Ebola virus Disease Progression

Ebola is a disease caused by the Ebola virus. Ebola virus belongs to the family Filoviridae. Filoviridae is the only virus family about which scientists know very less. Knowledge about the pathogenesis, the diseases caused by this virus family and the detailed virology is still very less. The recent epidemics have provided a considerable amount of understanding about the filoviruses. The first encounter of biomedical science with virus family Filoviridae took place in 1967 when Marburg virus appeared. Similar course of events were presaged by this virus for Ebola virus.

On an average, the incubation period for Ebola Virus disease in humans lasts for 5-9 days though the overall incubation period of Ebola Virus disease in humans ranges from 2 to 21 days. There are three distinct phases in the course of the disease: Generalization phase, early organ phase, late organ phase or convalescence phase depending upon the result of the infection.

• Generalization phase: This phase begins with symptoms that are largely similar to influenza. High fever, chills, myalgia, malaise, fatigue, loss of appetite, headache, stomachache, nausea, severe diarrhea have all been reported. This phase lasts for about five days after the beginning of the disease. In the middle or later part of the generalization phase, a rash might also be noticed on the face, trunk or other parts which later gets developed as maculopapular rash.
• Early organ phase: After 5 to 13 days of the onset of the disease, the disease gets progressed into this phase. It is associated with conditions like prostration, dyspnea, exanthema, abnormal vascular permeability, conjunctival injection and edema. This phase marks the beginning of severe phase of the disease. In the later stage of this phase, clear hemorrhagic manifestations can be seen in the patients. Multiple organs like liver, pancreas, and kidneys get affected.
• Late organ phase: This phase begins after 13 days until more than 20 days after the commencement of the disease. In this phase, the condition of the patient moves to a critical state with multiple organ failure, convulsions, shock etc. Patients may develop neurological symptoms including dementia, restlessness or coma.
• Convalescence phase: Those who survive the disease may not even enter the late organ phase. During recovery and convalescent phase, complications such as myalgia, arthralgia, asthenia, hepatitis, ocular disease and psychosis may occur.