Introduction: Diseases can be communicable or non-communicable. Communicable diseases are caused by infectious microorganisms which are pathogens. The aim of this passage is to discuss various types of microorganisms that cause disease. Microorganisms are simple organisms that are unicellular or live in colonies. The group contains bacteria, virus, algae, fungi, protozoa. They can be divided into pathogenic and non-pathogenic. In this passage pathogenic microorganisms that cause diseases are concerned. A disease is an abnormal condition affecting the body of an organism.
Some of them called infectious diseases such as common cold, influenza, etc. Pathogenic microorganisms: SARS coronavirus SARS coronavirus is an air-borne virus causes a respiratory disease in humans called Severe Acute Respiratory Syndrome (SARS). It transmits by riding on dust particles or small respiratory droplets and staying suspended in air and travel distances on air currents. SARS coronavirus is large, pleomorphic and spherical shape and consist of a single stranded of RNA. On the surface, it has bulbous surface projections.
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Its lipid envelop appears to consist of a distinct pair of electron dense shells. In order to infect a host, its replication takes place in the cytoplasm in a membrane-protected microenvironment. It incorporates the viral genetic materials into the host’s cells. Translation of the genome then takes place to produce the viral replicase. Viral replicase catalyzes that replication to produce new viral particles which move on to infect other cells. Different coronaviruses cause different transcription and translation patterns in the host.
The symptoms of SARS include fever of 38 ??C, Myalgia, lethargy, gastrointestinal symptoms, cough, sore throat, etc. Vibrio cholerae Vibrio cholerae is a water borne bacteria causes Cholera and transmits by being carried in water or contaminated food such as shellfish and plankton to get into human bodies. Vibrio cholerae is gram negative and comma-shaped. It has a polar flagellum and is composed of two circular chromosomes of unequal size. The bacteria get into human body by enter the alimentary canal.
Normally most of the bacteria will be killed by gastric juice in stomach but some of them are still able to survive. Vibrio cholerae is one of them which conserved energy and stored nutrients before arrives small intestine. They produce hollow cylindrical protein flagellin to make flagella as to propel themselves through the thick mucus that lines the small intestine. They also produce the toxic proteins which is made up of six protein subunits and the five B subunits binds to GM1 gangliosides on the surface of the intestinal epithelium cells.
The complex taken into the cell via receptor-mediated endocytosis Rapid dehydration is caused by further metabolism in the cell cause secretion of H2O, Na+, K+, Cl? , and HCO3? into the lumen of the small intestine and causing diarrhea The symptoms of cholera include diarrhea, dehydration, electrolyte imbalances, vomiting of clear fluid, poor skin turgor, sunken eyes, rapid pulse, etc Dengue virus Dengue virus is an insect-borne virus causing Dengue fever. It is transmitted by Aedes(Stegomyia) aegypti or Aedes albopictus mosquito , especially transmitted through the bites of the female striped Aedes aegypti mosquito (female).
Dengue vitrus is an single-strand RNA positive strand virus, contains a genome of abut 11000 bases that codes for three structural proteins and seven non-structural proteins which causes the disease. There are two types of life cycles, sylvatic and epidemic. The Dengue virus infect and replicate within humans and domesticated Aedes species. Initially it replicates in target organs like the liver, spleen, and thymus, then it eventually replicates in the lymphatic system. The symptoms of Dengue fever include headache, fever, exhaustion, severe muscle and joint pain, swollen glands, rash.
Helicobacter Pylori Helicobacter Pylori is a bacteria that causes inflammation on gastric cells. It also alters the secretion of gastrin, which in turn affect the production of gastric acid, in either increase or decrease in acid secretion. In case of increase acid secretion, peptic ulcer (duodenal ulcer and gastric ulcer) arise. In case of decrease acid secretion, Gastric adenocarcinoma arise. Also, a number of other extra intestinal diseases. Generally it transmit from person to person through gastro-oral, faeco-oral or oro-oral routes, likely through drinking water or food.
It is a spiral-shaped gram negative bacterium, have 4-6 unipolar flagella. Microaerophilic which grow in desire condition of 5%O2. Helicobacter Pylori colonizes the antral mucosa, as the gastric wall protect itself from the highly acidic gastric acid by the thick mucosa, the Helicobacter Pylori is inacessable to immune attack. It introduce gastric inflammation by urease which is toxic to human gastric epithelial cells by stimulating phagocytes activation and cytokine production.
It also produces chronic active gastritis, resulting in a defect in the regulation of gastrin, gastrin stimulate the production of gastric acid. The increase in acid production disrupt gastric mucosal barrier. Helicobacter Pylori cause peptic ulcer, which have symptoms like abdominal pain, bloating and abdominal fullness, waterbrash which is rush of saliva to neutralize the excess acid, vomiting, loss of weight, hematemesis which is vomiting of blood if some of the cells are disrupted. In some extreme cases, gastric or duodenal perforation because of some cells break down by acid.