Infectious Diseases Practice Questions

Q: Which of the following diseases is spread by mosquitoes?

Dengue. ***Dengue*** is the correct answer. - **Dengue fever** is a **mosquito-borne** viral disease transmitted primarily by **Aedes aegypti** and **Aedes albopictus** mosquitoes. - Symptoms range from mild flu-like illness to severe dengue hemorrhagic fever or dengue shock syndrome. *Listeriosis* - Caused by **Listeria monocytogenes**, transmitted through contaminated food consumption. - **Not spread by mosquitoes** but through foodborne routes or contact with infected animals. *Kala azar* - Visceral leishmaniasis caused by **Leishmania parasites**, transmitted by infected **sandflies**, not mosquitoes. - Affects internal organs including spleen, liver, and bone marrow. *Trypanosomiasis* - Includes **African sleeping sickness** (transmitted by **tsetse flies**) and **Chagas disease** (transmitted by **reduviid bugs/kissing bugs**). - Neither vector is a mosquito.

Q: Molar ratio of Sodium and Glucose in WHO ORS is:

1:1. ***1:1*** - The **WHO Low-Osmolarity ORS** (recommended since 2002) contains **75 mmol/L of both sodium and glucose**, resulting in a **1:1 molar ratio**. - This formulation is based on the principle of **sodium-glucose co-transport** across the intestinal mucosa, where glucose facilitates sodium absorption, and water follows passively. - The 1:1 ratio in the low-osmolarity formulation (total osmolarity ~245 mOsm/L) has been shown to **reduce stool output by 20%** and **decrease the need for IV therapy by 33%** compared to the older standard ORS. - This is the **current WHO and UNICEF recommendation** for managing acute diarrhea. *1:2* - This ratio is **not used in WHO ORS formulations**. - A higher glucose concentration relative to sodium would create a more **hyperosmolar solution**, potentially worsening osmotic diarrhea. - This does not represent any standard ORS formulation. *2:1* - A 2:1 ratio of sodium to glucose would provide **excessive sodium** relative to glucose. - This would result in a **hypertonic solution** that could draw water into the intestinal lumen, potentially worsening dehydration. - The sodium-glucose co-transport mechanism works optimally when both are present in **balanced proportions**. *1:4* - This ratio implies **excessive glucose** relative to sodium (4 times more glucose than sodium). - High glucose concentration would create significant **osmotic load**, potentially causing osmotic diarrhea. - The **reduced sodium content** would be insufficient for effective rehydration and electrolyte replacement in diarrheal diseases.

Q: In which of the following situations is rabies vaccination generally NOT indicated?

Rat bite. ***Rat bite*** - Rabies vaccination is generally **not indicated** for rat bites because rodents (like rats, mice, hamsters, guinea pigs) are **rarely** infected with rabies and are not known to transmit the disease to humans. - The **Centers for Disease Control and Prevention (CDC)** guidelines typically advise against post-exposure prophylaxis for rodent bites unless there's an unusual epidemiological circumstance. *Cat bite* - Cat bites are a significant concern for rabies transmission, especially if the cat is **feral**, unvaccinated, or its health status is unknown. - **Post-exposure prophylaxis** is often recommended following a cat bite, particularly if the animal cannot be observed or tested. *Monkey bite* - Monkey bites pose a risk for rabies transmission, especially in regions where rabies is **endemic** among wildlife and other animals. - Monkeys can carry and transmit the virus, and their bites often warrant **rabies prophylaxis**. *Dog bite* - Dog bites are a common reason for rabies vaccination, particularly in areas where rabies is **prevalent** among dog populations. - If the dog is **unvaccinated**, strays, or its vaccination status is unknown, **post-exposure prophylaxis** is usually indicated.

Q: Disinfection of urine is which type of disinfection ?

Concurrent. ***Concurrent*** - **Concurrent disinfection** refers to the immediate disinfection of infectious materials and objects **as soon as they are discharged** from the body of an infected person. - Disinfection of **body excretions** (urine, feces, sputum) and articles contaminated by them is done **promptly after they are voided**, making it concurrent disinfection. - In the context of urine from infected patients, it should be disinfected **immediately after collection** to prevent spread of infection. *Terminal* - **Terminal disinfection** is performed **after the patient has been discharged, died, or is no longer infectious**. - It involves thorough cleaning and disinfection of the **room, furniture, and environment** that the patient occupied. - Terminal disinfection is not the routine disinfection of body excretions, but rather the final cleaning of the patient's surroundings. *Preconcurrent* - **"Preconcurrent"** is not a standard or recognized term in the classification of disinfection types. - This option does not describe a method or timing of disinfection that is medically or scientifically established. *Precurrent* - Similar to "preconcurrent," **"precurrent"** is not a recognized category or term used to describe a type of disinfection process. - The standard classifications include **concurrent, terminal, and prophylactic disinfection**.

Q: Most sensitive index of transmission in leprosy is -

Incidence. ***Incidence*** - **Incidence rate** measures the number of **new cases** of a disease in a population over a specific period, directly reflecting the rate of disease transmission. - A higher incidence suggests more active transmission of *Mycobacterium leprae* within the community. *Disability rate* - The **disability rate** reflects the long-term consequences and severity of the disease, not its current transmission dynamics. - It indicates the burden of disease over time, but not the rate at which new infections are occurring. *Prevalence* - **Prevalence** measures the total number of **existing cases** (new and old) in a population at a given time or over a period. - While it shows the overall burden, it doesn't specifically indicate the rate of new infections or recent transmission. *Detection rate* - The **detection rate** refers to the number of cases diagnosed, which is influenced by surveillance and healthcare access. - It can be an indicator of case finding efforts rather than the true transmission rate, as undetected cases are not accounted for.

Q: Most important disease transmitted by louse -?

Epidemic typhus. ***Epidemic typhus*** - **Epidemic typhus** is caused by **Rickettsia prowazekii** and is primarily transmitted by the **human body louse** (*Pediculus humanus corporis*). - It is one of the most significant louse-borne diseases, causing severe illness and high mortality in conditions of overcrowding and poor hygiene. *Q fever* - **Q fever** is caused by **Coxiella burnetii** and is primarily transmitted through inhalation of aerosols from infected animals, such as livestock. - It is **not transmitted by lice**; rather, it is an occupational hazard for individuals working with animals. *Trench fever* - **Trench fever** is caused by **Bartonella quintana** and is transmitted by the **human body louse**. - While louse-borne, it is generally considered less severe and fatal than epidemic typhus, though it was a significant problem during the world wars. *Scrub Typhus* - **Scrub typhus** is caused by **Orientia tsutsugamushi** and is transmitted by the bites of infected **chigger mites (larval trombiculid mites)**. - It is **not transmitted by lice**, and its geographical distribution and vector are distinct from louse-borne illnesses.

Q: In which of the following conditions is man the mammalian reservoir?

Epidemic typhus. **Epidemic typhus** - In **epidemic typhus**, caused by *Rickettsia prowazekii*, humans are the primary reservoir for the pathogen. - The **human body louse** (*Pediculus humanus corporis*) acts as the vector, transmitting the infection from one human to another. *Endemic typhus* - **Endemic typhus**, caused by *Rickettsia typhi*, primarily has **rodents** (like rats) as its mammalian reservoir. - The disease is transmitted to humans through the **flea** (*Xenopsylla cheopis*). *Scrub typhus* - **Scrub typhus**, caused by *Orientia tsutsugamushi*, has **rodents** (e.g., wild rats and mice) as its reservoir. - It is transmitted to humans by the bite of infected **larval trombiculid mites** (chiggers). *Rickettsial pox* - **Rickettsial pox**, caused by *Rickettsia akari*, maintains a reservoir primarily in **mice**. - The infection is transmitted to humans through the bite of the **mouse mite** (*Liponyssoides sanguineus*).

Q: Standard dose of rifampicin for adults (≥50 kg) in RNTCP is -

600 mg. ***600 mg*** - For adults weighing **50 kg or more**, the standard daily dose of **rifampicin** under the **Revised National Tuberculosis Control Programme (RNTCP)** is 600 mg. - This dosage is crucial for achieving optimal therapeutic concentrations and ensuring effective treatment of **tuberculosis**. *300 mg* - This is **not a standard RNTCP dose** for any specific weight category in adults. - Administering only 300 mg to an adult weighing ≥50 kg would be a significant **underdose**, leading to treatment failure and potential drug resistance. *100 mg* - 100 mg is a significantly **subtherapeutic dose** for rifampicin in adults, regardless of weight. - Such a low dose would be entirely ineffective in treating tuberculosis and would promote the development of **drug-resistant strains**. *450 mg* - While 450 mg is the correct dose for patients in the **30-49 kg weight band** under RNTCP, it is not the standard dose for individuals weighing 50 kg or more. - Using 450 mg for a patient ≥50 kg would result in **under-dosing**, compromising treatment efficacy.

Question 1

Which of the following diseases is spread by mosquitoes?

Accepted Answer

Dengue

Answer

Listeriosis

Answer

Kala azar

Answer

Trypanosomiasis

Question 2

Molar ratio of Sodium and Glucose in WHO ORS is:

Accepted Answer

1:1

Answer

1:2

Answer

2:1

Answer

1:4

Question 3

In which of the following situations is rabies vaccination generally NOT indicated?

Accepted Answer

Rat bite

Answer

Cat bite

Answer

Monkey bite

Answer

Dog bite

Question 4

Transmission assessment survey (TAS) is done for which of the following purposes?

Accepted Answer

To determine when infections have been reduced below target transmission thresholds

Answer

To provide reliable estimates of birth rate, death rate and infant mortality rate

Answer

For assessing primary immunization coverage

Answer

All of the options

Question 5

Disinfection of urine is which type of disinfection ?

Accepted Answer

Concurrent

Answer

Terminal

Answer

Preconcurrent

Answer

Precurrent

Question 6

Most sensitive index of transmission in leprosy is -

Accepted Answer

Incidence

Answer

Disability rate

Answer

Prevalence

Answer

Detection rate

Question 7

Which statement is FALSE about '100 Day Cough'?

Accepted Answer

Incidence and fatality are more common in males than females.

Answer

Incubation period is 7-14 days.

Answer

Erythromycin is the drug of choice.

Answer

There is no subclinical or chronic carrier state.

Question 8

Most important disease transmitted by louse -?

Accepted Answer

Epidemic typhus

Answer

Q fever

Answer

Trench fever

Answer

Scrub Typhus

Question 9

In which of the following conditions is man the mammalian reservoir?

Accepted Answer

Epidemic typhus

Answer

Endemic typhus

Answer

Scrub typhus

Answer

Rickettsial pox

Question 10

Standard dose of rifampicin for adults (≥50 kg) in RNTCP is -

Accepted Answer

600 mg

Answer

300 mg

Answer

100 mg

Answer

450 mg

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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