Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 191: One of the following diseases has more than one route of transmission :

A. Influenza (Correct Answer)
B. Leprosy
C. Cholera
D. Typhoid fever

Explanation: ***Influenza*** - Influenza is primarily transmitted through **respiratory droplets** produced when an infected person coughs or sneezes. - It can also be spread by touching contaminated surfaces with the virus and then touching one's **mouth, nose, or eyes**. *Leprosy* - Leprosy is primarily transmitted through **prolonged, close contact** with an infected individual who is not undergoing treatment, via respiratory droplets from the nose and mouth. - It is not known to be transmitted through multiple, distinct routes beyond this **respiratory droplet transmission**. *Cholera* - Cholera is exclusively transmitted through the **fecal-oral route**, typically by consuming water or food contaminated with *Vibrio cholerae* bacteria. - There is no evidence of routine transmission via **respiratory droplets** or direct contact among humans. *Typhoid fever* - Typhoid fever is primarily transmitted via the **fecal-oral route**, through contaminated food or water with *Salmonella Typhi*. - While it has a single route of transmission, the means of contamination can vary, e.g., via **contaminated food handlers** or **poor sanitation**.

Question 192: Universal precautions to be followed by the surgical team include all of the following except :

A. Wearing boots
B. Wearing double gloves
C. Donning water repellent gown
D. Prophylactic antimicrobials (Correct Answer)

Explanation: **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.

Question 193: Which one of the following is a stomach poison for the larvae of insects of medical importance ?

A. Anti larva oil
B. Pyrethrum
C. D.D.T.
D. Paris Green (Correct Answer)

Explanation: ***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.

Question 194: The detection of sore throat cases in children and their treatment with Benzathine Penicillin in Community Control Programme of Rheumatic Fever/Rheumatic Heart Disease (RF/RHD) constitutes

A. Primary prevention of RF/RHD (Correct Answer)
B. Primordial prevention of RF/RHD
C. Tertiary prevention of RF/RHD
D. Secondary prevention of RF/RHD

Explanation: ***Primary prevention of RF/RHD*** - **Early detection and treatment** of streptococcal sore throat prevents the initial episode of **acute rheumatic fever (ARF)**, thus preventing the onset of **rheumatic heart disease (RHD)**. - This intervention targets preventing the disease's **initial occurrence** by eliminating the precipitating cause. *Primordial prevention of RF/RHD* - **Primordial prevention** focuses on preventing the development of **risk factors** in the first place, often through broad social or environmental changes. - This involves strategies like improving **socioeconomic conditions** or **housing sanitation** to reduce the overall burden of streptococcal infections, rather than treating individual cases. *Tertiary prevention of RF/RHD* - **Tertiary prevention** aims to **reduce the impact** of an established disease, minimizing complications and improving quality of life. - For RF/RHD, this would involve managing **existing RHD**, such as through cardiac surgery or long-term medication, to prevent further deterioration or disability. *Secondary prevention of RF/RHD* - **Secondary prevention** involves detecting and treating a disease **early** to prevent its progression or recurrence *after* an initial episode. - In the context of RF/RHD, this would refer to **secondary prophylaxis with penicillin** given to individuals who have already had ARF to prevent subsequent attacks and progression to RHD.

Question 195: Match List-I with List-II and select the correct answer using the code given below the Lists:

A. A→1 B→2 C→4 D→3
B. A→3 B→2 C→4 D→1
C. A→3 B→2 C→1 D→4 (Correct Answer)
D. A→2 B→1 C→3 D→4

Explanation: ***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

Question 196: The incubation period of mumps is

A. 2-3 weeks (Correct Answer)
B. 4-5 weeks
C. 1-2 weeks
D. 3-4 weeks

Explanation: ***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.

Question 197: 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 ?

A. 1 and 2 only (Correct Answer)
B. 2 and 3 only
C. 1 and 4
D. 1, 2 and 3

Explanation: ***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.

Question 198: Which of the following will qualify as a Class III exposure to Rabies?

A. Bites by wild animals (Correct Answer)
B. Bites on legs by a dog
C. Drinking unboiled milk of a suspect animal
D. Licks on intact skin by a dog

Explanation: ***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.

Question 199: A 15-month-old child presents with fever and cough since the last two days, the respiratory rate is 55/min and there is no drawing of the chest. According to the National Programme for Acute Respiratory Infections, the line of management should be

A. Immediate referral of the child to hospital for urgent admission
B. Administration of treatment for fever at home, advising the mother to return after two days for assessment of the need for an antibiotic
C. Referral of the child to hospital for admission, after administration of first dose of antibiotic
D. Administration of antibiotic at home along with treatment for fever, advising the mother to return for reassessment after two days (Correct Answer)

Explanation: ***Administration of antibiotic at home along with treatment for fever, advising the mother to return for reassessment after two days*** - A respiratory rate of 55/min in a 15-month-old child indicates **fast breathing**, which is a sign of pneumonia. However, the **absence of chest indrawing** means it's classified as **non-severe pneumonia**. - According to the National Programme for Acute Respiratory Infections (ARI) guidelines, **non-severe pneumonia** in children 2 months to 5 years without severe illness signs should be managed with **oral antibiotics at home** and outpatient follow-up. *Immediate referral of the child to hospital for urgent admission* - This action is indicated for **severe pneumonia** or **very severe disease**, characterized by signs such as chest indrawing, stridor, central cyanosis, or inability to drink, which are not present here. - While the child has fast breathing, the **absence of chest indrawing** suggests a less severe presentation that does not immediately warrant urgent hospital admission. *Administration of treatment for fever at home, advising the mother to return after two days for assessment of the need for an antibiotic* - This approach is inappropriate because **fast breathing** is a definitive sign of pneumonia in this age group, requiring immediate antibiotic treatment. - Delaying antibiotic administration could lead to the **progression of the infection** to a more severe form. *Referral of the child to hospital for admission, after administration of first dose of antibiotic* - Admission to the hospital is not required for **non-severe pneumonia** if the child can be managed at home and there are no signs of severe disease. - The guidelines suggest home management with oral antibiotics unless specific **danger signs** for referral are present.

Question 200: 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

A. Add one more drug, that is, to use 5 drugs until the sputum becomes negative
B. Continue the Intensive Phase of treatment with 4 drugs until the sputum becomes negative
C. Continue the Intensive Phase of treatment with 4 drugs for 1 more month only, regardless of sputum positivity after that (Correct Answer)
D. Start the continuation phase with INH and Rifampicin

Explanation: ***Continue the Intensive Phase of treatment with 4 drugs for 1 more month only, regardless of sputum positivity after that*** - In the **DOTS strategy** under earlier RNTCP guidelines, for Category I patients whose sputum remains positive after 2 months of the Intensive Phase, the recommended action was to **extend the Intensive Phase by one additional month**. - This step aimed to maximize the bactericidal effect of the four drugs (isoniazid, rifampicin, pyrazinamide, ethambutol) before transitioning to the Continuation Phase, even if sputum conversion was not achieved by the end of the third month. - **Note:** Current NTEP guidelines recommend sputum examination at 3 months, with drug susceptibility testing if positive, rather than automatic extension. *Add one more drug, that is, to use 5 drugs until the sputum becomes negative* - **Adding a fifth drug** is not the standard recommendation for a Category I patient who remains sputum positive after 2 months of the initial Intensive Phase. - This approach might be considered in cases of confirmed drug resistance after appropriate testing, which would typically involve more extensive evaluation beyond a single sputum result. *Continue the Intensive Phase of treatment with 4 drugs until the sputum becomes negative* - **Continuing the Intensive Phase indefinitely** until sputum conversion was not the standard protocol under DOTS. - Prolonged use of the intensive phase drugs beyond the specified duration can increase the risk of side effects and may not be more effective if underlying issues like drug resistance are present. *Start the continuation phase with INH and Rifampicin* - **Transitioning to the Continuation Phase** with only isoniazid (INH) and rifampicin (RMP) while sputum is still positive after 2 months of the Intensive Phase is inappropriate. - This would risk selecting for drug-resistant strains and lead to treatment failure due to insufficient bactericidal activity.

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