Emerging Zoonotic Diseases — MCQs
KFD is transmitted by:
Which one of the following is an emerging viral disease?
Which of the following diseases has the largest submerged portion in the iceberg model of disease?
Zoonotic diseases are all except -
A district reports increasing syphilis cases despite standard interventions. Which program response is most appropriate?
Six days after receiving several flea bites in a rat-infested shed, a homeless 24-year-old man develops fever, chills, and a rash that spreads from his abdomen to cover his extremities. He is seen at the hospital emergency department, where blood is drawn for analysis. Eight days later, the public health department reports the presence of antibody to one of the rickettsial group antigens. Which of the following is the most likely diagnosis?
Which of the following is known as monkey fever?
Following are examples of human "dead end" diseases except -
A militant presents with rashes all over his body sparing the palms and soles. On examination, he was febrile and lice were noted. Which of the following is responsible for his condition?
The following electron microscope image shows presence of:
Emerging Zoonotic Diseases Indian Medical PG Practice Questions and MCQs
Question 1: KFD is transmitted by:
- A. Sandfly
- B. Mosquito
- C. Tick (Correct Answer)
- D. Mite
Explanation: ***Tick*** - KFD, or **Kyasanur Forest Disease**, is a viral hemorrhagic fever endemic to India that is primarily transmitted by infected **ticks**, specifically *Haemaphysalis spinigera*. - Humans can contract the disease through a **tick bite** or contact with an **infected animal**, such as monkeys, which are reservoirs for the virus. *Sandfly* - **Sandflies** are vectors for diseases such as **leishmaniasis** and **bartonellosis**, not Kyasanur Forest Disease. - These insects transmit parasites or bacteria, whereas KFD is a **viral infection** transmitted by ticks. *Mosquito* - **Mosquitoes** are common vectors for many viral diseases, including **dengue**, **malaria**, and **chikungunya**, but they do not transmit Kyasanur Forest Disease. - KFD is exclusively associated with **tick transmission** in its endemic regions. *Mite* - **Mites** can transmit diseases like **scrub typhus** (via chiggers) or cause conditions like **scabies**, but they are not vectors for Kyasanur Forest Disease. - The primary vector for KFD is the **hard tick**.
Question 2: Which one of the following is an emerging viral disease?
- A. SARS (Correct Answer)
- B. Measles
- C. Chicken pox
- D. Rabies
Explanation: ***SARS*** - **SARS (Severe Acute Respiratory Syndrome)** emerged in 2002-2003 and caused a global outbreak, making it a classic example of an **emerging viral disease**. - Emerging viral diseases are those that have recently appeared in a population or whose incidence has increased rapidly in recent times. *Measles* - Measles is an **established and re-emerging disease**, meaning it has been present for a long time but has seen resurgence due to factors like declining vaccination rates. - It is caused by the **measles virus (MeV)**, a paramyxovirus, and has been a known human pathogen for centuries. *Chicken pox* - Chickenpox, caused by the **varicella-zoster virus (VZV)**, is a common and well-known childhood disease that has been endemic for a long time. - While it can be severe, it is not considered an emerging disease as its presence and characteristics have been established for many years. *Rabies* - Rabies, caused by the **rabies virus**, is a highly fatal disease primarily transmitted through animal bites and has been recognized globally for centuries. - Although it remains a significant public health concern, it is an **ancient and well-established zoonotic disease**, not an emerging one.
Question 3: Which of the following diseases has the largest submerged portion in the iceberg model of disease?
- A. Influenza (Correct Answer)
- B. Chickenpox
- C. Tetanus
- D. Rabies
Explanation: **The Iceberg Model of Disease** represents the concept that for many diseases, only a small portion of cases (the "tip" above water) are clinically apparent and reported, while a much larger portion (the "submerged" part) consists of asymptomatic, subclinical, or undiagnosed cases. ***Influenza*** - Has the **largest submerged portion** among the given options, with **50-75% of infections being asymptomatic or mild** and going undiagnosed - High transmissibility and varied clinical presentation contribute to significant hidden burden - Only severe cases requiring hospitalization typically get reported, representing just the "tip of the iceberg" - Classic example of diseases with large subclinical-to-clinical ratio *Chickenpox* - Most cases are **clinically apparent** with characteristic vesicular rash - Asymptomatic infections are rare due to distinctive clinical features - High visibility of cases reduces the submerged portion significantly *Tetanus* - **Severe, acute neurological condition** with distinct clinical manifestations (trismus, risus sardonicus, opisthotonus) - Almost all cases are diagnosed due to dramatic presentation - Virtually no submerged portion - what exists clinically is recognized *Rabies* - **Nearly uniformly fatal** once symptoms appear, making all symptomatic cases clinically evident - No asymptomatic or mild phase after symptom onset - Minimal to no submerged portion in the iceberg model
Question 4: Zoonotic diseases are all except -
- A. Q fever
- B. Typhoid (Correct Answer)
- C. Anthrax
- D. Rabies
Explanation: ***Typhoid*** - Typhoid fever is a **bacterial infection** caused by *Salmonella Typhi*, which is spread through contaminated food and water, primarily from human waste. - It is an exclusively **human disease**, meaning there is no animal reservoir involved in its transmission to humans. *Q fever* - Q fever is a **zoonotic disease** caused by the bacterium *Coxiella burnetii*, primarily spread from livestock (cattle, sheep, goats) to humans. - Transmission generally occurs through inhalation of contaminated aerosols from animal excreta or birth products. *Anthrax* - Anthrax is a serious **zoonotic disease** caused by the bacterium *Bacillus anthracis*, which can affect both animals and humans. - Humans usually contract anthrax through contact with infected animals or contaminated animal products. *Rabies* - Rabies is a fatal **viral zoonotic disease** that is transmitted to humans through the saliva of infected animals, most commonly from dog bites. - Wild animals like bats, raccoons, and foxes are important reservoirs for the rabies virus.
Question 5: A district reports increasing syphilis cases despite standard interventions. Which program response is most appropriate?
- A. Mass treatment campaign
- B. Enhanced surveillance with targeted outreach and screening (Correct Answer)
- C. Increasing clinic hours only
- D. Public awareness campaign only
Explanation: ***Enhanced surveillance with targeted outreach and screening*** - This approach specifically addresses the rise in cases by actively finding and treating infected individuals and their contacts, which is crucial for **controlling outbreaks** of sexually transmitted infections like **syphilis**. - **Targeted outreach** ensures high-risk populations are reached, and **enhanced surveillance** allows for better understanding of transmission patterns to guide interventions. *Mass treatment campaign* - **Mass treatment** campaigns are generally reserved for diseases with high prevalence and potential for rapid spread in a community, and are typically not the first response for **syphilis**, which often requires individual diagnosis and partner notification. - While it might reduce prevalence, it doesn't address ongoing transmission dynamics or identify specific **risk factors** at an individual level. *Increasing clinic hours only* - While increased clinic access is beneficial, it is a passive approach that does not actively identify cases or reach individuals who may not seek care, especially those who are **asymptomatic** or face barriers to accessing healthcare. - It might improve access for those already motivated to seek care but won't effectively address an increasing trend in cases by itself. *Public awareness campaign only* - A public awareness campaign can improve knowledge but does not directly lead to diagnosis and treatment, which are essential for controlling an active increase in syphilis cases. - It's a supportive measure but insufficient as a primary response to an **epidemic trend** without accompanying diagnostic and therapeutic services.
Question 6: Six days after receiving several flea bites in a rat-infested shed, a homeless 24-year-old man develops fever, chills, and a rash that spreads from his abdomen to cover his extremities. He is seen at the hospital emergency department, where blood is drawn for analysis. Eight days later, the public health department reports the presence of antibody to one of the rickettsial group antigens. Which of the following is the most likely diagnosis?
- A. Epidemic typhus
- B. Endemic typhus (Correct Answer)
- C. Q fever
- D. Rocky Mountain spotted fever
Explanation: ***Endemic typhus*** - The patient's history of exposure to a rat-infested shed and flea bites, followed by fever, chills, and a rash spreading from the abdomen to the extremities [1], is highly consistent with **endemic (murine) typhus** [1]. - **Endemic typhus** is caused by *Rickettsia typhi* and is transmitted by the **flea vector** with rats as the reservoir [1]. *Epidemic typhus* - **Epidemic typhus** is caused by *Rickettsia prowazekii* and is transmitted by the **human body louse**, typically in conditions of overcrowding and poor hygiene. - While it shares similar symptoms, the **flea bite** and **rat exposure** in this case point away from epidemic typhus. *Q fever* - **Q fever** is caused by *Coxiella burnetii* and is typically acquired through inhalation of **contaminated aerosols** from infected livestock (cattle, sheep, goats). - Symptoms usually include fever, headache, and flu-like illness, but a **rash is uncommon**, and the transmission vector (flea) is inconsistent with the patient's presentation. *Rocky Mountain spotted fever* - **Rocky Mountain spotted fever (RMSF)** is caused by *Rickettsia rickettsii* and is transmitted by **tick bites**. - The rash of RMSF typically starts on the **ankles and wrists** and spreads centrally, often involving the palms and soles, which differs from the described abdominal onset and flea vector.
Question 7: Which of the following is known as monkey fever?
- A. Plague
- B. Trench fever
- C. Yellow fever
- D. KFD (Correct Answer)
Explanation: ***KFD*** - **Kyasanur Forest Disease (KFD)** is also known as "monkey fever" due to its primary hosts and the observed mortality in monkeys before human outbreaks. - It is a **viral hemorrhagic fever** endemic to certain parts of India, transmitted by **ticks** (primarily *Haemaphysalis spinigera*). *Plague* - **Plague** is a bacterial infection caused by *Yersinia pestis*, primarily transmitted by **fleas** from rodents to humans. - While it can cause severe systemic illness, it is not colloquially known as "monkey fever." *Trench fever* - **Trench fever** is caused by the bacterium *Bartonella quintana* and is transmitted by **body lice**. - It is characterized by recurrent fevers, headaches, and often shin pain, and is not associated with monkeys or called "monkey fever." *Yellow fever* - **Yellow fever** is a viral hemorrhagic disease transmitted by mosquitoes, primarily *Aedes* and *Haemagogus* species. - While it can affect primates, its common name refers to the **jaundice** seen in some patients, not specifically "monkey fever."
Question 8: Following are examples of human "dead end" diseases except -
- A. Hydatid disease
- B. Japanese encephalitis
- C. Leishmaniasis
- D. Bubonic plague (Correct Answer)
Explanation: ***Bubonic plague (Plague)*** - The question refers to **plague in general**, which includes multiple clinical forms. - While **bubonic plague** (the most common form) is transmitted via **flea bites** from infected rodents and humans are typically dead-end hosts for this form, **pneumonic plague** (secondary complication or primary infection) allows **human-to-human transmission** via respiratory droplets. - This makes plague the **exception** among the listed diseases, as humans can serve as a source of infection to others in the pneumonic form, unlike true dead-end host situations. *Japanese encephalitis* - Humans are **dead-end hosts** for Japanese encephalitis virus. - Infected humans do not develop sufficient **viremia** to infect feeding mosquitoes. - The virus maintains its cycle between **Culex mosquitoes**, **pigs** (amplifying hosts), and **wading birds**, with humans being incidental hosts. *Hydatid disease* - Humans are **definitive dead-end hosts** for *Echinococcus granulosus* (causing cystic echinococcosis/hydatid disease). - The normal life cycle requires **definitive hosts** (dogs, canids) and **intermediate hosts** (sheep, cattle). - Humans develop **hydatid cysts** but cannot transmit the infection further as the parasite cannot complete its life cycle in humans. *Leishmaniasis* - In most forms of leishmaniasis, humans are considered **dead-end or accidental hosts**, particularly in **zoonotic cutaneous leishmaniasis** where animal reservoirs (rodents, dogs) maintain transmission. - However, in **anthroponotic visceral leishmaniasis** (*Leishmania donovani* in the Indian subcontinent), humans can serve as reservoir hosts. - For the purpose of this question, leishmaniasis is generally classified with dead-end diseases as the majority of leishmaniasis forms have zoonotic cycles where humans are incidental hosts with limited onward transmission.
Question 9: A militant presents with rashes all over his body sparing the palms and soles. On examination, he was febrile and lice were noted. Which of the following is responsible for his condition?
- A. Rickettsia typhi
- B. Rickettsia prowazekii (Correct Answer)
- C. Rickettsia akari
- D. Rickettsia conorii
Explanation: ***Rickettsia prowazekii*** - This bacterium is the causative agent of **epidemic typhus**, which is transmitted by the **body louse** (Pediculus humanus corporis), consistent with the presence of lice. - The characteristic rash of epidemic typhus **spares the palms and soles** and often begins on the trunk, spreading centrifugally. *Rickettsia typhi* - This organism causes **murine typhus**, which is transmitted by **fleas**, particularly those found on rodents. - While it can cause a rash that typically spares the palms and soles, the transmission vector and typical setting (exposure to rodents) do not fit the clinical scenario as well as **body lice**. *Rickettsia akari* - This bacterium causes **rickettsialpox**, transmitted by **mites**. - The rash of rickettsialpox is typically papulovesicular, and a characteristic **eschar** (or black scab) is usually present at the site of the mite bite, which is not mentioned in the case. *Rickettsia conorii* - This organism causes **Mediterranean spotted fever** (also known as Boutonneuse fever), transmitted by **ticks**. - A distinguishing feature of this infection is the presence of a **tache noire** (eschar) at the site of the tick bite, which is absent in the patient's presentation.
Question 10: The following electron microscope image shows presence of:
- A. Ebola virus (Correct Answer)
- B. Swine flu virus
- C. Rabies virus
- D. Polio virus
Explanation: ***Ebola virus*** - The electron micrograph clearly shows characteristic **filamentous, long, and pleomorphic viral particles**, some displaying coiled or branched structures, which are hallmarks of the **Filoviridae family**, to which Ebola belongs. - The presence of distinct, elongated forms, often appearing as "shepherd's crook" shapes or U-shaped structures (as indicated by the arrows), is highly indicative of the **Ebola virus morphology**. *Swine flu virus* - Swine flu, caused by influenza viruses, typically presents as **spherical or pleomorphic virions**, but not in the distinct elongated filamentous forms seen in the image. - Influenza viruses have a segmented RNA genome enclosed within a spherical capsid and an outer envelope, giving them a more rounded appearance. *Rabies virus* - Rabies virus has a classical **bullet-shaped morphology**, which is distinctly different from the long, filamentous structures observed in the image. - Its unique shape is a key identifying feature in electron microscopy. *Polio virus* - Poliovirus is a non-enveloped RNA virus with an **icosahedral (spherical) capsid structure**, much smaller and more geometrically regular than the filamentous particles shown. - It does not exhibit the elongated, flexible morphology characteristic of filoviruses.
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