Ebola virus disease (EVD; also Ebola hemorrhagic fever, or EHF), or simply Ebola, is a rare and deadly disease caused by infection with one of the Ebola virus strains. The Ebola virus causes an acute, serious illness which is often fatal if untreated. Ebola can cause disease in humans and nonhuman primates like monkeys, gorillas, and chimpanzees. Ebola viruses are found in several African countries. Ebola was first discovered in 1976 near the Ebola River in what is now the Democratic Republic of the Congo. Since then, outbreaks have appeared sporadically in Africa. More than 5,000 people have died from the Ebola virus.
Causes
Ebola virus has been found in African monkeys, chimps and other nonhuman primates.
Transmission from animals to humans
Experts suspect that both viruses are transmitted to humans through an infected animal’s bodily fluids. Examples include:
- Blood. Butchering or eating infected animals can spread the viruses. Scientists who have operated on infected animals as part of their research have also contracted the virus.
- Waste products. Tourists in certain African caves and some underground mine workers have been infected with the Marburg virus, possibly through contact with the feces or urine of infected bats.
Transmission from person to person
Infected people typically don’t become contagious until they develop symptoms. Family members are often infected as they care for sick relatives or prepare the dead for burial.
Medical personnel can be infected if they don’t use protective gear, such as surgical masks and gloves. Medical centers in Africa are often so poor that they must reuse needles and syringes. Some of the worst Ebola epidemics have occurred because contaminated injection equipment wasn’t sterilized between uses.
Symptoms of Ebola virus infection are similar to those produced by other hemorrhagic fever viruses and include:
- fever
- fatigue, malaise, and weakness
- reddened eyes
- joint and muscle pain
- headache
- diarrhea
- stomach discomfort
- decreased appetite
- nausea and vomiting
As the disease progresses, patients may develop other symptoms and signs such as:
- a rash
- eye redness
- hiccups
- sore throat
- cough
- chest pain
- bleeding both inside and outside the body (for example, mucosal surfaces, eyes)
- and difficulty breathing and swallowing
Ebola virus disease symptoms and signs may appear from about two to 21 days after exposure (average is eight to 10 days). It is unclear why some patients can survive and others die from this disease, but patients who die usually have a poor immune response to the virus.
Diagnosis
When EVD is suspected in a person, his or her travel and work history, along with an exposure to wildlife, are important factors to consider for possible further medical examination.
Nonspecific laboratory testing
Possible laboratory indicators of EVD include a low platelet count; an initially decreased white blood cell count followed by an increased white blood cell count; elevated levels of the liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST); and abnormalities in blood clotting often consistent with disseminated intravascular coagulation (DIC) such as a prolonged prothrombin time, partial thromboplastin time, and bleeding time.
Specific laboratory testing
The diagnosis of EVD is confirmed by isolating the virus, detecting its RNA or proteins, or detecting antibodies against the virus in a person’s blood. Isolating the virus by cell culture, detecting the viral RNA by polymerase chain reaction (PCR) and detecting proteins by enzyme-linked immunosorbent assay (ELISA) are methods best used in the early stages of the disease and also for detecting the virus in human remains. Detecting antibodies against the virus is most reliable in the later stages of the disease and in those who recover.
During an outbreak, isolation of the virus via cell culture methods is often not feasible. In field or mobile hospitals, the most common and sensitive diagnostic methods are real-time PCR and ELISA. In 2014, with new mobile testing facilities deployed in parts of Liberia, test results were obtained 3–5 hours after sample submission.
Filovirions, such as EBOV, may be identified by their unique filamentous shapes in cell cultures examined with electron microscopy, but this method cannot distinguish the various filoviruses.
Differential diagnosis
Early symptoms of EVD may be similar to those of other diseases common in Africa, including malaria and dengue fever. The symptoms are also similar to those of Marburg virus disease and other viral hemorrhagic fevers.
The complete differential diagnosis is extensive and requires consideration of many other infectious diseases such as typhoid fever, shigellosis, rickettsial diseases, cholera, sepsis, borreliosis, EHEC enteritis, leptospirosis, scrub typhus, plague, Q fever, candidiasis, histoplasmosis, trypanosomiasis, visceral leishmaniasis, measles and viral hepatitis among others.
Non-infectious diseases that may result in symptoms similar to those of EVD include acute promyelocytic leukemia, hemolytic uremic syndrome, snake envenomation, clotting factor deficiencies/platelet disorders, thrombotic thrombocytopenic purpura, hereditary hemorrhagic telangiectasia, Kawasaki disease and warfarin poisoning.
Treatments
According to the CDC and others, standard treatment for Ebola hemorrhagic fever is still limited to supportive therapy. Supportive therapy is balancing the patient’s fluid and electrolytes, maintaining their oxygen status and blood pressure, and treating such patients for any complicating infections. Any patients suspected of having Ebola hemorrhagic fever should be isolated, and caregivers should wear protective garments. Currently, there is no vaccine or specific treatment for Ebola hemorrhagic fever.
LATEST NEWS FOR TREATMENT
Nov. 11, 2014: An antiviral drug, favipiravir (Avigan), produced by Fujifilm Holdings Corporation in Japan, is likely to be approved by international government bodies to treat Ebola-infected patients as early as the end of 2014. Avigan, an antiviral originally approved in Japan to counter new forms of influenza viruses, has been used in France, Germany, Spain, and Norway. The drug was first tried on a French citizen who became infected with Ebola in October. Fujifilm Chairman Shigetaka Komori is quoted as saying, “So far, four Ebola patients have recovered after being treated with the drug.” If it continues to be proven effective in tests being conducted in Guinea, the drug will be approved to treat Ebola-infected patients in Africa by the end of 2014. Fujifilm says it has enough drug stockpiled to treat 20,000 patients and enough ingredients to make enough tablets to treat 300,000 people. Because this drug already has been approved as an antiviral drug to use in patients, approval for use in Ebola-infected patients should occur rapidly if ongoing tests show effectiveness against Ebola. The drug, Avigan, has activity against many RNA viruses, probably by the selective inhibition of viral RNA dependent RNA polymerase thereby inhibiting many viral gene types from replicating within an infected cell.
Dr. Craig Spencer, the doctor who returned to New York from West Africa and became ill with Ebola, has completed treatment and is currently Ebola free. He was released from Bellevue Hospital today. His girlfriend has a few more days of quarantine before she is considered Ebola free.
