Infectious Diseases Practice Questions

Q: Which one of the following is a stomach poison for the larvae of insects of medical importance ?

Paris Green. ***Paris Green*** - **Paris Green (copper acetoarsenite)** acts as a **stomach poison** when ingested by insect larvae, particularly effective against mosquito larvae. - It is an **arsenical compound** that disrupts cellular respiration and enzyme function in the insect's digestive system. *Anti larva oil* - **Anti-larval oils** primarily act by forming a **thin film on the water surface**, preventing mosquito larvae from breathing. - This method is a **physical action** causing suffocation, rather than a stomach poison. *Pyrethrum* - **Pyrethrum** is a broad-spectrum **contact insecticide** derived from chrysanthemum flowers. - It acts on the **nervous system** of insects, causing rapid knockdown and paralysis, but is not primarily a stomach poison for larvae. *D.D.T.* - **DDT (dichlorodiphenyltrichloroethane)** is a **contact insecticide** that acts on the nervous system of insects. - It was widely used for adult mosquito control but is not typically applied as a stomach poison for larvae in a water environment.

Q: Match List-I with List-II and select the correct answer using the code given below the Lists:

A→3 B→2 C→1 D→4. ***Correct Answer: A→3 B→2 C→1 D→4*** This option correctly matches each vector with its transmitted disease: - **A (Lice) → 3 (Epidemic Typhus fever)** - *Pediculus humanus corporis* transmits *Rickettsia prowazekii* - **B (Fleas) → 2 (Endemic Typhus fever)** - *Xenopsylla cheopis* transmits *Rickettsia typhi* - **C (Ticks) → 1 (Kyasanur Forest Disease)** - *Haemaphysalis* ticks transmit KFD virus - **D (Sand Flies) → 4 (Kala-azar)** - *Phlebotomus* species transmit *Leishmania donovani* Understanding these specific vector-disease pairings is crucial for epidemiology, disease surveillance, and vector control programs in public health. *Incorrect: A→1 B→2 C→4 D→3* - Incorrectly pairs **Lice with Kyasanur Forest Disease** (should be Epidemic Typhus) and **Ticks with Kala-azar** (should be KFD) - KFD is tick-borne, not transmitted by sand flies; Kala-azar is sand fly-borne, not tick-borne *Incorrect: A→3 B→2 C→4 D→1* - Incorrectly pairs **Ticks with Kala-azar** (should be KFD) and **Sand Flies with Kyasanur Forest Disease** (should be Kala-azar) - Reverses the correct tick and sand fly disease associations *Incorrect: A→2 B→1 C→3 D→4* - Multiple errors: **Lice with Endemic Typhus** (should be Epidemic), **Fleas with KFD** (should be Endemic Typhus), and **Ticks with Epidemic Typhus** (should be KFD) - Confuses both typhus types and mismatches the tick-borne disease entirely

Q: The incubation period of mumps is

2-3 weeks. ***2-3 weeks*** - The incubation period for **mumps** is typically 16 to 18 days, with a range of 12 to 25 days, which falls within the 2-3 week timeframe. - This period is the time from exposure to the mumps virus until the onset of symptoms, such as **parotitis**. *4-5 weeks* - An incubation period of 4-5 weeks is longer than the typical range for mumps, suggesting a different viral infection. - This duration is more characteristic of diseases like **hepatitis B** rather than mumps. *1-2 weeks* - An incubation period of 1-2 weeks is shorter than the typical range for mumps. - This timeframe is more commonly associated with various **respiratory viruses** or **influenza**. *3-4 weeks* - While 3-4 weeks (21-28 days) can include the upper end of the mumps incubation period, it is not the most common or typical duration. - The average incubation is closer to **2.5 weeks**, making 2-3 weeks the more accurate general range.

Q: Consider the following statements : HIV can be transmitted to a healthcare worker from a patient through : 1. A needle stick injury 2. Contact with the patient's blood 3. External examination of the patient 4. Inhalation Which of the statements given above is/are correct ?

1 and 2 only. ***1 and 2 only*** - **Needle stick injuries** pose a significant risk as they involve direct inoculation of infected blood into the healthcare worker's bloodstream. - **Contact with a patient's blood** can lead to transmission if there are cuts, abrasions, or mucous membrane exposures on the healthcare worker. *2 and 3 only* - **Contact with a patient's blood** is a known transmission route, but **external examination** alone, without blood contact or needle stick, typically carries no risk of HIV transmission. - HIV is not transmitted through casual contact or touch during an examination. *1 and 4* - **Needle stick injuries** are a recognized transmission route, but **inhalation** is not a mechanism for HIV transmission. - HIV is not an airborne virus and does not spread like respiratory illnesses. *1, 2 and 3* - While **needle stick injuries** and **contact with blood** are clear transmission pathways, **external examination** of a patient, in the absence of blood contact or needle stick injuries, does not transmit HIV. - HIV transmission requires specific fluid exchange (blood, semen, vaginal fluids, breast milk) entering the bloodstream or mucous membranes.

Q: Which of the following will qualify as a Class III exposure to Rabies?

Bites by wild animals. ***Bites by wild animals*** - All bites and scratches by **wild carnivores (dogs, jackals, wolves, foxes)** or **bats** are **ALWAYS considered Category III exposures** regardless of the wound severity or location. - This is because wild animals cannot be observed for 10 days, and the risk of rabies is extremely high. - This classification mandates immediate post-exposure prophylaxis (PEP) with both **rabies immunoglobulin (RIG)** and **vaccine**. - This is the **most definitive** Category III exposure among the options. *Bites on legs by a dog* - According to WHO guidelines, **any transdermal bite or scratch** (breaking the skin) is technically a **Category III exposure**. - However, the classification can be modified if the biting dog is a **healthy domestic dog** that can be kept under **observation for 10 days**. - If the dog remains healthy during observation, PEP can be discontinued. - The question stem asks which "will qualify" - implying certainty. Wild animal bites are **always** Category III, while domestic dog bites may have conditional management based on observation. *Drinking unboiled milk of a suspect animal* - Rabies virus is transmitted through **saliva** via bites, scratches, or mucous membrane contamination. - The virus is **inactivated by gastric acid** and cannot be transmitted through the gastrointestinal route. - Ingesting milk from a suspect animal poses **no risk** of rabies transmission. - This is **not a rabies exposure** and does not require PEP. *Licks on intact skin by a dog* - Licks on **intact skin** are classified as **Category I exposure**. - Rabies virus **cannot penetrate healthy, unbroken skin**. - Category I exposures do **not warrant** any rabies post-exposure prophylaxis.

Q: Match List-I with List-II and select the correct answer using the code given below the Lists: List-I (Vectors): A. Hard ticks B. Sandflies C. Louse D. Soft ticks List-II (Diseases): 1. Oriental sore 2. Epidemic typhus 3. Tularemia 4. Relapsing fever

A→3 B→1 C→2 D→4. ***A→3 B→1 C→2 D→4*** - **Hard ticks** (A) are primary vectors for **tularemia** (3), transmitting *Francisella tularensis* through their bite during blood feeding. - **Sandflies** (B) transmit **oriental sore** (1), the cutaneous form of **leishmaniasis** caused by *Leishmania tropica* and other species. *A→4 B→1 C→3 D→2* - Incorrectly matches **hard ticks** with **relapsing fever**, which is specifically transmitted by **soft ticks** (*Ornithodoros* species). - Misassociates **louse** with **tularemia**, when **body lice** are established vectors for **epidemic typhus**. *A→1 B→2 C→3 D→4* - Wrongly pairs **hard ticks** with **oriental sore**, which requires **sandfly** vectors for transmission of *Leishmania* parasites. - Incorrectly matches **sandflies** with **epidemic typhus**, a louse-borne disease caused by *Rickettsia prowazekii*. *A→2 B→4 C→1 D→3* - Mismatches **hard ticks** with **epidemic typhus**, which is transmitted by **body lice**, not tick species. - Incorrectly associates **soft ticks** with **tularemia**, when they are specific vectors for **relapsing fever** caused by *Borrelia* species.

Q: The larvae of which one of the following mosquitoes cannot successfully be killed by spreading oil on the surface of its breeding water sources?

Mansonoides. ***Mansonoides*** - The larvae of *Mansonoides* mosquitoes attach to the underwater stems and roots of **aquatic vegetation** for oxygen. - This adaptation means they do not surface to breathe, rendering **surface oiling ineffective** against them. *Aedes* - *Aedes* larvae are **surface breathers**, obtaining oxygen from the air-water interface. - Oiling the water surface forms a film that **prevents oxygen uptake**, suffocating the larvae. *Culex* - *Culex* larvae are also **surface breathers** and, like *Aedes*, rely on the air-water interface for oxygen. - An oil film on the water surface will **block their access to atmospheric oxygen**, leading to their demise. *Anopheles* - *Anopheles* larvae are **surface dwellers** that lie parallel to the water surface, using their **spiracles** to breathe air. - An oil layer effectively **obstructs these spiracles**, preventing respiration and killing the larvae.

Q: Consider the following strategies pertaining to National Anti-Malaria Programme: 1. Early case detection and prompt treatment with ACT (Artemisinin Combination Therapy) 2. Indoor Residual Spraying (IRS) in areas with API ≥2 3. Distribution and promotion of Long Lasting Insecticidal Nets (LLINs) Which of the above strategies is/are being used in India?

1, 2 and 3. ***1, 2 and 3*** - The **National Anti-Malaria Programme (NAMP)** in India utilizes all three strategies as core components for malaria control and elimination. - **Early case detection and prompt treatment with ACT** are crucial for reducing the parasite reservoir and preventing severe disease. **Indoor Residual Spraying (IRS)** is used for vector control, especially in high-burden areas (API ≥2), and **Long Lasting Insecticidal Nets (LLINs)** provide personal protection against mosquito bites. *2 and 3 only* - This option is incorrect because it excludes **early case detection and prompt treatment with ACT**, which is a fundamental and critical strategy in malaria control. - Effective **case management** is essential for reducing transmission and morbidity/mortality, alongside vector control methods like IRS and LLINs. *1 and 2 only* - This option is incorrect as it omits the **distribution and promotion of Long Lasting Insecticidal Nets (LLINs)**, which are a highly effective and widely implemented tool for preventing mosquito bites and reducing malaria transmission, particularly in endemic areas. - **LLINs** are a cost-effective intervention promoting personal protection, empowering communities in malaria prevention efforts. *1 only* - This option is incorrect because relying solely on **early case detection and prompt treatment** is insufficient for comprehensive malaria control. - Effective malaria control requires a multi-pronged approach that also incorporates **vector control strategies** like IRS and LLINs to reduce human-vector contact.

Q: Effective disinfection of a typhoid patient's faecal matter can be done with

2% bleaching powder. ***2% bleaching powder*** - **Bleaching powder** (calcium hypochlorite) is a strong oxidizing agent that effectively disinfects faecal matter by destroying microbial cell structures. - A **2% solution** provides sufficient concentration of free chlorine to kill *Salmonella Typhi* and other pathogens in faeces. *2% phenol* - While **phenol** is an antiseptic and disinfectant, a 2% solution may not be strong enough for the effective and rapid disinfection of heavily contaminated faecal matter. - **Phenol** acts by denaturing proteins and disrupting cell membranes, but higher concentrations or longer contact times are generally needed for spore-forming or highly resistant organisms, though *Salmonella Typhi* is not spore-forming. *5% formalin* - **Formalin** (a solution of formaldehyde) is a powerful disinfectant and fixative, but it is typically used for sterilizing medical equipment or preserving biological specimens. - Its **strong fumes** and irritating nature make it less suitable for routine, large-scale disinfection of faecal matter due to safety concerns and logistical challenges. *5% cresol* - **Cresol** is a phenolic disinfectant that is more potent than phenol and is effective against a broad spectrum of microorganisms. - While effective, **cresol** is typically used in higher concentrations (like 5%) for disinfecting surfaces or specific wastes, and its pungent odor and potential toxicity might make it a less practical choice for general faecal disinfection compared to bleaching powder.

Question 1

Which one of the following is a stomach poison for the larvae of insects of medical importance ?

Accepted Answer

Paris Green

Answer

Anti larva oil

Answer

Pyrethrum

Answer

D.D.T.

Question 2

Match List-I with List-II and select the correct answer using the code given below the Lists:

Accepted Answer

A→3  B→2  C→1  D→4

Answer

A→1  B→2  C→4  D→3

Answer

A→3  B→2  C→4  D→1

Answer

A→2  B→1  C→3  D→4

Question 3

The incubation period of mumps is

Accepted Answer

2-3 weeks

Answer

4-5 weeks

Answer

1-2 weeks

Answer

3-4 weeks

Question 4

Consider the following statements : HIV can be transmitted to a healthcare worker from a patient through :

1. A needle stick injury
2. Contact with the patient's blood
3. External examination of the patient
4. Inhalation
Which of the statements given above is/are correct ?

Accepted Answer

1 and 2 only

Answer

2 and 3 only

Answer

1 and 4

Answer

1, 2 and 3

Question 5

Which of the following will qualify as a Class III exposure to Rabies?

Accepted Answer

Bites by wild animals

Answer

Bites on legs by a dog

Answer

Drinking unboiled milk of a suspect animal

Answer

Licks on intact skin by a dog

Question 6

Under the DOTS strategy of Revised National Tuberculosis Programme, the recommended line of management in Category I patients, if the sputum is positive after 2 months of Intensive Phase treatment with 4 drugs, is to

Accepted Answer

Continue the Intensive Phase of treatment with 4 drugs for 1 more month only, regardless of sputum positivity after that

Answer

Add one more drug, that is, to use 5 drugs until the sputum becomes negative

Answer

Continue the Intensive Phase of treatment with 4 drugs until the sputum becomes negative

Answer

Start the continuation phase with INH and Rifampicin

Question 7

Match List-I with List-II and select the correct answer using the code given below the Lists:

List-I (Vectors):
A. Hard ticks
B. Sandflies
C. Louse
D. Soft ticks

List-II (Diseases):
1. Oriental sore
2. Epidemic typhus
3. Tularemia
4. Relapsing fever

Accepted Answer

A→3  B→1  C→2  D→4

Answer

A→4  B→1  C→3  D→2

Answer

A→1  B→2  C→3  D→4

Answer

A→2  B→4  C→1  D→3

Question 8

The larvae of which one of the following mosquitoes cannot successfully be killed by spreading oil on the surface of its breeding water sources?

Accepted Answer

Mansonoides

Answer

Aedes

Answer

Culex

Answer

Anopheles

Question 9

Consider the following strategies pertaining to National Anti-Malaria Programme:

1. Early case detection and prompt treatment with ACT (Artemisinin Combination Therapy)

2. Indoor Residual Spraying (IRS) in areas with API ≥2

3. Distribution and promotion of Long Lasting Insecticidal Nets (LLINs)

Which of the above strategies is/are being used in India?

Accepted Answer

1, 2 and 3

Answer

2 and 3 only

Answer

1 and 2 only

Answer

1 only

Question 10

Effective disinfection of a typhoid patient's faecal matter can be done with

Accepted Answer

2% bleaching powder

Answer

2% phenol

Answer

5% formalin

Answer

5% cresol

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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