Zoonotic Diseases Practice Questions

Q: Endemic typhus cause and vector are

R. typhi and Rat flea. ***R. typhi and Rat flea*** - **Endemic typhus**, also known as **murine typhus**, is caused by the bacterium **_Rickettsia typhi_**. - The **vector** for _R. typhi_ is the **rat flea** (_Xenopsylla cheopis_), which transmits the disease to humans through infected flea feces. - **Rats** serve as the natural **reservoir**, but the actual transmission vector is the flea that infests these rodents. - Humans become infected when flea feces contaminated with _R. typhi_ are rubbed into the bite wound or other skin breaks. *R. prowazekii and louse* - **_Rickettsia prowazekii_** is the causative agent of **epidemic typhus**, which is transmitted by the **human body louse** (_Pediculus humanus corporis_). - This form of typhus is typically associated with crowded, unsanitary conditions and can cause severe outbreaks. *R. akari and mite* - **_Rickettsia akari_** is the cause of **rickettsialpox**, which is transmitted by **mites** (_Liponyssoides sanguineus_) from **house mice**. - This disease presents with a characteristic eschar at the bite site followed by a papulovesicular rash. *R. conorii and tick* - **_Rickettsia conorii_** is the causative agent of **Mediterranean spotted fever** (boutonneuse fever), which is transmitted by **dog ticks** (_Rhipicephalus sanguineus_). - This disease typically presents with a fever, rash, and an eschar (tache noire) at the site of the tick bite.

Q: Rash is absent in ?

Q. fever. ***Q. fever*** - Q fever, caused by **Coxiella burnetii**, is characterized by **flu-like symptoms**, pneumonia, and hepatitis, but **does not typically present with a rash**. - This differentiates it from other rickettsial infections that commonly involve skin manifestations. *Endemic typhus* - Endemic (murine) typhus, caused by **Rickettsia typhi**, is transmitted by **fleas** and commonly presents with a **maculopapular rash** on the trunk and extremities [2]. - The rash usually appears several days after fever onset [2]. *Epidemic typhus* - Epidemic typhus, caused by **Rickettsia prowazekii** and transmitted by the **human body louse**, classically presents with a **centrifugal rash** that spares the face, palms, and soles [2]. - The rash typically starts on the trunk and spreads outwards [2]. *Scrub typhus* - Scrub typhus, caused by **Orientia tsutsugamushi**, is transmitted by **chiggers** and often features an **eschar** (a necrotic lesion at the bite site) along with a **maculopapular rash** [1]. - The rash may be transient or absent in some cases, but an eschar is a highly characteristic finding [1].

Q: All of the following statements are true regarding Q fever except -

Weil-felix reaction is very useful for diagnosis. ***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**.

Q: A 30-year-old man develops a pustular lesion at the site of a cat scratch on his forearm. This is followed 1 week later by malaise, fever, and lymphadenopathy. On examination, he has tender axillary lymph nodes. Which of the following is the most likely causative organism?

Bartonella henselae. ***Bartonella henselae*** - This organism is the definitive cause of **cat scratch disease**. The patient's presentation with a **pustular lesion at the site of a cat scratch**, followed by malaise, fever, and regional **lymphadenopathy (tender axillary lymph nodes)**, is classic for this infection. - *B. henselae* is transmitted to humans through scratches or bites from infected cats, especially kittens. *Bartonella quintana* - This bacterium is primarily associated with **trench fever** and **bacillary angiomatosis** in immunocompromised individuals. - It is transmitted by the human body louse, not typically from cat scratches. *Bartonella bacilliformis* - This organism is the causative agent of **Carrion's disease**, which presents in two stages: an acute febrile hemolytic anemia (**Oroya fever**) and a chronic verrucous skin eruption (**verruga peruana**). - It is transmitted by the **sand fly (Lutzomyia species)** and is endemic to certain Andean regions. *Coxiella burnetii* - This bacterium causes **Q fever**, a zoonotic infection typically transmitted through inhalation of aerosols from infected animals (cattle, sheep, goats). - Q fever commonly presents with **flu-like symptoms**, pneumonia, or hepatitis, and does not typically involve a pustular lesion at a scratch site with regional lymphadenopathy.

Q: What is the most common mode of transmission of Brucella?

Milk. ***Milk*** - **Brucellosis** is primarily a **zoonotic disease** that can be transmitted to humans through the consumption of **unpasteurized milk** and dairy products from infected animals. - The bacteria *Brucella* can survive in milk and infect individuals once ingested. *Water* - While *Brucella* can potentially contaminate water, it is not considered the primary or most common mode of transmission for brucellosis in humans. - **Ingestion of contaminated water** is a less frequent route compared to exposure through dairy products or animal contact. *Air* - **Airborne transmission** is not a typical mode for *Brucella*; the bacteria are not commonly spread through respiratory droplets in the general population. - Though *Brucella* can be aerosolized in specific laboratory or occupational settings (e.g., slaughterhouses), this is not a common community transmission route. *Aerosol* - As mentioned, **aerosol transmission** of *Brucella* mainly occurs in specific high-risk environments, such as laboratories working with concentrated cultures or close contact with infected animal tissues during veterinary procedures. - It is not a significant mode of transmission for the vast majority of human brucellosis cases.

Q: Rickettsial pox is transmitted by:

Mite. ***Mite*** - Rickettsialpox is caused by the bacterium *Rickettsia akari* and is primarily transmitted to humans through the bite of an infected **mite**, specifically the house mouse mite (*Liponyssoides sanguineus*). - The mite serves as both the **vector** and **reservoir** for the bacteria, perpetuating its life cycle between mice and occasionally humans. *Louse* - **Lice** are known vectors for other rickettsial diseases, such as **epidemic typhus** (*Rickettsia prowazekii*). - However, they are not involved in the transmission of **rickettsialpox**. *Soft tick* - **Soft ticks** (e.g., *Ornithodoros* species) are known to transmit various diseases, including **tick-borne relapsing fever**. - They are not associated with the transmission of **rickettsialpox**. *Hard tick* - **Hard ticks** (e.g., *Ixodes*, *Dermacentor* species) transmit a wide range of diseases, such as **Lyme disease**, **Rocky Mountain spotted fever**, and **ehrlichiosis**. - While they transmit other rickettsial diseases, **rickettsialpox** is not among them.

Q: Which is NOT transmitted by arthropods:

Coxiella burnetii. ***Coxiella burnetii*** - **Coxiella burnetii** is the causative agent of **Q fever**, which is primarily transmitted through **inhalation of contaminated aerosols** from infected animals (e.g., sheep, goats, cattle). - While animals can be infected via ticks, direct human transmission is **not arthropod-borne**. *Rickettsia rickettsii* - **Rickettsia rickettsii** causes **Rocky Mountain spotted fever**, which is transmitted by **ticks**, primarily the American dog tick (*Dermacentor variabilis*) and Rocky Mountain wood tick (*Dermacentor andersoni*). - This is a classic example of an **arthropod-borne disease**. *Rickettsia prowazekii* - **Rickettsia prowazekii** is the causative agent of **epidemic typhus**, which is transmitted by the **human body louse** (*Pediculus humanus corporis*). - This organism is transmitted when infected louse feces are scratched into the skin or inhaled. *Borrelia burgdorferi* - **Borrelia burgdorferi** causes **Lyme disease**, which is transmitted by **Ixodes ticks** (deer ticks), primarily *Ixodes scapularis* in the eastern US and *Ixodes pacificus* in the western US. - These ticks are **true arthropod vectors** for the bacteria.

Q: Not transmitted by mite -

Kyasanur forest disease. ***Kyasanur forest disease*** - **Kyasanur forest disease (KFD)** is a viral hemorrhagic fever transmitted by the **hard tick** (*Haemaphysalis spinigera*), not mites. - Humans typically acquire KFD through contact with infected ticks or sick animals like monkeys. *Rickettsialpox* - Rickettsialpox is caused by *Rickettsia akari* and transmitted by the **house mouse mite** (*Liponyssoides sanguineus*). - The mite serves as both the reservoir and vector for this disease. *Scabies* - Scabies is a skin infestation caused by the **human itch mite** (*Sarcoptes scabiei* var. *hominis*). - The mites burrow into the skin to lay eggs, leading to intense itching and rash. *Scrub typhus* - Scrub typhus is caused by *Orientia tsutsugamushi* and is transmitted to humans by the bite of infected **chiggers** (larval mites) of the family Trombiculidae. - These mites are often found in areas with scrub vegetation, hence the name.

Q: Which is not transmitted by arthropod?

Coxiella burnetii. ***Coxiella burnetii*** - *Coxiella burnetii* causes **Q fever**, which is primarily transmitted to humans through inhalation of **contaminated aerosols** from infected animals, particularly **cattle, sheep, and goats**. - While *Coxiella burnetii* can infect ticks, **tick bites are not the primary mode of transmission** to humans; instead, it's considered an occupational hazard for those working with livestock. *Rickettsia rickettsii* - *Rickettsia rickettsii* is the causative agent of **Rocky Mountain spotted fever**, which is transmitted to humans through the bite of infected **ticks**. - Ticks, such as the **American dog tick** and **Rocky Mountain wood tick**, are the primary vectors for this pathogen. *Rickettsia akari* - *Rickettsia akari* causes **rickettsialpox**, which is transmitted to humans by the bite of the **house mouse mite**. - The house mouse acts as the **reservoir**, and mites acquire the bacteria from feeding on infected mice. *Rickettsia prowazakii* - *Rickettsia prowazakii* is the cause of **epidemic typhus**, primarily transmitted to humans by the bite and feces of the **human body louse**. - The bacteria are rubbed into the skin through scratching or inhaled from dried louse feces.

Q: Louse-borne typhus fever is:

Epidemic typhus. ***Epidemic typhus*** - **Epidemic typhus** is caused by **Rickettsia prowazekii** and is primarily transmitted by the **human body louse** (Pediculus humanus corporis). - This form of typhus is associated with overcrowding and poor hygiene, often leading to large outbreaks. *Rickettsialpox* - **Rickettsialpox** is caused by **Rickettsia akari** and is transmitted by the **house mouse mite**, not lice. - It typically presents with an **initial papulovesicular lesion** (eschar) followed by a generalized rash. *Endemic typhus* - **Endemic typhus**, also known as murine typhus, is caused by **Rickettsia typhi** and is transmitted by the **rat flea**, not lice. - It is generally milder than epidemic typhus and is associated with sporadic cases rather than large epidemics. *Scrub typhus* - **Scrub typhus** is caused by **Orientia tsutsugamushi** and is transmitted by the bite of infected **chiggers** (larval mites), not lice. - It is characterized by an **eschar** at the bite site and involves symptoms like fever, headache, and rash, primarily in rural areas of Asia and the Pacific.

Question 1

Endemic typhus cause and vector are

Accepted Answer

R. typhi and Rat flea

Answer

R. prowazki and louse

Answer

R. akari and mite

Answer

R. conori and tick

Question 2

Rash is absent in ?

Accepted Answer

Q. fever

Answer

Endemic typhus

Answer

Epidemic typhus

Answer

Scrub typhus

Question 3

All of the following statements are true regarding Q fever except -

Accepted Answer

Weil-felix reaction is very useful for diagnosis

Answer

It is zoonotic disease

Answer

No rash is seen

Answer

Human disease is characterized by an interstitial pneumonia

Question 4

A 30-year-old man develops a pustular lesion at the site of a cat scratch on his forearm. This is followed 1 week later by malaise, fever, and lymphadenopathy. On examination, he has tender axillary lymph nodes. Which of the following is the most likely causative organism?

Accepted Answer

Bartonella henselae

Answer

Bartonella quintana

Answer

Bartonella bacilliformis

Answer

Coxiella burnetii

Question 5

What is the most common mode of transmission of Brucella?

Accepted Answer

Milk

Answer

Water

Answer

Air

Answer

Aerosol

Question 6

Rickettsial pox is transmitted by:

Accepted Answer

Mite

Answer

Louse

Answer

Soft tick

Answer

Hard tick

Question 7

Which is NOT transmitted by arthropods:

Accepted Answer

Coxiella burnetii

Answer

Rickettsia rickettsii

Answer

Rickettsia prowazekii

Answer

Borrelia burgdorferi

Question 8

Not transmitted by mite -

Accepted Answer

Kyasanur forest disease

Answer

Rickettsialpox

Answer

Scabies

Answer

Scrub typhus

Question 9

Which is not transmitted by arthropod?

Accepted Answer

Coxiella burnetii

Answer

Rickettsia rickettsii

Answer

Rickettsia akari

Answer

Rickettsia prowazakii

Question 10

Louse-borne typhus fever is:

Accepted Answer

Epidemic typhus

Answer

Rickettsialpox

Answer

Endemic typhus

Answer

Scrub typhus

Zoonotic Diseases — MCQs

Zoonotic Diseases — MCQs

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