How Microorganisms Cause Disease
Microbes or Microorganisms – Diseases Caused by include diarrhea, blindness, inflammation of the brain, and pneumonia among others. Microorganisms and Disease. How does the human body and various microorganisms interact in terms of disease? Infectious Disease. skin, mucous. A fundamental gap in disease ecology and microbiome research has yet they have a similar relationship between the microbiome and Bd.".
From plant to plant by insects that feed on plant sap. For example, Potato virus Y which is spread by aphids.
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From animal to animal by blood-sucking insects. For example, Dengue virus which is spread by mosquitos. Spread by aerosols through coughing and sneezing.
For example, influenza virus.
Diseases Caused by Microorganisms | PMF IAS
Spread by not washing hands after going to the toilet. For example, norovirus or rotavirus. Spread by sexual contact. Spread by exposure to infected blood. For example, Hepatitis B. Viruses can often be prevented through vaccines. Bacteria Bacteria are single-celled microorganisms.
Most bacteria are not harmful and some are actually beneficial.
Less than one per cent of bacteria will actually make you ill. Infectious bacteria can grow, divide and spread in the body, leading to infectious disease.
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Some infectious bacteria give off toxins which can make some diseases more severe. This is why you develop a rash from the measles virus a single stranded RNA virus of Morbillivirus genus or why your throat hurts so much when you have strep throat Streptococcus pyogenes. Each pathogen attacks specific cells that disrupt processes which then produce specific symptoms. Soon after the initial time of infection, many pathogens are destroyed through natural immune responses by the body.
The pathogen may be engulfed phagocytized by specialized white blood cells or made inactive by antibodies in the blood. Inflammation of tissues is triggered by the presence of a pathogen and may keep the infection localized. Keeping the infection contained allows more specific immune responses time to develop and fight the infection.
What happens if it is NOT contained? If a pathogen invades host body cells, multiplies, and is not contained, it can cause the host cell to burst and release even more pathogens into the body.
These then move to susceptible body cells and continue to multiply.
Enzymes help some pathogens invade the cells and help with the spread from the initial site of infection to other areas of the body. Other enzymes kill white blood cells that would have destroyed the pathogen. These processes result in the infection spreading throughout the body causing disease. The image of the microscopic slide at the right shows a gonococcal infection the small pink round-shaped bacteria cultured from a urethra.
The bacteria on this slide are both inside and outside the white blood cells shown. A microscopic slide of a gonococcal infection, pink round-shaped bacteria. Wikimedia This image shows the Gram-positive, rod-shaped Bacillus anthracis, the bacterium that causes anthrax.
The round, nucleated cells on the slide are white blood cells. Wikimedia Once pathogens are inside body cells, they cause disease by destroying cells and disrupting tissue and body functions. Some bacteria produce exotoxins—a poisonous substance that is released into cells. Examples of bacteria that produce exotoxins include Clostridium botulinum that produces botulism, Corynebacterium diphtheria which produces diphtheria, and Clostridium tetani which produces tetanus.
These bacteria can be fought by a variety of immune system factors, but sometimes the exotoxin is so poisonous that it is deadly to the host before the immune system can destroy it. Other bacteria produce exotoxins—poisons that are part of the bacterial cell well.
Unlike endotoxins, endotoxins are not released from the bacteria until the bacteria adhere to the surface of a body cell. Bacteria that secrete endotoxins include E. Viruses Digitally-colorized scanning electron micrograph showing filamentous Ebola virus particles.
What are infectious diseases?
It is possible that a virus that did not previously infect a human suddenly seems to have that capability. Scientists think that the likelihood of a virus jumping species is a combination of exposure factors and how closely related the species are. Viruses also cause infectious disease. Their structure consists of a protein coat wrapped around a nucleic acid core—its genetic material. They cannot replicate outside a living host cell.
Each type of virus can only reproduce inside certain hosts. For example, some viruses infect only humans, while others infect only dogs.
In order to infect a body cell, viruses chemically attach to the host cell. Viral DNA or RNA interferes with host genetic material and redirects the cell to produce copies and form new virus particles.
The reproduced viruses are released from the cell, usually when the cell ruptures and is destroyed. The new virus particles spread to other cells, the process is repeated, and infection and disease result.
Clearly, pathogens are not without their defenses and specialized ways of managing their spread throughout the body. Their structure may be simple, but they are not simple in their response mechanisms and the consequences to their invasion of the body can be lethal.
Check Your Understanding Describe transmission methods that allow pathogenic microorganisms to enter the body? How do microbes cause disease?