Zoonotic Infections — MCQs
Zoonotic diseases are -
Which of the following viral infections is transmitted by tick?
All of the following are zoonosis, except:
A man with chills, fever, and headache is thought to have "atypical" pneumonia. History reveals that he raises chickens, and that approximately 2 weeks ago he lost a large number of them to an undiagnosed disease. Which of the following is the most likely diagnosis of this man's condition?
Which of the following is a zoonotic disease?
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?
Neurological complications following rabies vaccine are common with
A young lady complains of sore throat for 3 days along with fever and headache. On examination, she was severely dehydrated, her BP was found to be 90/ 50 mm Hg and on the distal aspect of the cuff, small red spots were noted. What could be the most probable etiological agent responsible for causing these symptoms -
Infections transmitted to man from vertebrate animals are known as:
Which of the following statements about viral diseases is true?
Zoonotic Infections Indian Medical PG Practice Questions and MCQs
Question 1: Zoonotic diseases are -
- A. Anthrax
- B. Plague
- C. Salmonellosis
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - **Anthrax**, **Plague**, and **Salmonellosis** are all well-established examples of zoonotic diseases, which are infections naturally transmitted between vertebrate animals and humans. - These diseases represent a diverse spectrum of bacterial infections with significant public health implications worldwide. **Anthrax** - Caused by *Bacillus anthracis*, a spore-forming bacterium naturally found in soil that primarily affects livestock and wild herbivores. - Humans acquire infection through contact with infected animals or contaminated animal products (hides, wool, meat). - Clinical forms include cutaneous (most common), inhalational (most severe), and gastrointestinal anthrax. - Remains an important occupational hazard for veterinarians, farmers, and those handling animal products. **Plague** - Caused by *Yersinia pestis*, maintained in nature through rodent-flea cycles. - Transmission to humans occurs primarily via bites from infected fleas or direct contact with infected animals. - Historically responsible for devastating pandemics including the Black Death. - Clinical manifestations include bubonic (most common), pneumonic (person-to-person transmission possible), and septicemic plague. **Salmonellosis** - Caused by non-typhoidal *Salmonella* species, commonly colonizing the intestines of various animals including poultry, cattle, reptiles, and pets. - Humans typically acquire infection through consumption of contaminated food (undercooked meat, eggs, unpasteurized dairy) or direct animal contact. - Presents as acute gastroenteritis with diarrhea, fever, and abdominal cramps. - One of the most common foodborne zoonotic infections globally.
Question 2: Which of the following viral infections is transmitted by tick?
- A. Ehrlichiosis
- B. Lyme disease
- C. Rocky Mountain spotted fever
- D. Kyasanur forest disease (KFD) (Correct Answer)
Explanation: ***Kyasanur forest disease (KFD)*** - KFD is a **viral hemorrhagic fever** caused by the Kyasanur Forest disease virus, a member of the *Flaviviridae* family. - It is primarily transmitted to humans through the bite of infected **ticks**, especially *Haemaphysalis spinigera*. *Ehrlichiosis* - Ehrlichiosis is a **bacterial infection** caused by *Ehrlichia* species, not a viral infection. - It is transmitted by **ticks**, primarily the **lone star tick** (*Amblyomma americanum*). *Lyme disease* - Lyme disease is a **bacterial infection** caused by *Borrelia burgdorferi*, not a viral infection. - It is transmitted by **ticks**, notably the **black-legged tick** (*Ixodes scapularis*). *Rocky Mountain spotted fever* - Rocky Mountain spotted fever (RMSF) is a **bacterial infection** caused by *Rickettsia rickettsii*, not a viral infection. - It is transmitted by **ticks**, such as the **American dog tick**, **Rocky Mountain wood tick**, and **brown dog tick**.
Question 3: 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 4: A man with chills, fever, and headache is thought to have "atypical" pneumonia. History reveals that he raises chickens, and that approximately 2 weeks ago he lost a large number of them to an undiagnosed disease. Which of the following is the most likely diagnosis of this man's condition?
- A. Leptospirosis
- B. Relapsing fever
- C. Anthrax
- D. Ornithosis (Correct Answer)
Explanation: ***Ornithosis*** - The patient's symptoms of **chills, fever, headache, and atypical pneumonia**, combined with a history of **raising chickens** that recently died from an undiagnosed disease, are highly suggestive of ornithosis (also known as **psittacosis** or **parrot fever**). [2], [3] - This zoonotic infection is caused by **Chlamydophila psittaci** and is transmitted to humans through inhalation of contaminated aerosols from infected birds (poultry, parrots, pigeons). [2] *Leptospirosis* - **Leptospirosis** is typically associated with exposure to **contaminated water or soil** with animal urine, not direct contact with sick poultry. - While it can cause fever and headache, it often presents with **jaundice, renal failure, and hemorrhagic manifestations**, which are not mentioned here. *Relapsing fever* - **Relapsing fever** is characterized by **recurrent episodes of fever** separated by afebrile periods, caused by **Borrelia** species transmitted by lice or ticks. - The clinical presentation does not align with the typical course or epidemiological link to sick chickens. *Anthrax* - **Inhalational anthrax** can cause severe respiratory symptoms and fever but is primarily associated with exposure to **Bacillus anthracis spores**, often from infected livestock (cattle, sheep) or bioweapon exposure. [1] - The rapid death of a large number of chickens and the patient's "atypical pneumonia" do not fit the typical presentation or common transmission routes of anthrax. [1]
Question 5: 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 6: 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 7: Neurological complications following rabies vaccine are common with
- A. HDCS Vaccine
- B. Chick embryo Vaccine
- C. Semple Vaccine (Correct Answer)
- D. Duck Egg Vaccine
Explanation: ***Semple Vaccine*** - The **Semple vaccine (nerve tissue vaccine)** is associated with a higher incidence of **neurological complications** due to sensitisation to neural tissue components. - These complications can include **demyelinating encephalomyelitis** and paralysis, making it a less safe option compared to modern vaccines. *HDCS Vaccine* - The **Human Diploid Cell Vaccine (HDCV)** is a modern, highly purified rabies vaccine with a significantly **lower risk of neurological complications**. - It is considered one of the **safest and most effective** rabies vaccines available, rarely causing severe adverse events. *Chick embryo Vaccine* - **Chick embryo vaccines (CEV)** are produced in avian embryos and generally have a **low incidence of neurological complications** compared to nerve tissue vaccines. - While safer than older formulations, they are typically less used now than cell culture vaccines. *Duck Egg Vaccine* - **Duck embryo vaccines (DEV)** were an improvement over nerve tissue vaccines, offering a **reduced risk of neurological side effects**. - However, they still carried a slightly higher risk of adverse reactions compared to modern cell culture-derived vaccines.
Question 8: A young lady complains of sore throat for 3 days along with fever and headache. On examination, she was severely dehydrated, her BP was found to be 90/ 50 mm Hg and on the distal aspect of the cuff, small red spots were noted. What could be the most probable etiological agent responsible for causing these symptoms -
- A. Brucella suis
- B. Neisseria meningitidis (Correct Answer)
- C. Brucella abortus
- D. Staphylococcus aureus
Explanation: Neisseria meningitidis - The combination of sore throat, fever, headache, severe dehydration, hypotension, and petechiae (small red spots from broken capillaries, often seen with bleeding diathesis) is highly suggestive of meningococcemia [1]. - Neisseria meningitidis can cause fulminant sepsis and meningitis, leading to rapid progression of symptoms including DIC and widespread petechial rashes due to vasculitis [2]. Brucella suis - Brucellosis typically presents as an insidious illness with undulating fever, arthralgia, and organomegaly, not sudden onset severe symptoms with dehydration and petechiae. - While it can be severe, it does not commonly manifest with the acute, dramatic hemorrhagic signs seen in this patient. Brucella abortus - Similar to Brucella suis, Brucella abortus causes brucellosis, which is a chronic or subacute infection. - The clinical picture of acute onset, severe dehydration, hypotension, and petechiae points away from brucellosis. Staphylococcus aureus - Staphylococcus aureus can cause various infections, including sepsis, but a sore throat and the specific presentation of petechiae with hypotension following an apparent upper respiratory tract infection are less characteristic [3]. - While S. aureus can produce toxins leading to toxic shock syndrome, meningococcal sepsis is a more direct fit for the rapid onset and hemorrhagic signs.
Question 9: Infections transmitted to man from vertebrate animals are known as:
- A. Zooanthroponoses
- B. Anthropozoonoses (Correct Answer)
- C. Exotic
- D. Epizootic
Explanation: ***Anthropozoonoses*** - **Anthropozoonoses**, also known simply as **zoonoses**, are diseases primarily of animals that can be transmitted to humans. - This term specifically refers to infections that are naturally transmissible from **vertebrate animals** to humans. *Zooanthroponoses* - **Zooanthroponoses** refer to infections that are naturally transmissible from humans to animals. - While reflecting a human-animal disease relationship, the direction of transmission is opposite to what is described in the question. *Exotic* - An **exotic** disease refers to an infection or pathogen that is not native or endemic to a particular geographic region. It does not describe the mode of transmission from animals to humans. - This term describes the geographical origin or presence of a disease, not its interspecies transmissibility. *Epizootic* - An **epizootic** describes a disease outbreak in an animal population, analogous to an epidemic in humans. - This term defines the pattern and occurrence of disease within animal populations, rather than transmission to humans.
Question 10: Which of the following statements about viral diseases is true?
- A. Hanta virus pulmonary syndrome is caused by inhalation of rodent urine and feces (Correct Answer)
- B. Lyssa virus is transmitted by ticks
- C. None of the options
- D. Kyasanur forest disease is caused by bite of wild animal
Explanation: ***Hanta virus pulmonary syndrome is caused by inhalation of rodent urine and feces*** - **Hantavirus pulmonary syndrome (HPS)** is a severe, often fatal, respiratory disease in humans. - Humans can contract the disease when they breathe in **aerosolized virus** particles from **rodent urine, droppings, or saliva**. *Kyasanur forest disease is caused by bite of wild animal* - **Kyasanur Forest Disease (KFD)** is primarily transmitted by the bite of infected ticks, specifically **Haemaphysalis spinigera**, not directly by wild animal bites. - While wild animals (like monkeys and rodents) can be hosts for the ticks, the direct transmission to humans is via the **tick vector**. *Lyssa virus is transmitted by ticks* - **Lyssaviruses** (which include the rabies virus) are primarily transmitted to humans through the bite or scratch of an infected mammal, most commonly a **rabid animal**. - **Ticks** are not known vectors for Lyssaviruses.
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