The Ebola Virus
Ebola is the common term for a group of viruses belonging to genus Ebolavirus, family Filoviridae, which cause Ebola hemorrhagic fever. The disease can be deadly and encompasses a range of symptoms including vomiting, diarrhoea, changes in skin color, general body pain, internal and external bleeding, and fever. Mortality rates are generally high, ranging from 50% - 90%, with the cause of death usually due to hypovolemic shock or multiple organ failure.
The virus is named after the Ebola River in the African nation-state of the Democratic Republic of the Congo (formerly Zaire), near the site of the first outbreaks. The Democratic Republic of Congo has been the site of four recent outbreaks, including one in May 2005.
Symptoms are varied and often appear suddenly. Initial symptoms include: high fever (at least 38.8°C/101°F), severe headache, muscle, joint, or abdominal pain, severe weakness and exhaustion, sore throat, nausea, and dizziness. Before an outbreak is suspected, these early symptoms are easily mistaken for malaria, typhoid fever, dysentery, influenza, or various bacterial infections, which are all far more common.
Ebola goes on to cause diarrhea, dark or bloody stool, vomiting blood, red eyes from swollen blood vessels, red spots on the skin from subcutaneous bleeding, maculopapular rash, purpura, and bleeding internally and externally from any orifice, including from the nose, mouth, rectum, genitals or needle puncture sites.
Other secondary symptoms include hypotension (less than 90mm Hg), hypovolemia, tachycardia, severe organ damage (especially the kidneys, spleen, and liver) as a result of disseminated systemic necrosis, and proteinuria. The span of time from onset of symptoms to death (usually due to hypovolemic shock and/or multiple organ failure) is usually between 7 and 14 days. By the second week of infection, patients will either defervesce (the fever will lessen) or undergo systemic multiorgan failure.
We still don't know how primates contract filoviruses in nature. The secondary cases of filovirus infection have been the result of contact with contaminated blood, organs, semen or other bodily secretions. Marburg, a filovirus closely related to Ebola, can be transmitted via semen up to 12 weeks after clinical recovery. Ebola can also be transmitted through the handling of ill or dead chimpanzees. Amongst humans, Ebola is transmitted by contact with infected bodily fluids and/or tissues. There is evidence of a possible respiratory route of transmission of Ebola in nonhuman primates. Even if Ebola is transmitted via the respiratory route to nonhuman primates, humans may be resistant to the airborne/aerosol transmission of Ebola (may not have the right receptors).
No specific treatment or vaccine exists for Ebola haemorrhagic fever.
Severe cases require intensive supportive care, as patients are frequently dehydrated and in need of intravenous fluids. Suspected cases should be isolated from other patients and strict barrier nursing techniques practiced.
All hospital personnel should be briefed on the nature of the disease and its routes of transmission. Particular emphasis should be placed on ensuring that high-risk procedures such as the placing of intravenous lines and the handling of blood, secretions, catheters and suction devices are carried out under barrier nursing conditions. Hospital staff should have individual gowns, gloves and masks. Gloves and masks must not be reused unless disinfected. Patients who die from the disease should be promptly buried or cremated.
As the primary mode of person-to-person transmission is contact with contaminated blood, secretions or body fluids, any person who has had close physical contact with patients should be kept under strict surveillance, i.e. body temperature checks twice a day, with immediate hospitalization and strict isolation recommended in case of temperatures above 38.3Â°C (101Â°F). Casual contacts should be placed on alert and asked to report any fever. Surveillance of suspected cases should continue for three weeks after the date of their last contact. Hospital personnel who come into close contact with patients or contaminated materials without barrier nursing attire must be considered exposed and put under close supervised surveillance.
© 2006 Paula Atwell