OVERVIEW

What is Ebola Hemorrhagic Fever?

Ebola hemorrhagic fever (EBHF), also known as Ebola virus disease or Ebola hemorrhagic fever, is an acute, severe, and hemorrhagic infectious disease caused by the Ebola virus (EBOV), affecting both humans and primates. It is classified as a zoonotic disease.

The disease is characterized by the "three highs"—high infectivity, high pathogenicity, and high fatality rate, with mortality rates reaching up to 90% after infection. The first outbreak occurred in the spring and summer of 1976, presenting primarily with fever and hemorrhage. Hundreds of people along the Ebola River died during this epidemic, leading to its naming as Ebola hemorrhagic fever.

As there are currently no specific treatments or vaccines for Ebola hemorrhagic fever, prevention remains the primary method of controlling its spread. Early detection, diagnosis, and timely treatment and isolation measures can effectively curb the progression of an outbreak.

Is Ebola Hemorrhagic Fever Common? Where is Ebola Hemorrhagic Fever Commonly Found (Epidemic Areas)?

Ebola hemorrhagic fever first emerged in the spring and summer of 1976. Since then, outbreaks of varying scales have occurred in several African countries at different times.

From 1976 to the present, there have been 25 outbreaks on the African continent, all originating in epidemic areas located in Central and West African countries such as Sudan, Zaire, Uganda, Congo, and Côte d'Ivoire.

Have There Been Cases of Ebola Hemorrhagic Fever in China?

To date, no cases of Ebola hemorrhagic fever have been reported in China. However, due to the close trade and personnel exchanges between China and African countries, there is a possibility of the virus being introduced into China through various channels during an outbreak.

Therefore, vigilance should be heightened if an outbreak occurs, with close monitoring of international epidemic developments and appropriate protective measures in place.

SYMPTOMS

What symptoms does Ebola hemorrhagic fever cause?

• Fever: Most patients initially experience sudden fever and chills, referred to as the initial syndrome. However, some may first develop mild fever and malaise, followed by more severe symptoms. Common manifestations include fever, fatigue, headache, vomiting, diarrhea, loss of appetite, muscle pain, and a lack of significant increase in heart rate despite high fever.
• Rash: A rash may appear 5–7 days after onset, typically a non-itchy, diffuse red maculopapular rash, often on the face, neck, torso, and arms. It can cause skin peeling and is usually more noticeable in fair-skinned patients.
• Gastrointestinal symptoms: Gastrointestinal manifestations are also common within days of onset, including watery diarrhea (up to 10 liters per day), nausea, vomiting, and abdominal pain. Severe fluid loss from vomiting and diarrhea can lead to dehydration, hypotension, and shock.
• Bleeding: Many patients experience some degree of bleeding during the illness, most commonly bloody stools (~6%), skin bleeding (petechiae or ecchymosis), oozing at injection or blood draw sites, mucosal bleeding (nose, mouth, conjunctiva), vaginal bleeding, hemoptysis, or hematuria. Severe bleeding may occur in the terminal stages or during pregnancy.
• Neuropsychiatric symptoms: Neurological symptoms, such as meningoencephalitis, may appear around days 8–10, including altered consciousness (e.g., lethargy, delirium), neck stiffness, unsteady gait, and seizures.
• Cardiac symptoms: Cardiac-related manifestations may also occur, such as a lack of increased heart rate despite rising body temperature. Pericarditis can cause retrosternal chest pain and palpitations.
• Respiratory symptoms: Rapid or labored breathing may develop.
• Ocular symptoms: Patients may experience conjunctival injection, uveitis (manifesting as blurred vision, photophobia, or blindness).

What severe complications can Ebola hemorrhagic fever cause?

Ebola hemorrhagic fever can lead to multi-organ failure, such as respiratory failure, kidney failure, and adrenal insufficiency. Over 50% of patients experience severe bleeding. The case fatality rate exceeds 50%.

CAUSES

What is the pathogen of Ebola hemorrhagic fever?

It is the Ebola virus, a member of the Filoviridae family and the genus Filovirus, which is an RNA virus. The Ebola virus is considered one of the most terrifying viruses in human history.

There are five subtypes of the Ebola virus: Zaire, Sudan, Bundibugyo, Reston, and Taï Forest. Except for the Reston subtype, the other four can cause disease in humans, with mortality rates as high as 90% for the Zaire, Sudan, and Bundibugyo subtypes.

The Ebola virus is relatively stable at room temperature and moderately resistant to heat. Heating at 60°C for 1 hour or 100°C for 5 minutes can completely inactivate it. The virus can survive for several days at 4°C and is highly stable at -70°C, allowing long-term preservation.

The Ebola virus is highly sensitive to disinfectants such as ultraviolet (UV) light, gamma rays, formaldehyde, and phenols. UV irradiation for 2 minutes can completely inactivate the virus; ether, methyl alcohol, and peracetic acid can also fully inactivate it. However, trypsin and phenol cannot completely inactivate the virus, only reducing its infectivity.

How does the Ebola virus cause illness in humans?

The Ebola virus enters the patient's body through mucous membranes, broken skin, or other non-intestinal routes, then moves from the initial infection site to local lymph nodes before entering the bloodstream, causing viremia. It further spreads to organs such as the liver, spleen, and adrenal glands, infecting various cells like macrophages, fibroblasts, endothelial cells, hepatocytes, renal cells, and adrenal cortical cells.

Once in the bloodstream, the virus releases substances that promote coagulation, disrupting the body's clotting mechanism and causing coagulation dysfunction. This leads to microvascular clotting, thrombosis, and blockage, resulting in ischemic necrosis of organs like the liver, spleen, kidneys, and adrenal glands, ultimately triggering multi-organ failure and widespread disseminated intravascular coagulation.

Additionally, the virus produces other substances that damage the integrity of blood vessel walls, causing leakage and hemorrhage. The adrenal glands, as critical endocrine organs, may suffer ischemic necrosis, leading to hypotension and hyponatremia.

How is Ebola hemorrhagic fever transmitted?

Contact transmission is the primary route of infection. People can become infected by exposure to the blood, bodily fluids, secretions, excretions, or contaminated items of infected patients or animals. The virus has been isolated from patients' semen, suggesting the possibility of sexual transmission.

Whether the virus can spread via aerosols requires further confirmation. Currently, there is no evidence of airborne, foodborne, or waterborne transmission.

Who is commonly affected by Ebola hemorrhagic fever?

People of all ages and genders are generally susceptible to the Ebola virus. Cases are mainly concentrated in adults, likely due to higher exposure or contact opportunities.

During outbreaks, those at higher risk include: healthcare workers, family members or others in close contact with patients, individuals directly handling corpses during funeral rites, and people in rainforest areas who come into contact with dead animals.

Since patients' blood contains high viral loads, healthcare workers treating or caring for patients, or handling corpses, are at significant risk of infection if strict protective measures are not followed.

DIAGNOSIS

How to Identify a Suspected Ebola Hemorrhagic Fever Patient?

If, within 21 days before the onset of symptoms, an individual had contact with the blood, body fluids, secretions, excretions, or corpses of an Ebola patient without proper personal protective equipment, or had contact with or handled bats or non-human primates from epidemic areas, and meets any one of the following three conditions, Ebola hemorrhagic fever should be suspected:

• Body temperature ≥ 38.6 °C, accompanied by severe headache, muscle pain, vomiting, diarrhea, or abdominal pain;
• Fever with unexplained bleeding;
• Unexplained sudden death.

What Tests Are Required for Diagnosing Ebola Hemorrhagic Fever?

• General laboratory tests:

  • Complete blood count: May show leukopenia, lymphopenia, atypical lymphocytes in some patients, elevated neutrophils, and significantly reduced platelets.
  • Coagulation-related indicators: Prolonged prothrombin time and partial thromboplastin time, increased fibrin degradation products.
  • Liver function: Elevated transaminases.
  • Kidney function: Elevated blood urea nitrogen and creatinine.
  • Urinalysis: May show proteinuria.

• Viral serological testing: Specific IgM antibodies can be detected in serum during the early stages of the disease and may persist for months. Specific IgG antibodies can be detected 7–10 days after symptom onset and may persist for years. A diagnosis of Ebola hemorrhagic fever is supported if IgM antibodies become positive or IgG antibody titers increase fourfold or more in two blood samples collected at least one week apart.

• Viral pathogen testing: Confirms Ebola hemorrhagic fever.

  • Viral antigen: Virus-specific antigens can usually be detected in the patient's blood within 2–3 weeks after symptom onset.
  • Viral nucleic acid: Viral nucleic acid can usually be detected in the patient's blood within 2 weeks after symptom onset, with higher detection rates in samples collected within the first week.
  • Virus isolation: High rates of virus isolation from blood are typically observed within the first week of illness.

How Is Ebola Hemorrhagic Fever Confirmed?

First, the patient must have an epidemiological history, meeting any one of the following criteria:

• Residence in or travel to an area with active Ebola transmission within 21 days before symptom onset;
• Contact with the blood, body fluids, secretions, excretions, or corpses of an Ebola patient without proper personal protective equipment within 21 days before symptom onset;
• Contact with or handling of bats or non-human primates from epidemic areas without proper personal protective equipment within 21 days before symptom onset.

A confirmed diagnosis is made if any of the following test results are positive:

• Positive nucleic acid test (if negative but symptom duration is less than 72 hours, retest after 72 hours);
• Positive viral antigen test;
• Virus isolation;
• Positive serum-specific IgM antibody test, or seroconversion of IgG antibodies or a fourfold or greater increase in IgG antibody titers in convalescent versus acute-phase samples;
• Positive pathogen detection in tissues.

What Diseases Have Similar Symptoms to Ebola Hemorrhagic Fever? How to Differentiate Them?

Ebola hemorrhagic fever shares clinical features with the following diseases and requires differentiation:

• Malaria: Symptoms overlap, and co-infection is possible. Malaria is diagnosed via blood smear microscopy or rapid antigen testing, distinguishing it from Ebola.
• Lassa fever: Primarily transmitted via aerosolized excreta of West African multimammate mice or, rarely, contact with infected bodily fluids. Nucleic acid or serological testing differentiates it from Ebola.
• Typhoid fever: Caused by Salmonella Typhi, diagnosed by identifying the pathogen in blood cultures.
• Meningococcal disease: Caused by Neisseria meningitidis, distinguished from Ebola via blood or cerebrospinal fluid cultures.
• Influenza: Typically involves respiratory symptoms (e.g., dry cough, sore throat, rhinorrhea), absent in Ebola. Specific antibodies or rapid tests aid differentiation.
• Measles: Presents with conjunctivitis, rhinorrhea, cough, and a characteristic blanching maculopapular rash on the face. Differentiated via antibody or nucleic acid testing.

TREATMENT

Which department should I visit for Ebola hemorrhagic fever?

Infectious Diseases Department, Infection Department, Infectious Diseases Department.

Can Ebola hemorrhagic fever heal on its own?

Ebola hemorrhagic fever primarily relies on the patient's immune system to clear the virus, and there is currently no specific treatment.

However, this does not mean patients should avoid seeking medical attention after onset. The disease is often accompanied by complications such as dehydration, electrolyte imbalances, bleeding, secondary infections, and multi-organ failure, with an extremely high mortality rate. Only through active supportive and symptomatic treatment can patients overcome the crisis and increase their chances of recovery.

Should suspected Ebola hemorrhagic fever patients be isolated?

Yes.

• Suspected cases should be isolated in a single room with a private bathroom and a sealed door leading to the hallway.
• Healthcare workers entering the room should wear gloves, gowns, goggles, or face shields.
• In certain situations (e.g., large amounts of blood, bodily fluids, vomit, or feces in the environment), additional protective equipment may be required, including double gloves, disposable shoe covers, and leg coverings.
• Limit visitors and prevent them from entering the patient's room.
• Avoid aerosol-generating procedures (e.g., nebulizer therapy, sputum collection, bronchoscopy, intubation, oxygen mask use). If such procedures are necessary, personal protective equipment should include respiratory protection (N95 or higher-level respirators) and should be performed in an airborne infection isolation room.
• Environmental cleaning and disinfection are crucial. Potentially contaminated materials, including blood, sweat, vomit, feces, urine, and other secretions, should be handled safely according to hospital protocols.

How is Ebola hemorrhagic fever treated?

Currently, there are no specific antiviral drugs or vaccines for Ebola hemorrhagic fever.

Severe cases require supportive and symptomatic treatment. Patients often experience dehydration and need intravenous or oral rehydration for electrolyte replenishment. Some patients may recover with appropriate medical care.

To prevent further virus spread, suspected or confirmed cases should be isolated from other patients and treated by healthcare workers following strict infection control measures.

Can Ebola hemorrhagic fever be completely cured? Will there be sequelae?

Some infected individuals may recover with appropriate treatment.

Recovery from Ebola virus infection can be prolonged, lasting over two years.

Some patients may experience sequelae affecting the brain, eyes, adrenal glands, muscles, joints, etc., manifesting as weakness, fatigue, muscle/joint pain, insomnia, headaches, frequent urination, memory loss, inability to regain pre-illness weight, vision problems, and reduced quality of life.

DIET & LIFESTYLE

What dietary precautions should be taken during Ebola hemorrhagic fever treatment?

Patients often experience dehydration, so it is important to drink plenty of fluids to replenish lost water.

Patients may have reduced appetite, often accompanied by gastrointestinal symptoms such as nausea and diarrhea. Food should be light, soft, and easy to digest.

When can Ebola hemorrhagic fever patients be released from isolation?

Surviving patients typically begin to improve in the second week of illness, as virus-specific IgM and IgG antibodies appear and the virus is gradually cleared from the bloodstream.

Viral nucleic acid testing is used to determine when a patient can be released from isolation and discharged.

According to WHO recommendations, patients can be discharged and released from isolation once their symptoms have resolved and two consecutive blood nucleic acid tests, taken at least 48 hours apart, are negative.

PREVENTION

How to prevent Ebola hemorrhagic fever? Is there a vaccine available for Ebola hemorrhagic fever?

The initial Ebola cases were caused by handling infected animals or their carcasses, but subsequent cases often resulted from direct contact with patients' bodily fluids or unsafe case management and burial practices.

Therefore, outbreaks of this disease are primarily caused by human-to-human transmission. The following measures can be taken to prevent infection and limit its spread:

• Understand the nature of the disease, how it spreads, and how to prevent further transmission;
• Follow guidance documents issued by national health authorities. If someone nearby is suspected of being infected with Ebola, encourage and support them to seek medical treatment;
• Appropriate protective equipment must be worn when handling Ebola-related deaths;
• In affected tropical rainforest areas, individuals should minimize contact with high-risk animals (such as fruit bats, monkeys, or apes). If an animal is suspected to be infected, avoid handling it;
• Ensure animal products (blood and meat) are thoroughly cooked before consumption.

Currently, there is no available vaccine.