Disease Surveillance Systems — MCQs
Which of the following is NOT a core component of the WHO's global STI control strategy?
HIV sentinel surveillance is used for:
All of the following conditions are immediate priorities in the WHO's "Vision -2020: The Right to sight" except:
Why is sentinel surveillance preferred over passive surveillance in STI control programs?
Which method is most accurate for estimating the incidence of a disease?
Which of the following diseases is not covered under the Integrated Disease Surveillance Project (IDSP)?
Which disease was removed from active WHO surveillance requirements following its global eradication?
The web-based IT system for case-based surveillance under National Tuberculosis Elimination Programme (NTEP, formerly RNTCP) is
A state reports increased incidence of scrub typhus with unusual antibiotic resistance patterns. Molecular analysis reveals genetic recombination between different Orientia tsutsugamushi strains. Considering One Health approach, which integrated strategy would be most effective for long-term control?
A novel coronavirus outbreak is detected with high transmissibility but variable mortality across age groups. Phylogenetic analysis shows 80% similarity with SARS-CoV. To predict pandemic potential, which epidemiological parameter would be most critical to evaluate first?
Disease Surveillance Systems Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following is NOT a core component of the WHO's global STI control strategy?
- A. Case management
- B. Universal mandatory screening (Correct Answer)
- C. Strategic information systems
- D. Prevention services
Explanation: ***Universal mandatory screening*** - While screening is part of STI control, **universal mandatory screening** for all STIs in the general population is not a core component of the WHO's strategy due to feasibility, cost, and ethical considerations. - The strategy emphasizes **targeted screening** for at-risk populations and opportunistic screening. *Case management* - **Case management**, including accurate diagnosis and effective treatment, is a critical component for managing current infections and preventing further transmission. - This involves syndromic or etiologic approaches to treatment and partner notification. *Strategic information systems* - **Strategic information systems** are essential for monitoring trends, evaluating interventions, and informing policy decisions related to STI control. - This includes surveillance data, program monitoring, and research. *Prevention services* - **Prevention services** are a cornerstone of the WHO's strategy, aiming to reduce the incidence of new infections. - These services encompass health education, condom promotion and distribution, vaccination, and pre-exposure prophylaxis (PrEP).
Question 2: HIV sentinel surveillance is used for:
- A. Detection of high-risk group
- B. Prevalence of HIV infection
- C. Monitoring trends in HIV infection (Correct Answer)
- D. Monitoring disease trends
Explanation: ***Monitoring trends in HIV infection*** - **HIV sentinel surveillance** is specifically designed to track **HIV prevalence trends** over time in selected sentinel populations (ANC attendees, STD clinic attendees, high-risk groups). - The primary objective is to monitor **how HIV infection rates change** over time, helping identify emerging epidemics, evaluate intervention programs, and guide public health policy. - As per **NACO and WHO guidelines**, sentinel surveillance provides repeated cross-sectional prevalence measurements at fixed sites to detect temporal trends in HIV infection. *Monitoring disease trends* - This is **too broad and vague** for the specific purpose of HIV sentinel surveillance. - "Disease trends" could refer to AIDS progression, opportunistic infections, or other disease manifestations, which are **not the focus** of sentinel surveillance. - Sentinel surveillance specifically tracks **infection (seroprevalence)**, not general disease patterns. *Prevalence of HIV infection* - While sentinel surveillance **does measure prevalence**, this is a **method rather than the ultimate purpose**. - Prevalence measurements are taken repeatedly at different time points specifically to **monitor trends**, making this incomplete as the primary objective. *Detection of high-risk group* - Identification of high-risk groups is typically done through **epidemiological studies** and behavioral surveys, not sentinel surveillance. - Sentinel surveillance may **include** high-risk populations as sentinel sites, but its purpose is to monitor trends **within** these groups, not to detect them.
Question 3: All of the following conditions are immediate priorities in the WHO's "Vision -2020: The Right to sight" except:
- A. Cataract
- B. Epidemic conjunctivitis (Correct Answer)
- C. Onchocerciasis
- D. Trachoma
Explanation: ***Epidemic conjunctivitis*** - While **epidemic conjunctivitis** can cause significant discomfort and temporary vision impairment, it is generally **self-limiting** and rarely leads to permanent blindness. - It was not identified as one of the top five global causes of avoidable blindness targeted by the Vision 2020 initiative. *Cataract* - **Cataract** is the **leading cause of blindness** globally, accounting for approximately half of all cases. - It is a highly treatable condition through surgery, making it a critical priority for Vision 2020. *Onchocerciasis* - Also known as **river blindness**, onchocerciasis is a parasitic disease that causes severe visual impairment and blindness. - It is a significant public health problem in several regions, particularly in Africa, and was a key focus of Vision 2020 due to its widespread impact and the availability of preventive chemotherapy. *Trachoma* - **Trachoma** is the **leading infectious cause of blindness** worldwide, caused by *Chlamydia trachomatis*. - Given its preventable and treatable nature, and its prevalence in many impoverished areas, it was designated as one of the priority diseases under Vision 2020.
Question 4: Why is sentinel surveillance preferred over passive surveillance in STI control programs?
- A. Eliminates reporting bias
- B. Covers larger population
- C. Provides more detailed and accurate data from selected sites (Correct Answer)
- D. Requires less resources
Explanation: ***Provides more detailed and accurate data from selected sites*** - **Sentinel surveillance** involves selected, well-defined sites that actively collect high-quality, detailed data, providing a more accurate picture of STI trends and characteristics. - This focused data collection allows for better understanding of specific risk factors and population subgroups, which is crucial for targeted interventions. *Eliminates reporting bias* - While sentinel surveillance aims to **reduce reporting bias** through systematic, active data collection, it does not entirely eliminate it, as some biases related to site selection or specific patient populations may still exist. - No surveillance system is completely free of bias, but sentinel systems are designed to minimize it compared to passive systems. *Covers larger population* - **Passive surveillance**, by virtue of collecting data from all healthcare providers, theoretically covers a larger, more general population. - Sentinel surveillance focuses on specific sites or populations, providing in-depth data rather than broad population coverage. *Requires less resources* - **Sentinel surveillance** typically requires more resources per case, as it involves active data collection, specialized training, and potentially enhanced laboratory testing at selected sites. - **Passive surveillance** often requires fewer designated resources for active data collection since reporting is voluntary and relies on existing healthcare infrastructure.
Question 5: Which method is most accurate for estimating the incidence of a disease?
- A. Case-control study
- B. Cohort study (Correct Answer)
- C. Cross-sectional study
- D. Ecological study
Explanation: ***Cohort study*** - A **cohort study** tracks a group of individuals over time to observe the development of new cases of a disease, allowing for direct calculation of **incidence rates**. - It starts with a healthy population and identifies who develops the disease, providing the most accurate measure of **risk** and incidence. *Case-control study* - **Case-control studies** are primarily used to investigate **risk factors** for a disease by comparing exposures between individuals with the disease (cases) and those without (controls). - They **cannot directly estimate incidence** because they are retrospective and select participants based on disease status. *Cross-sectional study* - A **cross-sectional study** assesses the prevalence of a disease and/or exposure at a single point in time. - It provides a snapshot of the population's health status but **cannot determine incidence** as it doesn't observe new cases developing over time. *Ecological study* - An **ecological study** examines disease rates and exposures across populations rather than individuals. - While useful for generating hypotheses, it is prone to the **ecological fallacy** and cannot determine individual-level incidence.
Question 6: Which of the following diseases is not covered under the Integrated Disease Surveillance Project (IDSP)?
- A. Tuberculosis
- B. Cholera
- C. Herpes zoster (Correct Answer)
- D. Meningococcal disease
Explanation: ***Herpes zoster*** - **Herpes zoster** (shingles) is not included in the Integrated Disease Surveillance Project (IDSP) as it is neither an epidemic-prone disease nor a notifiable disease under the program. - IDSP focuses on diseases with significant public health impact, epidemic potential, or those requiring immediate public health response. - While herpes zoster can cause morbidity in immunocompromised individuals, it does not pose a widespread public health threat requiring national surveillance. *Tuberculosis* - **Tuberculosis (TB)** is explicitly covered under IDSP as a major notifiable disease due to its high burden in India and significant public health importance. - TB surveillance under IDSP helps monitor disease trends, detect outbreaks, and evaluate the effectiveness of the National Tuberculosis Elimination Programme. - Regular reporting and surveillance are essential for achieving TB elimination goals. *Cholera* - **Cholera** is a priority disease under IDSP as an epidemic-prone disease with potential for rapid outbreaks and high mortality if untreated. - It is part of the core surveillance list due to its ability to cause severe dehydration and waterborne epidemics. - Early detection through IDSP enables timely implementation of control measures including safe water supply and oral rehydration therapy. *Meningococcal disease* - **Meningococcal disease** (acute bacterial meningitis) is covered under IDSP due to its high case fatality rate, epidemic potential, and need for urgent public health response. - Surveillance is critical for early outbreak detection and implementation of preventive measures such as mass vaccination and chemoprophylaxis. - Close monitoring helps identify circulating serotypes and guide vaccination strategies.
Question 7: Which disease was removed from active WHO surveillance requirements following its global eradication?
- A. Guinea worm
- B. Typhoid
- C. HIV/AIDS
- D. Smallpox (Correct Answer)
Explanation: ***Smallpox*** - Smallpox was **globally eradicated** in 1980 through a concerted vaccination effort, making it the first human disease eradicated. - Due to its eradication, it has been **removed from active WHO surveillance requirements** as it no longer poses a threat to public health. *Guinea worm* - While significant progress has been made in Guinea worm eradication, it has **not yet been fully eradicated**, with a few endemic areas remaining. - It is currently still subject to **active surveillance efforts** by the WHO to monitor progress towards elimination. *Typhoid* - Typhoid is caused by *Salmonella Typhi* and remains a significant public health issue, especially in areas with poor sanitation. - It is a **notifiable disease** and continuously monitored by the WHO and national health agencies, especially with concerns about **antimicrobial resistance**. *HIV/AIDS* - HIV/AIDS is a **global pandemic** with ongoing high prevalence and incidence rates worldwide, particularly in certain regions. - It is under **intensive surveillance and control programs** by the WHO, given its significant global health burden and lack of a definitive cure or vaccine for complete eradication.
Question 8: The web-based IT system for case-based surveillance under National Tuberculosis Elimination Programme (NTEP, formerly RNTCP) is
- A. NIKSHAY (Correct Answer)
- B. E-TB Tracker
- C. SURAKSHA
- D. SAFETY-NET
Explanation: ***NIKSHAY*** - **NIKSHAY** is the official web-based IT system used by the National Tuberculosis Elimination Programme (NTEP, formerly RNTCP) in India for **case-based surveillance** and monitoring of TB cases. - Launched in 2012, it facilitates **real-time data entry**, tracking of patient outcomes, drug logistics management, and program monitoring, significantly improving the efficiency of TB control efforts. - It enables **notification of all TB cases**, both from public and private sectors, ensuring comprehensive surveillance. *E-TB Tracker* - **E-TB Tracker** is not the designated IT system for TB surveillance under NTEP in India. - This term may refer to other electronic tracking systems used in different contexts, but NIKSHAY remains the official platform for India's TB programme. *SURAKSHA* - **SURAKSHA** means safety or protection in Hindi and is not associated with any specific web-based IT system for TB surveillance under NTEP. - This is not a recognized TB surveillance platform in the Indian context. *SAFETY-NET* - **SAFETY-NET** is a generic term referring to social protection programs or health support systems. - There is no specific NTEP initiative for TB surveillance identified by this name.
Question 9: A state reports increased incidence of scrub typhus with unusual antibiotic resistance patterns. Molecular analysis reveals genetic recombination between different Orientia tsutsugamushi strains. Considering One Health approach, which integrated strategy would be most effective for long-term control?
- A. Development of new antibiotics for resistant strains as sole measure
- B. Environmental modification, rodent control, public education, and surveillance strengthening (Correct Answer)
- C. Mass chemoprophylaxis with doxycycline during outbreak season only
- D. Isolation of all suspected cases in specialized centers
Explanation: ***Environmental modification, rodent control, public education, and surveillance strengthening*** - The **One Health approach** emphasizes the interconnectedness of **humans, animals, and the environment** to control zoonotic diseases like **Scrub Typhus**. - This strategy targets the **chigger vector habitat** and the **rodent reservoir**, while ensuring early detection of **emerging antibiotic resistance** through robust surveillance. *Development of new antibiotics for resistant strains as sole measure* - Relying solely on drug development fails to address the **environmental and animal drivers** of the disease cycle, leading to further **recombination and resistance**. - Antibiotic monotherapy is a reactive measure rather than a sustainable **long-term prevention** strategy. *Mass chemoprophylaxis with doxycycline during outbreak season only* - Routine use of **chemoprophylaxis** in large populations can actually accelerate the development of **antibiotic resistance** in *Orientia tsutsugamushi*. - Seasonal prophylaxis provides only temporary protection and does not reduce the **mite index** or **rodent population** in the environment. *Isolation of all suspected cases in specialized centers* - **Scrub Typhus** is not transmitted through **person-to-person** contact, so isolation is not a medically indicated or effective control measure. - Focus should be on **vector prevention** and **early diagnosis** rather than patient quarantine.
Question 10: A novel coronavirus outbreak is detected with high transmissibility but variable mortality across age groups. Phylogenetic analysis shows 80% similarity with SARS-CoV. To predict pandemic potential, which epidemiological parameter would be most critical to evaluate first?
- A. Cross-immunity from previous coronavirus infections
- B. Basic reproduction number (R0) and serial interval (Correct Answer)
- C. Viral load in asymptomatic individuals only
- D. Case fatality rate alone
Explanation: ***Basic reproduction number (R0) and serial interval*** - The **Basic reproduction number (R0)** indicates the number of secondary infections generated by one case; an **R0 > 1** is the primary indicator of sustained transmission and pandemic potential. - The **serial interval** (time between symptom onset in successive cases) combined with **R0** allows modeling the **growth rate** of the outbreak to determine how quickly it will spread. *Cross-immunity from previous coronavirus infections* - While **cross-reactive T-cells** or antibodies can influence disease severity, they do not dictate the intrinsic **transmissibility** or early epidemic growth kinetics as directly as R0. - Assessing **herd immunity** or cross-protection is a secondary step after establishing that the pathogen has a high baseline **attack rate**. *Viral load in asymptomatic individuals only* - Monitoring **viral kinetics** in asymptomatic patients is important, but focusing **only** on this group misses the overall transmission dynamics of the entire population. - **Symptomatic transmission** often contributes significantly to the spread of respiratory viruses like SARS-like coronaviruses, making subset-only analysis insufficient for **pandemic prediction**. *Case fatality rate alone* - The **Case Fatality Rate (CFR)** measures the **virulence** or severity of the pathogen but serves as a poor predictor of how widely the virus will spread across borders. - High-mortality viruses often have lower **pandemic potential** if they kill the host too quickly to allow for wide-scale **asymptomatic or pre-symptomatic transmission**.
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