Occupational Exposure to Zoonoses — MCQs
A forest officer develops the lesion as shown in the image. Which of the following is not a differential to consider?
Which among the following occupations is a risk factor for cutaneous larva migrans?
All of the following statements are true regarding Q fever except -
For the prevention of human rabies, immediate flushing and washing the wound(s) in animal bite cases, with plenty of soap and water, under running tap should be carried out for how much time?
Most common widespread zoonotic disease in the world is -
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?
Zoonotic disease of viral etiology includes -
Considering that dogs are the most common carriers of rabies and that the disease predominantly affects children in developing countries, what is the most effective and direct method to significantly reduce the incidence of rabies?
A farmer presents you with a cauliflower-shaped mass on foot, which developed after a minor injury. Microscopy shows copper penny bodies. What is the most likely diagnosis?
Which organism does not require a vector for transmission?
Occupational Exposure to Zoonoses Indian Medical PG Practice Questions and MCQs
Question 1: A forest officer develops the lesion as shown in the image. Which of the following is not a differential to consider?
- A. Cutaneous anthrax
- B. KFD (Correct Answer)
- C. Scrub typhus
- D. Healing brown recluse spider bite
Explanation: ***KFD*** - **Kyasanur Forest Disease** (KFD) is a viral hemorrhagic fever, but it does **not** typically present with a **skin lesion** or eschar like the one shown. - KFD is characterized by fever, headache, myalgia, and gastrointestinal symptoms, with hemorrhagic manifestations in severe cases, but not a primary cutaneous lesion. *Cutaneous anthrax* - **Cutaneous anthrax** commonly presents as an **eschar**, often with surrounding edema and vesicles, which can resemble the lesion in the image. - Exposure through handling infected animal products or contact with contaminated soil is common, aligning with a forest officer's occupation. *Scrub typhus* - **Scrub typhus** characteristically causes an **eschar** (tache noire) at the bite site of the chigger mite. - The lesion in the image, an ulcer with a central black crust, is highly suggestive of such an eschar seen in rickettsial infections. *Healing brown recluse spider bite* - A **brown recluse spider bite** can cause a **necrotic ulcer** with a central dark eschar as the wound heals, fitting the appearance of the lesion. - The profession of a forest officer increases the likelihood of exposure to spiders in their natural habitat.
Question 2: Which among the following occupations is a risk factor for cutaneous larva migrans?
- A. A poultry worker
- B. A kennel worker
- C. A lifeguard in a swimming pool
- D. Farmer (Correct Answer)
Explanation: ***Farmer*** - Farmers are at high risk due to frequent direct contact with **contaminated soil** or sandy environments where animal feces, especially from dogs and cats, might be present. - Exposure to **larvae of hookworms** such as *Ancylostoma braziliense* and *Ancylostoma caninum*, which can penetrate unprotected skin (e.g., bare feet while working) from the soil. *A lifeguard in a swimming pool* - Lifeguards primarily work in **chlorinated water** or on clean, well-maintained pool decks, which do not typically harbor hookworm larvae. - While they might be exposed to other skin conditions, **cutaneous larva migrans** is not a common risk associated with this occupation. *A poultry worker* - Poultry workers are primarily exposed to avian environments, where hookworm species that cause cutaneous larva migrans in humans are typically **not found**. - Their work environment generally does not involve direct contact with soil contaminated by **canine or feline feces**. *A kennel worker* - While kennel workers handle dogs and cats, which are carriers of hookworms, their primary exposure is to the animals themselves or their immediate cleaned environments, not typically **soil contaminated with larvae**. - The mode of transmission for cutaneous larva migrans is through **soil contact** rather than direct animal handling in a controlled kennel setting.
Question 3: All of the following statements are true regarding Q fever except -
- A. It is zoonotic disease
- B. No rash is seen
- C. Human disease is characterized by an interstitial pneumonia
- D. Weil-felix reaction is very useful for diagnosis (Correct Answer)
Explanation: ***Weil-felix reaction is very useful for diagnosis*** - The **Weil-Felix reaction** is a test primarily used for diagnosing certain **Rickettsial infections**, which belong to a different genus than *Coxiella burnetii*. - It detects antibodies against specific **Proteus antigens**, which cross-react with Rickettsial antigens, but it is **not sensitive or specific** for Q fever. *It is zoonotic disease* - Q fever is indeed a **zoonotic disease** [1], meaning it is transmitted from animals to humans, primarily through **aerosols** from infected livestock. - The main reservoirs include **cattle, sheep, and goats**, and exposure often occurs in occupational settings involving these animals. *No rash is seen* - A characteristic feature of Q fever is the **absence of a rash**, which helps differentiate it from many other febrile illnesses, particularly other **rickettsial diseases**. - While other symptoms like fever, headache, and myalgia are common, **cutaneous manifestations are rare**. *Human disease is characterized by an interstitial pneumonia* - **Pneumonia**, often an **interstitial pneumonia**, is a common and characteristic manifestation of acute Q fever in humans. - This respiratory involvement can range from mild to severe, and diagnosis often relies on imaging findings consistent with **atypical pneumonia**.
Question 4: For the prevention of human rabies, immediate flushing and washing the wound(s) in animal bite cases, with plenty of soap and water, under running tap should be carried out for how much time?
- A. 15 minutes (Correct Answer)
- B. 5 minutes
- C. 2 minutes
- D. 1 minute
Explanation: ***15 minutes*** - **Immediate and thorough wound cleansing** with soap and water for at least 15 minutes is crucial for reducing the risk of rabies infection after an animal bite. - This physical removal of the *rabies virus* from the wound site is the **most effective first-aid measure** in preventing the disease. *5 minutes* - While some cleansing is better than none, five minutes may not be sufficient for **maximal removal of viral particles**, especially from deeper or more contaminated wounds. - The extended duration of 15 minutes ensures a more **thorough decontamination** and increased safety margin. *2 minutes* - This short duration of washing is **inadequate** for effective removal of the rabies virus from the wound. - It significantly increases the **risk of viral persistence** in the wound, undermining the primary goal of immediate first aid. *1 minute* - Washing for only one minute is **grossly insufficient** and offers minimal protective benefit against rabies transmission following an animal bite. - **Thorough mechanical scrubbing** and flushing for a longer period are essential.
Question 5: Most common widespread zoonotic disease in the world is -
- A. Leptospirosis (Correct Answer)
- B. Brucellosis
- C. Rabies
- D. Anthrax
Explanation: ***Leptospirosis*** - **Leptospirosis** is considered the most common widespread **zoonotic disease** globally, with an estimated 1.03 million cases per year. - It is caused by **spirochetes** of the genus *Leptospira* and is transmitted to humans through contact with urine from infected animals or contaminated water/soil. *Brucellosis* - **Brucellosis** is a significant zoonotic disease but is generally less widespread than leptospirosis, particularly in regions with effective control programs for livestock. - It is transmitted through direct contact with infected animals or consumption of unpasteurized dairy products, often causing **undulant fever**. *Rabies* - **Rabies** is a severe and nearly universally fatal zoonotic disease, but its global incidence is lower than leptospirosis, largely due to successful vaccination campaigns in animals. - Transmission occurs primarily through the bite of an infected animal, leading to **neurological symptoms**. *Anthrax* - **Anthrax** is a serious bacterial disease, but its occurrence is relatively rare and often localized to specific regions or outbreak events. - It is caused by *Bacillus anthracis* and is typically acquired through contact with infected animals or their products, presenting in **cutaneous**, **inhalational**, **gastrointestinal**, or **injectional** forms.
Question 6: 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 7: Zoonotic disease of viral etiology includes -
- A. Q fever
- B. Rickettsial disease
- C. Rubella
- D. Rabies (Correct Answer)
Explanation: ***Rabies*** - Rabies is a classic example of a **zoonotic disease** caused by the **rabies virus**, transmitted to humans primarily through the bite of an infected animal. - The virus affects the **central nervous system** and is almost invariably fatal once clinical symptoms appear. *Q fever* - Q fever is a **zoonotic disease**, but it is caused by the bacterium **Coxiella burnetii**, not a virus. - It is often transmitted from farm animals and can cause acute or chronic illness. *Rickettsial disease* - Rickettsial diseases are caused by various species of **Rickettsia bacteria**, which are spread by arthropod vectors like ticks, fleas, and lice. - These are bacterial infections and not viral in origin. *Rubella* - Rubella, also known as German measles, is a **viral disease** caused by the rubella virus, but it is typically spread directly from person to person through respiratory droplets. - It is **not considered a zoonotic disease** as it does not primarily originate in animals and transmit to humans.
Question 8: Considering that dogs are the most common carriers of rabies and that the disease predominantly affects children in developing countries, what is the most effective and direct method to significantly reduce the incidence of rabies?
- A. Conduct rabies testing for all dogs
- B. Control the stray dog population and vaccinate all dogs (Correct Answer)
- C. Enhance laboratory testing capabilities
- D. Improve healthcare worker training for disease surveillance
Explanation: ***Control the stray dog population and vaccinate all dogs*** - As dogs are the primary reservoirs of rabies, controlling their population, coupled with widespread **dog vaccination**, is the most direct and effective strategy to break the transmission cycle to humans. - This approach tackles the root cause of the disease in areas where dog-mediated transmission is endemic, leading to a significant reduction in human rabies cases. *Conduct rabies testing for all dogs* - While testing identifies infected animals, it is **resource-intensive** and impractical for large dog populations, especially in low-resource settings, and does not prevent future infections. - This strategy is reactive rather than **proactive** in preventing the spread of rabies. *Enhance laboratory testing capabilities* - Improving laboratory testing capabilities is crucial for **surveillance** and accurate diagnosis but does not directly prevent rabies transmission at the source. - It's a supportive measure that helps monitor disease burden but isn't the most effective **primary intervention** for incidence reduction. *Improve healthcare worker training for disease surveillance* - Training healthcare workers enhances case detection and reporting, which is vital for **epidemiological monitoring** and timely post-exposure prophylaxis (PEP). - However, it does not address the fundamental issue of rabies transmission from dogs to humans and is not a direct prevention method for reducing disease incidence.
Question 9: A farmer presents you with a cauliflower-shaped mass on foot, which developed after a minor injury. Microscopy shows copper penny bodies. What is the most likely diagnosis?
- A. Sporotrichosis
- B. Blastomycosis
- C. Chromoblastomycosis (Correct Answer)
- D. Phaeohyphomycosis
Explanation: **Chromoblastomycosis** - The characteristic "cauliflower-shaped" lesion on the foot following a minor injury, especially in a farmer (indicating outdoor exposure), is highly suggestive of chromoblastomycosis. - The presence of **copper penny bodies** (also known as **sclerotic** or **muriform cells**) on microscopy is **pathognomonic** for chromoblastomycosis. *Blastomycosis* - Blastomycosis typically presents with **granulomatous lesions** that can ulcerate but are rarely described as cauliflower-shaped. - Microscopic examination would reveal **broad-based budding yeast cells**, not copper penny bodies. *Sporotrichosis* - Sporotrichosis usually presents as **subcutaneous nodules** that can ulcerate and spread lymphatically, forming a chain of lesions. - Microscopy shows **cigar-shaped budding yeasts** within macrophages or neutrophils, which are distinct from copper penny bodies. *Phaeohyphomycosis* - Phaeohyphomycosis encompasses a broad group of infections by dematiaceous fungi that produce **dark-walled hyphae** or yeast-like cells in tissue. - While it can cause subcutaneous nodules or cysts, the presence of distinct copper penny bodies points away from phaeohyphomycosis as the primary diagnosis.
Question 10: Which organism does not require a vector for transmission?
- A. Rickettsia rickettsii
- B. Borrelia recurrentis
- C. Rickettsia prowazekii
- D. Coxiella burnetii (Correct Answer)
Explanation: ***Coxiella burnetii*** - This organism causes **Q fever** and does not require an arthropod vector; it is primarily transmitted via **aerosols** from infected animals. - Humans usually acquire the infection by inhaling **contaminated aerosols** from infected livestock (cattle, sheep, goats). *Rickettsia prowazekii* - This bacterium is the causative agent of **epidemic typhus** and is transmitted by the **human body louse** (*Pediculus humanus corporis*). - The louse acts as a **biological vector**, acquiring the organism from an infected human and transmitting it through its feces, which are then scratched into the skin. *Rickettsia rickettsii* - This organism causes **Rocky Mountain Spotted Fever (RMSF)** and is transmitted by **ticks**, primarily the American dog tick (*Dermacentor variabilis*) and the Rocky Mountain wood tick (*Dermacentor andersoni*). - Ticks serve as both **vectors** and **reservoirs** for *Rickettsia rickettsii*. *Borrelia recurrentis* - This spirochete causes **louse-borne relapsing fever** and is transmitted by the **human body louse** (*Pediculus humanus corporis*). - Transmission occurs when the louse is crushed and its hemolymph, containing the bacteria, comes into contact with broken skin or mucous membranes.
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