Clarification on Transmission of Disease

[Mt_Rider]

Just some terms to define so that we can make informed choices on the level and method of protection we choose.

 

From Wikipedia

http://en.wikipedia.org/wiki/Transmission_(medicine)

 

Transmission (medicine)

From Wikipedia, the free encyclopedia

In medicine, transmission is the passing of a disease from an infected individual or group to a previously uninfected individual or group. The microorganisms (bacteria and viruses) that cause disease may be transmitted from one person to another by one or more of the following means:

 

droplet contact - coughing or sneezing on another person

direct physical contact - touching an infected person, including sexual contact

indirect contact - usually by touching soil contamination or a contaminated surface

airborne transmission - if the microorganism can remain in the air for long periods

fecal-oral transmission - usually from contaminated food or water sources

vector borne transmission - carried by insects or other animals

 

Microorganisms vary widely in the length of time that they can survive outside the human body, and so vary in how they are transmitted.

 

 

{red is mine} As you can see, there is a HUGE difference in ability of a virus to be transmitted if it is droplet contact [you have to be within range of the cough...] or actual AIRBORNE transmission [its running thru ventilations systems, etc]

 

Airbone means it is in aerosol form and it will "fly".

 

Droplet is heavy and will sink with gravity down to surfaces..... Naturally that is where you get "indirect surface contact" transmissions. Then you have to know how long a particular virus/bacteria will remain alive on a surface. Factors like sunshine, heat, cold, moisture or lack of, etc will cause variations in this answer and THIS is important cuz then you have clues on how you kill it. [besides Lysol, etc]

 

 

 

MtRider [Part One cuz the danged program won't allow me to post more than ONe quote at a time... ]

[Mt_Rider]

A bit more information from same site [above]:

In transmission, a locus is the point on the body where a pathogen enters.

 

In droplet contact and other airborne transmission it is generally the respiratory system

In direct physical and indirect contact it is generally through a wound in the skin or through a mucous membrane

In fecal-oral transmission, it is through the mouth.

In vector borne transmission, it is at the bite or sting of the vector.

 

MtR

[Mt_Rider]

OK, so with that in mind, here's the pandemicflu.gov site information on the transmission of microbes [bacterial/viral]:

 

http://www.pandemicflu.gov/plan/healthcare...cehc.html#modes

 

Modes of Influenza Transmission

 

Influenza is transmitted person to person through close contact. Transmission occurs through multiple routes, including large droplets and direct and indirect contact. Fine droplet inhalational transmission may also occur.

 

Most information on the modes of influenza transmission from person to person is indirect and largely obtained through analysis of outbreaks in health care facilities and other settings (e.g., cruise ships, airplanes, schools, and colleges). Although the knowledge base is limited, the epidemiologic pattern observed is consistent with transmission through close contact (i.e., exposure to large respiratory droplets, direct contact transfer of virus from contaminated hands to the nose or eyes, or exposure to small-particle aerosols in the immediate vicinity of the infectious individual [known as “short-range exposure to aerosols”]). The relative contributions and clinical importance of the different modes of influenza transmission are unknown. While some observational studies (1, 2) and animal studies (3, 4, 5) raise the possibility of short-range airborne transmission through small-particle aerosols, convincing evidence of airborne transmission of influenza viruses from person to person over long distances (e.g., through air-handling systems, or beyond a single room) has not been demonstrated. (6, 7, 8). However, one study in mice performed in a room outfitted with a slowly rotating fan to continuously agitate the air found that influenza virus sprayed into the room remained infective for some mice for extended periods (up to 24 hours) at room atmospheres of low humidity (17 to 24%). Room atmospheres with higher humidities into which virus suspension was sprayed were no longer infective in mice after one hour (3).

 

Droplet Transmission

 

Droplet transmission involves contact of the mucous membranes of the nose or mouth or the conjunctivae of a susceptible person with large-particle droplets containing microorganisms generated by an infected person during coughing, sneezing, or talking. Transmission via large-particle droplets requires close contact between source and recipient persons because these larger droplets do not remain suspended in the air and generally travel only short distances. Three feet has often been used by infection control professionals as a guide for “short distance” and is based on studies of respiratory infections (9, 10); however, for practical purposes, this distance may range from three to six feet. Special air handling and ventilation are not required to prevent droplet transmission.

 

On the basis of epidemiologic patterns of disease transmission, large droplet transmission—via coughing and sneezing—has traditionally been considered a major route of seasonal influenza transmission (7, 8).

 

>>Airborne Transmission

 

Airborne transmission occurs by dissemination of small particles or droplet nuclei through the air (see Appendix A: Aerosol Science and Disease Transmission). Some organisms (e.g., Mycobacterium tuberculosis, measles virus, and varicella [chickenpox] virus) can remain infectious while dispersed over long distances by air currents, causing infection in susceptible individuals who have not had face-to-face contact (or been in the same room) with the infectious individual. Special air handling and ventilation systems (e.g., negative-pressure rooms or airborne isolation rooms) are used in health care settings to assist in preventing spread of agents that may be dispersed over long distances.

 

In contrast to tuberculosis, measles, and varicella, the pattern of disease spread for seasonal influenza does not suggest transmission across long distances (e.g., through ventilation systems); therefore, negative pressure rooms are not needed for patients with seasonal influenza (6, 8). However, localized airborne transmission may occur over short distances (i.e., three to six feet) via droplet nuclei or particles that are small enough to be inhaled. The relative contribution of short-range airborne transmission to influenza outbreaks is unknown.

 

Several often-cited papers raise concern about short-range aerosol transmission as a possible route of spread for influenza. These include laboratory studies in animals ( 3, 4, 5, 11), observational studies during the 1957-58 influenza pandemic (1), and an epidemiologic study of transmission on an airplane with an inoperative ventilation system (2). An experimental study in which the infectious dose of influenza virus was found to be as much as 100-fold lower for persons infected with small aerosols than with nasal drops (12) has further raised this concern. Although data are limited, the possibility remains that short-range aerosol transmission is a route of influenza transmission in humans and requires further study (13).

 

Aerosol-Generating Procedures

 

It is likely that some aerosol-generating medical procedures (e.g., endotracheal intubation, open suctioning, nebulizer treatment, bronchosocopy) could increase the potential for generation of small aerosols in the immediate vicinity of the patient. Although this mode of transmission has not been evaluated for influenza, given what is known about these procedures, additional precautions for health care personnel who perform aerosol-generating procedures on influenza patients are warranted.

 

Contact Transmission (Direct and via Fomites)

 

Contact transmission of influenza may occur through direct contact with contaminated hands, skin, or fomites followed by auto-inoculation of the respiratory mucosa. Influenza transmission via contaminated hands and fomites has been suggested as a contributing factor in some studies (14). There are insufficient data to determine the proportion of influenza transmission that is attributable to direct or indirect contact. However, it is prudent to reinforce recommendations for thorough and frequent handwashing, which is known to reduce the likelihood of contamination of the environment and to reduce transmission of respiratory infections (15, 16, 17). Surgical mask or respirator use may provide an additional benefit by discouraging facial contact and subsequent autoinoculation.

 

Pathogenesis of Influenza and Implications for Infection Control

 

Human influenza is a disease of the respiratory tract. Influenza virus infects respiratory epithelial cells via receptors found principally in non-ciliated cells of the upper respiratory tract; infection also can occur in the lower respiratory tract (18, 19). There is no natural or experimental evidence that human seasonal influenza virus infection of the gastrointestinal tract can occur.

 

While conjunctivitis may be associated with human infection with some avian influenza viruses (20, 21), ocular infection does not appear to be a primary route for transmission of human influenza viruses, although data are very limited. Nonetheless, it is prudent to prevent exposure of the eyes as well as the mucous membranes of the respiratory tract to possibly infectious material (e.g., as may occur when health care workers perform splash-generating procedures).

{snip}

{colors are mine}

 

OK, there is more there if you want to read the whole thing. But if I'm understanding this, it's saying that influenza generally does not have the "airborne" designation except in a very limited range. It drops fairly quickly down to the lower surfaces. This means that the spreading rate is slower than if it could travel thru the air ducts easily as some diseases do.

 

 

Now....do you trust the data? I'm not saying what is true and what is going to be found true with this PARTICULAR virus. Just sharing some data I found.

 

 

MtRider [be informed so that you can act effectively and quickly ]