Difference Between Parasite and Bacteria

Parasites are living organisms that completely rely on other organisms for food. The organisms that they use for their living are called Hosts.

Parasite vs Bacteria

The main difference between parasites and bacteria is that the Parasite needs a living organism as a host to survive and get their needs fulfilled from whereas the Bacteria may or may not need a host. Bacteria can also survive in environmental conditions with harsh surroundings.

Parasite vs Bacteria

Parasites seek nourishment and shelter on their and exists in a symbiotic relationship with them. The organism acting as host is generally a different species and is much bigger than Parasites in size.

Bacteria are single-celled organisms that live and reciprocate in great numbers. Bacteria lacks membrane and the nuclear material inside it is scattered within the cell.

Comparison Table Between Parasite and Bacteria

Parameters of ComparisonParasiteBacteria  
Cell StructureIt possesses well-bounded cellular walls. The nucleus is enclosed within nuclear walls so that the material does not lie scattered.It does not have distinct organelles or a well-defined nucleus. It is a simple cell with scattered nuclear matter.
Number of CellsIt is mostly multicellular (except protozoa) and is categorized under Eukaryotes due to its complex cell structure.It is unicellular and is categorized under Prokaryotes due to its primitive cell structure.
Need of HostIt needs a host to survive. It can exist inside or outside the host but has to be connected to it.It might or might not need a host and derive the food from the surroundings, can exist inside or outside a body or even on the surfaces.
SizeThey are bigger in size and can be seen through naked eyes.It is smaller in size and some of them are microscopic.
Nature of the OrganismThey are always pathogenic. They can replicate inside or outside host but exist when they are few in number.They can be sometimes harmful but mostly beneficial. They exist in millions and form colonies.

What is Parasite?

Parasites are organisms that exist in symbiosis with another organism as host to seek food and shelter from them for survival. This symbiotic relationship is beneficial to parasites but harmful to the host.

Protozoa and Helminths affect the human body by affecting the guts and the gastrointestinal system causing problems like Diarrhea, abdominal cramps, and fatigue.

Helminths are also known as worms and do not multiply inside the human body. They are further classified as flatworms, roundworms, and hookworms.

Ectoparasites like ticks, lice, fleas, and mites get attached to the skin and live their for a prolonged period causing itchiness. These diseases by parasites can be prevented by improving sanitation and cleanliness at places.

What is Bacteria?

Bacteria is the most primitive form of life existing in nature. They can survive in any ecological condition and might or might not need a host to survive.

Some species of bacteria are pathogenic and can cause infectious diseases like cholera, syphilis, and also some respiratory diseases that might prove fatal.

It also plays a key role in the mining sector to recover metals like gold, copper, and palladium. It can convert biomass into bioenergy by decomposition of organic matter into usable energy.

Main Differences Between Parasite and Bacteria

  1. Parasites are larger in size and are visible through naked eyes. Bacteria are small in size and some of them are microscopic.
  2. Parasites are always pathogenic. They can replicate inside or outside host but exist when they are few in number. Bacteria can be sometimes harmful but mostly beneficial. It exist in millions in number and form colonies.
Difference Between Parasite and Bacteria


Parasites and Bacteria both can harm human body under some circumstances so as a preventive measure, one is always advised to keep their surroundings clean and maintain proper sanitation and hygiene.

Bacteria is considered to be most primitive form of life and it exists everywhere that our human minds can think of. It is involved in almost every process and is capable of nourishing itself from any organic and some inorganic compounds.

When parasites get attached to animal or human body they live there for prolonged periods causing irritation and in some cases rupturing the internal tissues as they use the body as per their need which proves to be harmful for the other one.  


  1. https://doi.org/10.1016/S0020-7519(96)80070-1
  2. https://doi.org/10.1146/annurev.micro.55.1.105

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