Infectious Diseases Practice Questions

Q: In which condition is a night blood survey performed?

Lymphatic filariasis. ***Lymphatic filariasis*** - A **night blood survey** is crucial for diagnosing lymphatic filariasis because the microfilariae of species like *Wuchereria bancrofti* and *Brugia malayi* exhibit **nocturnal periodicity**, meaning they are most abundant in peripheral blood between 10 PM and 2 AM. - Collecting blood at night maximizes the chance of detecting these parasites, which are responsible for the disease. *Typhoid fever* - Diagnosis of **typhoid fever** primarily relies on **blood cultures** taken during the febrile phase, or stool/urine cultures later in the disease. - A night blood survey is not relevant for detecting the causative bacterium, *Salmonella Typhi*. *Malaria infection* - While a **blood smear** is essential for diagnosing malaria, the timing of blood collection is less critical than for filariasis, although peak parasite density can vary. - **Malaria parasites** are typically detected in blood samples taken during symptomatic periods, regardless of specific time of day. *Visceral leishmaniasis* - **Visceral leishmaniasis** is diagnosed by detecting parasites in samples from **bone marrow**, spleen, or lymph nodes, or through serological tests for antibodies. - A night blood survey is not used in the diagnosis of *Leishmania donovani* infection.

Q: Which of the following diseases is NOT transmitted by sandflies?

Relapsing fever. ***Relapsing fever*** - **Relapsing fever** is primarily transmitted by **ticks** (tick-borne relapsing fever) or **lice** (louse-borne relapsing fever), not sandflies. - It is caused by **spirochetes** of the genus *Borrelia*, which are distinct from the *Leishmania* parasites transmitted by sandflies. *Cutaneous Leishmaniasis* - **Cutaneous leishmaniasis** is a **sandfly-borne disease** caused by *Leishmania* parasites, leading to skin sores. - Sandflies (genus **Phlebotomus** in the Old World and **Lutzomyia** in the New World) transmit these parasites. *Visceral Leishmaniasis* - **Visceral leishmaniasis**, also known as **kala-azar**, is a severe form of leishmaniasis transmitted by the bite of **infected female sandflies**. - It affects internal organs like the **spleen**, **liver**, and **bone marrow**. *Oriental sore* - **Oriental sore** is another name for **cutaneous leishmaniasis**, indicating that it is also transmitted by **sandflies**. - It refers to the characteristic **skin lesions** caused by *Leishmania* parasites following a sandfly bite.

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 diseases is classified under category-B of bioterrorism?

Cholera. ***Cholera*** - **Cholera** is classified under **Category B** agents due to its moderate ease of dissemination, moderate morbidity rates, and low mortality rates. - While it can cause severe diarrheal disease, its treatment is relatively straightforward with **rehydration therapy**, and it poses a lower risk of mass casualties compared to Category A agents. *Anthrax* - **Anthrax** is a **Category A** bioterrorism agent, characterized by its high mortality rate, ease of dissemination, and potential for major public health impact. - It poses a significant threat due to its ability to form **spores** that are highly resistant and can cause severe lung infection. *Plague* - **Plague** is designated as a **Category A** agent because of its high potential for mass dissemination, high mortality if untreated, and potential to cause widespread panic. - It can be spread via **aerosols** and can lead to severe systemic illness. *Botulism* - **Botulism** is classified as a **Category A** agent due to the extreme potency of the **botulinum toxin**, even in minute quantities, which can cause severe flaccid paralysis and death. - It has a high potential for causing severe public health impact and requires complex medical interventions.

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.

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: What is the recommended concentration of diethylcarbamazine in DEC medicated salt for the treatment of endemic filariasis?

0.1-0.2 gm/kg. ***0.1-0.2 gm/kg*** - The recommended concentration of **diethylcarbamazine (DEC)** in medicated salt for the treatment of endemic filariasis is typically 0.1-0.2 gm/kg of salt. - This low, sustained dose helps to gradually eliminate microfilariae and prevent transmission without causing severe adverse reactions. *0.5-1.0 gm/kg* - This concentration is significantly higher than the standard recommendation for mass drug administration using DEC medicated salt. - Such a higher dose would increase the risk of adverse drug reactions, making it unsuitable for community-wide use. *2-4 gm/kg* - This concentration is far too high for safe and effective use in DEC medicated salt programs. - Administering DEC at this level would likely lead to widespread and potentially severe side effects among the treated population. *5-10 gm/kg* - Concentrations in this range are excessively high and would be toxic if used in medicated salt for filariasis treatment. - This would result in widespread and severe adverse events, making it an unacceptable option.

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: 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: 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.

Question 1

In which condition is a night blood survey performed?

Accepted Answer

Lymphatic filariasis

Answer

Typhoid fever

Answer

Malaria infection

Answer

Visceral leishmaniasis

Question 2

Which of the following diseases is NOT transmitted by sandflies?

Accepted Answer

Relapsing fever

Answer

Visceral Leishmaniasis

Answer

Oriental sore

Answer

Cutaneous Leishmaniasis

Question 3

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 4

Which of the following diseases is classified under category-B of bioterrorism?

Accepted Answer

Cholera

Answer

Anthrax

Answer

Plague

Answer

Botulism

Question 5

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

Question 6

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 7

What is the recommended concentration of diethylcarbamazine in DEC medicated salt for the treatment of endemic filariasis?

Accepted Answer

0.1-0.2 gm/kg

Answer

5-10 gm/kg

Answer

0.5-1.0 gm/kg

Answer

2-4 gm/kg

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

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 10

Most effective preventive measure against rabies

Accepted Answer

Avoiding contact with infected animals and vaccination

Answer

Heat

Answer

Humidity

Answer

None of the options

Infectious Diseases — MCQs

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