Ebola

News & Information About Ebola

Tag: transmission

How does Ebola Spread?

Ebola is frequently portrayed as a virus that is transmitted via direct contact with an infected individual but this can be misleading. The term is technically correct and not unfair to use but can result in misunderstanding by the general public and even so called medical experts. Ebola has been observed to transmit through direct contact with a single virus. Direct contact with the virus is not akin to direct contact with an infected patient. Contact with the virus can occur in the absence of the individual if the virus survives on a surface or in fluids.

How does Ebola Spread (Handshake)

By Tobias Wolter (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or CC-BY-SA-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/2.5-2.0-1.0)], via Wikimedia Commons

The virus is known to survive outside the human body on several surfaces including plastic and glass and can survive for several days outside a host if contained in bodily fluids. The virus is found in all human fluids in sufficient amounts to allow for transmission. Tears, Mucus, Sweat, Urine, etc. all contain the virus and are all infectious. In contrast HIV is not transmitted with common bodily fluids and usually only via blood or intimate contact.

Any and all objects that come into contact with Ebola must be disinfected or destroyed. Blankets and clothing used by sick individuals are of particular concern and are often burnt after use. The following table attempts to describe the possible transmission methods based on current knowledge from the CDC, WHO & Doctors in the field. The table is expected to change as a broader understanding of the virus is reached.

Action Transmission Potential Reason
Sexual Intercourse Highly Probable Bodily Fluids
Sharing Needles Highly Probable Bodily Fluids
Sharing Eating Utensils Probable Saliva Contamination
Sharing Food Probable Saliva Contamination
Sharing Drinks Probable Saliva Contamination
Sharing Clothing Probable Sweat/Bodily Fluids
Sharing Bed Linen Probable Sweat/Bodily Fluids
Being Sneezed On Probable Bodily Fluids
Being Coughed On Probable Bodily Fluids
Contact with Sweat Probable Known Transmission
Contact with Urine Probable Known Transmission
Contact with Feces Highly Probable Known Transmission
Contact with Blood Highly Probable Known Transmission
Kissing Highly Probable Saliva Contamination
Hugging Probable Sweat/Bodily Fluids
Hand Shaking Low Probability Sweat/Bodily Fluids
Breast Milk Consumption Highly Probable Known Transmission
Semen Contact Highly Probable Known Transmission
Bush meat consumption Probable Known Transmission
Contact with Ebola Body Highly Probable Known Transmission
Sharing a home Low Probability Not Airborne

A key point to remember is that current knowledge of Ebola indicates that the virus must be transferred to the host directly by entering through open wounds, the mouth or the eyes. As an example shaking hand in itself may not transmit the virus but if the virus is transferred via sweat from one hand to another and a person touches their face there is an increased risk of transmission. By the same thinking sharing a home does not always result in transmission however it does increase the chances of physical contact which could lead to transmission.

Common Questions:

Can Ebola spread in sewage?

Yes Ebola can and will spread via raw sewage however there is no evidence of transmission via treated water. Modern water treatment facilities add chemicals to filtered water including chlorine which is known to kill the Ebola virus. Ebola is not considered a waterborne virus either further reducing the chances of infection via treated tap water.

Will I get Ebola from from being near an infected person?

Currently there is no indication that simply being near a person infected with Ebola will transmit the virus. The reality however is that by being in close proximity the chances of transmission occurring are increased substantially. There is some evidence to support limited aerosol transmission which also indicates a higher risk for close proximity transmission. The virus is classified as a bio safety level 4 agent requiring extreme protective measures to prevent infection. Health care workers are often infected while providing care to patients.

Can my pets carry Ebola?

Very Likely. Some studies indicate that dogs may be asymptomatic carriers of the virus. A dog would need to consume infected meat or bodily fluids to become a carrier.

Can I get infected from a public restroom?

Yes, Ebola can survive outside the human body for several hours. Restroom activities have a high risk for transmission.

Are the experts wrong about how Ebola is spread?

Possibly, it took several years for doctors and scientists to fully understand how HIV was spread. The understanding of Ebola will increase as more experience is gained.

My neighbor has Ebola, am I safe?

Most likely, Ebola requires contact transmission. If you are not in direct contact with you neighbor the chance of transmission is low.

 

How long does Ebola survive outside the body?

Ebola is only known to transfer via bodily fluids but it can survive outside the human body for several hours and is further confirmed to survive in bodily fluids outside a host for several days. The common flu is able to survive for three days outside the body while Ebola can survive for up to 6 days according to the CDC (CDC Website:”Several Days”). By contrast HIV can only survive without a host for a few minutes in addition to requiring a high viral load for transmission.

The virus is susceptible to UV and rapidly becomes inactive upon exposure to sunlight when not surrounded by bodily fluids. Multiple studies have confirmed that the virus deteriorates upon being dried. When the ambulance collected the first American patient from his apartment he vomited on the way to the ambulance which was allegedly only cleaned several days later leaving multiple people concerned that the virus may be transmitted to pets or residents in the area. Dogs are known carriers of the Ebola virus and likely carriers in an urban setting where pets are common.

The virus is able to survive for particularly long periods at low temperatures. In one experiment the virus remained infectious for up to 5 weeks at 4 degrees Celsius. Ebola outbreaks have historically occurred in Africa where temperatures that low are uncommon and rarely last for more than a few hours even during the harshest of winters. The upcoming winter in America could change the dynamics of transmission during the snow season if the outbreak is not contained.

Ebola is an incredibly infectious virus with a single particle required for successful infection of a host. The virus is sensitive to several detergents including bleach and chlorine making basic hygiene the first line defense against transmission. Avoiding infected patients and minimizing contact with people are common methods used to stop the spread of the virus.

Could Ebola Become Airborne?

Fears that Ebola could mutate into an airborne strain have recently attracted significant attention from both the scientific community and the media. Although a lot of claims could be easily be dismissed as speculative it is still interesting to examine evidence supporting the theory:

Statistics and the nature of RNA viruses which create mutations each time they replicate could result in the mutation of an airborne strain of Ebola. As the Virus spreads and replicates it has more opportunities to mutate and given the selective pressure on Ebola to survive outside the host body there is a chance that if an airborne mutation occurred it would have a very good chance of survival.

Additionally there are already several examples of airborne transmission between animals most notably, pigs. However, many of the experiments and accounts were not entirely scientific in that they were simply observations and not extensively tested. The Ebola virus in humans is traditionally transmitted via relatively large droplets of bodily fluid, which in the case of sneezing could mean through the air. However, this is entirely different from an airborne virus that can survive fully exposed with no medium to carry it. It is the difference between infections occurring in close proximity and infections being possible across far greater distances or time. It will also significantly increase the rate of infection.

It is for this exact reason that medical personnel dealing with Ebola patients protect themselves against as many forms of transmission as possible including air even if the virus is currently only transmitted through bodily fluids. By blocking as many potential transmission paths as possible, selection of an airborne strain is minimized since it would simply not find a new host. The current situation in Liberia, where patients are being turned away from hospitals, elevates risks as the virus is free to mutate as a natural response to selection pressure.

Ebola is a rapidly spreading virus and with the current rate of infection it is becoming far more difficult to keep track of the it and any potential changes. However, there is no evidence at this point that the virus has or will become airborne. That being noted, it is an unlikely possibility worthy of further investigation.

 

 

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