Infectious Diseases Practice Questions

Q: Most important strategy for control of malaria in an endemic area:

Vector control. ***Vector control*** - **Vector control** strategies, such as **insecticide-treated bed nets (ITNs)** and **indoor residual spraying (IRS)**, are the most effective in reducing malaria transmission by targeting the Anopheles mosquito - By reducing the mosquito population and their biting rates, vector control significantly cuts down the number of infected bites, leading to a substantial decrease in malaria incidence - This is the **cornerstone of WHO's Global Malaria Programme** and has proven most cost-effective for endemic areas *Incorrect: Chemoprophylaxis* - Chemoprophylaxis involves taking antimalarial drugs to prevent infection, which is effective for individuals or travelers but not sustainable or scalable for mass control in endemic populations - Widespread use would be cost-prohibitive and could accelerate **antimalarial drug resistance** *Incorrect: Early treatment of cases* - Early treatment with effective antimalarials reduces disease severity and prevents onward transmission, which is crucial for managing the disease burden - However, it does not directly prevent new infections or interrupt the transmission cycle as effectively as vector control at a population level - This is a **secondary strategy** that complements but does not replace vector control *Incorrect: Elimination of plasmodium* - Elimination of Plasmodium refers to eradication of the parasite, which is the ultimate goal, but it is not a direct "strategy" in itself but rather the **outcome** of successful control measures - Complete eradication is ambitious and challenging; current efforts focus on breaking the transmission cycle through vector control and effective case management

Q: The case fatality rate of untreated typhoid fever is:

10%. ***10%*** - The **case fatality rate** of untreated typhoid fever is approximately **10-20%**, with **10%** being the commonly cited average figure. - Without antibiotic treatment, complications like **intestinal perforation**, **hemorrhage**, **myocarditis**, and **encephalopathy** contribute to mortality. - This high fatality rate emphasizes the critical importance of early diagnosis and treatment. *20%* - While 20% represents the upper limit of the range for untreated typhoid, **10%** is the more commonly used average estimate in epidemiological studies. - The actual rate can vary based on **host factors** (age, nutritional status, immunity), **strain virulence**, and **supportive care availability**. *30%* - A 30% case fatality rate exceeds the typical range for untreated typhoid fever. - Even in the pre-antibiotic era and resource-limited settings, the rate rarely reached this level. *40%* - A 40% case fatality rate is far higher than observed for untreated typhoid fever. - Such high mortality would be characteristic of other severe infections like **untreated plague** or **severe viral hemorrhagic fevers**, not typhoid. **Note:** With appropriate antibiotic treatment, the case fatality rate of typhoid fever drops to **<1-2%**, highlighting the dramatic impact of modern therapeutics.

Q: All of the following statements regarding Dracunculiasis are true except -

Niridazole is effective in treating the disease.. ***Niridazole is effective in treating the disease.*** - There are currently **no effective antiparasitic drugs** to treat Dracunculiasis. - Treatment focuses on **manual extraction of the worm** and symptom management, not chemotherapy. - Niridazole and other antiparasitic agents have been tried but are **not effective** for curing the infection. *The disease is limited to tropical and subtropical regions* - Dracunculiasis is predominantly found in **arid and semi-arid regions** of Africa, particularly those with poor access to safe drinking water. - Its geographical distribution is indeed restricted to **tropical and subtropical areas**, matching the environmental needs of its lifecycle. *India has eradicated this disease* - India successfully **eradicated Dracunculiasis in 2000**, a significant public health achievement. - This demonstrates that elimination is possible through sustained public health interventions focused on providing safe drinking water and community education. *No animal reservoir has been identified* - Humans have traditionally been considered the **primary definitive host** for *Dracunculus medinensis*. - While dogs and other animals can occasionally be infected, they play a **minimal role in transmission**, and the disease is primarily sustained through the human-cyclops-human cycle. - The statement is essentially **correct** from a classical epidemiological perspective where humans are the main reservoir.

Q: You are the DOTS provider for a patient. He has completed his 6 months of treatment. He was sputum +ve to begin with, but after the intensive phase of treatment he became sputum -ve. He was again confirmed to be sputum negative 2 months after starting the continuation phase. This patient can be termed as:

Cured. ***Cured*** - According to **RNTCP guidelines**, a patient is classified as **cured** when they are initially sputum smear-positive, complete the full course of treatment, and have **negative sputum smear results on at least two occasions** - one at the end of treatment and another on a previous occasion. - This patient was initially **sputum positive**, became **sputum negative after the intensive phase**, and was confirmed **sputum negative 2 months into the continuation phase**, meeting the criteria for cured status. - With documented negative sputum on multiple occasions during treatment, this represents successful bacteriological cure. *Treatment completed* - This category is used for TB patients who have **completed their full course of treatment** but do NOT have sputum smear results available at the end of treatment (either not done or results unavailable). - Since this patient has **documented negative sputum results** on multiple occasions, the appropriate classification is "cured" rather than "treatment completed". - Treatment completed is reserved for cases where bacteriological confirmation of cure is absent. *Transfer out* - This classification is for patients who are **transferred to another treatment unit** and whose treatment outcome is **unknown to the original reporting unit**. - The patient completed treatment under the same DOTS provider without transfer, making this classification incorrect. *Defaulted* - A patient is classified as having **defaulted** if they interrupt their treatment for **two consecutive months or more** after registration. - This patient completed the full 6-month treatment course without interruption, making defaulting an incorrect classification.

Q: Incidence of TB in a community is measured by

Sputum smear positive. ***Sputum smear positive*** - The **incidence of TB** in a community is best measured by the number of new **sputum smear-positive** cases, as these individuals are actively shedding bacilli and are infectious. - This method directly identifies individuals with **active disease** who are capable of transmitting the infection, thus reflecting new cases rather than past exposure. *Tuberculin test positive* - A **positive tuberculin test** (or TST) indicates exposure to TB bacilli and an immune response, but it does not differentiate between **latent TB infection (LTBI)** and active disease. - Many individuals with a positive test will never develop active TB, making it a poor measure of the *incidence of new active cases*. *Mantoux test positive* - The **Mantoux test** is another name for the **tuberculin skin test (TST)**, yielding the same limitations as "tuberculin test positive." - It primarily measures **delayed-type hypersensitivity** to tuberculin proteins, reflecting prior exposure rather than current, active, and transmissible disease. *Sputum culture* - While **sputum culture** is the gold standard for diagnosing active TB disease due to its high sensitivity, it is more expensive and time-consuming than sputum smear microscopy. - For measuring incidence at a community level, **sputum smear positivity** is often preferred for its practicality, speed, and ability to identify the most infectious cases promptly.

Q: Under passive surveillance for tuberculosis, what is the indication for sputum microscopy?

3 weeks. ***3 weeks*** - In **passive surveillance** for tuberculosis, symptoms present for **three weeks or more** warrant investigation with sputum microscopy. - This duration allows for the manifestation of typical TB symptoms that distinguish it from common, self-limiting respiratory infections. *8 weeks* - A period of **eight weeks** for symptom duration is typically too long for initiating sputum microscopy in suspected TB, delaying diagnosis and potential treatment. - Delayed diagnosis can lead to more severe disease progression and increased transmission. *4 weeks* - While **four weeks** might seem reasonable, the standard guideline for initiating sputum microscopy under passive surveillance is slightly shorter at three weeks. - Waiting an additional week could slightly increase the risk of disease progression or transmission. *6 weeks* - Similar to 8 weeks, a **six-week** duration for symptoms before performing sputum microscopy is often considered too long for early TB detection during passive surveillance. - Early detection is crucial for effective treatment and preventing spread.

Q: A patient with sputum positive pulmonary tuberculosis is on ATT for the last 5 months but the patient is still positive for AFB in the sputum. This case refers to -

Failure case. ***Failure case*** - A **failure case** in TB treatment is defined as a patient who remains sputum smear positive at 5 months or more after starting treatment, indicating that the initial drug regimen was unsuccessful. - This scenario suggests **drug resistance** or inadequate treatment, necessitating a re-evaluation of the treatment regimen. *Drug defaulter* - A **defaulter** is a patient who interrupts their TB treatment for two consecutive months or more. - In this patient, treatment has been continuous for 5 months, making "defaulter" an incorrect classification. *New case* - A **new case** refers to a patient who has never been treated for TB before or has received anti-TB drugs for less than one month. - This patient has already been on ATT for 5 months, so they are not a new case. *Relapse case* - A **relapse case** is a patient who was previously treated for TB, declared cured, but has become sputum smear positive again. - This patient has never been declared cured because the sputum has remained positive throughout the treatment.

Q: Under the RNTCP, sputum culture for MDR TB is to be examined for at least:

8 weeks. ***8 weeks*** - Under the Revised National Tuberculosis Control Programme (RNTCP), **sputum culture for MDR TB** (Multidrug-Resistant Tuberculosis) is typically incubated and examined for a minimum of **8 weeks** to ensure optimal detection of Mycobacterium tuberculosis. - This extended incubation period is crucial because *M. tuberculosis* is a **slow-growing organism**, and a shorter period might lead to false-negative results, missing actual MDR TB cases. *4 weeks* - A 4-week incubation period is generally too short for reliable detection of *Mycobacterium tuberculosis*, especially in cases of MDR TB where growth can be further delayed. - This duration is more commonly associated with conventional culture procedures for faster-growing bacteria, not *M. tuberculosis*. *12 weeks* - While a 12-week incubation period would certainly allow for ample time for *M. tuberculosis* growth, it generally exceeds the standard recommendations for routine MDR TB sputum culture within the RNTCP. - Prolonging incubation beyond 8 weeks often does not yield significant additional benefit in detection rates and increases laboratory workload and turnaround time without substantial clinical justification. *10 weeks* - A 10-week incubation period is longer than the standard 8 weeks but is not the minimum recommended period under the RNTCP for sputum culture of MDR TB. - It would also extend the diagnostic process unnecessarily compared to the established and effective 8-week protocol.

Q: Chikungunya is transmitted by which mosquito?

Aedes. ***Aedes*** - **Chikungunya virus** is primarily transmitted to humans by **Aedes mosquitos**, specifically **Aedes aegypti** and **Aedes albopictus**. - These mosquitos are **day-biting** and thrive in urban and semi-urban environments, often breeding in and around human habitations. - Aedes aegypti is also the vector for **dengue**, **Zika**, and **yellow fever**. *Culex* - **Culex mosquitos** are vectors for diseases like **West Nile virus**, **Japanese encephalitis**, and **lymphatic filariasis**. - They are primarily **night-biting** mosquitos and breed in stagnant water. - Not involved in Chikungunya transmission. *Mansonia* - **Mansonia mosquitos** are vectors for **Brugia malayi**, causing **lymphatic filariasis** (especially in rural Asia). - They have unique breeding habits, attaching eggs to aquatic vegetation. - Not involved in Chikungunya transmission. *Anopheles* - **Anopheles mosquitos** are the primary vectors for **malaria**, a disease caused by Plasmodium parasites. - They are generally **night-biting** and have distinct breeding habits compared to the Aedes mosquito. - Not involved in Chikungunya transmission.

Q: True about kala-azar -

Non-human reservoirs are present. ***Non-human reservoirs are present*** - **Globally correct**: Visceral leishmaniasis has **non-human reservoirs** (dogs, foxes, rodents) in many endemic regions, particularly in Mediterranean countries, Brazil, and China where **zoonotic transmission** (L. infantum/L. chagasi) occurs. - **Indian context**: In the **Indian subcontinent** (India, Bangladesh, Nepal), kala-azar (L. donovani) is primarily **anthroponotic** with **humans as the main reservoir**. However, recent evidence suggests potential animal reservoirs may exist in some areas. - This option is considered **true** because non-human reservoirs do exist globally in visceral leishmaniasis, and emerging data suggests possible animal involvement even in anthroponotic regions. *All of the options* - Incorrect because not all statements are true regarding kala-azar. - Kala-azar has not been eliminated from India, and there is no consistent female predominance. *Eliminated from India* - **Incorrect**: Kala-azar has **not been eliminated** from India; it remains endemic in several districts, particularly in **Bihar, Jharkhand, Uttar Pradesh, and West Bengal**. - India launched the **National Kala-azar Elimination Program** targeting elimination (incidence <1 case per 10,000 population at block level) by 2023, but **elimination has not yet been achieved**. - Significant progress has been made with case reduction, but active transmission continues. *More common in female than male* - **Incorrect**: Kala-azar shows **equal or slight male predominance** in most epidemiological studies. - Males may have slightly higher incidence due to occupational exposure patterns and outdoor activities increasing sandfly contact. - There is no consistent evidence of higher prevalence in females.

Question 1

Most important strategy for control of malaria in an endemic area:

Accepted Answer

Vector control

Answer

Chemoprophylaxis

Answer

Early treatment of cases

Answer

Elimination of plasmodium

Question 2

The case fatality rate of untreated typhoid fever is:

Accepted Answer

10%

Answer

20%

Answer

30%

Answer

40%

Question 3

All of the following statements regarding Dracunculiasis are true except -

Accepted Answer

Niridazole is effective in treating the disease.

Answer

The disease is limited to tropical and subtropical regions

Answer

India has eradicated this disease

Answer

No animal reservoir has been identified

Question 4

You are the DOTS provider for a patient. He has completed his 6 months of treatment. He was sputum +ve to begin with, but after the intensive phase of treatment he became sputum -ve. He was again confirmed to be sputum negative 2 months after starting the continuation phase. This patient can be termed as:

Accepted Answer

Cured

Answer

Transfer out

Answer

Defaulted

Answer

Treatment completed

Question 5

Incidence of TB in a community is measured by

Accepted Answer

Sputum smear positive

Answer

Tuberculin test positive

Answer

Mantoux test positive

Answer

Sputum culture

Question 6

Under passive surveillance for tuberculosis, what is the indication for sputum microscopy?

Accepted Answer

3 weeks

Answer

8 weeks

Answer

4 weeks

Answer

6 weeks

Question 7

A patient with sputum positive pulmonary tuberculosis is on ATT for the last 5 months but the patient is still positive for AFB in the sputum. This case refers to -

Accepted Answer

Failure case

Answer

Drug defaulter

Answer

New case

Answer

Relapse case

Question 8

Under the RNTCP, sputum culture for MDR TB is to be examined for at least:

Accepted Answer

8 weeks

Answer

4 weeks

Answer

12 weeks

Answer

10 weeks

Question 9

Chikungunya is transmitted by which mosquito?

Accepted Answer

Aedes

Answer

Culex

Answer

Mansonia

Answer

Anopheles

Question 10

True about kala-azar -

Accepted Answer

Non-human reservoirs are present

Answer

All of the options

Answer

Eliminated from India

Answer

More common in female than male

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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