Community Medicine
7 questionsWhich of the following is NOT a criterion for defining a polio epidemic?
Infectivity period of chickenpox is ?
Which of the following is the primary component of the AFP (Acute Flaccid Paralysis) case definition used in polio surveillance?
In typhoid, a person is considered a permanent carrier if they excrete bacilli for more than how many months?
What is the annual infection rate of tuberculosis?
According to the immunization schedule, how many doses of influenza vaccine should children under 9 years of age receiving the vaccine for the first time typically receive?
At what age is the BCG vaccination administered in India?
NEET-PG 2013 - Community Medicine NEET-PG Practice Questions and MCQs
Question 761: Which of the following is NOT a criterion for defining a polio epidemic?
- A. Caused by same virus type
- B. Cases should occur in same locality
- C. 2 or more cases
- D. Cases occurring during a 6 month period (Correct Answer)
Explanation: ***Correct: Cases occurring during a 6 month period*** - The definition of a polio epidemic primarily focuses on criteria like the number of cases, their geographical proximity, and the viral serotype causing the infection, not a specific duration of time over which cases occur. - While an outbreak naturally unfolds over a period, a fixed 6-month window is **not a formal defining criterion** for an epidemic, which typically emphasizes a sudden, significant increase above expected levels. *Incorrect: 2 or more cases* - An epidemic is generally defined by an **unusual increase in disease incidence**, and even two confirmed cases, especially in areas with low endemicity or where polio is eradicated, can signal an outbreak. - The presence of **two or more paralytic polio cases** within a specific area is often considered a critical threshold for declaring an epidemic, particularly for **wild poliovirus**. *Incorrect: Cases should occur in same locality* - For an epidemic to be declared, the cases must be **geographically linked** to indicate a common source or local transmission. - Cases spread across different, unconnected regions would suggest **sporadic occurrences** rather than a localized epidemic. *Incorrect: Caused by same virus type* - An epidemic implies a **common etiologic agent**, meaning the cases should be linked to the same serotype of **poliovirus** (e.g., wild poliovirus type 1). - If cases are caused by different serotypes, it indicates **multiple independent introductions** rather than a single epidemic outbreak.
Question 762: Infectivity period of chickenpox is ?
- A. 1 day before and 4 days after appearance of rash (Correct Answer)
- B. Only when scab falls
- C. Entire incubation period
- D. 4 days before and 5 days after appearance of rash
Explanation: ***1 day before and 4 days after appearance of rash*** - The infectivity period of **chickenpox (varicella)** begins approximately **1-2 days (24-48 hours) before the rash appears**. - It extends until **all lesions have crusted over**, which typically occurs around **5-6 days after rash onset**, though some sources cite **4-5 days**. - This option represents the **commonly accepted timeframe** taught in Indian medical curricula and NEET PG examinations. *4 days before and 5 days after appearance of rash* - The **pre-rash infectivity period is too long** in this option; chickenpox is infectious for only **1-2 days before rash**, not 4 days. - While the "5 days after" is medically accurate, the incorrect pre-rash duration makes this option wrong. *Only when scab falls* - This statement is **incorrect**; infectivity starts much earlier, **1-2 days before the rash appears**. - By the time scabs fall, the person is **no longer infectious**, as crusted lesions contain non-infectious material. - This option ignores the critical **pre-rash and early rash infectious period**. *Entire incubation period* - The **incubation period** for chickenpox is usually **10-21 days**, during which the individual is **not infectious** for most of this time. - Infectivity begins only in the **last 1-2 days of incubation** (just before rash onset) and continues into the eruptive phase, not for the entire duration.
Question 763: Which of the following is the primary component of the AFP (Acute Flaccid Paralysis) case definition used in polio surveillance?
- A. All of the above
- B. Stool specimen positive for poliovirus
- C. Onset of acute flaccid paralysis (Correct Answer)
- D. Presence of residual paralysis after 60 days
Explanation: ***Onset of acute flaccid paralysis*** - The primary component of the **AFP case definition** for polio surveillance is the acute onset of **flaccid paralysis** in a child under 15 years, or paralytic illness in a person of any age when polio is suspected. - This definition is crucial for identifying all potential cases of polio, regardless of the cause, to ensure thorough investigation and prevent outbreaks. *Stool specimen positive for poliovirus* - A positive stool specimen for poliovirus is a **laboratory confirmation** of polio infection, but it is not the primary component of the initial case definition. - The AFP case definition aims for **high sensitivity** to capture all possible cases for investigation, even before laboratory results are available. *Presence of residual paralysis after 60 days* - Residual paralysis after 60 days is an important indicator for **classifying a confirmed polio case** and understanding the long-term impact. - However, it is a **follow-up criterion** used after the initial detection of AFP, not the primary component that triggers the initial surveillance. *All of the above* - While laboratory confirmation and residual paralysis provide further information about a case, the **initial identification relies specifically on the clinical presentation** of acute flaccid paralysis. - The broad clinical definition ensures that no potential polio case is missed, initiating an immediate public health response.
Question 764: In typhoid, a person is considered a permanent carrier if they excrete bacilli for more than how many months?
- A. 3 months
- B. 6 months
- C. 1 year (Correct Answer)
- D. 3 years
Explanation: **1 year** - A person is defined as a permanent carrier of typhoid if they excrete **Salmonella Typhi** in their feces or urine for **more than one year** after the acute illness. - This long-term excretion is often associated with chronic infection of the **gallbladder**, particularly in individuals with gallstones. - The definition of chronic/permanent carrier status is set at **≥12 months** of continuous bacillary excretion. *3 months* - Excreting bacilli for 3 months after acute typhoid is considered a **convalescent carrier state**, not a permanent one. - Many individuals clear the infection within this timeframe without becoming chronic carriers. *6 months* - While prolonged, 6 months of excretion still falls under the definition of a **convalescent or temporary carrier**, rather than a permanent carrier. - The threshold for "permanent" or "chronic" carrier status is typically set at 12 months. *3 years* - While a person excreting bacilli for 3 years would certainly be a permanent carrier, the established definition for permanent carrier status is met at **1 year**, not 3 years. - This option represents an unnecessarily longer duration than the standard definition.
Question 765: What is the annual infection rate of tuberculosis?
- A. Percentage of total patients positive for tuberculin test
- B. Percentage of new patients positive for tuberculin test (Correct Answer)
- C. Percentage of sputum positive total patients
- D. Percentage of sputum positive new patients
Explanation: ***Percentage of new patients positive for tuberculin test*** - The **annual infection rate of tuberculosis (AIRT)** is defined as the percentage of individuals (typically children aged 1-9 years) who show **tuberculin conversion** (from negative to positive) in a given year. - Among the given options, this is the **closest representation** as it focuses on **newly infected individuals** rather than prevalent cases. - AIRT is a key epidemiological indicator reflecting **ongoing transmission** and the **annual risk of tuberculous infection** in a community. - This measure helps assess TB control program effectiveness and disease burden. *Percentage of total patients positive for tuberculin test* - This represents the **prevalence of tuberculosis infection** in the population, including both old and new infections. - It does not specifically measure the **annual rate of acquiring new infections**, which is what AIRT captures. *Percentage of sputum positive total patients* - This indicates the **prevalence of active, infectious pulmonary tuberculosis** in a population. - It refers to individuals with **active TB disease** who are shedding bacteria in sputum, not latent infection detected by tuberculin testing. *Percentage of sputum positive new patients* - This represents the **incidence of new, active, infectious tuberculosis cases** (case detection rate). - While important for TB surveillance, it measures **active disease** rather than **infection rate** detected by tuberculin skin test.
Question 766: According to the immunization schedule, how many doses of influenza vaccine should children under 9 years of age receiving the vaccine for the first time typically receive?
- A. 2 doses at 4 weeks interval with a booster dose for high-risk children
- B. 2 doses at 4 weeks interval (Correct Answer)
- C. 3 doses at 4 weeks interval
- D. None of the options
Explanation: ***2 doses at 4 weeks interval*** - Children **under 9 years of age** receiving the influenza vaccine for the **first time** require **two doses** administered at least **4 weeks (28 days) apart**. - This two-dose priming schedule is essential to ensure adequate immune response and protection against circulating influenza strains. - This recommendation is consistent across **IAP (Indian Academy of Pediatrics)** and **CDC guidelines**. - Children 9 years and older, and younger children who have been previously vaccinated, require only **1 dose annually**. *3 doses at 4 weeks interval* - The standard protocol for influenza vaccination does **not involve three doses**. - A three-dose schedule is typically seen with vaccines like **Hepatitis B**, **DTaP**, or **Hib**, but not for influenza. *2 doses at 4 weeks interval with a booster dose for high-risk children* - While high-risk children (chronic lung disease, heart disease, immunocompromised) are priority groups for influenza vaccination, the schedule remains **two initial doses** for first-time recipients under 9 years. - There is **no additional booster dose** beyond the two-dose series within the same influenza season, even for high-risk children. - Subsequent years require only **1 dose annually**. *None of the options* - This is incorrect as the standard recommendation is clearly established in immunization guidelines. - The **two-dose schedule at 4-week intervals** for first-time recipients under 9 years is well-documented by IAP and international guidelines.
Question 767: At what age is the BCG vaccination administered in India?
- A. At birth (Correct Answer)
- B. 1 year
- C. 2 years
- D. 6 weeks
Explanation: ***At birth*** - In India, the **BCG vaccine** is routinely administered to infants **at birth** or as early as possible thereafter as per the **Universal Immunization Programme (UIP)**. - This early vaccination aims to provide protection against **severe forms of tuberculosis (TB)**, particularly **tuberculous meningitis** and **disseminated (miliary) TB** in young children. - Early administration is crucial as infants are at highest risk of developing severe TB if exposed. *Incorrect: 1 year* - While other vaccinations might be given at 1 year (such as MMR), the BCG vaccine is specifically recommended at or soon after birth. - Delaying BCG vaccination until 1 year increases the risk of early exposure to TB before immunity can be established, defeating its protective purpose. *Incorrect: 2 years* - The recommended schedule for BCG vaccination in India does not include administration at 2 years of age. - By 2 years, potential exposure to TB may have already occurred, and the vaccine's efficacy in preventing severe forms of the disease would be compromised. *Incorrect: 6 weeks* - At 6 weeks, other vaccines like OPV, DPT, Hepatitis B, Hib, and Rotavirus are administered as part of the UIP schedule. - BCG is specifically given at birth, not at 6 weeks, to provide early protection against severe childhood tuberculosis.
Internal Medicine
1 questionsWhich of the following statements about polio is false?
NEET-PG 2013 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 761: Which of the following statements about polio is false?
- A. 99% non paralytic
- B. Aseptic meningitis
- C. Flaccid paralysis
- D. Increased tendon reflexes (Correct Answer)
Explanation: ***Increased tendon reflexes*** - Polio causes **lower motor neuron damage**, specifically to the anterior horn cells of the spinal cord [1]. - This damage leads to **flaccid paralysis** and **decreased or absent deep tendon reflexes**, not increased reflexes [3]. *99% non paralytic* - The vast majority of poliovirus infections (approximately 95-99%) are **asymptomatic** or cause only mild, non-specific symptoms. - Only a small percentage of infected individuals develop the more severe paralytic form of the disease. *Flaccid paralysis* - Poliovirus directly attacks and destroys **motor neurons** in the anterior horn of the spinal cord [1]. - This damage results in **muscle weakness** and loss of muscle tone, leading to **flaccid paralysis** [3]. *Aseptic meningitis* - About 1-5% of poliovirus infections can manifest as **aseptic meningitis**, characterized by symptoms like fever, headache, neck stiffness, and vomiting without bacterial infection [2]. - This form of meningitis is typically **self-limiting** and does not lead to paralysis [2].
Microbiology
2 questionsWhich of the following bacteria does not exhibit bipolar staining?
In a patient presenting with respiratory symptoms, acute angled septate hyphae are seen in which of the following fungi?
NEET-PG 2013 - Microbiology NEET-PG Practice Questions and MCQs
Question 761: Which of the following bacteria does not exhibit bipolar staining?
- A. Haemophilus influenzae (Correct Answer)
- B. Yersinia pestis
- C. Calymmatobacterium granulomatis
- D. Francisella tularensis
Explanation: ***Haemophilus influenzae*** - *Haemophilus influenzae* is a **pleomorphic coccobacillus** that typically stains uniformly and does not exhibit characteristic **bipolar staining**. - Its presence is often identified by Gram stain showing small, Gram-negative rods, but without the distinctive safety pin appearance. *Calymmatobacterium granulomatis* - *Calymmatobacterium granulomatis* (now *Klebsiella granulomatis*) is known to exhibit **bipolar staining**, often described as a **"safety pin" appearance**, especially in tissue smears from granuloma inguinale lesions. - This characteristic staining is due to the concentration of stain at the ends of the rod-shaped bacteria. *Yersinia pestis* - *Yersinia pestis*, the causative agent of plague, is classically described as having **bipolar staining**, giving it a distinctive **"safety pin" appearance** under a microscope. - This finding is a key diagnostic feature, particularly when observed in Gram-stained smears of clinical samples. *Francisella tularensis* - *Francisella tularensis* is a small, Gram-negative coccobacillus that is known to exhibit **bipolar staining**, though it may be less prominent than in *Yersinia pestis*. - This characteristic can assist in the microscopic identification of the bacterium, which causes tularemia.
Question 762: In a patient presenting with respiratory symptoms, acute angled septate hyphae are seen in which of the following fungi?
- A. Aspergillus (Correct Answer)
- B. Mucor
- C. Penicillium
- D. Candida
Explanation: ***Aspergillus*** - *Aspergillus* species are characterized by their distinctive **acute-angled (dichotomous) septate hyphae** when observed microscopically in tissue sections or clinical samples. - This morphological feature is crucial for differentiating *Aspergillus* infections, such as **aspergillosis**, from other fungal infections. *Mucor* - *Mucor* (along with *Rhizopus* and *Lichtheimia*) belongs to the Zygomycetes class, which are characterized by **broad, non-septate, ribbon-like hyphae** with irregular branching, not acute-angled septate hyphae. - These fungi are associated with **mucormycosis**, often seen in immunocompromised patients, particularly those with diabetes. *Penicillium* - *Penicillium* is a common mold known for producing penicillin and typically appears as **septate hyphae** but is more often recognized by its branching, brush-like conidiophores (penicilli) in culture rather than a distinct acute-angled septate hyphal morphology in clinical samples causing invasive disease. - While it can cause opportunistic infections, its hyphae are less commonly described as having uniquely acute angles compared to *Aspergillus*. *Candida* - *Candida* species are typically observed as **yeast cells (oval budding forms)**, often forming **pseudohyphae** (elongated yeast cells that remain attached) or true hyphae under specific conditions, but not as acute-angled septate hyphae. - *Candida* is a common cause of superficial and invasive candidiasis, and its microscopic appearance is distinct from filamentous fungi.