Biological Sciences
Modes of Transmission
Modes of transmission refer to the various ways in which infectious agents, such as bacteria, viruses, and parasites, are spread from one host to another. These modes can include direct contact, such as through touch or bodily fluids, as well as indirect contact through contaminated objects or the air. Understanding these modes is crucial for preventing and controlling the spread of infectious diseases.
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4 Key excerpts on "Modes of Transmission"
- Ram Shringar Raw, Vishal Jain, Sanjoy Das, Meenakshi Sharma(Authors)
- 2022(Publication Date)
- Apple Academic Press(Publisher)
19 ].1.3 CLASSIFICATION OF ‘MODES IF TRANSMISSION’
Microorganisms vary in size, length of time of their life cycle, or time for which they survive on surface or air. Transmission is critical for the study of epidemiology and any disease, and transmission of pathogen is complex and multifaceted [20 ]. Furthermore, not only the term ‘mode’ of transmission but also the ‘route’ of transmission is important for studying disease biology because patterns of contact differ between different populations and classes of the population depending on a variety of factors such as socioeconomic and cultural characteristics [21 ]. Poor hygienic conditions at the personal and food level, for example, due to a lack of clean water in a given area, can result in increased transmission of infection through the fecal-oral path, as in the case of Cholera. Differences in the occurrence of these diseases among different groups can also be linked to the disease’s transmission routes [22 ]. It is important to note that the two terms ‘mode’ and ‘route’ are often used interchangeably which often confuses the two concepts that are used for evaluating the process by which transmission evolves [23 ]. In general usage, ‘mode’ means the origin of anything and ‘route’ is the destination of that starting point. For example, in common usage, ‘mode’ is used for means of transport (e.g., bus, car, train, and bicycle) is easily different from, ‘route’ taken to reach their destinations (e.g., via which country, or via which specific international departure). Concerning pathogenic infections, [24 ] we can say that the ‘mode’ refers to the path taken by the pathogen to get from point A to point B, while the ‘route’ refers to the path taken by the pathogen to get from point A to point B, and includes the starting point [25 ]. Table 1.1
eBook - ePubHealth, Disease and Society
A Critical Medical Geography
- Kelvyn Jones, Graham Moon(Authors)
- 2022(Publication Date)
- Routledge(Publisher)
Examples include hookworms, which attack the wall of the intestine and feed off blood, thereby producing anaemia in the host, and the Ascaris roundworm which can be present in such numbers as to mechanically block the gut. Modes of Transmission There are five main Modes of Transmission: By air Coughs and sneezes are said to spread diseases and this they can do if the host is infected. Diseases which spread in this way include mumps, measles, chicken pox, colds and influenza (viruses) and whooping cough, diphtheria, tuberculosis (bacteria). Such diseases are easily spread and while they tend to be fairly mild childhood diseases in advanced countries, they cause about a third of all deaths in the Third World countries. By physical contact Diseases transmitted in this way include syphilis and gonorrhoea (bacteria), herpes (virus) and pubic lice (insects). Leprosy and yaws are two other diseases that fall in this category and they are estimated to affect some 10 and 40 million people respectively. By food and water Examples of diseases that spread in this way include the cholera bacillus which is transmitted by sewage-infected water, and infectious hepatitis, a viral infection of the liver. Another such disease is hookworm which is estimated to infect some 450 million people. By an insect Diseases in this category include the plague, which is produced when the Versinia Pestis is transferred to humans from the rat by blood-sucking fleas; and malaria, which results from the injection of the protozoa Plasmodium into the bloodstream by mosquitoes. It is estimated that half a billion people are at risk from this latter disease. By being there already Many organisms may be living quite happily within the host as ‘commensals’ but changes (such as other illness or drug treatment) may lead them to multiply to produce disease
No longer available |Learn more- Margaret Rodriguez(Author)
- 2016(Publication Date)
- Cengage Learning EMEA(Publisher)
115 Learning Objectives After completing the study of this chapter, the learner will be able to: 1. Define key terms. 2. Compare and contrast the three types of disease outbreak. 3. Describe various methods of disease transmission. 4. Discuss factors relating to pathogenicity. 5. Describe the non-specific host defenses in humans. Key Terms Adherence Cytopathic effects Determinants Disseminated Eradicated Helminth Homeostasis Host Hydrolyze Keratin Neurotransmitter Phagosome Phlegm Sharps injuries Surface receptors CHAPTER 9 Microbial Disease Transmission Copyright 2017 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 116 Microbiology for Surgical Technologists Disease Transmission Diseases that affect humans can come from nearly every member (eukaryotes, prokaryotes, viruses, viroids, and prions) of the classification models: Two Empires, Three Kingdoms, Tree of Life, and others. As has been discussed in preceding chapters, humans have a fundamental, intimate, and compli- cated relationship with the microbial world, both internally and externally. We rely on our individual microbiomes to maintain homeostasis and to break down foods into usable nutrient forms. Our bodies are taught how to coexist with the microbial world from our first encounter with the birth canal of our mother, inoculating us with our first microbes. The ma- jority of our total body weight is actually microbial cells. The vast majority of life on earth is microbial. It is counterintuitive, then, to consider the microbial world as our enemy, except when it actually does become just that—the enemy.
eBook - PDF- Neil A. Croll, John H Cross, Neil A. Croll, John H Cross(Authors)
- 2013(Publication Date)
- Academic Press(Publisher)
334 Α. D . Μ. Smith II. Theoretical Background A. Disease Transmission An important factor in the epidemiology of all infectious diseases is the rate at which new cases of infection are acquired by individuals in the host population. In theoretical models that seek to explain observed patterns of disease incidence within one or more host populations, it is the transmission term that describes the rate at which susceptible individuals in the population acquire infection. Since the early theoretical work of Ross (1911) and Kermack and McKendrick (1927), it has invariably been assumed that the transmission term in models for directly transmitted infectious diseases is of the form βΧΚ, where X and Y represent, respectively, the number (or the density) of susceptible and infectious individuals in the population and where β is some ''transmission coefficient.'' There are a number of key behavioral assumptions underlying this form of the transmission term. One of the most important assumptions is that the population is ''closed, that is, there is no immigration of infectious individuals. The population is also assumed to be homogeneous and freely mixing, so that there is a constant probability of contact between any two individuals in the popula-tion in any given period of time. Thus the actual rate of contact for any one Black, 1966) and on isolated hunter-gatherer societies (Black, 1980; McNeill, 1980). Nevertheless, behavioral factors clearly must be important in determining regional and national patterns in disease incidence and transmission. Moreover, for a number of the directly transmitted diseases, but especially for the common childhood diseases (such as measles, whooping cough, diphtheria, and scarlet fever), compulsory notifications coupled with high levels of incidence and na-tional recording at relatively fine spatial scales provide a good data base from which to explore some of the behavioral factors underlying disease transmission.
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