What is Ebola Disease?
Ebolavirus Ecology and Transmission
Infection with an ebolavirus causes Ebola disease, a zoonotic disease that involves animals
and people.
Animal-to-Animal Transmission
Evidence suggests that bats are the reservoir hosts for ebolaviruses. Bats carrying an
ebolavirus can spread the virus to other animals, like apes, mon- keys, and duikers
(antelopes), as well as to people.
Spillover Event
A “spillover event occurs when an animal (bat, ape, monkey, duiker) or person becomes
infected with an ebolavirus through contact with the reservoir host. This contact could occur
through hunting or preparing the animal’s meat for eating.
Human-to-Human Transmission
Once an ebolavirus has infected the first person, spread of the virus from
One person to another can occur through contact with the blood and body fluids of sick
people or with the bodies of those who have died of Ebola disease.
Survivor
Survivors of Ebola disease face new challenges after recovery. Some sur- vivors report effects
such as tired- ness and muscle aches. Although rare, the virus can persist in certain parts of
the body (brain, eyes, placenta, and testicles) and spread through contact to other people.
Example, causes,
CDC
Traditional funeral practice
Unprotected healthcare worker
Unprotected contact with blood and
Body fluids
Ebola disease is the term for a group of deadly diseases in people caused by four ebolaviruses
within the genus Ebolavirus. There are occasional Ebola diseases.
The name of each of the four ebolaviruses that cause illness in people, with their associated
viral species1 and disease name2 can be found below:
• Ebola virus (species Zaire ebolavirus) causes Ebola virus disease.
• Sudan virus (species Sudan ebolavirus) causes Sudan virus disease.
• Taï Forest virus (species Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus) causes
Taï Forest virus disease.
• Bundibugyo virus (species Bundibugyo ebolavirus) causes Bundibugyo virus disease.
,There are two additional ebolaviruses that are not known to cause disease in people. Reston
virus (species Reston ebolavirus) is known to cause illness in nonhuman primates and pigs,
but not in people. Bombali virus (species Bombali ebolavirus) was recently identified in bats,
but it is unknown if it causes illness in either animals or people.
Emergence of Ebolaviruses
Ebolaviruses were first discovered in 1976 when two consecutive outbreaks of fatal
hemorrhagic fever occurred in different parts of Central Africa. The first outbreak occurred in
the Democratic Republic of Congo (formerly Zaire) in a village near the Ebola River, which
gave the virus its name. The second outbreak occurred in what is now South Sudan,
approximately 500 miles.
Initially, public health officials assumed these outbreaks were a single event associated with
an infected person who traveled between the two locations. Scientists later discovered that the
two outbreaks were caused by two genetically distinct viruses: Zaire ebolavirus and Sudan
ebolavirus. After this discovery, scientists concluded that these viruses came from two
different sources and spread independently to people in each of the affected areas.
Following the discovery of these ebolaviruses, scientists studied thousands of animals,
insects, and plants in search of the source, or reservoir host. It is believed that African fruit
bats are likely involved in the spread of ebolaviruses and may even be the reservoir host.
Scientists continue to search for conclusive evidence of the bat's role in transmission of
ebolaviruses. The most recent ebolavirus to be detected, Bombali virus, was identified in
samples from bats collected in Sierra Leone.
Like other viruses of its kind, it is possible that the reservoir host animal does not experience
serious illness despite being infected with the virus. Ebolaviruses are likely maintained in the
environment by spreading from host to host or through intermediate hosts or vectors
(organisms that can spread pathogens from infected animals to other living organisms).
Infected animals carrying the virus can transmit it to other animals, like apes, monkeys,
duikers (antelopes), and people. Most infected animals will not get sick; however,
ebolaviruses are known to cause severe illness in nonhuman primates (such as monkeys,
gorillas, and chimpanzees) similar to Ebola disease in humans. Once an ebolavirus has
infected a person, the virus can spread to other people through contact with the body fluids of
the infected person. Learn more about Ebola disease transmission.
Transmission
Scientists think people are initially infected with an ebolavirus through contact with an
infected animal, such as a fruit bat or nonhuman primate. This is called a
Spillover event. After that, the virus spreads from person to person, potentially affecting
many people.
Ebolaviruses spread through contact (such as through broken skin or mucous membranes in
the eyes, nose, or mouth) with:
Blood or body fluids (urine, saliva, sweat, feces, vomit, breast milk, Amniotic fluid,
and semen) of a person Who is sick with or has died from Ebola disease.
Objects (such as clothes, bedding, needles, and medical equipment) contaminated
with body fluids from a person who is sick with or has died from Ebola disease.
Infected fruit bats or nonhuman primates (such as apes and monkeys).
, Semen from a man who recovered from Ebola disease (through oral, vaginal, or anal
sex). Ebolaviruses can remain in certain body fluids (including semen) of a patient
who has recovered from Ebola disease, even if they no longer have symptoms of
severe illness. There is no evidence
When people become infected with an ebolavirus, they do not start developing signs or
symptoms right away. This period between exposure to an illness and having symptoms is
known as the incubation period. A person can only spread an ebolavirus to other people
after they develop signs and symptoms of Ebola disease.
Additionally, ebolaviruses are not known to be transmitted through food. However, in certain
parts of the world, ebolaviruses may spread through the handling and consumption of wild
animal meat or
Hunted wild animals infected with an ebolavirus. There is no evidence that
Mosquitoes or other insects can transmit ebolaviruses.
Risk
• Health workers and family members who do not use proper infection control while caring
for patients with suspected or confirmed Ebola disease are at the highest risk of getting sick.
Ebolaviruses can spread when people come into contact with infected blood or body fluids.
• Ebolaviruses pose little risk to travelers or the general public who
Have not cared for or been in contact with someone sick with Ebola.
Persistence of Ebolaviruses
Ebolaviruses can remain in areas of the body that are immunologically privileged sites after
acute infection. These are sites where viruses and pathogens, like ebolaviruses, are shielded
from the survivor’s immune system, even after being cleared elsewhere in the body. These
areas include the testes, interior of the eyes, placenta, and central nervous system, particularly
the cerebrospinal fluid. Whether an ebolavirus is present in these body parts and for how long
varies by survivor. Scientists are now studying how long ebolaviruses stay in these body
fluids among Ebola disease survivors.
During an Ebola outbreak, the virus can spread quickly within healthcare settings (such as
clinics or hospitals). Clinicians and other healthcare personnel providing care should use
dedicated, preferably disposable, medical equipment. Proper cleaning and disposal of
instruments such as needles and syringes are important. If instruments are not disposable,
they must be sterilized before using again.
Ebolaviruses can survive on dry surfaces, like doorknobs and countertops for several hours;
in body fluids like blood, ebolaviruses can survive up to several days at room temperature.
Cleaning and disinfection should be performed using a hospital-grade disinfectant.
In the United States, hospital-grade disinfectant refers to U.S. Environmental Protection
Agency (EPA)-registered hospital disinfectant with a label claim for a non-enveloped virus.
Signs and Symptoms
Symptoms may appear anywhere from 2 to 21 days after contact with an ebolavirus, with an
average of 8 to 10 days. The course of the illness typically progresses from “dry” symptoms
Ebolavirus Ecology and Transmission
Infection with an ebolavirus causes Ebola disease, a zoonotic disease that involves animals
and people.
Animal-to-Animal Transmission
Evidence suggests that bats are the reservoir hosts for ebolaviruses. Bats carrying an
ebolavirus can spread the virus to other animals, like apes, mon- keys, and duikers
(antelopes), as well as to people.
Spillover Event
A “spillover event occurs when an animal (bat, ape, monkey, duiker) or person becomes
infected with an ebolavirus through contact with the reservoir host. This contact could occur
through hunting or preparing the animal’s meat for eating.
Human-to-Human Transmission
Once an ebolavirus has infected the first person, spread of the virus from
One person to another can occur through contact with the blood and body fluids of sick
people or with the bodies of those who have died of Ebola disease.
Survivor
Survivors of Ebola disease face new challenges after recovery. Some sur- vivors report effects
such as tired- ness and muscle aches. Although rare, the virus can persist in certain parts of
the body (brain, eyes, placenta, and testicles) and spread through contact to other people.
Example, causes,
CDC
Traditional funeral practice
Unprotected healthcare worker
Unprotected contact with blood and
Body fluids
Ebola disease is the term for a group of deadly diseases in people caused by four ebolaviruses
within the genus Ebolavirus. There are occasional Ebola diseases.
The name of each of the four ebolaviruses that cause illness in people, with their associated
viral species1 and disease name2 can be found below:
• Ebola virus (species Zaire ebolavirus) causes Ebola virus disease.
• Sudan virus (species Sudan ebolavirus) causes Sudan virus disease.
• Taï Forest virus (species Taï Forest ebolavirus, formerly Côte d’Ivoire ebolavirus) causes
Taï Forest virus disease.
• Bundibugyo virus (species Bundibugyo ebolavirus) causes Bundibugyo virus disease.
,There are two additional ebolaviruses that are not known to cause disease in people. Reston
virus (species Reston ebolavirus) is known to cause illness in nonhuman primates and pigs,
but not in people. Bombali virus (species Bombali ebolavirus) was recently identified in bats,
but it is unknown if it causes illness in either animals or people.
Emergence of Ebolaviruses
Ebolaviruses were first discovered in 1976 when two consecutive outbreaks of fatal
hemorrhagic fever occurred in different parts of Central Africa. The first outbreak occurred in
the Democratic Republic of Congo (formerly Zaire) in a village near the Ebola River, which
gave the virus its name. The second outbreak occurred in what is now South Sudan,
approximately 500 miles.
Initially, public health officials assumed these outbreaks were a single event associated with
an infected person who traveled between the two locations. Scientists later discovered that the
two outbreaks were caused by two genetically distinct viruses: Zaire ebolavirus and Sudan
ebolavirus. After this discovery, scientists concluded that these viruses came from two
different sources and spread independently to people in each of the affected areas.
Following the discovery of these ebolaviruses, scientists studied thousands of animals,
insects, and plants in search of the source, or reservoir host. It is believed that African fruit
bats are likely involved in the spread of ebolaviruses and may even be the reservoir host.
Scientists continue to search for conclusive evidence of the bat's role in transmission of
ebolaviruses. The most recent ebolavirus to be detected, Bombali virus, was identified in
samples from bats collected in Sierra Leone.
Like other viruses of its kind, it is possible that the reservoir host animal does not experience
serious illness despite being infected with the virus. Ebolaviruses are likely maintained in the
environment by spreading from host to host or through intermediate hosts or vectors
(organisms that can spread pathogens from infected animals to other living organisms).
Infected animals carrying the virus can transmit it to other animals, like apes, monkeys,
duikers (antelopes), and people. Most infected animals will not get sick; however,
ebolaviruses are known to cause severe illness in nonhuman primates (such as monkeys,
gorillas, and chimpanzees) similar to Ebola disease in humans. Once an ebolavirus has
infected a person, the virus can spread to other people through contact with the body fluids of
the infected person. Learn more about Ebola disease transmission.
Transmission
Scientists think people are initially infected with an ebolavirus through contact with an
infected animal, such as a fruit bat or nonhuman primate. This is called a
Spillover event. After that, the virus spreads from person to person, potentially affecting
many people.
Ebolaviruses spread through contact (such as through broken skin or mucous membranes in
the eyes, nose, or mouth) with:
Blood or body fluids (urine, saliva, sweat, feces, vomit, breast milk, Amniotic fluid,
and semen) of a person Who is sick with or has died from Ebola disease.
Objects (such as clothes, bedding, needles, and medical equipment) contaminated
with body fluids from a person who is sick with or has died from Ebola disease.
Infected fruit bats or nonhuman primates (such as apes and monkeys).
, Semen from a man who recovered from Ebola disease (through oral, vaginal, or anal
sex). Ebolaviruses can remain in certain body fluids (including semen) of a patient
who has recovered from Ebola disease, even if they no longer have symptoms of
severe illness. There is no evidence
When people become infected with an ebolavirus, they do not start developing signs or
symptoms right away. This period between exposure to an illness and having symptoms is
known as the incubation period. A person can only spread an ebolavirus to other people
after they develop signs and symptoms of Ebola disease.
Additionally, ebolaviruses are not known to be transmitted through food. However, in certain
parts of the world, ebolaviruses may spread through the handling and consumption of wild
animal meat or
Hunted wild animals infected with an ebolavirus. There is no evidence that
Mosquitoes or other insects can transmit ebolaviruses.
Risk
• Health workers and family members who do not use proper infection control while caring
for patients with suspected or confirmed Ebola disease are at the highest risk of getting sick.
Ebolaviruses can spread when people come into contact with infected blood or body fluids.
• Ebolaviruses pose little risk to travelers or the general public who
Have not cared for or been in contact with someone sick with Ebola.
Persistence of Ebolaviruses
Ebolaviruses can remain in areas of the body that are immunologically privileged sites after
acute infection. These are sites where viruses and pathogens, like ebolaviruses, are shielded
from the survivor’s immune system, even after being cleared elsewhere in the body. These
areas include the testes, interior of the eyes, placenta, and central nervous system, particularly
the cerebrospinal fluid. Whether an ebolavirus is present in these body parts and for how long
varies by survivor. Scientists are now studying how long ebolaviruses stay in these body
fluids among Ebola disease survivors.
During an Ebola outbreak, the virus can spread quickly within healthcare settings (such as
clinics or hospitals). Clinicians and other healthcare personnel providing care should use
dedicated, preferably disposable, medical equipment. Proper cleaning and disposal of
instruments such as needles and syringes are important. If instruments are not disposable,
they must be sterilized before using again.
Ebolaviruses can survive on dry surfaces, like doorknobs and countertops for several hours;
in body fluids like blood, ebolaviruses can survive up to several days at room temperature.
Cleaning and disinfection should be performed using a hospital-grade disinfectant.
In the United States, hospital-grade disinfectant refers to U.S. Environmental Protection
Agency (EPA)-registered hospital disinfectant with a label claim for a non-enveloped virus.
Signs and Symptoms
Symptoms may appear anywhere from 2 to 21 days after contact with an ebolavirus, with an
average of 8 to 10 days. The course of the illness typically progresses from “dry” symptoms
