Smallpox Survivors - Cause - Transmission

Transmission

Transmission occurs through inhalation of airborne variola virus, usually droplets expressed from the oral, nasal, or pharyngeal mucosa of an infected person. It is transmitted from one person to another primarily through prolonged face-to-face contact with an infected person, usually within a distance of 6 feet (1.8 m), but can also be spread through direct contact with infected bodily fluids or contaminated objects (fomites) such as bedding or clothing. Rarely, smallpox has been spread by virus carried in the air in enclosed settings such as buildings, buses, and trains. The virus can cross the placenta, but the incidence of congenital smallpox is relatively low. Smallpox is not notably infectious in the prodromal period and viral shedding is usually delayed until the appearance of the rash, which is often accompanied by lesions in the mouth and pharynx. The virus can be transmitted throughout the course of the illness, but is most frequent during the first week of the rash, when most of the skin lesions are intact. Infectivity wanes in 7 to 10 days when scabs form over the lesions, but the infected person is contagious until the last smallpox scab falls off.

Smallpox is highly contagious, but generally spreads more slowly and less widely than some other viral diseases, perhaps because transmission requires close contact and occurs after the onset of the rash. The overall rate of infection is also affected by the short duration of the infectious stage. In temperate areas, the number of smallpox infections were highest during the winter and spring. In tropical areas, seasonal variation was less evident and the disease was present throughout the year. Age distribution of smallpox infections depends on acquired immunity. Vaccination immunity declines over time and is probably lost in all but the most recently vaccinated populations. Smallpox is not known to be transmitted by insects or animals and there is no asymptomatic carrier state.

Read more about this topic:  Smallpox Survivors, Cause

Other articles related to "transmission":

Transmission - Media
... Transmission (album), the fourth album by the Canadian band The Tea Party Transmission (band), an experimental/post-rock band based in the United ...
Blood-borne Disease
... seeks to minimize this sort of disease transmission ... treat blood components prior to their transfusion, and can reduce the risk of disease transmission ... of platelet and plasma components to prevent transmission of blood-borne diseases caused by bacteria, viruses, and protozoa ...
VTi Transmission
... The VTi is a continuously variable transmission for automobiles ... ended in 2005 in favor of the GM-Ford 6-speed automatic transmission ... In 2004 GM extended the transmission's warranty on all 2002 - 2004 GM vehicles with the VTi to 5 years / 75,000 miles (120,700 km) due to high failure rates ...
Hydro-Québec - Activities - Transmission System
... TransÉnergie, Hydro-Québec's transmission division, operates the largest electricity transmission network in North America ... TransÉnergie's network, upon payment of a transmission fee ... the United States by 17 ties, with a maximum reception capacity of 10,850 MW and a maximum transmission capacity of 7,994 MW ...
Locomobile Company Of America - Switch To Internal Combustion Engines
... A 3-speed sliding transmission was fitted, as on the Système Panhard cars it competed with ... a 17.7-liter (1080ci) racer after suffering a transmission gear failure, and with no spare available, driver Joe Tracy only managed two circuits of Auvergne ...