Study Says Prompt Isolation of Symptomatic Patients is Key to Eliminating Ebola

Isolating the sickest Ebola-infected individuals before they progress into their late phase of illness can effectively eliminate the Ebola epidemic in Liberia, according to a modeling study being published in Annals of Internal Medicine.

Currently, West Africa is in the midst of the largest and deadliest Ebola epidemic ever recorded. Liberia has been especially hard-hit with more than 3,500 infections and 2,000 deaths in the past three months. Researchers developed a random transmission model to determine how disease progression and case fatality affect transmission and how patient isolation could achieve disease elimination.

They found that the risk for transmitting Ebola depends on the magnitude of viral load in an infected individual and the number of people with which the infected individual interacts. Here, differentiating between survivors and non-survivors is important because survivors tend to achieve peak viral load approximately four days after symptoms develop and then viral load declines. The survivors were found to have a 32 percent probability of infecting at least one other individual during their infection period.

In non-survivors, viral load is 100-fold higher than that of survivors throughout infection and does not decline after peak. Non-survivors also exhibit more severe Ebola-specific symptoms as illness progresses. Non-survivors had a 67 percent probability of transmitting Ebola to at least one other person.

The researchers' model suggests that isolating the most severely ill individuals (the likely non-survivors) within four days of symptom onset could achieve disease elimination in Liberia.

Source: Annals of Internal Medicine