Infectious Diseases Practice Questions

Q: In typhoid, a person is considered a permanent carrier if they excrete bacilli for more than how many months?

1 year. **1 year** - A person is defined as a permanent carrier of typhoid if they excrete **Salmonella Typhi** in their feces or urine for **more than one year** after the acute illness. - This long-term excretion is often associated with chronic infection of the **gallbladder**, particularly in individuals with gallstones. - The definition of chronic/permanent carrier status is set at **≥12 months** of continuous bacillary excretion. *3 months* - Excreting bacilli for 3 months after acute typhoid is considered a **convalescent carrier state**, not a permanent one. - Many individuals clear the infection within this timeframe without becoming chronic carriers. *6 months* - While prolonged, 6 months of excretion still falls under the definition of a **convalescent or temporary carrier**, rather than a permanent carrier. - The threshold for "permanent" or "chronic" carrier status is typically set at 12 months. *3 years* - While a person excreting bacilli for 3 years would certainly be a permanent carrier, the established definition for permanent carrier status is met at **1 year**, not 3 years. - This option represents an unnecessarily longer duration than the standard definition.

Q: Based on the type of life cycle, zoonoses are classified into all of the following except -

Anthropozoonoses. ***Anthropozoonoses*** - This is **NOT a life cycle-based classification** of zoonoses. - It describes the **direction of transmission** (animals to humans), not the complexity or types of hosts required in the parasite's life cycle. - While a valid classification of zoonoses, it is based on **transmission pattern**, not life cycle characteristics. *Cyclo-zoonoses* - These are zoonoses that require **more than one vertebrate host species** to complete their life cycle, but **no invertebrate host** is involved. - This IS a life cycle-based classification. - Examples include **taeniasis** (tapeworm infections) where the parasite cycles between humans and livestock. *Meta-zoonoses* - These zoonoses require **both vertebrate and invertebrate hosts** to complete their life cycle. - This IS a life cycle-based classification. - The **invertebrate host** acts as an essential part of the life cycle for maturation or multiplication of the pathogen (e.g., **arboviruses** transmitted by mosquitoes, **plague** via fleas). *Sporozoonoses* - While this term is **not part of the standard WHO classification** of zoonoses by life cycle, the prefix "sporo-" refers to **spore-forming stages** in parasitic life cycles. - The standard WHO classification includes: **Orthozoonoses** (direct), **Cyclozoonoses**, **Metazoonoses**, and **Saprozoonoses** (requiring inanimate environment). - However, this term relates to life cycle characteristics (spore stages), not transmission direction.

Q: Which of the following characteristics can be used to differentiate the rash of chickenpox from the rash of smallpox?

Pleomorphic. ***Pleomorphic*** - The rash of **chickenpox** is **pleomorphic**, meaning lesions at various stages of development (macules, papules, vesicles, scabs) are present simultaneously in the same body area. - In contrast, a **smallpox** rash is **monomorphic**, with all lesions in a given area appearing at the same stage of development. *Centrifugal* - A **centrifugal distribution** (lesions more concentrated on the face and extremities) is characteristic of **smallpox**. - **Chickenpox** typically has a **centripetal distribution**, with lesions more concentrated on the trunk. *Deep-seated* - **Smallpox** lesions are described as **deep-seated** and feel like "shot under the skin," often associated with significant scarring. - **Chickenpox** lesions are superficial and less likely to cause scarring unless secondarily infected. *Multilocular* - **Smallpox** vesicles and pustules are typically **multilocular**, meaning they have internal septations and do not collapse when punctured. - **Chickenpox** vesicles are unilocular, appearing as a single compartment, and collapse when punctured.

Q: Which of the following insects has shown the least widespread development of resistance to DDT?

Tsetse flies. ***Tsetse flies*** - **Tsetse flies** have shown the least widespread development of **resistance to DDT**, likely due to their specific life cycles and limited exposure in widespread application campaigns. - This has made DDT, or its successor compounds, remain effective in certain tsetse control programs where other insects have developed high resistance. *Mosquitoes* - **Mosquitoes** have developed **widespread resistance to DDT** globally, significantly impacting malaria control efforts. - Their rapid breeding cycles and extensive exposure to DDT over decades led to the selection and proliferation of resistant strains. *Fleas* - **Fleas** have also developed **significant resistance to DDT**, especially in regions where it was heavily used for pest control in homes and livestock. - This resistance is a major factor in the continued prevalence of flea-borne diseases in certain areas. *Ticks* - **Ticks** have shown considerable development of **resistance to DDT** and other acaricides due to widespread use in livestock and agricultural settings. - Their resistance has complicated efforts to control tick-borne diseases and protect animal health.

Q: Malaria is transmitted in Rural areas by?

Anopheles culicifacies. ***Anopheles culicifacies*** - **_Anopheles culicifacies_** is the **primary vector of malaria in rural areas of India** and is also found in Southeast Asia. - Its breeding habitats often include **rice fields, irrigation channels, and temporary water collections** common in rural agricultural settings. - It accounts for a major proportion of rural malaria transmission in the Indian subcontinent. *Anopheles stephensi* - **_Anopheles stephensi_** is a significant malaria vector primarily found in **urban and semi-urban areas**, including parts of the Middle East, India, and Iran. - Its preferred breeding sites are **artificial containers found in urban environments**, such as water storage tanks, overhead tanks, and cisterns. *Anopheles dirus* - **_Anopheles dirus_** is a dominant malaria vector in **forested and hilly regions of Southeast Asia**, often associated with forest malaria. - It's known for outdoor feeding behavior and maintaining transmission in relatively undisturbed natural environments. *None of the options* - This option is incorrect because **_Anopheles culicifacies_** is a well-established and significant vector for malaria in rural areas of India. - Identification of a specific primary vector for rural transmission makes this choice invalid.

Q: Most effective preventive measure against rabies

Avoiding contact with infected animals and vaccination. ***Avoiding contact with infected animals and vaccination*** ✓ - The most effective preventive measure against rabies is to **avoid contact with potentially infected animals**, especially wild animals and unvaccinated domestic animals. - **Vaccination** (pre-exposure prophylaxis) is crucial for individuals at high risk of exposure (veterinarians, animal handlers, laboratory workers) and for domestic animals, forming the cornerstone of rabies prevention. - Post-exposure prophylaxis (PEP) with immunoglobulin and vaccine series is highly effective when administered promptly after exposure. *Heat* - While high temperatures can inactivate the rabies virus in a laboratory setting, it is **not a practical or effective preventive measure** against rabies in real-world scenarios. - The virus is transmitted through bites, scratches, and mucous membrane contact with infected saliva; environmental heat does not prevent transmission or infection. *Humidity* - **Humidity does not play a significant role** in the prevention or transmission of rabies. - The rabies virus is labile outside of a host and does not survive long in the environment, regardless of humidity levels. *None of the options* - This option is incorrect because there are highly effective preventive measures against rabies, as detailed in the correct option. - Rabies prevention is well-established through public health interventions (animal vaccination programs, post-exposure prophylaxis) and individual precautions.

Q: Which indicator best measures the operational efficiency of a malaria control programme?

Annual blood examination rate. ***Annual blood examination rate*** - The **Annual Blood Examination Rate (ABER)** directly reflects the proportion of the population that has been tested for malaria, indicating the reach and effectiveness of surveillance activities. - A high ABER suggests that active case detection and diagnosis are being effectively implemented, which is crucial for operational efficiency in identifying and managing cases. *Infant parasite rate* - The **infant parasite rate** measures the prevalence of malaria infection among infants, serving as an indicator of recent transmission intensity. - While important for assessing disease burden and transmission, it doesn't directly measure the operational effectiveness of interventions like testing or treatment programs. *Slide positivity rate* - The **slide positivity rate (SPR)** is the proportion of positive malaria slides among all slides examined, indicating the likelihood of an individual seeking testing to actually have malaria. - While SPR helps understand disease activity among tested individuals, it doesn't reflect the full operational reach of a program in the general population or the overall testing effort. *Mosquito bite rate* - The **mosquito bite rate** measures the number of mosquito bites per person per night, indicating the level of human exposure to malaria vectors. - This is an entomological indicator of transmission risk and the impact of vector control, but it does not directly assess the operational efficiency of human-centric interventions like diagnosis and treatment programs.

Q: What is the date observed as World AIDS Day?

1 December. ***Correct Answer: 1 December*** - **World AIDS Day** is observed annually on **December 1st** to raise awareness about the AIDS pandemic caused by the spread of **HIV infection** and to mourn those who have died of the disease. - This date was chosen by James W. Bunn and Thomas Netter, two public information officers for the Global Programme on AIDS at the **World Health Organization (WHO)**, in August 1987. - The first World AIDS Day was observed in **1988**. *Incorrect: 7 April* - **April 7th** is recognized as **World Health Day**, which marks the anniversary of the founding of the World Health Organization (WHO) in 1948. - This day focuses on a specific health theme each year to highlight a priority area of concern for the WHO. *Incorrect: 3 May* - **May 3rd** is celebrated as **World Press Freedom Day**, which aims to raise awareness of the importance of freedom of the press and to remind governments of their duty to respect and uphold the right to freedom of expression. - This date does not have a direct association with AIDS awareness or public health campaigns. *Incorrect: 5 June* - **June 5th** is designated as **World Environment Day**, the United Nations' principal vehicle for encouraging worldwide awareness and action for the protection of our environment. - This day is focused on environmental issues and sustainability, not specifically on HIV/AIDS.

Q: Infectivity period of chickenpox is ?

1 day before and 4 days after appearance of rash. ***1 day before and 4 days after appearance of rash*** - The infectivity period of **chickenpox (varicella)** begins approximately **1-2 days (24-48 hours) before the rash appears**. - It extends until **all lesions have crusted over**, which typically occurs around **5-6 days after rash onset**, though some sources cite **4-5 days**. - This option represents the **commonly accepted timeframe** taught in Indian medical curricula and NEET PG examinations. *4 days before and 5 days after appearance of rash* - The **pre-rash infectivity period is too long** in this option; chickenpox is infectious for only **1-2 days before rash**, not 4 days. - While the "5 days after" is medically accurate, the incorrect pre-rash duration makes this option wrong. *Only when scab falls* - This statement is **incorrect**; infectivity starts much earlier, **1-2 days before the rash appears**. - By the time scabs fall, the person is **no longer infectious**, as crusted lesions contain non-infectious material. - This option ignores the critical **pre-rash and early rash infectious period**. *Entire incubation period* - The **incubation period** for chickenpox is usually **10-21 days**, during which the individual is **not infectious** for most of this time. - Infectivity begins only in the **last 1-2 days of incubation** (just before rash onset) and continues into the eruptive phase, not for the entire duration.

Q: The international quarantine period for yellow fever as approved by the Government of India is ?

6 days. ***6 days*** - The **incubation period** for yellow fever is typically 3-6 days, and the 6-day quarantine period is internationally accepted to cover this range. - This period is established to prevent the importation and spread of the disease by ensuring that individuals arriving from endemic areas do not develop symptoms after arrival. *9 days* - This duration is **longer than the internationally recognized incubation period** for yellow fever and is not the standard quarantine period. - Implementing a 9-day quarantine would be excessive and not based on the typical disease progression. *10 days* - A 10-day quarantine period is also **not the standard** for yellow fever as approved by international health regulations or by the Government of India. - While some diseases may require a 10-day quarantine, yellow fever's incubation period makes 6 days sufficient. *12 days* - A 12-day quarantine is **significantly longer** than necessary for yellow fever, as virtually all cases would manifest symptoms within the first 6 days. - This period is typically associated with diseases with much longer incubation periods, which is not the case for yellow fever.

Question 1

In typhoid, a person is considered a permanent carrier if they excrete bacilli for more than how many months?

Accepted Answer

1 year

Answer

3 months

Answer

6 months

Answer

3 years

Question 2

Based on the type of life cycle, zoonoses are classified into all of the following except -

Accepted Answer

Anthropozoonoses

Answer

Cyclo-zoonoses

Answer

Sporozoonoses

Answer

Meta-zoonoses

Question 3

Which of the following characteristics can be used to differentiate the rash of chickenpox from the rash of smallpox?

Accepted Answer

Pleomorphic

Answer

Deep-seated

Answer

Centrifugal

Answer

Multilocular

Question 4

Which of the following insects has shown the least widespread development of resistance to DDT?

Accepted Answer

Tsetse flies

Answer

Mosquitoes

Answer

Fleas

Answer

Ticks

Question 5

Malaria is transmitted in Rural areas by?

Accepted Answer

Anopheles culicifacies

Answer

Anopheles stephensi

Answer

Anopheles dirus

Answer

None of the options

Question 6

Most effective preventive measure against rabies

Accepted Answer

Avoiding contact with infected animals and vaccination

Answer

Heat

Answer

Humidity

Answer

None of the options

Question 7

Which indicator best measures the operational efficiency of a malaria control programme?

Accepted Answer

Annual blood examination rate

Answer

Infant parasite rate

Answer

Slide positivity rate

Answer

Mosquito bite rate

Question 8

What is the date observed as World AIDS Day?

Accepted Answer

1 December

Answer

7 April

Answer

3 May

Answer

5 June

Question 9

Infectivity period of chickenpox is ?

Accepted Answer

1 day before and 4 days after appearance of rash

Answer

Only when scab falls

Answer

Entire incubation period

Answer

4 days before and 5 days after appearance of rash

Question 10

The international quarantine period for yellow fever as approved by the Government of India is ?

Accepted Answer

6 days

Answer

9 days

Answer

10 days

Answer

12 days

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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