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Enteric viruses primarily infect the intestinal tract through ingestion of food and water contaminated with viruses of fecal origin. Some viruses can be transmitted through all three routes of transmission. Water virology started about half a century ago when scientists attempted to detect the polio virus in water samples. [3]
Since viruses are obligate intracellular parasites they must develop direct methods of transmission, between hosts, in order to survive. The mobility of animals increases the mechanisms of viral transmission that have evolved, whereas plants remain immobile, and thus plant viruses must rely on environmental factors to be transmitted between hosts.
Fecal–oral transmission is primarily considered as an indirect contact route through contaminated food or water. However, it can also operate through direct contact with feces or contaminated body parts, such as through anal sex. [19] [20] It can also operate through droplet or airborne transmission through the toilet plume from contaminated ...
Cross-species transmission is the most significant cause of disease emergence in humans and other species. [citation needed] Wildlife zoonotic diseases of microbial origin are also the most common group of human emerging diseases, and CST between wildlife and livestock has appreciable economic impacts in agriculture by reducing livestock productivity and imposing export restrictions. [2]
This specificity restricts the virus to a very limited type of cell. For example, the human immunodeficiency virus (HIV) infects only human T cells, because its surface protein, gp120, can only react with CD4 and other molecules on the T cell's surface. Plant viruses can only attach to plant cells and cannot infect animals.
In most plant pathosystems, virulence depends on hydrolases and enzymes that degrade the cell wall. The vast majority of these act on pectins (for example, pectinesterase, pectate lyase, and pectinases). For microbes, the cell wall polysaccharides are both a food source and a barrier to be overcome.
Vehicle transmission, transmission by an inanimate reservoir (food, water, soil). [32] Vertical transmission, directly from the mother to an embryo, fetus or baby during pregnancy or childbirth. It can occur as a result of a pre-existing infection or one acquired during pregnancy. Iatrogenic transmission, due to medical procedures such as ...
A human pathogen is a pathogen (microbe or microorganism such as a virus, bacterium, prion, or fungus) that causes disease in humans.. The human physiological defense against common pathogens (such as Pneumocystis) is mainly the responsibility of the immune system with help by some of the body's normal microbiota.