Mode of transmission of Q fever:
**Core Concept**
Q fever is a zoonotic disease caused by the bacterium *Coxiella burnetii*. The mode of transmission of Q fever is primarily through inhalation of aerosolized bacteria from infected animals, particularly sheep, goats, and cattle.
**Why the Correct Answer is Right**
The correct mode of transmission of Q fever involves the inhalation of aerosolized bacteria from infected animals. This occurs when contaminated animal products, such as wool, milk, or placenta, are disturbed, releasing the bacteria into the air. The bacteria can then be inhaled by humans, leading to infection. This mode of transmission is thought to be the primary mechanism by which Q fever is spread.
**Why Each Wrong Option is Incorrect**
* **Option A:** Direct contact with infected animals is not the primary mode of transmission of Q fever. While direct contact can occur, the bacteria are highly resistant to environmental factors, allowing them to survive outside of the host for long periods of time, making inhalation a more likely mode of transmission.
* **Option B:** Contaminated food and water are not the primary mode of transmission of Q fever. While theoretically possible, the bacteria are highly resistant to environmental factors, making this mode of transmission less likely.
* **Option C:** Tick vectors are not the primary mode of transmission of Q fever. While ticks can be infected with *Coxiella burnetii*, they are not the primary vector for human infection.
**Clinical Pearl / High-Yield Fact**
Q fever can be contracted through inhalation of aerosolized bacteria from infected animals, making it an occupational hazard for veterinarians, farmers, and laboratory workers.
**Correct Answer:** C.