects against **tuberculosis** and is widely used, particularly in countries with high TB prevalence. - However, its use is **not universal** – many countries with low TB incidence (such as the USA and several European nations) do not include BCG in routine childhood schedules, limiting its global "universality" compared to DPT. - BCG is typically given as a **single dose at birth**, whereas DPT requires multiple doses throughout infancy. *Influenza vaccine* - The **influenza vaccine** is recommended annually due to antigenic drift of the virus, but its global childhood vaccination coverage is significantly lower compared to standard EPI vaccines like DPT. - It is often prioritized for specific risk groups rather than universal immunization for all children in many parts of the world. *Pneumococcal vaccine* - The **pneumococcal vaccine** targets **Streptococcus pneumoniae**, a cause of pneumonia, meningitis, and other severe diseases. - While increasingly integrated into national immunization schedules, its global adoption (especially as of 2015) was still lower than DPT, with many low- and middle-income countries only recently introducing it.
Obstetrics and Gynecology
1 questionsAfter taking MMR live vaccine, conception should not occur within ?
NEET-PG 2015 - Obstetrics and Gynecology NEET-PG Practice Questions and MCQs
Question 941: After taking MMR live vaccine, conception should not occur within ?
- A. 4 weeks (Correct Answer)
- B. 8 weeks
- C. 2 weeks
- D. 10 weeks
Explanation: ***4 weeks*** - The **MMR (measles, mumps, and rubella) vaccine** is a **live attenuated vaccine**, meaning it contains weakened forms of the viruses. - To minimize any theoretical risk of congenital rubella syndrome, women are advised to **avoid conception for at least 4 weeks** (or one month) after receiving the MMR vaccine. *2 weeks* - This period is generally considered too short for ensuring the complete clearance of the attenuated live virus from the woman's system before conception. - The standard recommendation for live attenuated vaccines like MMR is typically longer due to potential, though rare, viral transmission risks to the fetus. *8 weeks* - While a longer waiting period like 8 weeks would certainly be safe, it is **not the minimum recommended duration** by public health guidelines. - Waiting 4 weeks (one month) is sufficient and a more practical guideline for most women planning conception. *10 weeks* - This duration is significantly longer than the standard recommendation and is not necessary to ensure safety after an MMR vaccination. - The 4-week guideline balances safety with practicality for reproductive planning.
Pharmacology
1 questionsWhich of the following vaccines is not freeze-dried?
NEET-PG 2015 - Pharmacology NEET-PG Practice Questions and MCQs
Question 941: Which of the following vaccines is not freeze-dried?
- A. Measles Vaccine
- B. Diphtheria, Pertussis, and Tetanus (DPT) Vaccine (Correct Answer)
- C. Rubella Vaccine
- D. BCG Vaccine
Explanation: ***Diphtheria, Pertussis, and Tetanus (DPT) Vaccine*** - The DPT vaccine is a **liquid vaccine** that contains inactivated toxins and bacterial components, making it stable in liquid form. - It does not require **freeze-drying** because its components are chemically stable and do not degrade significantly in solution. *Measles Vaccine* - The measles vaccine is a **live attenuated vaccine** that needs to be freeze-dried to maintain the viability and stability of the live virus. - Freeze-drying helps preserve the vaccine's potency by removing water, which prevents degradation during storage and transport. *Rubella Vaccine* - Similar to the measles vaccine, the rubella vaccine is a **live attenuated vaccine** and is therefore provided in a freeze-dried form. - This process ensures the long-term stability and efficacy of the viral components, which would otherwise degrade in a liquid state. *BCG Vaccine* - The BCG (Bacillus Calmette-Guérin) vaccine is a **live attenuated bacterial vaccine** used against tuberculosis, and it is also manufactured as a freeze-dried product. - Freeze-drying is essential for maintaining the viability of the live attenuated *Mycobacterium bovis* strain.