Epidemiology Practice Questions

Q: The time interval between reception of infection and maximum infectivity of the host is known as-

Latent period. ***Latent period*** - This is the time from **infection to infectiousness**, meaning the period until the host can transmit the pathogen to another susceptible host. - The highest infectivity typically occurs during this period or shortly after its completion, making it a critical measure for understanding disease transmission. *Median incubation period* - The **incubation period** is the time from exposure to a pathogen until the first appearance of symptoms. - The median incubation period represents the **midpoint** of this time frame across an infected population. *Generation time* - **Generation time** is defined as the interval between the onset of infectiousness in a primary case and the onset of infectiousness in a secondary case infected by the primary case. - It measures the **time between successive generations of infection**, not the time to maximum infectivity within a single host. *Serial interval* - The **serial interval** is the time from symptom onset in a primary case to symptom onset in a secondary case infected by the primary case. - It is a measure related to the **spread of symptomatic illness**, and while often correlated with generation time, it is not specifically about the host's infectivity level.

Q: WER stands for

Weekly epidemiological record. ***Weekly epidemiological record*** - The **Weekly Epidemiological Record (WER)** is a key publication of the **World Health Organization (WHO)**. - It serves as an essential instrument for the rapid dissemination of **epidemiological information** on cases and outbreaks of diseases under the **International Health Regulations**. *World epidemic record* - This option is incorrect because while the WER deals with **epidemics**, the full and correct name emphasizes the **weekly publication schedule** and broader "epidemiological" scope, not just "epidemic." - Using "World epidemic record" is not the accepted or official nomenclature for the publication. *Weekly environmental record* - This option is incorrect as the **WER** focuses specifically on **disease surveillance** and **epidemiology**, not environmental data. - While environmental factors can influence disease, the primary scope of the WER is on disease prevalence, incidence, and outbreaks. *World epidemiological record* - This option is incorrect because the official publication is called the **"Weekly" Epidemiological Record**, highlighting its regular, week-by-week updates. - Omission of "Weekly" changes the accuracy of the title.

Q: Disease highly transmitted during incubation period is -

Chickenpox. ***Chickenpox (Varicella)*** - Chickenpox is **highly contagious during the late incubation period**, specifically **1-2 days before the rash appears**. - The incubation period is 10-21 days (usually 14-16 days), and transmission begins **before any clinical symptoms** are evident. - This makes chickenpox unique as it spreads efficiently during the true incubation period (asymptomatic phase). - Transmission continues until **all lesions have crusted over** (usually 5-7 days after rash onset). *Measles* - While measles is highly contagious, it is most infectious during the **prodromal phase** (fever, cough, coryza, conjunctivitis) and early rash phase. - The prodromal phase occurs **after the incubation period ends** (incubation is 10-14 days of asymptomatic infection). - Some transmission may occur in the last 1-2 days of incubation, but peak infectivity is during the symptomatic prodromal phase. *Pertussis* - Pertussis is most contagious during the **catarrhal stage**, which follows the incubation period. - The catarrhal stage is characterized by runny nose, low-grade fever, and mild cough (symptomatic phase). - Infectivity decreases significantly after 3 weeks of illness or after 5 days of appropriate antibiotic therapy. *Cholera* - Cholera is transmitted via the **fecal-oral route** through contaminated water or food. - While some bacterial shedding occurs during incubation, peak transmission happens during the **symptomatic phase** with severe diarrhea causing massive bacterial shedding. - Most transmission occurs from symptomatic or recently symptomatic individuals.

Q: Which of the following is primordial prevention for non-communicable diseases?

Preservation of traditional diet in low NCD area. ***Preservation of traditional diet in low NCD area*** - **Primordial prevention** targets the underlying causes of disease before risk factors are established, often at a population level. - Preserving a **healthy traditional diet** in an area with low rates of non-communicable diseases (NCDs) prevents the emergence of shared risk factors like processed food consumption and sedentary lifestyles. *Salt restriction in high NCD area* - This is an example of **primary prevention**, as it aims to reduce a specific risk factor (high salt intake) in a population susceptible to NCDs like hypertension. - It intervenes when risk factors are already present or emerging, unlike primordial prevention which aims to prevent their development. *Smoking cessation in high NCD area* - Also a form of **primary prevention**, as it targets an existing modifiable risk factor (smoking) to prevent the onset of NCDs. - It focuses on individuals or groups already exposed to a risk factor rather than preventing the societal conditions that lead to its emergence. *Early diagnosis & Treatment* - This falls under **secondary prevention**, which aims to detect and treat diseases early to halt their progression and prevent complications. - It occurs after the disease has already begun but before significant symptoms or irreversible damage have occurred.

Q: Population of a village on 1st January is 16,500. Since 1st January, 22 new cases of TB were detected during the year. Total registered cases were 220. What is the incidence of TB?

133 per 100,000. ***133 per 100,000*** - The **incidence rate** calculates the frequency of new occurrences of a disease in a population over a specified time period. - It is calculated as (Number of new cases / Population at risk) * 100,000. Here, (22 / 16,500) * 100,000 = **133.33 per 100,000**. *100 per 100,000* - This value would be obtained if the number of new cases was 16.5 (16.5 / 16,500 * 100,000). - This calculation does not reflect the given number of **new cases (22)**. *121 per 100,000* - This value would be obtained if the number of new cases was 20 (20 / 16,500 * 100,000) or if the **population was different**. - This option does not match the actual data provided for the new cases and population. *111 per 100,000* - This value would be obtained if the number of new cases was approximately 18.3 (18.3 / 16,500 * 100,000). - It does not correctly reflect the **incidence calculation** based on the given number of 22 new cases.

Q: First step in control of cholera epidemic:

Verification of diagnosis. ***Verification of diagnosis*** - The initial and crucial step in controlling any epidemic, including cholera, is to **confirm the diagnosis** to ensure that the public health response is appropriate for the identified pathogen. - This involves **laboratory confirmation** of *Vibrio cholerae* from patient samples, which guides subsequent interventions. *Chemoprophylaxis* - While **antibiotics** can be used as prophylaxis for close contacts in some cholera outbreaks, it is not the *first* step in controlling an epidemic. - Widespread chemoprophylaxis is generally not recommended due to concerns about **antibiotic resistance** and its limited impact on the overall epidemic curve. *Provision of safe water* - **Providing safe water** is a critical, long-term intervention for preventing and controlling cholera, addressing the root cause of transmission. - However, it typically follows diagnosis and other immediate containment measures, and its implementation can take time. *ORS therapy* - **Oral Rehydration Solution (ORS) therapy** is a cornerstone of cholera patient *management* to prevent dehydration and death. - While essential for affected individuals, it is a treatment for cases, not the first step in *controlling the epidemic* at a public health level.

Q: The infectivity of chicken pox lasts for -

6 days after onset of rash. ***6 days after onset of rash*** - The infectious period for **chickenpox** (varicella) typically starts 1-2 days before the rash appears and lasts until all lesions have **crusted over**, which usually takes about 6 days after the onset of the rash. - This timeframe is crucial for **infection control** as the virus is highly contagious during this period. *3 days after onset of rash* - This period is **too short** to cover the entire infectious phase of chickenpox. - Many lesions may still be in the vesicular stage and highly contagious at only 3 days after rash onset. *Till the fever subsides* - While fever is a common symptom, the cessation of fever **does not reliably indicate** the end of the infectious period for chickenpox. - Patients can still be contagious even after their fever has gone down if lesions are still active. *Till the last scab falls off* - This duration is **longer** than the actual infectious period. Once all lesions have **crusted over**, the risk of transmission significantly decreases, even if the scabs have not yet fallen off. - The crusted lesions are generally not considered infectious.

Q: The chemoprophylaxis in malaria is an example of -

Primary prevention. ***Primary prevention*** - **Chemoprophylaxis** aims to prevent the **onset of disease** in individuals who are at risk, but currently healthy. - It involves administering medication to individuals before exposure to the malaria parasite to prevent infection or clinical disease. *Tertiary prevention* - Focuses on **reducing the impact of an existing disease** and preventing disability or complications. - This would include rehabilitation or long-term management for individuals who have already suffered from malaria. *Secondary prevention* - Involves **early detection and prompt treatment** of existing disease to prevent its progression. - An example would be screening for malaria in endemic areas and treating positive cases early. *Primordial prevention* - Aims to prevent the development of risk factors themselves, often at a population level. - This would involve addressing broader **socioeconomic determinants** that contribute to malaria transmission, not directly preventing the disease in individuals.

Q: The demographic measure that indicates the average number of children a woman would bear during her reproductive lifetime is -

Total Fertility Rate (TFR). ***Total Fertility Rate (TFR)*** - The **Total Fertility Rate (TFR)** is defined as the average number of children that would be born to a woman over her lifetime if she were to experience the exact current age-specific fertility rates through her reproductive years. - It's a synthetic measure reflecting current fertility levels and is used to estimate the **average family size**. - TFR is calculated by summing age-specific fertility rates across all reproductive age groups (usually 15-49 years). *General Fertility Rate (GFR)* - The **General Fertility Rate (GFR)** measures the number of live births per 1,000 women of reproductive age (15-49 years) in a given year. - Unlike TFR, it does not provide the **average number of children per woman** over her entire reproductive lifetime but rather a population-level fertility measure for a specific period. *Birth Rate (BR)* - The **Birth Rate (BR)**, often referred to as the crude birth rate, indicates the number of live births per 1,000 people in the total population over a given period. - It does not specifically measure the average number of children a woman would bear in her reproductive lifetime but rather the **overall natality of the population**. *Net Reproduction Rate (NRR)* - The **Net Reproduction Rate (NRR)** considers both fertility and mortality rates, indicating the average number of **daughters** a woman would have if she survived to the end of her reproductive years. - It reflects whether a population is **replacing itself** from one generation to the next, focusing on female offspring only and accounting for mortality before the end of the reproductive period.

Question 1

The time interval between reception of infection and maximum infectivity of the host is known as-

Accepted Answer

Latent period

Answer

Median incubation period

Answer

Generation time

Answer

Serial interval

Question 2

WER stands for

Accepted Answer

Weekly epidemiological record

Answer

World epidemic record

Answer

Weekly environmental record

Answer

World epidemiological record

Question 3

Disease highly transmitted during incubation period is -

Accepted Answer

Chickenpox

Answer

Pertussis

Answer

Cholera

Answer

Measles

Answer

Brucellosis

Question 4

Which of the following is primordial prevention for non-communicable diseases?

Accepted Answer

Preservation of traditional diet in low NCD area

Answer

Salt restriction in high NCD area

Answer

Smoking cessation in high NCD area

Answer

Early diagnosis & Treatment

Question 5

Population of a village on 1st January is 16,500. Since 1st January, 22 new cases of TB were detected during the year. Total registered cases were 220. What is the incidence of TB?

Accepted Answer

133 per 100,000

Answer

100 per 100,000

Answer

121 per 100,000

Answer

111 per 100,000

Question 6

First step in control of cholera epidemic:

Accepted Answer

Verification of diagnosis

Answer

Chemoprophylaxis

Answer

Provision of safe water

Answer

ORS therapy

Question 7

"Tracking" of blood pressure means:

Accepted Answer

High blood pressures in children tend to perpetuate in adults

Answer

Controlling high BP with nifedipine

Answer

Pictorial representation of serial blood pressures of an individual

Answer

None of the options

Question 8

The infectivity of chicken pox lasts for -

Accepted Answer

6 days after onset of rash

Answer

3 days after onset of rash

Answer

Till the fever subsides

Answer

Till the last scab falls off

Question 9

The chemoprophylaxis in malaria is an example of -

Accepted Answer

Primary prevention

Answer

Tertiary prevention

Answer

Secondary prevention

Answer

Primordial prevention

Question 10

The demographic measure that indicates the average number of children a woman would bear during her reproductive lifetime is -

Accepted Answer

Total Fertility Rate (TFR)

Answer

General Fertility Rate (GFR)

Answer

Birth Rate (BR)

Answer

Net Reproduction Rate (NRR)

Epidemiology — MCQs

Epidemiology — MCQs

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