Читать книгу Principles of Virology, Volume 2 - Jane Flint, S. Jane Flint - Страница 97

Particles of enteric and hepatic viruses that are shed into the intestine and transmitted via a fecal route are generally more resistant to inactivation by environmental conditions than those released at other sites. Viruses transmitted by fecal spread usually survive dilution in water, as well as drying. An important exception is hepatitis B virus, which is shed in bile that is released into the intestine, but is inactivated as a consequence and therefore not transmitted in feces.

Inefficient sewage treatment or its absence, contaminated irrigation systems, and the use of animal manures are prime sources of fecal contamination of food, water supplies, and living areas. Any one of these conditions provides an effective mode for continual reentry of these viruses into the alimentary canals of new hosts, the so-called “fecal-oral route.” Two hundred years ago, such contamination was inevitable in most of the world, as disposal of human feces in the streets was a common practice. Communities downstream of sites of defecation and waste removal used contaminated water for cooking and drinking. With modern sanitation, the fecal-oral cycle has been largely interrupted in developed countries, but it remains a major cause of viral spread throughout the rest of the world.