Zoonotic Diseases Practice Questions

Q: Which disease does not have a known animal reservoir?

Bordetella pertussis. ***Bordetella pertussis*** - **Bordetella pertussis**, the causative agent of whooping cough, is unique among these options as it has **no known animal reservoir**. It is exclusively a human pathogen. - Transmission occurs directly from person to person via respiratory droplets, highlighting its **anthroponotic** nature. *Brucella melitensis* - **Brucella melitensis** is primarily associated with **goats and sheep**, acting as a significant animal reservoir. - Humans typically acquire brucellosis through contact with infected animals or consumption of unpasteurized dairy products. *Pasteurella multocida* - **Pasteurella multocida** is a common commensal bacterium found in the oral flora of various animals, including **cats and dogs**. - Human infections usually result from **animal bites or scratches**, demonstrating clear zoonotic transmission. *Francisella tularensis* - **Francisella tularensis**, which causes **tularemia**, has numerous animal reservoirs, including **rabbits, rodents, and ticks**. - Humans can contract tularemia through direct contact with infected animals, insect bites, or inhalation of contaminated aerosols.

Q: Transovarian transmission is seen in which infection?

Rocky Mountain spotted fever. ***Rocky Mountain spotted fever*** - Transovarian transmission is a key characteristic of the **Rickettsia rickettsii** bacteria, the causative agent of Rocky Mountain spotted fever. - This mechanism ensures that the pathogen is passed from an infected female tick to her offspring, thereby maintaining the infection in the **tick population**. *Plague* - Plague (caused by **Yersinia pestis**) is primarily transmitted to humans through the bite of infected **fleas** or contact with infected animals. - It does not demonstrate transovarian transmission within its vector (fleas) as a common mode of perpetuation. *Filarial* - Filarial infections are caused by **nematodes** and are transmitted by insect vectors like mosquitoes or blackflies. - While these vectors transmit the larvae, they do not typically pass the parasitic infection to their offspring via transovarian transmission. *Guinea* - Guinea worm disease (**Dracunculus medinensis**) is transmitted when people drink water contaminated with copepods (water fleas) infected with **Guinea worm larvae**. - There is no transovarian transmission involved in the life cycle of the Guinea worm or its intermediate host.

Q: Which of the following prion diseases is most commonly associated with cattle and has been linked to variant Creutzfeldt-Jakob disease in humans?

Bovine spongiform encephalopathy. ***Bovine spongiform encephalopathy*** - **Bovine spongiform encephalopathy (BSE)**, also known as **"mad cow disease,"** is a prion disease of cattle strongly linked to the development of **variant Creutzfeldt-Jakob disease (vCJD)** in humans through consumption of contaminated beef products. - The disease causes **neurodegeneration** in cattle, leading to **neurological symptoms** such as incoordination, behavioral changes, and aggression. *Transmissible mink encephalopathy* - This is a rare **prion disease** affecting farm-raised **mink**, known to be transmissible among mink. - It is **not associated with cattle** as its primary host, nor has it been linked to human prion diseases like vCJD. *Scrapie* - **Scrapie** is a **prion disease** specific to **sheep and goats**, and it is not known to be transmissible to humans or to cause human disease. - While it was one of the earliest recognized prion diseases, it does not affect cattle or cause vCJD. *Progressive multifocal leucoencephalopathy* - This is a **demyelinating disease** of the central nervous system caused by the **JC virus**, not a prion. - It primarily affects individuals with **compromised immune systems** and is unrelated to cattle and variant CJD.

Q: Which of the following diseases is not transmitted by lice?

Q fever. ***Correct: Q fever*** - **Q fever** is caused by *Coxiella burnetii* and is primarily transmitted by **inhalation of aerosols** from infected animal products or excretions, not by lice - Exposure to infected livestock (cattle, sheep, goats) or their birth products is the most common route of transmission - This is a zoonotic disease with no arthropod vector involvement *Incorrect: Relapsing fever* - Louse-borne relapsing fever is caused by *Borrelia recurrentis* and transmitted by the body louse (*Pediculus humanus corporis*) - Infection occurs when infected lice are crushed, releasing bacteria into breaks in the skin - Characterized by recurrent episodes of fever, prevalent in areas with poor hygiene and overcrowding *Incorrect: Trench fever* - Caused by *Bartonella quintana* and transmitted by the body louse (*Pediculus humanus corporis*) through its feces - Infection occurs when louse feces are scratched into the skin or mucous membranes, or when inhaled - Associated with homelessness, overcrowding, and poor hygiene *Incorrect: Epidemic typhus* - Caused by *Rickettsia prowazekii* and transmitted by the body louse when its feces containing bacteria are rubbed into abraded skin or mucous membranes - Associated with poor hygiene and crowded conditions, particularly during wars, disasters, or refugee situations - Can cause severe systemic illness with high fever and rash

Question 1

Which disease does not have a known animal reservoir?

Accepted Answer

Bordetella pertussis

Answer

Brucella melitensis

Answer

Francisella tularensis

Answer

Pasteurella multocida

Question 2

Transovarian transmission is seen in which infection?

Accepted Answer

Rocky Mountain spotted fever

Answer

Plague

Answer

Filarial

Answer

Guinea

Question 3

Which of the following prion diseases is most commonly associated with cattle and has been linked to variant Creutzfeldt-Jakob disease in humans?

Accepted Answer

Bovine spongiform encephalopathy

Answer

Scrapie

Answer

Transmissible mink encephalopathy

Answer

Progressive multifocal leucoencephalopathy

Question 4

Which of the following diseases is not transmitted by lice?

Accepted Answer

Q fever

Answer

Relapsing fever

Answer

Trench fever

Answer

Epidemic typhus

Zoonotic Diseases — MCQs

Zoonotic Diseases — MCQs

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