Which of the following is an example of direct transmission of a pathogen?
A. Skin to skin contact with an infected wound
B. Injection with a contaminated needle
C. Drinking contaminated water
D. Getting bitten by a mosquito
The correct answer and explanation is:
The correct answer is A. Skin to skin contact with an infected wound.
Direct transmission refers to the transfer of a pathogen from an infected individual to a susceptible individual through immediate physical contact or exchange of bodily fluids. This type of transmission happens without an intermediary, such as an object or vector. Skin-to-skin contact with an infected wound is a prime example of this mode, as the pathogen can be transferred directly from the wound of an infected person to the skin of the person who is in contact. Pathogens such as bacteria, viruses, or fungi can be spread this way, causing infections in the new host.
The other options describe indirect or vector-mediated transmission:
- B. Injection with a contaminated needle: This is an example of indirect transmission. Although the needle introduces the pathogen directly into the bloodstream, it requires a foreign object (the needle) to facilitate the transmission.
- C. Drinking contaminated water: This is an example of indirect transmission via the fecal-oral route. Pathogens are present in the water and enter the body when consumed. The water acts as the vector.
- D. Getting bitten by a mosquito: This is an example of vector-borne transmission. The mosquito acts as a vector, transferring pathogens like the malaria parasite or the dengue virus to the human host during the bite.
In summary, skin-to-skin contact with an infected wound is the best example of direct transmission because it involves immediate physical contact between an infected individual and a susceptible individual without any intermediary.