Infectious Diseases Practice Questions

Q: Universal precautions to be followed by the surgical team include all of the following except :

Prophylactic antimicrobials. **Prophylactic antimicrobials** - **Prophylactic antimicrobials** are given to prevent surgical site infections and are not considered a part of **universal precautions** themselves. - Universal precautions are primarily focused on preventing the transmission of bloodborne pathogens through physical barriers. *Wearing boots* - **Wearing boots** or shoe covers is an important component of **universal precautions** in the operating room to protect against splashes and contamination from blood and body fluids. - They also help maintain a sterile environment by preventing the introduction of contaminants from street shoes. *Wearing double gloves* - **Wearing double gloves** offers an extra layer of protection against sharps injuries and potential exposure to blood and body fluids, especially during procedures with a higher risk of puncture. - This practice reinforces the **barrier protection** aspect of universal precautions. *Donning water repellent gown* - A **water-repellent gown** acts as a crucial barrier to protect the surgical team's skin and clothing from contamination with blood, body fluids, and other potentially infectious materials. - This aligns with the principle of **universal precautions** to minimize exposure risks.

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.

Question 1

Universal precautions to be followed by the surgical team include all of the following except :

Accepted Answer

Prophylactic antimicrobials

Answer

Wearing boots

Answer

Wearing double gloves

Answer

Donning water repellent gown

Question 2

Which one of the following formulae is used for computing the Aedes aegypti Index at International Airports and sea ports ?

Accepted Answer

Number of containers positive for Aedes aegypti breeding / Total number of containers x 100

Answer

Number of houses positive for Aedes aegypti breeding / Total number of houses x 100

Answer

Number of bites of Aedes aegypti / Total number of man hours x 100

Answer

Number of containers positive for Aedes aegypti breeding / Total number of houses x 100

Question 3

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 4

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 5

The incubation period of mumps is

Accepted Answer

2-3 weeks

Answer

4-5 weeks

Answer

1-2 weeks

Answer

3-4 weeks

Question 6

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 7

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 8

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 9

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 10

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

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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