The key difference between mechanical and biological transmission is that mechanical transmission occurs when mechanical vectors, such as flies, pick up pathogens on the outside of their bodies and transmit them to new hosts like humans through physical contact, while biological transmission occurs when biological vectors such as mosquitoes and ticks carry pathogens within their bodies and deliver them to new hosts like humans through biting.
A vector is a living organism that transmits an infectious agent (pathogen) from an infected animal to a human or another animal. Vectors can transmit infectious diseases actively or passively. Active transmission occurs when vectors like biological vectors (mosquitoes and ticks) transmit pathogens to a new host. This is called biological transmission. On the other hand, passive transmission occurs when vectors like mechanical vectors (flies) transmit pathogens to a new host. This is called mechanical transmission.
CONTENTS
1. Overview and Key Difference
2. What is Mechanical Transmission
3. What is Biological Transmission
4. Similarities – Mechanical and Biological Transmission
5. Mechanical vs Biological Transmission in Tabular Form
6. Summary – Mechanical vs Biological Transmission
What is Mechanical Transmission?
Mechanical transmission occurs when mechanical vectors such as flies pick up pathogens on the outside of their bodies and transmit them to new hosts like humans through physical contact. Mechanical transmission of disease pathogens occurs when a vector transports organisms like bacteria that cause diseases like dysentery on its feet, body hair, or body surfaces to a new host like humans. In this disease transmission mode, there is no multiplication or development of the disease pathogen within the body of the vector.
A good example of mechanical transmission is the passive transmission of bacillary dysentery by house flies (Musca domestica) to humans. Furthermore, mechanical transmission can be considered accidental.
What is Biological Transmission?
Biological transmission occurs when biological vectors such as mosquitoes and ticks carry pathogens within their bodies and deliver them to new hosts like humans through biting. It is a type of active disease transmission mode. Arthropods are the main vectors responsible for biological transmission. Most of the time, arthropod vectors transmit pathogens by biting hosts like humans. Before delivering the pathogen to the new host, the pathogen may go through a part of its reproductive cycle in the gut or salivary glands of the arthropod. A good example of biological transmission is kissing bugs that transmit the Chagas disease parasites to humans. This is also known as American trypanosomiasis.
Figure 02: Biological Transmission
Furthermore, another example of biological transmission is biological insect vectors like mosquitoes that transmit malaria and other diseases and lice that transmit typhus. In addition to that, arachnids and ticks also carry out biological transmission causing Lyme disease and other diseases. Mites that transmit typhus and rickettsialpox are also involved with the biological transmission.
What are the Similarities Between Mechanical and Biological Transmission?
- Mechanical and biological transmission are two different types of disease transmission modes.
- Both transmission modes deliver pathogens through vectors.
- They transmit deadly human and animal diseases.
- Infectious diseases can be prevented by controlling both of these transmission modes.
What is the Difference Between Mechanical and Biological Transmission?
Mechanical transmission occurs when mechanical vectors such as flies pick up pathogens on the outside of their bodies and transmit them to new hosts like humans through physical contact. Meanwhile, biological transmission occurs when biological vectors such as mosquitoes and ticks carry pathogens within their bodies and deliver them to new hosts like humans through biting. Thus, this is the key difference between mechanical and biological transmission. Furthermore, mechanical transmission is a passive transmission mode, while the biological transmission is an active transmission mode.
The below infographic presents the differences between mechanical and biological transmission in tabular form for side-by-side comparison.
Summary – Mechanical vs Biological Transmission
Mechanical and biological transmission are two different types of disease transmission modes. Both transmission modes deliver pathogens to the new host through specific vectors. Mechanical transmission occurs when mechanical vectors such as flies pick up pathogens on the outside of their bodies and transmit them to new hosts like humans through physical contact. Biological transmission occurs when biological vectors such as mosquitoes and ticks carry pathogens within their bodies and deliver them to new hosts like humans through biting. So, this is the key difference between mechanical and biological transmission.
Reference:
1. Foil, Lane D., and J. Richard Gorham. “Mechanical Transmission of Disease Agents by Arthropods.” SpringerLink, Springer Netherlands, 1 Jan. 1970.
2. “10.3D: Infectious Disease Transmission.” Biology LibreTexts, Libretexts, 24 Dec. 2022.
Image Courtesy:
1. “F-diagram-01” By UNICEF Philippines and Luis Gatmaitan / 2014 / Gilbert F. Lavides – (CC BY 2.0) via Commons Wikimedia
2. “Life Cycle of the Malaria Parasite” By Bbkkk – Own work (CC BY-SA 4.0) via Commons Wikimedia