Zoonotic Diseases — MCQs
All are zoonotic disease except -
All of the following are zoonosis, except:
Which of the following is a zoonotic disease?
Fever of unknown origin in a farmer who raises goats would most likely be caused by which of the following organisms?
Which of the following is known as monkey fever?
A girl from Shimla presented to OPD with fever, hypotension, malaise and axillary and inguinal lymphadenopathy. Culture in glucose broth shows stalactite growth. Most likely causative organism is?
Rickettsial organisms infect humans worldwide, although geographic locations may be limited for some species and possibly produce some challenges in medical diagnosis. All are obligate intracellular parasites, except C. burnetii, and transmitted by an insect vector. Typhus, spotted fever, and scrub typhus share which of the following manifestations of disease?
A patient presents with severe abdominal pain and jaundice. Imaging reveals calcified cysts in the liver, and serological testing is positive for Echinococcus. What is a potential complication of this infection?
All of the following are true statements for Arbovirus EXCEPT:
What is the primary cause of malignant hydatid disease?
Zoonotic Diseases Indian Medical PG Practice Questions and MCQs
Question 1: All are zoonotic disease except -
- A. Leptospirosis
- B. Rabies
- C. Scabies (Correct Answer)
- D. Brucellosis
Explanation: ***Scabies*** - **Scabies** is a parasitic skin infestation caused by the **Sarcoptes scabiei mite**, which typically spreads from person to person through direct skin contact. - While animal scabies exists, human scabies is primarily a **human-to-human transmission** disease and is not generally considered a zoonosis in the context of common human infections. *Leptospirosis* - **Leptospirosis** is a bacterial disease transmitted through contact with urine from infected animals or contaminated water/soil. - It is a classic example of a **zoonotic disease** affecting a wide range of mammals, including rodents, livestock, and pets. *Rabies* - **Rabies** is a viral disease primarily transmitted to humans through the bite of an infected animal, usually a mammal. - It is a well-known and fatal **zoonotic disease** worldwide, with dogs being the most common source of human infection in many regions. *Brucellosis* - **Brucellosis** is a bacterial infection transmitted to humans through contact with infected animals (e.g., cattle, goats, sheep) or consumption of contaminated unpasteurized dairy products. - It is a prominent **zoonotic disease** resulting in fever, sweating, and weakness, among other symptoms.
Question 2: All of the following are zoonosis, except:
- A. Japanese Encephalitis
- B. Plague
- C. Tuberculosis
- D. HIV (Correct Answer)
Explanation: ***HIV*** - While HIV originated from **simian immunodeficiency virus (SIV)** in non-human primates, it is **no longer considered a zoonosis** because transmission now occurs exclusively **human-to-human**. - The virus has fully adapted to **human hosts**, and there is **no ongoing animal reservoir** contributing to the current epidemic. - Zoonotic diseases require **active animal-to-human transmission**, which does not apply to HIV in its current form. *Japanese Encephalitis* - This is a **mosquito-borne viral disease** that primarily circulates between **mosquitoes, pigs, and birds**. - Humans are **accidental dead-end hosts**, making this a true **zoonotic disease**. *Plague* - Caused by **Yersinia pestis**, which naturally infects **small mammals (rodents)** and their fleas. - Humans become infected through **flea bites** or direct contact with infected animals, making it a **classic zoonosis**. *Tuberculosis* - While most human TB is caused by **M. tuberculosis** (human-to-human), **M. bovis** causes **zoonotic TB**. - Transmitted from **infected cattle** to humans via **unpasteurized dairy products** or close contact with infected animals. - This animal-to-human transmission qualifies TB as a **zoonotic disease**.
Question 3: Which of the following is a zoonotic disease?
- A. Hydatid cyst (Correct Answer)
- B. Malaria
- C. Filariasis
- D. Dengue fever
Explanation: ***Hydatid cyst*** - This disease is caused by the larval stage of the tapeworm **Echinococcus granulosus**, which completes its life cycle in dogs and sheep. - Humans can become infected by ingesting material contaminated with **Echinococcus eggs**, typically from contact with infected dogs or contaminated food/water, making it a zoonotic disease. *Malaria* - Malaria is transmitted by the **Anopheles mosquito** biting infected humans and then uninfected humans. - While it involves a vector, its primary reservoir is humans and it is not typically considered zoonotic as there is no animal-to-human transmission from a non-human primary reservoir. *Filariasis* - Filariasis is spread by various mosquito vectors (e.g., **Culex, Anopheles, Aedes**) that transmit parasitic worms to humans. - The life cycle primarily involves humans and mosquitos, and it is not classified as a zoonotic disease. *Dengue fever* - Dengue fever is a viral infection transmitted by **Aedes mosquitoes** (primarily *Aedes aegypti* and *Aedes albopictus*) between humans. - Similar to malaria, while it involves a vector, the primary reservoir is humans, and it is not considered zoonotic.
Question 4: Fever of unknown origin in a farmer who raises goats would most likely be caused by which of the following organisms?
- A. T. pallidum
- B. Histoplasma capsulatum
- C. Clostridium novyi
- D. Brucella melitensis (Correct Answer)
Explanation: ***Brucella melitensis*** - **Brucellosis** is a zoonotic infection commonly acquired through contact with infected animals or consumption of unpasteurized dairy products. - ***Brucella melitensis* is specifically associated with goats and sheep**, making it the most likely organism in this clinical scenario. - It classically presents as **fever of unknown origin (FUO)** due to its varied and non-specific clinical manifestations, including undulating fever, malaise, myalgia, arthralgia, and hepatosplenomegaly. *T. pallidum* - *Treponema pallidum* is the causative agent of **syphilis**, a sexually transmitted infection. - While syphilis can cause fever, its primary modes of transmission (sexual contact, vertical transmission) and clinical manifestations (e.g., chancres, rash, mucous patches) are distinct from the scenario described. - Not associated with occupational goat exposure. *Histoplasma capsulatum* - *Histoplasma capsulatum* causes **histoplasmosis**, a fungal infection associated with exposure to **bird or bat droppings**, particularly in endemic areas (e.g., Ohio and Mississippi River valleys). - Although it can cause disseminated disease and fever, the epidemiological context (exposure to goats, not birds/bats) makes it unlikely in this scenario. *Clostridium novyi* - *Clostridium novyi* is an anaerobic bacterium known to cause **gas gangrene** (clostridial myonecrosis) and occasionally **black disease** in livestock. - It is not typically associated with human fever of unknown origin in the context of occupational animal contact described. - More relevant to wound infections or animal disease rather than systemic FUO in farmers.
Question 5: 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 6: A girl from Shimla presented to OPD with fever, hypotension, malaise and axillary and inguinal lymphadenopathy. Culture in glucose broth shows stalactite growth. Most likely causative organism is?
- A. Yersinia pestis (Correct Answer)
- B. Brucella abortus
- C. Coxiella burnetii
- D. Francisella tularensis
Explanation: ***Yersinia pestis*** - The combination of **fever**, **hypotension**, **malaise**, and **inguinal and axillary lymphadenopathy** (buboes) is highly characteristic of **bubonic plague**, caused by *Yersinia pestis*. - **Stalactite growth** in broth culture is a classic identifying feature of *Yersinia pestis* when incubated without agitation, due to the organism's **lipid A-modified LPS** which allows self-aggregation. *Brucella abortus* - *Brucella abortus* causes **brucellosis**, which presents with **undulant fever**, **arthralgia**, and **hepatosplenomegaly**, but typically not with prominent acute lymphadenopathy and hypotension to this degree. - While it is a **facultative intracellular pathogen**, it does not exhibit stalactite growth in glucose broth. *Coxiella burnetii* - *Coxiella burnetii* causes **Q fever**, which is characterized by **fever**, **headache**, and **pneumonia**, often without prominent lymphadenopathy. - It is an **obligate intracellular bacterium** and cannot be cultivated in standard glucose broth, much less show stalactite growth. *Francisella tularensis* - *Francisella tularensis* causes **tularemia**, which can manifest with **fever**, **lymphadenopathy** (ulceroglandular form), and **malaise**. - However, it typically requires **specialized culture media** like cysteine-enriched agar and does not exhibit stalactite growth in glucose broth.
Question 7: Rickettsial organisms infect humans worldwide, although geographic locations may be limited for some species and possibly produce some challenges in medical diagnosis. All are obligate intracellular parasites, except C. burnetii, and transmitted by an insect vector. Typhus, spotted fever, and scrub typhus share which of the following manifestations of disease?
- A. Arthritis
- B. Common vector
- C. Fever and rash (Correct Answer)
- D. Short incubation period (<48 hours)
Explanation: ***Fever and rash*** - **Fever** is a universal response to infection, and **rash** is a common dermatological manifestation due to **vascular damage** caused by rickettsial organisms. [1] - The combination of **fever** and **rash** is a hallmark sign in clinical presentations of **typhus**, **spotted fever group rickettsioses**, and **scrub typhus**. [1] *Arthritis* - While arthritis can occur in some infectious diseases, it is **not a characteristic or common manifestation** across all rickettsial diseases mentioned. - The primary targets for rickettsial organisms are **endothelial cells**, leading to vasculitis, rather than direct joint involvement. *Common vector* - The rickettsial diseases mentioned are transmitted by **different vectors**: typhus by **lice or fleas**, spotted fever by **ticks**, and scrub typhus by **chiggers**. [1] - Therefore, they do **not share a common insect vector**. *Short incubation period (<48 hours)* - Rickettsial diseases typically have an incubation period ranging from **5 to 14 days**, which is considerably longer than 48 hours. [1] - A very short incubation period (<48 hours) is more typical of **bacterial food poisonings** or **viral infections** like influenza.
Question 8: A patient presents with severe abdominal pain and jaundice. Imaging reveals calcified cysts in the liver, and serological testing is positive for Echinococcus. What is a potential complication of this infection?
- A. Portal hypertension due to cyst compression
- B. Rupture of cysts leading to anaphylactic shock
- C. No significant complications
- D. Secondary bacterial infection of cysts (Correct Answer)
Explanation: ***Secondary bacterial infection of cysts*** - **Hydatid cysts** can become secondarily infected, typically after rupture or surgical manipulation, leading to an **abscess formation** within the liver. - This complication can present with features like fever, worsening abdominal pain, and an elevated **white blood cell count**, distinct from the initial presentation. *Rupture of cysts leading to anaphylactic shock* - While rupture of **hydatid cysts** can lead to **anaphylactic shock** due to the release of hydatid fluid, it is not the *most common immediate complication* or the scenario implied by abdominal pain and jaundice. - **Anaphylaxis** implies a rapid, severe systemic allergic reaction, which is a life-threatening acute event. *Portal hypertension due to cyst compression* - While large cysts can compress structures, significant **portal hypertension** due to direct compression of the portal vein by **hydatid cysts** is rare. - More commonly, portal hypertension is a complication of advanced **cirrhosis**, not typically direct cyst compression in the early stages described. *No significant complications* - **Echinococcosis** (hydatid disease) is a serious parasitic infection that almost always leads to significant morbidity if left untreated. - Cysts grow over time and inevitably cause **organ dysfunction**, pain, obstruction, or other complications.
Question 9: All of the following are true statements for Arbovirus EXCEPT:
- A. West nile fever is transmitted by Culex mosquito
- B. Chikungunya fever is transmitted by Aedes mosquito
- C. Kyasanur Forest Disease is transmitted by mites (Correct Answer)
- D. Japanese encephalitis is caused by group B Arbovirus (Flavivirus)
Explanation: ***Kyasanur Forest Disease is transmitted by mites*** - This statement is **false**. Kyasanur Forest Disease (KFD) is transmitted by **ticks**, specifically the *Haemaphysalis spinigera* tick, not mites. - KFD is a **tick-borne viral hemorrhagic fever** endemic to certain regions of India, caused by a flavivirus. *West nile fever is transmitted by Culex mosquito* - This statement is **true**. **West Nile virus** is primarily transmitted to humans through the bite of infected mosquitos, mainly species of **Culex**. - The virus circulates naturally between mosquitos and **birds**, with humans being incidental hosts. *Chikungunya fever is transmitted by Aedes mosquito* - This statement is **true**. **Chikungunya virus** is transmitted to humans through the bites of infected female mosquitos, primarily **Aedes aegypti** and **Aedes albopictus**. - These mosquitos are also vectors for other diseases such as dengue and Zika. *Japanese encephalitis is caused by group B Arbovirus (Flavivirus)* - This statement is **true**. Japanese encephalitis is caused by the **Japanese encephalitis virus (JEV)**, which belongs to the **Flaviviridae family**, often referred to as group B Arboviruses. - Most human infections are asymptomatic, but severe cases can lead to **encephalitis** with high mortality.
Question 10: What is the primary cause of malignant hydatid disease?
- A. Malignant transformation of hydatid cysts
- B. Infection with Echinococcus multilocularis (Correct Answer)
- C. Hydatid disease in immunocompromised patients
- D. Caused by Echinococcus granulosus
Explanation: ***Infection with Echinococcus multilocularis*** - **Malignant hydatid disease** is specifically associated with *Echinococcus multilocularis*, which causes alveolar echinococcosis. - This parasite's larval stage grows in a highly **infiltrative** and **destructive** manner, resembling a malignant tumor, hence the term "malignant hydatid disease." *Malignant transformation of hydatid cysts* - Hydatid cysts themselves are parasitic structures and do not undergo **malignant transformation** in the conventional sense of human tissue developing cancer. - The term "malignant" in this context refers to the **aggressive growth pattern** of *E. multilocularis* rather than cellular anaplasia. *Hydatid disease in immunocompromised patients* - While immunocompromised individuals may experience more severe or disseminated hydatid disease, this does not directly cause the **"malignant" characteristic** of alveolar echinococcosis. - The inherent **aggressive growth** of *Echinococcus multilocularis* is the primary factor, regardless of host immune status. *Caused by Echinococcus granulosus* - *Echinococcus granulosus* causes **cystic echinococcosis** (CE), which typically forms unilocular cysts, often considered benign. - CE is generally less aggressive and does not exhibit the **infiltrative growth pattern** characteristic of "malignant hydatid disease" caused by *E. multilocularis*.
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