Introduction.
Infectious and non-infectious diseases spread to affect the body through various means.
Infectious diseases usually spread from person to person or animal to animal and are
transmitted by bacteria, parasites, viruses, fungi or protozoa. Non-infectious diseases such
as cancer cannot be caught and usually because of environmental factors or genetics.
These diseases cause an abnormality condition that negatively affects the function or
structure of a part of an organism that is not because of external injury.
Causes of Infectious diseases
Bacteria.
Bacteria is small, only a few micrometres, and they have an extensive range of different
shapes; they are unicellular; they also don't haven't membrane-bound membrane organelles
or a nucleus. Some bacteria structure may also contain a double cell wall or thick slime
capsule. Many bacteria are beneficial to the human body. However, some can be dangerous
beers are called pathogenic and are formed into two groups gram-positive or gram-negative.
Gram-negative bacteria are severe and antibiotic-resistant pathogens, proving a challenge in
the healthcare system; gram-positive bacteria can be treated with antibiotics. Bacteria
reproduce very rapidly and cause damage to the cells around the human body. Scientists
can identify if a pathogen is bacteria by performing tests and specialised tests on the
pathogen. These could be antibiotic inhibition patterns or using newer technology by
sequencing their DNA directly from a specimen. The life cycle of bacteria is split into four
sections. In the lag phase, where the bacteria do not grow but become acclimated to the
surroundings and produce vital chemicals needed during division, the bacteria also make
copies of their DNA during this time. The second phase, or the log phase, is where the
bacteria multiply rapidly; this can take as quickly as 15 minutes. The third stage is known as
the stationary phase, where the growth of bacteria declines, and death rates are equal to
bacteria development. Finally, the fourth phase, also known as the death phase, is where the
bacteria lose the ability to reproduce. (1)(2)
Salmonella is a bacteria-caused disease.
,Salmonella is the bacteria that causes food poisoning, and the symptoms of this are usually
stomach cramping, nausea and vomiting; another symptom could also be diarrhoea. People
often get food poisoning from salmonella because of undercooked meats or eggs such as
Poultry. You can also get salmonella poisoning from foods that have not been appropriately
reheated after cooking, such as rice. In the UK, all poultry are vaccinated against salmonella;
it is crucial to prepare poultry dishes carefully to avoid food poisoning from salmonella.
Salmonella is gram-negative bacteria. The symptoms mentioned above can last several
days salmonella makes the body so sick because once salmonella enters the body, the
bacteria infects the epithelial cells inside the intestines. Bacteria then confuses the host
cells inside the epithelial tissue, allowing the bacteria to enter into other cells. Once inside
the epithelial tissue of the intestines. Bacteria rapidly multiply inside the membrane-bound
vacuoles of other organelles; the bacteria causes the disease by excreting toxins which
happens when the bacteria disintegrate which in turn can damage healthy tissues which
make you sick however, the human immune system can fight off salmonella using
neutrophils and macrophages. (3)
Viruses
Viruses are small all infectious agents that replicate only inside a living organism. They can
affect all types of life forms, including bacteria; they also have no nucleus; they are tiny in
size; an example of a virus is the flu—strains of viruses often identified by their DNA which is
surrounded by a protein. The identification and sequencing of a virus DNA are done in a
laboratory. Each virus has different DNA; when the virus changes, this is usually identified by
the change in the virus’s DNA. When treating a virus, antibiotics do not cure or treat the
disease; a vaccine is needed to treat the virus and restrict the virus’s spreading. The life
cycle of a virus is similar to other pathogens, where the virus can often survive outside a
host for a long time. They infect cells or host cells and replicate themselves inside several
times; however, they do not divide and reproduce but replicate the DNA and the protein
coats of the DNA. This causes the host cell to burst, and then the other cells, and by
becoming infected with the disease, can be a fast process in the norovirus or several days in
ebola. (4)
HIV/AIDs a viral disease
, HIV is transmitted through bodily fluids; this can be through unprotected sex, shared needle
usage when injecting drugs, and cuts. Usually, after that infection of the virus, people suffer
mild flu-like symptoms; however, this passes, and then people generally do not know that
they are infected with the virus. HIV, which is the virus, develops when not treated into
AIDS; this disease attacks the immune system.The life cycle of a virus mainly depends on
the different values of reproduction of a cell and the metabolic processes of the virus most
viruses by themselves do not carry all the information for replication but once inside a host
cell a virus can command different organelles to produce more viral particles some viruses
only replicate inside the cytoplasm if the cell does not have a nucleus or other organelles
which needed however most of the time and eukaryotic cells the DNA of the virus can
replicate inside the nucleus.Is process of the DNA replicating inside a cell usually disrupts
the cell function and either continues disrupting them or kills the cells this in turn makes the
bodies respond with a fever which may help activate viruses as well as specialised
chemicals are released which help block viruses reproducing within cells usually after this
the immune system makes and releases antibodies to target the virus.In HIV this can
happen after months or years of infection of the virus; there is no cure for AIDS or HIV,
although many people are still trying to find a cure. Infected people are usually given antiviral
drugs that slow the development of the disease in the UK; between 0.1% and 0.5% of the
population have AIDS. HIV infects and attacks the body by attacking the t cells in the
immune system. When these t cells are attacked, the person’s immune system is affected,
and it is harder to fight off a common cold, for example. Not only are the T cells attacked,
HIV also uses them to replicate the virus. Once the virus has destroyed a certain number of
T cells and the number of T cells in a person drops below 200, HIV has now progressed to
AIDS. (5)
Fungi
Fungi can come in all different types, such as yeast, mould and mushrooms. Fungi are a
different Kingdom from other living things and are different from animals and plants, they are
eukaryotic, and the cell walls are not made from cellulose. The study of the effects of fungi in
humans is called medical mycology. Recognising a fungus can be easy, and similarly,
bacteria can be viewed under a microscope. Staining of a sample may need to be conducted
and other tests such as blood tests to rule out superficial infections may need to be
performed on the patient before concluding if it is a fungus. The life cycle of fungus can
either be asexual or two sexually reproducing fungus; in the life cycle of sexually reproducing
fungus, two stages alternate the haploid stage where nuclear fusion ends the diploid phase,
which ends with the formation of a zygote. With two sexually reproducing fungus, the
reproduction and the formation of a zygote always are followed by mitosis immediately.
When reproducing asexually, the cycle consists of producing mitospores, leading to
reproduction; many fungi will reproduce asexually before reproducing sexually. However,
some fungi may only reproduce asexually, and some may produce only sexually, although
the most common way is first and more often reproducing asexually and then reproducing
sexually. (6)
