Micro-Organism Biology of Mosquitoes - Click to Solution

Question: Discuss about the Micro-Organism for Biology of Mosquitoes. Answer: Micro-organisms are living organism which is too small to be seen by naked eye and is visible under a microscope. It may be unicellular or multi-cellular or in clusters. It is present everywhere on earth and plays a significant role in maintaining the ecosystem. It helps in oxygen production, decomposition of organic material, providing nutrient to plants and marinating health. But some are pathogenic and cause disease in plants and humans. The microorganism is classified into six types according to their specific function. Each type has their own cellular composition, morphology, locomotion and production. The features of different kinds of micro-organisms are as follows: Bacteria: These are a prokaryotic unicellular organism. Its cell wall is made up of peptidoglycan, and they divide by binary fission. According to shapes, it is classified in to four types-bacillus (rod-shaped), coccus (spherical), spirilla (spiral) and Vibrio (curved shape). They locomote using flagella. It is also classified as gram positive and gram negative bacteria due to a difference in cell wall structure and a way the structure stains. According to gaseous exchange, it is divided into anaerobic, aerobic and facultative anaerobes. It is also divided into heterotrophs, autotrophs or saprophytes according to the way they utilize energy. Archaea: One feature that distinguishes archaebacteria from true bacteria is its cell wall structure. It lacks peptidoglycan in their cell wall. They can survive in adverse environmental condition. Based on these characteristics, it is divided into halophiles (living in the saline environment), thermophiles (found in extremely hot temperature), psychrophiles (living in cold-temperature) and methanogens (methane-producing organisms). They utilize different energy sources like hydrogen, carbon dioxide, and sulfur. They use sunlight using bacteriorhodopsin pigments (Madigan et al. 2012). Fungi: Fungi like mushrooms, molds and yeast are eukaryotic organisms. These are multi-cellular, and cell wall is composed of chitin. They may be decomposers absorbing organic material from environment, symbionts having a symbiotic reaction with plants and parasite harming the host. Absorption takes place by hyphae and release of spores. Protozoa: These are unicellular eukaryotes. They obtain nourishment through the specialized structure, and their cell wall is composed of cellulose. They have a whip like flagella, tiny cilia, and pseudopodia for locomotion. There is great diversity in protozoa and different means of nutrition (Lwoff 2014). Algae: Algae or Cyanobacteria may be unicellular or multicellular. They live in a damp environment and obtain nourishment by photosynthesis. Viruses: Virus is non-cellular consisting of DNA or RNA and surrounded by a protein coat. Although they are microgorganism they also behave as the non-living organism. This is because it does not reproduce outside host cells and they cannot metabolize on their own (Hattaf et al., 2012). Some microorganism is beneficial for humans while some may be harmful and cause diseases. Commensal is organism that causes no harm to host cells. The human gut contains a variety of microorganism, but there may be some bacteria in food which has a beneficial effect on health. They are commensal bacteria and have a probiotic effect. They supply the host with necessary nutrients and defend against pathogens (Kamada et al. 2013). Pathogens have a contrasting role from commensals. These are harmful microorganism responsible for the causing major diseases in humans and plants.They invade the host through different pathways and reproduce inside the host to cause different diseases (Ostfeld 2015). Microbes are present everywhere in the environment. They develop the ability to adapt to the different environmental condition. They are transmitted in the environment in various ways for their survival. Disease or infection occurs when microbes are transmitted from one person to another by coughing or sneezing. The microbes travel through the air to other person and causes diseases like common cold, flu and tuberculosis. Close contact with body parts also passes germs from one individual to others. Examples are HIV, which causes AIDS and Neisseria gonorrhea which causes gonorrhea. These microbes move to another person through sexual intercourse. Bacteria also enter the body by touching infectious materials like feces. Rotavirus and Giardia lambia are passed through this way. It may also be transmitted through droplet transmission and contamination of soil and water. Example Pseudomona aeruginosa grows in the warm and moist area (Clements 2012). Microbes gain access to entry and exit of the human body through two ways-by mucosal surface within the body such as respiratory tract, digestive or urinary tract and by epithelial surfaces such as damaged skin due to insect bites or wounds. As they enter the body, they invade and infect the host cell and then escape. Horizontal transmission takes place by body surface or through the blood stream. Vertical transmission occurs by the placenta during birth or by the colostrums. Infectious diseases are caused by microorganisms like virus, bacteria, fungi and parasites. The disease does not occur abruptly after entry into the human body. It follows a series of events which lead to the appearance of diseases. This chain consists of pathogens, mode of transmission, route of entry and a susceptible host to infect. The pathogen is the first link in the infection chain. Immune systems in the body also act to fight against the entry of foreign body. The level of exposure that leads to diseases depends on the virulence of microorganism, the resistance of host cell and amount of microorganism entering into the body. Certain groups of people are more vulnerable to infection because of weak immune systems. Example are children, elderly and immune-compromised patients (Nash et al. 2015). The chain of events includes entry of infectious agent into a susceptible host, exit, and transmission to the new host. All the events occur in chronological order for an infection to develop. The first step is colonization when microorganism enters the body, grows and multiplies. Entry occurs through wounds or oral mucosa. Some colonize at the site of entry while many migrate to cause systemic infection in different organs. The disease occurs when the immune system cannot destroy pathogen and pathogens enter the body to cause damage by release of toxins or destructive enzymes. Example-Clostridium tetani release toxins that paralyze muscles. Continuous infection occurs only when the body is not able to fight the pathogen after initial infection. For repeating any infectious cycle in the new host, pathogens have to leave existing reservoir and cause infection in the new host. Route of transmission of infection has already been discussing above. For a disease to occur, organism attache s to the target site, multiply rapidly and obtain nutrients from host cells and survive an immune attack from host cells. This multiplication of microorganisms leads to an appearance of various symptoms in the human body which helps to diagnose diseases. Example Escherichia coli causes cystitis and Clostridium tetani causes tetanus (Anderson 2013). All infection does not lead to disease because of the role of the immune system. The immune system consists of a network of cells, tissues and organs that function together to protect the body against diseases. White blood cells or leucocytes stored in spleen and bone marrow fight aginst antigen entering the body. Phagocytes engulf foreign body, and lymphocytes develop memory after initial infection to give a quick response in case of the second invasion by pathogens. B lymphocytes and T lymphocytes destroy the antigens entering into the body. When antigens are detected, it triggers the B lymphocyte to produce antibodies which bind to specific antibodies. This antibody remains in the immune system and gives a speedy response if the particular antigen is encountered again. That is why a person infected with chickenpox does not get the disease again (Parham 2014). This section will discuss logical sequence of symptoms, cause and treatment of malaria. This disease is transmitted by the bite of Anopheles mosquito. This infected mosquito carries the parasite Plasmodium vivax. When a mosquito bites any person, the parasite enters the bloodstream, travels to the liver and matures. After many days, the mature parasites enter and infect red blood cells. These parasites multiplies in the blood cell and burst out. The symptoms develop after 2-4 weeks of infection (Gazzinelli et al. 2014). Common symptoms include shivering, high fever, vomiting, nausea, headache, muscle pain, etc. The disease is confirmed by physical examination which detects enlargement of spleen or liver. The condition can be avoided by taking anti-malarial drugs and using mosquito repellents to prevent mosquito bites. The medicines for malaria are chloroquine, quinine, etc. which are active against the parasites formed in blood. Treatment also depends on the type of infecting parasit e, the area of infection and accompanying illness of the patient (Breman and OMeara 2015). From the whole study, it can be concluded that the essay gave a detailed explanation of the relationship between microorganism and diseases. It gave the feature of common types of bacteria and explained the role of commensal and pathogens. It highlighted the ways microorganisms are transmitted and their route of entry into human body to cause diseases. It discussed the chain of events that lead to the manifestation of disease symptoms starting from entry pint of the pathogen. It also gave an example of cause and treatment of one infectious disease. Reference Anderson, R.M., 2013.The population dynamics of infectious diseases: theory and applications. Springer. Breman, J.G. and OMeara, W.P., 2015. Intermittent preventive treatment for malaria in infants: moving forward cautiously [editorial].Journal of Infectious Diseases,192, pp.1869-1871. Clements, A.N., 2012.The biology of mosquitoes, Volume 3 Transmission of viruses and interactions with bacteria(Vol. 3). Cabi. Gazzinelli, R.T., Kalantari, P., Fitzgerald, K.A. and Golenbock, D.T., 2014. Innate sensing of malaria parasites.Nature Reviews Immunology,14(11), pp.744-757. 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