Infectious Diseases Practice Questions

Q: Chemoprophylaxis can be done for the following except:

Typhoid fever. ***Typhoid fever*** - **Typhoid fever** is primarily controlled through **vaccination** (Vi polysaccharide vaccine, Ty21a oral vaccine) and **improved sanitation** (safe water supply, proper sewage disposal). - **Chemoprophylaxis is NOT routinely recommended** for typhoid fever, even for travelers to endemic areas. Vaccination and food/water precautions are the mainstay of prevention. - Unlike other diseases requiring post-exposure prophylaxis, typhoid contacts are monitored rather than given prophylactic antibiotics. *Meningococcal meningitis* - **Chemoprophylaxis is essential** for close contacts of meningococcal disease cases. - **Rifampicin, ciprofloxacin, or ceftriaxone** are given to household contacts, healthcare workers exposed to respiratory secretions, and other close contacts. - This prevents secondary cases and interrupts transmission in high-risk individuals. *Cholera* - During cholera outbreaks, **chemoprophylaxis with doxycycline or azithromycin** may be used for household contacts and high-risk groups. - This is a **targeted intervention** during acute public health emergencies to prevent rapid spread. - Not routine, but justified in outbreak settings when transmission risk is high. *Influenza* - **Chemoprophylaxis with oseltamivir or zanamivir** is recommended for high-risk unvaccinated individuals exposed to confirmed influenza cases. - Used in institutional outbreaks, for immunocompromised patients, and during the window period before vaccine takes effect. - Particularly important when circulating strain doesn't match vaccine or vaccine is contraindicated.

Q: Animal to man transmission (zoonosis) is seen in -

Rabies. ***Rabies*** - **Rabies** is a classic zoonotic disease, primarily transmitted to humans through the bite or scratch of an infected animal, most commonly **dogs, bats, or other wild carnivores**. - The virus travels from the site of infection to the central nervous system, leading to characteristic neurological symptoms. *Tuberculosis* - While certain strains of **Mycobacterium bovis** can cause zoonotic tuberculosis, the question implies common human tuberculosis (**Mycobacterium tuberculosis**), which is primarily transmitted person-to-person via airborne droplets. - While bovine TB is zoonotic, general "Tuberculosis" in this context usually refers to the human-to-human transmitted form. *Measles* - **Measles** is a highly contagious disease caused by the **measles virus**, which is a **human paramyxovirus**. - It is spread exclusively from **person to person** through respiratory droplets and has no known animal reservoir. *HIV* - **HIV (Human Immunodeficiency Virus)** is thought to have originated from **simian immunodeficiency virus (SIV)** in non-human primates, thus representing a historic zoonotic jump. - However, current and continued transmission of HIV is almost exclusively through **human-to-human contact**, not ongoing animal-to-human transmission.

Q: Elimination of leprosy is defined as prevalence rate of:

< 1 per 10000. ***< 1 per 10,000*** - The World Health Organization (WHO) defines **elimination of leprosy as a public health problem** as achieving a prevalence rate of **less than 1 case per 10,000 population** at the national level. - This target was set to highlight significant progress in disease control and public health efforts. - India achieved this milestone in December 2005. *< 1 per 1 lakh (100,000)* - This rate is significantly lower than the internationally accepted threshold for leprosy elimination and is not the standard definition. - A prevalence rate of less than 1 per 100,000 population indicates a level beyond elimination, often nearing eradication. *< 1 per 100* - A prevalence rate of less than 1 per 100 population (1%) is still a high prevalence and does not constitute elimination of leprosy. - This level would indicate a substantial burden of disease within the population. *< 1 per 1,000* - While a reduction from higher prevalence, a rate of less than 1 per 1,000 population is not the defined threshold for leprosy elimination. - This rate still suggests an ongoing public health concern that has not met the global elimination target.

Q: According to WHO, leprosy is considered a major public health problem when the prevalence is:

0.01%. ***0.01% or more (≥ 1 case per 10,000 population)*** - The World Health Organization (WHO) defines **elimination of leprosy as a public health problem** when prevalence falls **below 1 case per 10,000 population** (< 0.01%). - Conversely, leprosy **remains a public health problem** when prevalence is **≥ 1 case per 10,000 population** (≥ 0.01%). - This threshold is used for global monitoring to assess disease control and elimination targets. *1%* - A prevalence of 1% (100 cases per 10,000 population) would indicate a **severe hyperendemic** situation, far exceeding the WHO threshold. - This represents **uncontrolled transmission** and would be seen in areas with no leprosy control programs. *0.50%* - A prevalence of 0.50% (50 cases per 10,000 population) is significantly high, indicating a **major endemic burden**. - This is **50 times higher** than the WHO elimination threshold and represents poor disease control. *0.10%* - A prevalence of 0.10% (10 cases per 10,000 population) is **10 times higher** than the WHO threshold. - While indicating substantial burden requiring intervention, it is not the specific WHO-defined threshold for public health problem status.

Q: World Malaria Day is observed in which month?

April. ***April*** - **World Malaria Day** is observed annually on **April 25th**. - Its purpose is to raise awareness about malaria and celebrate the efforts made globally to control and eradicate this disease. *September* - While September hosts various health observances, it is not the month for **World Malaria Day**. - Other public health campaigns, such as **World Alzheimer's Month**, are observed in September. *May* - May is recognized for several health-related days, but not specifically for **World Malaria Day**. - For example, **World Hypertension Day** is observed in May. *June* - June includes observances like **World Blood Donor Day**, but it is not the month designated for **World Malaria Day**. - Public health calendars indicate April 25th for this specific event.

Q: White death is

TB. ***TB*** - **Tuberculosis (TB)**, particularly the pulmonary form, has historically been known as the **"White Death"** due to the characteristic pallor, weight loss, and widespread prevalence it caused, leading to death. - This term reflects the devastating impact of the disease, which left victims looking pale and wasted due to chronic illness and cachexia. *Plague* - The **Plague** is famously known as the **"Black Death"** due to the development of **gangrene** and **hemorrhages** that turned the skin black. - It is caused by the bacterium *Yersinia pestis* and is characterized by rapidly progressing, severe symptoms, often in the form of bubonic, pneumonic, or septicemic plague. *Yellow fever* - **Yellow fever** is named for the **jaundice (yellowing of the skin and eyes)** that affects some patients due to liver damage. - It is a viral hemorrhagic disease transmitted by mosquitoes and is not associated with the term "White Death." *HIV* - **HIV (Human Immunodeficiency Virus)** infection leads to **AIDS (Acquired Immunodeficiency Syndrome)**, which was historically known as the **"slim disease"** due to the severe weight loss and wasting it caused, but not specifically the "White Death." - HIV primarily targets the immune system, leading to opportunistic infections and cancers, rather than the pallor associated with chronic lung disease.

Q: The following statements are true regarding leptospirosis, except -

Lice act as reservoirs of infection. ***Lice act as reservoirs of infection*** - **Lice** are not known reservoirs or vectors for leptospirosis; the infection is primarily spread through the urine of infected animals. - The main reservoirs are **rodents**, **livestock**, and **wild animals**, which excrete bacteria in their urine. *It is zoonosis* - **Leptospirosis** is indeed a **zoonotic disease**, meaning it is transmitted from animals to humans. - Humans typically acquire the infection through contact with the urine of infected animals or contaminated water/soil. *Man is the dead end host* - Humans are considered **dead-end hosts** for leptospirosis, meaning they typically do not transmit the infection to others. - While humans can become severely ill, their role in maintaining the natural cycle of the disease is minimal. *Man is an accidental host* - Humans are also considered an **accidental host**, as they contract the disease incidentally from the environment rather than being a natural part of the pathogen's life cycle. - The primary cycle of transmission occurs between infected animals and the environment.

Q: All of the following statements about tetanus are true except:

Uterine tetanus is the least severe.. ***Uterine tetanus is the least severe.*** - Uterine tetanus (or **puerperal tetanus**) is actually a severe form of tetanus, often leading to high morbidity and mortality in mothers and neonates due to complications associated with childbirth. - The severity of tetanus is generally related to the **amount of toxin produced** and disseminated, and uterine infections can lead to significant toxin production due to anaerobic conditions. *Soil and intestines of infected humans and animals act as chief reservoirs.* - **Clostridium tetani** spores are widely distributed in the environment, especially in **soil contaminated with feces** from humans and animals. This makes soil a primary reservoir. - The gastrointestinal tracts of humans and animals can harbor the bacterium without causing disease, thus serving as an additional reservoir. *Incubation period is 6-12 days.* - The typical incubation period for tetanus is generally reported to be **3 to 21 days**, with a common range of **6 to 12 days**. - A shorter incubation period is often associated with more severe disease and a worse prognosis due to greater toxin load or closer proximity to the central nervous system. *Tetanospasmin is the neurotoxin responsible for clinical manifestations* - **Tetanospasmin** is indeed the potent neurotoxin produced by *Clostridium tetani* that is responsible for all the clinical manifestations of tetanus. - This toxin acts by blocking the release of **inhibitory neurotransmitters** (glycine and GABA) in the spinal cord, leading to uncontrolled muscle spasms and rigidity.

Q: The most practical way of treating typhoid carrier is -

Cholecystectomy. ***Correct Option: Cholecystectomy*** - **Cholecystectomy** (surgical removal of the gallbladder) is the **most practical and definitive treatment** for chronic typhoid carriers - Chronic carriers harbor *Salmonella typhi* in the **gallbladder**, especially when **gallstones** are present, where bacteria form biofilms - **Success rate >90%** in eliminating the carrier state permanently - Particularly important for **food handlers** and healthcare workers where definitive cure is essential - While surgical, it provides a **permanent solution** unlike antibiotics which have high failure/relapse rates *Incorrect Option: Chemotherapy* - Antibiotic therapy alone has a **poor success rate** (~80% failure) in chronic typhoid carriers - Bacteria in the gallbladder are protected by **biofilms** on gallstones and poor antibiotic penetration - High **relapse rates** even after prolonged courses of ciprofloxacin or ampicillin - May be attempted first but is not the most practical definitive treatment *Incorrect Option: Isolation* - **Isolation** is a public health measure to prevent transmission, not a treatment - Does not eliminate the bacteria from the carrier's body - Only controls spread to others, not a therapeutic intervention *Incorrect Option: Vaccination* - Provides **prophylactic immunity** against future infection but does not treat existing carrier state - Does not eliminate *Salmonella typhi* bacteria already colonizing the gallbladder - Used for prevention, not treatment of carriers

Q: All of the following statements about plague are wrong except -

Bubonic is the most common variety. ***Bubonic is the most common variety*** - **Bubonic plague** is indeed the most frequent clinical form of plague, accounting for 80-95% of cases. - It results from the bite of an infected flea, leading to the development of **buboes** (swollen, tender lymph nodes). *Incubation period for pneumonic plague is 10-14 days* - The incubation period for **pneumonic plague** is typically much shorter, usually 1 to 3 days, not 10-14 days. - A longer incubation period would be atypical for such an aggressive and rapidly progressing disease. *The causative bacillus can survive up to 10 years in the soil of rodent burrows* - While *Yersinia pestis* can survive in the environment, its survival in soil is typically for days to weeks, not years. - The primary survival mechanism is within infected animals and fleas, not as dormant free-living bacteria for a prolonged period in soil. *Domestic rat is main reservoir* - While domestic rats (Rattus species) can be involved in urban plague cycles, the main reservoirs of *Yersinia pestis* are wild rodents such as **ground squirrels, marmots, and prairie dogs**. - These wild rodents maintain the enzootic cycle in nature, and fleas often transmit the bacteria between them.

Question 1

Chemoprophylaxis can be done for the following except:

Accepted Answer

Typhoid fever

Answer

Meningococcal meningitis

Answer

Cholera

Answer

Influenza

Question 2

Animal to man transmission (zoonosis) is seen in -

Accepted Answer

Rabies

Answer

Tuberculosis

Answer

Measles

Answer

HIV

Question 3

Elimination of leprosy is defined as prevalence rate of:

Accepted Answer

< 1 per 10000

Answer

< 1 per 1 lakh

Answer

< 1 per 100

Answer

< 1 per 1000

Question 4

According to WHO, leprosy is considered a major public health problem when the prevalence is:

Accepted Answer

0.01%

Answer

1%

Answer

0.50%

Answer

0.10%

Question 5

World Malaria Day is observed in which month?

Accepted Answer

April

Answer

September

Answer

May

Answer

June

Question 6

White death is

Accepted Answer

TB

Answer

Plague

Answer

Yellow fever

Answer

HIV

Question 7

The following statements are true regarding leptospirosis, except -

Accepted Answer

Lice act as reservoirs of infection

Answer

It is zoonosis

Answer

Man is the dead end host

Answer

Man is an accidental host

Question 8

All of the following statements about tetanus are true except:

Accepted Answer

Uterine tetanus is the least severe.

Answer

Soil and intestines of infected humans and animals act as chief reservoirs.

Answer

Incubation period is 6-12 days.

Answer

Tetanospasmin is the neurotoxin responsible for clinical manifestations

Question 9

The most practical way of treating typhoid carrier is -

Accepted Answer

Cholecystectomy

Answer

Chemotherapy

Answer

Vaccination

Answer

Isolation

Question 10

All of the following statements about plague are wrong except -

Accepted Answer

Bubonic is the most common variety

Answer

Incubation period for pneumonic plague is 10-14 days

Answer

The causative bacillus can survive up to 10 years in the soil of rodent burrows

Answer

Domestic rat is main reservoir

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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