VIRUSES have been around humans for ages now. These cause a wide range of infections like HIV-AIDS, Herpes, Rubella, Rabies, Hepatitis etc.
But VIRUSES ARE VERY DIFFERENT FROM BACTERIAS.
Let us see what are the PROPERTIES OF VIRUSES that make them different from bacterias.
In the end we have discussed some epidemics and pandemics caused by viruses
What other epidemics do you remember that we’re caused by viruses ? Mention them in the comment below.
VIRUS differs from BACTERIA in following ways–
- VIRUS are amongst the SMALLEST DISEASE CAUSING AGENTS
- they range from sizes 20-300 nano meter
- bacterias are larger than virus
- VIRUS are NOT VISIBLE in SIMPLE or LIGHT MICROSCOPES
- this is due to their minute sizes
- bacterias are visible in light microscopes and hence are easy to isolate and identify in the laboratories
- VIRUS easily FILTER THROUGH MOST FILTERS
- this is again due to their small sizes
- bacteria can not be filtered because of their large sizes
- VIRUS DO NOT HAVE PROPER ORGANIZED CELL
- bacterial cell contains various organelles, and each performs a specific function. This helps in proper functional organization.
- for example- ribosomes for protein synthesis, lysosomes for phagocytosis
- such organelles are absent in viruses
- VIRUS CAN NOT GROW ON THEIR OWN
- these RESIDE and GROW INSIDE cells of other living organism
- this is beacause, these do not contain necessary enzymes for protein and nucleic acids
- hence they NEED a LIVING CELL to REPRODUCE and SURVIVE
- this is the reason why when something is isolated for a certain time, the virus on it dies
- VIRUS possess either DNA or RNA, never both
- bacteria contain DNA inside the nucleus
- VIRUS MULTIPLY / GROW by COMPLEX MECHANISMS
- bacteria grow by processes such as mitosis and mieosis
- virus multiplication process includes process like adsorption, penetration, uncoating, biosynthesies, assembly, maturation and release
- VIRUS CAN NOT be GROWN ON CULTURE MEDIAS
- unlike bacteria that can be grown in artificial medias and examined under light microscope
- VIRUS DO NOT RESPOND to ANTI-BIOTICS
- only bacterial infections can be treated using anti-biotics
- antibiotics are given in some stages of viral infections mainly to protect from secondary bacterial infection and can not do any harm to the virus.
Medical science is full of exceptions. Similarly there are some exceptions to many points stated above.
Viruses have been responsible for various epidemics that have occurred in past at various locations in world!
- INLFUENZA VIRUS-
- SWINE flu-2009
- AVAIAN flu
These are a group of virus which primarily infect animals and birds. Found rarely in humans. But some types of corona viruses have been a reason for epidemics and pandemics. When these infect humans, these primarily cause upper respiratory tract infections and gastro-intestinal infections.
CORONAVIRUSES have caused 2 epidemics and 1 pandemic so far in the history-
- SARS-COV (severe acute respiratory syndrome coronavirus)
- 1st recognised in China in 2003.
- this affected 2 countries and caused more than 700 deaths
- MERS-CoV (middle East respiratory syndrome coronavirus)
- 1st recognised in Saudi Arabia in 2012
- caused epidemic in Arabian peninsular region
- 1st recognised in China in 2019
- caused a pandemic affecting almost all countries in world
- Check out – various testing methods of coronavirus
What other epidemics or pandemics caused due to viruses do you remember? Mention them below
That’s all for this topic !!
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- HARRISON 19th edition
- apuba sastry’s essential of Medical Parasitology
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